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A comparison of energy use in conventional and integrated arable farming systems in the UK
Agriculture, Ecosystems and Environment 97 (2003) 241–253
A comparison of energy use in conventional and integrated arable farming systems in the UK A.P. Bailey a,∗ , W.D. Basford b , N. Penlington b , J.R. Park a , J.D.H. Keatinge a , T. Rehman a , R.B. Tranter c , C.M. Yates a a
School of Agriculture, Policy and Development, The University of Reading, Earley Gate, PO Box 237, Reading, Berkshire RG6 6AR, UK b ADAS Gleadthorpe Grange, Meden Vale, Mansfield, Nottinghamshire NG20 9PD, UK c Centre for Agricultural Strategy, The University of Reading, Earley Gate, PO Box 237, Reading, Berkshire RG6 6AR, UK Received 25 April 2002; received in revised form 3 January 2003; accepted 17 January 2003
Abstract The LINK Integrated Farming Systems (LINK-IFS) Project (1992–1997) was set up to compare conventional and integrated arable farming systems (IAFS), concentrating on practical feasibility and economic viability, but also taking into account the level of inputs used and environmental impact. As part of this, an examination into energy use within the two systems was also undertaken. This paper presents the results from that analysis. The data used is from the six sites within the LINK-IFS Project, spread through the arable production areas of England and from the one site in Scotland, covering the 5 years of the project. The comparison of the energy used is based on the equipment and inputs used to produce 1 kg of each crop within the conventional and integrated rotations, and thereby the overall energy used for each system. The results suggest that, in terms of total energy used, the integrated system appears to be the most efficient. However, in terms of energy efficiency, energy use per kilogram of output, the results are less conclusive. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Integrated arable farming systems; Energy use; Efficiency
1. Introduction 1.1. Integrated arable farming systems Over the last 50 years, the intensity of agriculture in much of North-western Europe has increased dramatically with higher yields per hectare and, in some cases, an improvement in the quality of food produced. However, this has been achieved against a backcloth of increasing public concern about the environment, ∗ Corresponding author. Tel.: +44-118-378-6270; fax: +44-118-935-2421. E-mail address: [email protected] (A.P. Bailey).
especially in terms of agriculture’s effects on the soil, water, air and habitat resources. Awareness of the environmental impacts of agricultural production, coupled with over-supply of some products such as wheat for animal feed, has highlighted the need to find more sustainable farming practices (see, for instance, Park and Seaton, 1996). Integrated arable farming systems (IAFS) are seen by some as one way of achieving this goal, leading to a plethora of research activity throughout Europe (see Holland et al., 1994) concerning these “innovative” cropping systems. Research projects in the UK which have been, and are, examining IAFS are attempting to ascertain results
0167-8809/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0167-8809(03)00115-4
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in three areas: the technical feasibility of such systems; their profitability; and an assessment of the environmental changes that result (Vereijken, 1992, 1994, 1995; Ogilvy, 1996). Early low input projects (see Holland et al., 1994) such as the Boxworth Project (1981–1988), SCARAB (1989–1996) and TALISMAN (1989–1996) examined the effect of reduced inputs, primarily pesticides, on the environment and, in the case of TALISMAN, the economic effect of both reduced pesticide and fertiliser use. RISC (1991–2000) in Northern Ireland was also set up to examine the effects of reduced pesticide and fertiliser use. The Long Ashton Low Input Farming and the Environment Project (LA-LIFE) (1989–1999) (Jordan and Hutcheon, 1996) was the first to develop and investigate a fully integrated farming system in the UK. This was followed by the much larger LINK Integrated Farming Systems (LINK-IFS) Project (1992–1997) (Ogilvy et al., 1994). The two most recently established IAFS projects are the CWS Focus on Farming Practice (CWS-FOFP) Project (1993 onwards) (Leake, 1996) and the Rhone–Poulenc Management Study (RPMS) (1994–2000) (Higginbotham et al., 1996).
tion to sustainability. The main focus of this previous research is in the definition of the most appropriate techniques to use and the trends in the energy efficiency of agricultural production over time. There has been a limited number of applications of energy analysis to the comparison of different methods of agricultural production. The most notable exceptions are in the field of organic farming (see, for example, Lampkin, 1990; Dalgaard et al., 2001; Loake, 2001) and a comparison by Donaldson et al. (1994) of energy usage for machinery operations of different more benign farming systems based on the LA-LIFE study. The LINK-IFS Project encompassed a study of energy use in conventional farming practices (CFP) and the more integrated approach (IFS). In this paper, a comparative analysis of the two systems in terms of their energy efficiency is presented together with discussion of output values and financial considerations. The broader methodological issues associated with the LINK-IFS experiments are reported prior to a detailed examination of the energy relations in the contrasting systems.
2. The LINK-IFS Project 1.2. Energy analysis Energy use in agriculture, and the externalities arising from it, have attracted recent interest from the viewpoint of sustainability. Indeed, energy analysis may provide one of the few cradle to grave measures capable of making comparative analysis between agricultural systems. At the farm level, tools such as the LEAF audit, highlight the importance of energy use and there is clearly also a financial incentive associated with saving energy on the farm. Energy analysis of agricultural systems dates back to the early 1970s (e.g. Pimental et al., 1973). Since then there has been a variety of research highlighting the use of energy in agricultural production systems (Fluck, 1979; Bonny, 1993; Panesar and Fluck, 1993; Taylor et al., 1993; Swanton et al., 1996) and, more recently, in relation to reducing greenhouse gas emissions (e.g. Konyar, 2001; Pervanchon et al., 2002). The inclusion of energy indicators in both the “Quality of Life Counts” (DETR, 2000) and the “Pilot Agricultural Indicators” (MAFF, 2000) establish the importance of energy use as a useful indicator in rela-
The LINK-IFS Project (see Ogilvy et al., 1994) was set up in 1992 “to compare, on a farm scale, conventional and integrated systems in terms of economics, and agronomic and environmental impact” (Holland et al., 1994). This involved 5 years of field trials ending with the 1997 harvest. The conventional system used “crop husbandry which maximises profitability using external inputs applied within permitted limits to overcome constraints on production”, whereas the integrated system “maximises profitability with a different balance of inputs, and aims to achieve environmental benefits” (Ogilvy, 1993). The experimental design extended to six geographically dispersed locations (see Table 1) with a variety of soil types. Four of the sites were located on commercial farms: the Manydown (MD) Estate near Basingstoke; the Scott Abbott Arable Crop Station at Sacrewell (SW) in Cambridgeshire; on the Lower Hope (LH) Farms Estate near Hereford; and at Pathhead (PH) in Midlothian. The remaining two sites were at ADAS research centres: Boxworth (BW) in Cambridgeshire and High Mowthorpe (HM) in North Yorkshire. The
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Table 1 The LINK Integrated Farming Systems experimental site crop rotation patterns Site
Conventional
Integrated
Sacrewell, Cambridgeshire Boxworth, Cambridgeshire
Wheat, set-aside, peas, wheat, potatoes Winter oilseed rape, wheat, winter beans, wheat, wheat Wheat, set-aside, winter oilseed rape, wheat, seed potatoes Wheat, set-aside, winter oilseed rape, wheat, potatoes Wheat, wheat, spring barley, peas, winter oilseed rape Winter oilseed rape, wheat, set-aside, wheat, winter barley
Wheat, set-aside, peas, wheat, potatoes Linseed, wheat, winter beans, wheat, wheat
High Mowthorpe, North Yorkshire Lower Hope Farms, Hereford Manydown Estates, Hampshire Pathhead, Midlothian
basis of the experiment was a five-course rotation with crops chosen that were appropriate to the locality of each site. Four of the sites included set-aside in their rotation, at Manydown oilseed rape for industrial use was grown, and at Boxworth non-rotational set-aside on the field margins were incorporated. The rotations for each site are shown in Table 1. The area covered at each site was approximately 55 ha. To achieve the farm level aims associated with IFS, specific objectives and parameters which measured the level of achievement were outlined based on protocols provided by Vereijken (1992, 1994, 1995, 1996, 1997) and the IOBC guidelines (see El Titi et al., 1993; Boller et al., 1997). These include objectives covering profit, food production quantity and quality, soil protection, irrigation, nutrient management, crop protection, energy efficiency and management of flora, fauna and landscape. Husbandry methods advocated (see Table 2) are a multi-functional crop rotation, minimal
Wheat, set-aside, spring beans, wheat, seed potatoes Wheat, set-aside, spring beans, wheat, potatoes Wheat, wheat, spring barley, peas, winter oilseed rape Spring oilseed rape, wheat, set-aside, wheat, spring barley
soil cultivation, integrated nutrient management and crop protection, and finally, ecological infrastructure management. Within these, the focus was on practices such as using disease resistance as opposed to high yielding cultivars, non-inversion or minimal tillage as opposed to the use of the plough, a later sowing date in October, nutrition based more on soil/plant chemistry, and crop protection using forecasting for pest control, thresholds for diseases, and the control of weeds using mechanical options and low dose herbicides. In relation to the above objectives, protocols and guidelines, site leaders at each location were given full control over the choice of their primary objectives and the husbandry practices adopted, bearing in mind the need to maximise profitability and achieve environmental benefits. In most cases, the protocols and guidelines were not fully adopted for the reasons summarised below.
Table 2 Integrated Farming Systems husbandry methods Husbandry method
Description
Multi-functional crop rotation
Limiting crop species frequency to 25% and crop group frequencies to 50% for the preservation of biological, physical and chemical soil fertility. To reduce soil erosion, nutrient residues, and adverse effects on soil invertebrates. Soil cover and organic matter content are also important. Balancing inputs against outputs to maintain soil reserves without leaving excess residues. Control whilst minimising impacts on the environment, consideration should be given to e.g. pesticide selection, timing of crop establishment, mechanical weeding. Encouragement and maintenance of habitats within the farm boundary, to provide biological diversity and minimise pollution problems, through e.g. linear features such as hedges, field margins, wildflower strips and beetlebanks.
Minimal soil cultivation Integrated nutrient management Integrated crop protection Ecological infrastructure management
Source: Adapted from Vereijken (1992, 1994, 1995, 1996, 1997), El Titi et al. (1993), and Boller et al. (1997).
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At all sites, maintaining profits was a primary concern and is reflected in the predominance of wheat in the rotations and the failure to meet the guidelines for a multi-functional crop rotation. However, most sites aimed to minimise their soil cultivation opting for minimal/non-inversion tillage and direct drilling where appropriate (see Table A.1) and only ploughing where there was a requirement to contain weeds. This was a key concern at two sites, Boxworth and High Mowthorpe. The potential for soil erosion was also taken into consideration and was the main concern at Lower Hope as a result of growing potatoes in the rotation. The adoption of non-inversion tillage was not possible at two of the sites. In the first case, Manydown, this was due to the lack of suitable equipment available. In the second case, Pathhead, the use of the plough and the benefits derived from this were seen as a more important priority. In terms of nutrient management, the sites concentrated on inorganic fertiliser usage because of the environmental concern associated with nitrate leaching at Sacrewell, High Mowthorpe, Lower Hope and Pathhead. Strategies for reducing nitrate leaching included the introduction of less nitrogen-demanding crops, such as legumes, and/or a change to spring cropping. In certain cases, however, reductions were not achieved at some sites where the concerns over nitrate leaching had been expressed. Protocols for nitrate sampling and a full discussion of the method can be found in Ogilvy (2000). Pesticide use was also minimised where possible. At Sacrewell, pesticide use and the associated environmental problems were a key concern, particularly in relation to potato production. The use, toxicity and leaching of pesticides were also of concern at High Mowthorpe, Manydown, and Lower Hope. Common crop protection practices to reduce pesticide use at all sites included the choice of crop variety and drilling date, and the use of mechanical weeding, crop monitoring and thresholds. Greatest reductions were achieved in the use of fungicides, insecticides and molluscicides, with some reduction in herbicide use. At some sites molluscicides were not used at all in the integrated system. Attempts were also made, where possible, to use a more selective and less toxic alternative. This sometimes led to a greater pesticide cost due to using a more expensive product and/or having to repeat the application at a later date.
Ecological infrastructure management is difficult to quantify separately for the two systems due to the nature of the experimental comparison. This is because improving field margins and introducing linear features such as wildflower strips and beetlebanks is likely to impact on both systems equally. Nevertheless, within the project, attempts were made to improve the ecological infrastructure of each site with the introduction of various features designed to improve available habitat and thereby encourage wildlife. At the High Mowthorpe site, for example, the introduction of grass margins, wildflower borders and strips of Phacelia tanecetifolia led to increased numbers of beneficial insects (Ogilvy, 1996). Similar features were also introduced at other sites, and use was also made of set-aside, both non-rotational and rotational.
3. Energy use The overall aim of these farming systems experiments was to assess the economic viability and environmental impact of the differing systems. As part of the environmental analyses, data on energy use, both direct and indirect, was also collected and analysed. 3.1. Calculation of energy use Energy used in agricultural systems can be calculated in a number of ways. In the LINK-IFS experiment, the analysis focused on the energy input required by the two systems being compared. The calculation was based on estimating the total energy consumed in all the processes of production up to, but not including, harvesting and all processing and storage of inputs. Where desiccants were used pre-harvest these, and the operations to apply them, were included in the energy use estimates. Total energy is defined as the direct energy used, i.e. the fuel consumed (diesel), and the indirect energy involved in the production of all other inputs from equipment to agrochemicals. The overall comparison of energy used is based on the equipment and inputs used to produce 1 kg of each crop within the conventional and integrated rotations and thereby the overall energy used for each system. Information and data for the two systems, conventional and integrated, regarding the type of operations undertaken, specifically non-inversion tillage, the use of fertiliser
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and pesticides, and yields obtained for winter wheat are shown in the Appendix A. Energy costs of harvesting were assumed to be very similar for both systems. 3.2. Direct energy Direct energy use, i.e. fuel use, was estimated using published engine test data on fuel use (Butterworth and Nix, 1983; DLG, 1996–1998) taking into account the different operations and equipment combinations used in each system and at each site. This included the work rates (ha/h) for all combinations of equipment on the basis of forward speed, width of working and field efficiency for each task. Each operation was then assigned a fuel use in litres per hectare to calculate the energy consumed. Fuel usage was suggested for each power unit running at 80% full engine power. Using a mean value of 0.230 g diesel/kWh this was then converted to MJ/ha using a factor of 37 MJ/l (Conoco Ltd., Grimsby, personal communication, 1996). This approach was used as, within the scope of the study, it was impossible to have all the equipment fitted with fuel monitoring equipment. This was primarily a result of the large plot areas within the project which meant that as near commercial operations as possible were involved and thus several tractors fitted with a variety of equipment were in use at each site. 3.3. Indirect energy Many researchers have considered the energy required to construct equipment or contained within raw material inputs used within the agricultural industry (Leach, 1976; Fluck, 1979; Helsel, 1987; Swanton et al., 1996). Within this study, energy requirements were estimated for tractor and equipment construction
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as well as that involved in seed, fertiliser and pesticide manufacture. This included all aspects of packaging, delivery and handling to the site. To estimate the energy used for tractor and equipment construction, the financial value of each piece of equipment was calculated based on its annual use, market value, depreciation and costs for spares and repairs (Nix, 1996). This value was then converted to an energy figure based on a conversion of 31.3 MJ/£ (Department of Energy, 1991). Relating this to the work rates calculated earlier, the indirect energy per hectare for each hour of operation, i.e. tractor and implement, was found. Values used in all these calculations were chosen to reflect commercial use as far as possible. The direct and indirect energy values for each piece of equipment were combined to give the total estimated energy value. A wide range of equipment was employed over all sites with additions and deletions during the life of the study. As far as possible power units and systems were inspected and allocated into comparable groups for recording purposes. Power inputs were therefore assigned to the task, soil type and conditions at each site to permit comparison of the systems rather than a comparison of the equipment available at each site. Typical values, reflecting the complexity, capital involvement, draught requirement and work rate of each operation, for a range of equipment used at the sites is given in Table 3. Indirect energy values for inputs such as seed, fertiliser and sprays were estimated based on their use at each site and in each system combined with information on their application rate. The energy values for the seeds and different chemicals were taken from published data (see Helsel, 1987). Whilst it was
Table 3 Typical total energy values (MJ/ha) for a range of equipment including appropriate power units Equipment
Direct energy
Percentage of total
Indirect energy
Percentage of total
Total
Plough Heavy disc Power harrow Seed drill Fertiliser spreader Sprayer
1160 860 840 280 32 51
57 55 53 58 64 60
890 700 750 200 18 34
43 45 47 42 36 40
2050 1560 1590 480 50 85
Source: Derived from Butterworth and Nix (1983), Conoco, personal communication (1996), DLG (1996–1998), Department of Energy (1991), Fluck (1979), Helsel (1987), Leach (1976), Nix (1996), and Swanton et al. (1996).
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possible to determine some specific values for some pesticide active ingredients, in certain cases mean values for pesticide active ingredients were used due to the difficulty of obtaining information on some of the pesticides used. With regard to the above calculations for direct and indirect energy use and thus total energy, it is pertinent to highlight the uncertainty that arises in relation to the estimates as a result of such aspects as field measurements, estimates of energy in construction and different machinery type comparisons. However, given that the calculations for energy use in both the conventional and integrated systems followed the same approach, they do permit a valid systems comparison.
4. Results 4.1. Total energy use The total energy used in each system at each site was calculated based on the summation of the values for direct and indirect energy use. Fig. 1 presents the energy use per hectare at each site for the full 5 years of the rotation and includes all crops grown. This covers direct and indirect energy used in operations and indirect energy use incorporated within the agrochemicals employed at each site. A mean, averaged across all sites, is also given, with the conventional system using 14,667 MJ/ha and the integrated system using 13,428 MJ/ha. This is a difference in total energy input of 1239 MJ/ha, i.e. an 8% saving in total energy input on the integrated system. This is equivalent to
33.5 l/ha of diesel fuel using the standard conversion figure quoted earlier of 37 MJ/l. Fig. 2 shows the percentage change in energy input for all sites and all years for the integrated relative to the conventional farming system. Only one site (SW) expended more energy per hectare on the integrated system, although this was less than a 1% difference, with the other sites showing reductions in energy use in the integrated system ranging from 3 to 17%. The savings in the energy used on the integrated system were primarily achieved through reduced cultivations. In general, ploughing and the associated seedbed preparation, used extensively on the conventional system, were very energy intensive operations and required the highest energy inputs. These were reduced in the integrated system by adopting less intensive cultivations such as a minimum tillage system. Three of the six sites in the experiment (BW, HM and LH) increased the frequency of non-inversion tillage on their integrated system. A fourth site (SW), which had previously not used non-inversion tillage, adopted the practice on its integrated system. Overall, the difference between the two systems in terms of fuel actually consumed during operations was estimated to be 20 l/ha or £3/ha (red diesel price of 15 p/l) as a result of the changes in cultivations, and also taking into account the crops grown and reduced pesticide and fertiliser applications. There were also some differences in the amount of energy use associated with the fertiliser and pesticides themselves, such that reductions at each site in terms of fertiliser and pesticide use are reflected in the overall energy used. At individual sites, however, and
Fig. 1. Total energy use (excluding harvesting) per hectare, all sites, all years, all crops—mean values.
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Fig. 2. Total energy use (excluding harvesting) per hectare, all sites, all years, all crops—mean percentage change integrated to conventional.
for a range of crops there are differences in chemical amounts applied and therefore energy used in some cases favouring the integrated system and in other cases favouring the conventional system. For example, with respect to cereals, and in particular wheat, there was frequently little difference between the amount of fertiliser used at any of the sites. This was also, to some extent, determined by the cereal variety grown. For example, quality wheat and barley were grown on the integrated systems at Boxworth and Pathhead, respectively. This suggests the potential need for greater applications of fertiliser and therefore increased energy use. However, in the case of the Pathhead barley crop this was a spring variety which, along with the introduction of spring oilseed rape in the integrated system, allowed reductions in fertiliser use and therefore energy use to be attained. Spring crops were also incorporated on the integrated system at a number of other sites (HM and LH) with some sites also opting for a switch in crop type away from oilseed crops to pulses (HM and LH). This again allowed for reductions in fertiliser use. Energy use in relation to pesticides was also dependent on the crops grown. Incorporating spring crops within the integrated rotation (HM, LH and PH) allowed reductions in pesticide use and therefore also
energy use. However, reductions were not achieved where potatoes were grown in the rotation (SW, HM and LH) nor where reduced cultivation on the integrated system led to later problems with weed growth as this led to the need for either mechanical weeding or greater use of pesticides. Figs. 3 and 4 illustrate the typical sector inputs in total energy use per hectare for two crops, winter wheat at Boxworth and potatoes at High Mowthorpe. The Boxworth example has been chosen as it demonstrates the difference in energy inputs in the cultivation and crop establishment operations between the two systems. Only two passes were used on the integrated system, the first was a cultivator drill unit followed by simple harrowing. In contrast, there were five passes on the conventional system, including a plough, power harrow, tined cultivator, seed drill and separate light harrow. The figure also illustrates the relativity of seed, fertiliser and pesticide energy inputs against operation energy inputs. In the case of Boxworth, the reduced cultivations led to a serious weed problem resulting in the increased use of herbicides, reflected in the higher energy use in pesticides and spraying. The example also highlights the lack of difference in energy use associated with fertiliser. This reflects the decision of the site leader to grow
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Fig. 3. Total energy use at Boxworth—example of input sectors for one field of winter wheat in 1 year.
quality wheat and high yielding varieties in order to maintain profit margins. The High Mowthorpe example, Fig. 4, is included as a comparison and highlights the difficulties of achieving input reductions with a potato crop. The only reduction achieved is that related to pesticides. At High Mowthorpe this was as a result of reductions in herbicide used, considered a risky decision which in some years did not pay off. Considering all the sites individually, the greatest energy reductions on the integrated system were achieved as a result of reduced cultivations, either through the adoption of non-inversion tillage, such as at Boxworth, and/or the switch to spring cropping, such as at Pathhead. At Boxworth the frequency of non-inversion tillage on the integrated system was over 50% despite the requirement to contain weeds. At Pathhead the reductions in energy use result from the switch to spring cropping in more than one phase of the rotation. It is worth noting that the reduction
in energy use at Pathhead was achieved without the adoption of non-inversion tillage. Substantial reductions in energy use were also achieved at Lower Hope. This reflects the reduced cultivations on the integrated system, although not as substantial as those at Boxworth, in combination with a switch to a spring crop in one phase of the rotation. Set against this is the production of potatoes in one phase of the rotation where it is difficult to reduce energy use in any way. A limited reduction in energy use is also realised at High Mowthorpe and Manydown. In the case of High Mowthorpe, the site manager again faced the problem of reducing inputs in the potato phase of the rotation, but was able to make some reduction, first, as a result of reducing cultivations despite the requirement to contain weeds, and second, switching from a winter oilseed crop to spring beans to reduce the agrochemical input. At the Manydown site reductions in energy input were achieved through small
Fig. 4. Total energy use at High Mowthorpe—example of input sectors for one field of potatoes in 1 year.
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Fig. 5. Total energy (excluding harvesting) per kilogram yield, all years, all crops, by site.
differences in the amounts of fertiliser and pesticides used. Non-inversion tillage was not adopted in the integrated system and there was also no difference between the two systems in terms of the type of crops grown. Finally, the negligible increase in energy input in the integrated system at Sacrewell is a reflection of using the same rotation in the conventional and integrated systems including the production of potatoes in one phase and is in spite of the adoption of non-inversion tillage on the integrated system. 4.2. Energy use in relation to output The results discussed so far have focused on inputs only, with no account taken of crop yields. It is therefore appropriate to examine whether the variation in inputs is reflected in yield. The yields at all sites for all crops were recorded, and for the purpose of this analysis all yields were standardised for relevant moisture contents. The yields of all crops were then considered against energy inputs, again excluding harvesting. The mean values for energy used per kilogram of output are given in Fig. 5. This shows that, overall, there was very little difference in energy values between the conventional and integrated systems when considered on energy input to kilogram of crop yield basis. Slight increases in energy use on the integrated system, however, were seen at Boxworth and High Mowthorpe. This is probably related to the lower mean yields at these sites, where in one phase of the rotation it is the yields of different crops being compared. At Boxworth, there is a winter oilseed rape versus linseed phase where there is a
substantial difference in yield between the two crops which affects the overall picture. At High Mowthorpe there is a winter oilseed rape versus spring bean phase where the beans were low yielding. However, at Lower Hope which has a similar rotation, and despite a bean crop failure in 1 year, this did not lead to increased energy use in relation to output on the integrated system. This is perhaps a reflection of the greater difference between the two systems at Lower Hope in terms of the use of non-inversion tillage, with limited use on the conventional system and more substantial use on the integrated system. Where the rotations incorporate the same crop within both systems (SW, MD and PH) there is little difference between the two in terms of energy use in relation to output. At Sacrewell, the reduction in energy use on the integrated system could again, as with Lower Hope, be a reflection of the adoption of non-inversion tillage in that system as it is not used within the conventional system. At Manydown and Pathhead, where there is a negligible difference in energy use in relation to output, non-inversion tillage is not used in either system for reasons stated earlier.
5. Discussion The above analysis highlights the potential for energy inputs to be reduced on integrated farming systems, in comparison to conventional farming systems, through reductions in cultivations and agrochemical inputs. The operations associated with cultivations and the application of chemicals in agricultural systems are often perceived as being detrimental to the
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environment, and the reduction in their use alongside a corresponding reduction in energy use is likely to be considered beneficial. However, the energy input to output ratio of the two types of system, when considering the mean levels recorded on all sites, suggests there is little difference overall, with the reduction in energy input reflected by a reduction in crop yield. This generalisation, however, must be treated with some caution as findings from individual sites within the experimental project suggest that there might be some potential, through the adoption of more integrated farming practices, for reductions in energy use without corresponding crop yield reductions. In relation to this suggestion, it is the adoption or greater use of minimum, including non-inversion, tillage that appears to yield the greater savings in energy use, although it should be recognised that, for individual farms, reduced cultivations may not always be possible. This is particularly the case where these reduced cultivations lead to difficulties associated with crop establishment and increased weed problems. However, in certain cases, reduced cultivations may prove beneficial in reducing or preventing weed establishment and growth. Furthermore, many “mainstream” farmers are currently adopting or seriously considering the use of minimal tillage systems primarily as a mechanism for reducing costs and/or increasing workrates. In energy terms and also in financial terms, this change needs balancing against any subsequent increase in pesticide usage. As regards fertilisers, which generally have a high energy cost, the differences between the two systems in many instances was not found to be significant. Despite the exclusion of harvesting and subsequent operations from the energy use calculation, consideration was given to the differences in the two systems being compared. In terms of harvesting, there was insufficient data to judge whether harvesting time was significantly different between the two systems studied. Some minor problems with weed growth were reported in the integrated system but not on all sites nor in all years. Some records, again not representing a significant number of sites and plots, suggested that there could have been a slight increase in the amount of drying required for crops from the integrated plots. This could have been due to increased weed populations and possible lodging. It was indicated that this might have resulted in crops being harvested at 1.5–2%
higher moisture content on occasions, but no conclusive evidence was found for this. However, a calculation based on the same approach as for other inputs was made to consider the energy used in harvesting, transport to store, drier use and fuel to dry crops by an additional 3% moisture content, i.e. from 17 to 14%. This suggested that this would add another 5150 MJ/ha to the figures for total energy use in the integrated system. Clearly, the analysis of energy use should also take account of financial information, as that is likely to be of more direct importance to farmers in their decision making. Thus, the costs associated with the operation and inputs and the revenues received for the crops produced need to be compared. This is of particular interest where the difference between the two systems is as a result of a switch from one crop or crop variety to another, and where there is the potential to obtain a greater return from that change, whilst at the same time reducing overall energy use. In this respect, reduced yields in the integrated system may be offset by higher crop prices although this was not the case for the switches from winter oilseed rape to linseed and spring beans (BW, HM and LH). However, where crop varieties on the integrated system were changed with the emphasis on growing better quality crops (BW and PH), financial margins were improved or maintained (see Ogilvy, 2000; Keatinge et al., 1999; Park et al., 1997, 1999). Although energy input in relation to output was similar in both systems, overall energy use was reduced on the integrated system.
6. Conclusions Energy use is now seen as one of the key indicators of sustainable development and was listed in both the UK Governments “Quality of Life Counts” and “Pilot Agricultural Indicators” (DETR, 2000; MAFF, 2000). As agriculture currently accounts for about 5% of national energy consumption, reductions due to changes in farming systems could have an effect on national energy usage. The evidence presented here suggests that integrated arable systems, when compared with conventional farming systems on a per hectare basis, have the potential to reduce overall energy consumption by about 8%, although there was inevitable variation in this measure between the sites studied. Much
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of this saving resulted from reduced cultivation activity, in particular the use of minimal tillage systems. However, when energy use comparisons are made by weight of output, there is little difference between the two systems because of the generally lower yields per hectare under the integrated systems. Thus, initially, at a national level, it appears that a wide-spread adoption of IAFS would mean a reduction in energy use, but it would also result in less overall output. However, if national output was to be maintained under a regime of IAFS, it is clear that a larger area would have to be cultivated using more energy, with the probable result of a neutral energy effect. Furthermore, the surplus land at a national level under the current mainly conventional system, set-aside land, has an increasing value in environmental terms or as a land resource for the generation of bio-energy. In addition, in this series of experiments, the IAFS plots are very much the exception to a “conventional” cropping rule and it could be argued that they might be benefiting from the generally high level of weed and pest control in the surrounding countryside. Although as yet unproven, a significant shift to IAFS at a national level, may lead to a greater pesticide burden in the countryside generally and therefore make it increasingly difficult to maintain the lower levels of pesticide usage associated with the IAFS in this experiment. Overall, it has to be said that this analysis of energy use in integrated arable farming systems does not provide conclusive evidence that the introduction of such systems reduce energy input. However, it has been demonstrated that the systems and their associated practices, particularly the use of minimum tillage, have the potential to reduce energy use although this may mean an increased complexity in making management decisions and creating an increased risk of fluctuations in output. There is also a suggestion that part of the reason for the emergence of this somewhat confused picture is a result of the compounding of a number of factors, inevitable in this type of rotational systems multi-site project. UK arable farmers have been under severe financial pressure for several years (DEFRA et al., 2002). As a result, many have been adopting some integrated techniques (such as less cultivation, more precise fertilisation and the use of reduced dose pesticides) as a mechanism for reducing their costs of production.
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Some of these farmers, for instance, those who have undertaken a LEAF audit, will have considered their energy use in more detail. However, many farmers will not have undertaken a vigorous energy analysis of their cropping operations and, whilst agricultural ‘red’ diesel continues to carry its current fuel tax exemption, the message to farmers concerning the importance of energy saving on farms will remain confusing. Acknowledgements The authors would like to thank those involved in the LINK-IFS Project, particularly the six site leaders for their help in the provision and analyses of data. We are grateful for valuable comments from David Pimental on an earlier draft of this paper. Nevertheless, the opinions expressed here, and conclusions reached, are solely the responsibility of the authors. Financial support from the LINK sponsors, MAFF, SOAEFD, HGCA, Zeneca and BAA, and the MAFF Open Contracting Scheme is also gratefully acknowledged. Appendix A. See Tables A.1–A.4. Table A.1 Frequency of use of non-inversion tillage at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional (%)
Integrated (%)
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
0 28 25 5 0 0
35 56 35 28 0 0
Table A.2 Annual fertiliser nitrogen use (kg N/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
115 148 151 155 144 166
117 117 121 120 129 121
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Table A.3 Pesticide use (units/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
42.55 30.75 40.56 35.20 33.26 24.79
24.54 19.71 31.08 20.17 29.58 15.18
Note: A unit of pesticide is the maximum amount, in grams, of an active ingredient recommended for arable crops.
Table A.4 Average winter wheat yields (t/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
8.14 9.34 8.15 9.41 7.62 9.17
6.91 8.09 7.45 8.55 7.24 8.96
References Boller, E.F., Malavolta, C., Jorg, E. (Eds.), 1997. Guidelines for integrated production of arable crops in Europe. IOBC Technical Guideline 111, first ed. IOBC/WPRS Bull. 20 (5). Bonny, S., 1993. Is agriculture using more and more energy? A French case study. Agric. Syst. 43, 51–66. Butterworth, W., Nix, J.S., 1983. Farm Mechanisation for Profit. Granada Publishing, St. Albans. Dalgaard, T., Halberg, N., Porter, J.R., 2001. A model for fossil energy use in Danish agriculture used to compare organic and conventional farming. Agric. Ecosyst. Environ. 87, 51–65. DEFRA, SEERAD, DARD, NAWAD, 2002. Agriculture in the United Kingdom 2001. The Stationery Office, London. Department of Energy, 1991. Digest of United Kingdom Energy Statistics. HMSO, UK. DETR, 2000. Quality of Life Counts. Government Statistical Service, London. DLG, 1996–1998. OECD Tractor Test Reports—Various. Germany. Donaldson, J.V.G., Hutcheon, J.A., Jordan, V.W.L., Osborne, N.J., 1994. Evaluation of energy usage for machinery operations in the development of more environmentally benign farming systems. Aspects Appl. Biol. 40, 87–91. El Titi, A., Boller, E.F., Gendrier, J.P., 1993. Integrated production: principles and technical guidelines. IOBC/WPRS Bull. 16 (1).
Fluck, R.C., 1979. Energy productivity: a measure of energy utilisation in agricultural systems. Agric. Syst. 4, 29–37. Helsel, Z.R. (Ed.), 1987. Energy in Plant Nutrition and Pest Control. University of Missouri, Columbia, USA. Higginbotham, S., Noble, L., Joice, R., 1996. The profitability of integrated crop management, organic and conventional regimes. Aspects Appl. Biol. 47, 327–333. Holland, J.M., Frampton, G.K., Cilgi, T., Wratten, S.D., 1994. Arable acronyms analysed—a review of integrated farming systems research in Western Europe. Annals Appl. Biol. 125, 399–438. Jordan, V.W.L., Hutcheon, J.A., 1996. Multifunctional crop rotation: the contributions and interactions for integrated crop protection and nutrient management in sustainable cropping systems. Aspects Appl. Biol. 47, 301–308. Keatinge, J.D.H., Park, J.R., Bailey, A.P., Rehman, T., Tranter, R.B., Yates, C.M., 1999. Assessment of the financial and economic impacts demonstrated by low-input, integrated farm system experiments. Report Prepared for Ministry of Agriculture, Fisheries and Food (under reference CSA 2935). Department of Agriculture, The University of Reading. Konyar, K., 2001. Assessing the role of US agriculture in reducing greenhouse gas emissions and generating additional environmental benefits. Ecol. Econ. 38, 85–103. Lampkin, N.H., 1990. Organic Farming. Farming Press, Ipswich. Leach, G., 1976. Energy and Food Production. IPC Science and Technology Press, Guildford. Leake, A.R., 1996. The effect of cropping sequences and rotational management: an economic comparison of conventional, integrated and organic systems. Aspects Appl. Biol. 47, 185– 194. Loake, C., 2001. Energy accounting and well-being—examining UK organic and conventional farming systems through a human energy perspective. Agric. Syst. 70, 275–294. MAFF, 2000. Towards Sustainable Agriculture: A Set of Pilot Indicators. HMSO, London. Nix, J.S., 1996. Farm Management Pocketbook, 27th ed. Wye College, University of London, London. Ogilvy, S. (Ed.), 1993. LINK Project, Integrated Farming Systems. Annual Interim Report 1993. Ogilvy, S.E., 1996. LINK IFS—an integrated approach to crop husbandry. Aspects Appl. Biol. 47, 335–342. Ogilvy, S.E. (Ed.), 2000. LINK Integrated Farming Systems (A Field-Scale Comparison of Farming Systems), vol. 1 (Experimental Work; Project Report No. 173). HGCA, London. Ogilvy, S.E., Turley, D.B., Cook, S.K., Fisher, N.M., Holland, J., Prew, R.D., Spink, J., 1994. Integrated farming—putting together systems for farm use. Aspects Appl. Biol. 40, 53–60. Panesar, B.S., Fluck, R.C., 1993. Energy productivity of a production system: analysis and measurement. Agric. Syst. 43, 415–437. Park, J.R., Seaton, R., 1996. Integrative research and sustainable agriculture. Agric. Syst. 50, 81–100. Park, J.R., Farmer, D.P., Bailey, A.P., Keatinge, J.D.H., Rehman, T., Tranter, R.B., 1997. Integrated arable farming systems and their potential uptake in the UK. Farm Manage. 9, 483–494.
A.P. Bailey et al. / Agriculture, Ecosystems and Environment 97 (2003) 241–253 Park, J.R., Bailey, A.P., Yates, C.M., Keatinge, J.D.H., Rehman, T., Tranter, R.B., 1999. Do integrated arable farming systems provide a more sustainable form of agricultural production in the UK? Farm Manage. 10, 379–391. Pervanchon, F., Bockstaller, C., Girardin, P., 2002. Assessment of energy use in arable farming systems by means of an agro-ecological indicator: the energy indicator. Agric. Syst. 72, 149–172. Pimental, D., Hurd, L.E., Belloti, A.C., Forster, M.J., Oka, I.N., Sholes, O.O., Whitman, R.J., 1973. Food production and the energy crisis. Science 182, 443–449. Swanton, C.J., Murphy, S.D., Hume, D.J., Clements, D.R., 1996. Recent improvements in the energy efficiency of agriculture: case studies from Ontario, Canada. Agric. Syst. 52, 399–418. Taylor, A.E.B., O’Callaghan, P.W., Probert, S.D., 1993. Energy audit of an English farm. Appl. Energy 44, 315–335. Vereijken, P., 1992. A methodic way to more sustainable farming systems. Neth. J. Agric. Sci. 40, 209–223.
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Vereijken, P., 1994. Designing Prototypes. 1. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and associated countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO, p. 87. Vereijken, P., 1995. Designing and Testing Prototypes. 2. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and associated countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO, p. 90. Vereijken, P., 1996. Testing and Improving Prototypes. 3. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and Associated Countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO. Vereijken, P., 1997. A methodical way of prototyping integrated and ecological arable farming systems (I/EAFS) in interaction with pilot farms. Eur. J. Agronom. 7, 235–250.
A comparison of energy use in conventional and integrated arable farming systems in the UK A.P. Bailey a,∗ , W.D. Basford b , N. Penlington b , J.R. Park a , J.D.H. Keatinge a , T. Rehman a , R.B. Tranter c , C.M. Yates a a
School of Agriculture, Policy and Development, The University of Reading, Earley Gate, PO Box 237, Reading, Berkshire RG6 6AR, UK b ADAS Gleadthorpe Grange, Meden Vale, Mansfield, Nottinghamshire NG20 9PD, UK c Centre for Agricultural Strategy, The University of Reading, Earley Gate, PO Box 237, Reading, Berkshire RG6 6AR, UK Received 25 April 2002; received in revised form 3 January 2003; accepted 17 January 2003
Abstract The LINK Integrated Farming Systems (LINK-IFS) Project (1992–1997) was set up to compare conventional and integrated arable farming systems (IAFS), concentrating on practical feasibility and economic viability, but also taking into account the level of inputs used and environmental impact. As part of this, an examination into energy use within the two systems was also undertaken. This paper presents the results from that analysis. The data used is from the six sites within the LINK-IFS Project, spread through the arable production areas of England and from the one site in Scotland, covering the 5 years of the project. The comparison of the energy used is based on the equipment and inputs used to produce 1 kg of each crop within the conventional and integrated rotations, and thereby the overall energy used for each system. The results suggest that, in terms of total energy used, the integrated system appears to be the most efficient. However, in terms of energy efficiency, energy use per kilogram of output, the results are less conclusive. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Integrated arable farming systems; Energy use; Efficiency
1. Introduction 1.1. Integrated arable farming systems Over the last 50 years, the intensity of agriculture in much of North-western Europe has increased dramatically with higher yields per hectare and, in some cases, an improvement in the quality of food produced. However, this has been achieved against a backcloth of increasing public concern about the environment, ∗ Corresponding author. Tel.: +44-118-378-6270; fax: +44-118-935-2421. E-mail address: [email protected] (A.P. Bailey).
especially in terms of agriculture’s effects on the soil, water, air and habitat resources. Awareness of the environmental impacts of agricultural production, coupled with over-supply of some products such as wheat for animal feed, has highlighted the need to find more sustainable farming practices (see, for instance, Park and Seaton, 1996). Integrated arable farming systems (IAFS) are seen by some as one way of achieving this goal, leading to a plethora of research activity throughout Europe (see Holland et al., 1994) concerning these “innovative” cropping systems. Research projects in the UK which have been, and are, examining IAFS are attempting to ascertain results
0167-8809/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0167-8809(03)00115-4
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in three areas: the technical feasibility of such systems; their profitability; and an assessment of the environmental changes that result (Vereijken, 1992, 1994, 1995; Ogilvy, 1996). Early low input projects (see Holland et al., 1994) such as the Boxworth Project (1981–1988), SCARAB (1989–1996) and TALISMAN (1989–1996) examined the effect of reduced inputs, primarily pesticides, on the environment and, in the case of TALISMAN, the economic effect of both reduced pesticide and fertiliser use. RISC (1991–2000) in Northern Ireland was also set up to examine the effects of reduced pesticide and fertiliser use. The Long Ashton Low Input Farming and the Environment Project (LA-LIFE) (1989–1999) (Jordan and Hutcheon, 1996) was the first to develop and investigate a fully integrated farming system in the UK. This was followed by the much larger LINK Integrated Farming Systems (LINK-IFS) Project (1992–1997) (Ogilvy et al., 1994). The two most recently established IAFS projects are the CWS Focus on Farming Practice (CWS-FOFP) Project (1993 onwards) (Leake, 1996) and the Rhone–Poulenc Management Study (RPMS) (1994–2000) (Higginbotham et al., 1996).
tion to sustainability. The main focus of this previous research is in the definition of the most appropriate techniques to use and the trends in the energy efficiency of agricultural production over time. There has been a limited number of applications of energy analysis to the comparison of different methods of agricultural production. The most notable exceptions are in the field of organic farming (see, for example, Lampkin, 1990; Dalgaard et al., 2001; Loake, 2001) and a comparison by Donaldson et al. (1994) of energy usage for machinery operations of different more benign farming systems based on the LA-LIFE study. The LINK-IFS Project encompassed a study of energy use in conventional farming practices (CFP) and the more integrated approach (IFS). In this paper, a comparative analysis of the two systems in terms of their energy efficiency is presented together with discussion of output values and financial considerations. The broader methodological issues associated with the LINK-IFS experiments are reported prior to a detailed examination of the energy relations in the contrasting systems.
2. The LINK-IFS Project 1.2. Energy analysis Energy use in agriculture, and the externalities arising from it, have attracted recent interest from the viewpoint of sustainability. Indeed, energy analysis may provide one of the few cradle to grave measures capable of making comparative analysis between agricultural systems. At the farm level, tools such as the LEAF audit, highlight the importance of energy use and there is clearly also a financial incentive associated with saving energy on the farm. Energy analysis of agricultural systems dates back to the early 1970s (e.g. Pimental et al., 1973). Since then there has been a variety of research highlighting the use of energy in agricultural production systems (Fluck, 1979; Bonny, 1993; Panesar and Fluck, 1993; Taylor et al., 1993; Swanton et al., 1996) and, more recently, in relation to reducing greenhouse gas emissions (e.g. Konyar, 2001; Pervanchon et al., 2002). The inclusion of energy indicators in both the “Quality of Life Counts” (DETR, 2000) and the “Pilot Agricultural Indicators” (MAFF, 2000) establish the importance of energy use as a useful indicator in rela-
The LINK-IFS Project (see Ogilvy et al., 1994) was set up in 1992 “to compare, on a farm scale, conventional and integrated systems in terms of economics, and agronomic and environmental impact” (Holland et al., 1994). This involved 5 years of field trials ending with the 1997 harvest. The conventional system used “crop husbandry which maximises profitability using external inputs applied within permitted limits to overcome constraints on production”, whereas the integrated system “maximises profitability with a different balance of inputs, and aims to achieve environmental benefits” (Ogilvy, 1993). The experimental design extended to six geographically dispersed locations (see Table 1) with a variety of soil types. Four of the sites were located on commercial farms: the Manydown (MD) Estate near Basingstoke; the Scott Abbott Arable Crop Station at Sacrewell (SW) in Cambridgeshire; on the Lower Hope (LH) Farms Estate near Hereford; and at Pathhead (PH) in Midlothian. The remaining two sites were at ADAS research centres: Boxworth (BW) in Cambridgeshire and High Mowthorpe (HM) in North Yorkshire. The
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Table 1 The LINK Integrated Farming Systems experimental site crop rotation patterns Site
Conventional
Integrated
Sacrewell, Cambridgeshire Boxworth, Cambridgeshire
Wheat, set-aside, peas, wheat, potatoes Winter oilseed rape, wheat, winter beans, wheat, wheat Wheat, set-aside, winter oilseed rape, wheat, seed potatoes Wheat, set-aside, winter oilseed rape, wheat, potatoes Wheat, wheat, spring barley, peas, winter oilseed rape Winter oilseed rape, wheat, set-aside, wheat, winter barley
Wheat, set-aside, peas, wheat, potatoes Linseed, wheat, winter beans, wheat, wheat
High Mowthorpe, North Yorkshire Lower Hope Farms, Hereford Manydown Estates, Hampshire Pathhead, Midlothian
basis of the experiment was a five-course rotation with crops chosen that were appropriate to the locality of each site. Four of the sites included set-aside in their rotation, at Manydown oilseed rape for industrial use was grown, and at Boxworth non-rotational set-aside on the field margins were incorporated. The rotations for each site are shown in Table 1. The area covered at each site was approximately 55 ha. To achieve the farm level aims associated with IFS, specific objectives and parameters which measured the level of achievement were outlined based on protocols provided by Vereijken (1992, 1994, 1995, 1996, 1997) and the IOBC guidelines (see El Titi et al., 1993; Boller et al., 1997). These include objectives covering profit, food production quantity and quality, soil protection, irrigation, nutrient management, crop protection, energy efficiency and management of flora, fauna and landscape. Husbandry methods advocated (see Table 2) are a multi-functional crop rotation, minimal
Wheat, set-aside, spring beans, wheat, seed potatoes Wheat, set-aside, spring beans, wheat, potatoes Wheat, wheat, spring barley, peas, winter oilseed rape Spring oilseed rape, wheat, set-aside, wheat, spring barley
soil cultivation, integrated nutrient management and crop protection, and finally, ecological infrastructure management. Within these, the focus was on practices such as using disease resistance as opposed to high yielding cultivars, non-inversion or minimal tillage as opposed to the use of the plough, a later sowing date in October, nutrition based more on soil/plant chemistry, and crop protection using forecasting for pest control, thresholds for diseases, and the control of weeds using mechanical options and low dose herbicides. In relation to the above objectives, protocols and guidelines, site leaders at each location were given full control over the choice of their primary objectives and the husbandry practices adopted, bearing in mind the need to maximise profitability and achieve environmental benefits. In most cases, the protocols and guidelines were not fully adopted for the reasons summarised below.
Table 2 Integrated Farming Systems husbandry methods Husbandry method
Description
Multi-functional crop rotation
Limiting crop species frequency to 25% and crop group frequencies to 50% for the preservation of biological, physical and chemical soil fertility. To reduce soil erosion, nutrient residues, and adverse effects on soil invertebrates. Soil cover and organic matter content are also important. Balancing inputs against outputs to maintain soil reserves without leaving excess residues. Control whilst minimising impacts on the environment, consideration should be given to e.g. pesticide selection, timing of crop establishment, mechanical weeding. Encouragement and maintenance of habitats within the farm boundary, to provide biological diversity and minimise pollution problems, through e.g. linear features such as hedges, field margins, wildflower strips and beetlebanks.
Minimal soil cultivation Integrated nutrient management Integrated crop protection Ecological infrastructure management
Source: Adapted from Vereijken (1992, 1994, 1995, 1996, 1997), El Titi et al. (1993), and Boller et al. (1997).
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At all sites, maintaining profits was a primary concern and is reflected in the predominance of wheat in the rotations and the failure to meet the guidelines for a multi-functional crop rotation. However, most sites aimed to minimise their soil cultivation opting for minimal/non-inversion tillage and direct drilling where appropriate (see Table A.1) and only ploughing where there was a requirement to contain weeds. This was a key concern at two sites, Boxworth and High Mowthorpe. The potential for soil erosion was also taken into consideration and was the main concern at Lower Hope as a result of growing potatoes in the rotation. The adoption of non-inversion tillage was not possible at two of the sites. In the first case, Manydown, this was due to the lack of suitable equipment available. In the second case, Pathhead, the use of the plough and the benefits derived from this were seen as a more important priority. In terms of nutrient management, the sites concentrated on inorganic fertiliser usage because of the environmental concern associated with nitrate leaching at Sacrewell, High Mowthorpe, Lower Hope and Pathhead. Strategies for reducing nitrate leaching included the introduction of less nitrogen-demanding crops, such as legumes, and/or a change to spring cropping. In certain cases, however, reductions were not achieved at some sites where the concerns over nitrate leaching had been expressed. Protocols for nitrate sampling and a full discussion of the method can be found in Ogilvy (2000). Pesticide use was also minimised where possible. At Sacrewell, pesticide use and the associated environmental problems were a key concern, particularly in relation to potato production. The use, toxicity and leaching of pesticides were also of concern at High Mowthorpe, Manydown, and Lower Hope. Common crop protection practices to reduce pesticide use at all sites included the choice of crop variety and drilling date, and the use of mechanical weeding, crop monitoring and thresholds. Greatest reductions were achieved in the use of fungicides, insecticides and molluscicides, with some reduction in herbicide use. At some sites molluscicides were not used at all in the integrated system. Attempts were also made, where possible, to use a more selective and less toxic alternative. This sometimes led to a greater pesticide cost due to using a more expensive product and/or having to repeat the application at a later date.
Ecological infrastructure management is difficult to quantify separately for the two systems due to the nature of the experimental comparison. This is because improving field margins and introducing linear features such as wildflower strips and beetlebanks is likely to impact on both systems equally. Nevertheless, within the project, attempts were made to improve the ecological infrastructure of each site with the introduction of various features designed to improve available habitat and thereby encourage wildlife. At the High Mowthorpe site, for example, the introduction of grass margins, wildflower borders and strips of Phacelia tanecetifolia led to increased numbers of beneficial insects (Ogilvy, 1996). Similar features were also introduced at other sites, and use was also made of set-aside, both non-rotational and rotational.
3. Energy use The overall aim of these farming systems experiments was to assess the economic viability and environmental impact of the differing systems. As part of the environmental analyses, data on energy use, both direct and indirect, was also collected and analysed. 3.1. Calculation of energy use Energy used in agricultural systems can be calculated in a number of ways. In the LINK-IFS experiment, the analysis focused on the energy input required by the two systems being compared. The calculation was based on estimating the total energy consumed in all the processes of production up to, but not including, harvesting and all processing and storage of inputs. Where desiccants were used pre-harvest these, and the operations to apply them, were included in the energy use estimates. Total energy is defined as the direct energy used, i.e. the fuel consumed (diesel), and the indirect energy involved in the production of all other inputs from equipment to agrochemicals. The overall comparison of energy used is based on the equipment and inputs used to produce 1 kg of each crop within the conventional and integrated rotations and thereby the overall energy used for each system. Information and data for the two systems, conventional and integrated, regarding the type of operations undertaken, specifically non-inversion tillage, the use of fertiliser
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and pesticides, and yields obtained for winter wheat are shown in the Appendix A. Energy costs of harvesting were assumed to be very similar for both systems. 3.2. Direct energy Direct energy use, i.e. fuel use, was estimated using published engine test data on fuel use (Butterworth and Nix, 1983; DLG, 1996–1998) taking into account the different operations and equipment combinations used in each system and at each site. This included the work rates (ha/h) for all combinations of equipment on the basis of forward speed, width of working and field efficiency for each task. Each operation was then assigned a fuel use in litres per hectare to calculate the energy consumed. Fuel usage was suggested for each power unit running at 80% full engine power. Using a mean value of 0.230 g diesel/kWh this was then converted to MJ/ha using a factor of 37 MJ/l (Conoco Ltd., Grimsby, personal communication, 1996). This approach was used as, within the scope of the study, it was impossible to have all the equipment fitted with fuel monitoring equipment. This was primarily a result of the large plot areas within the project which meant that as near commercial operations as possible were involved and thus several tractors fitted with a variety of equipment were in use at each site. 3.3. Indirect energy Many researchers have considered the energy required to construct equipment or contained within raw material inputs used within the agricultural industry (Leach, 1976; Fluck, 1979; Helsel, 1987; Swanton et al., 1996). Within this study, energy requirements were estimated for tractor and equipment construction
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as well as that involved in seed, fertiliser and pesticide manufacture. This included all aspects of packaging, delivery and handling to the site. To estimate the energy used for tractor and equipment construction, the financial value of each piece of equipment was calculated based on its annual use, market value, depreciation and costs for spares and repairs (Nix, 1996). This value was then converted to an energy figure based on a conversion of 31.3 MJ/£ (Department of Energy, 1991). Relating this to the work rates calculated earlier, the indirect energy per hectare for each hour of operation, i.e. tractor and implement, was found. Values used in all these calculations were chosen to reflect commercial use as far as possible. The direct and indirect energy values for each piece of equipment were combined to give the total estimated energy value. A wide range of equipment was employed over all sites with additions and deletions during the life of the study. As far as possible power units and systems were inspected and allocated into comparable groups for recording purposes. Power inputs were therefore assigned to the task, soil type and conditions at each site to permit comparison of the systems rather than a comparison of the equipment available at each site. Typical values, reflecting the complexity, capital involvement, draught requirement and work rate of each operation, for a range of equipment used at the sites is given in Table 3. Indirect energy values for inputs such as seed, fertiliser and sprays were estimated based on their use at each site and in each system combined with information on their application rate. The energy values for the seeds and different chemicals were taken from published data (see Helsel, 1987). Whilst it was
Table 3 Typical total energy values (MJ/ha) for a range of equipment including appropriate power units Equipment
Direct energy
Percentage of total
Indirect energy
Percentage of total
Total
Plough Heavy disc Power harrow Seed drill Fertiliser spreader Sprayer
1160 860 840 280 32 51
57 55 53 58 64 60
890 700 750 200 18 34
43 45 47 42 36 40
2050 1560 1590 480 50 85
Source: Derived from Butterworth and Nix (1983), Conoco, personal communication (1996), DLG (1996–1998), Department of Energy (1991), Fluck (1979), Helsel (1987), Leach (1976), Nix (1996), and Swanton et al. (1996).
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possible to determine some specific values for some pesticide active ingredients, in certain cases mean values for pesticide active ingredients were used due to the difficulty of obtaining information on some of the pesticides used. With regard to the above calculations for direct and indirect energy use and thus total energy, it is pertinent to highlight the uncertainty that arises in relation to the estimates as a result of such aspects as field measurements, estimates of energy in construction and different machinery type comparisons. However, given that the calculations for energy use in both the conventional and integrated systems followed the same approach, they do permit a valid systems comparison.
4. Results 4.1. Total energy use The total energy used in each system at each site was calculated based on the summation of the values for direct and indirect energy use. Fig. 1 presents the energy use per hectare at each site for the full 5 years of the rotation and includes all crops grown. This covers direct and indirect energy used in operations and indirect energy use incorporated within the agrochemicals employed at each site. A mean, averaged across all sites, is also given, with the conventional system using 14,667 MJ/ha and the integrated system using 13,428 MJ/ha. This is a difference in total energy input of 1239 MJ/ha, i.e. an 8% saving in total energy input on the integrated system. This is equivalent to
33.5 l/ha of diesel fuel using the standard conversion figure quoted earlier of 37 MJ/l. Fig. 2 shows the percentage change in energy input for all sites and all years for the integrated relative to the conventional farming system. Only one site (SW) expended more energy per hectare on the integrated system, although this was less than a 1% difference, with the other sites showing reductions in energy use in the integrated system ranging from 3 to 17%. The savings in the energy used on the integrated system were primarily achieved through reduced cultivations. In general, ploughing and the associated seedbed preparation, used extensively on the conventional system, were very energy intensive operations and required the highest energy inputs. These were reduced in the integrated system by adopting less intensive cultivations such as a minimum tillage system. Three of the six sites in the experiment (BW, HM and LH) increased the frequency of non-inversion tillage on their integrated system. A fourth site (SW), which had previously not used non-inversion tillage, adopted the practice on its integrated system. Overall, the difference between the two systems in terms of fuel actually consumed during operations was estimated to be 20 l/ha or £3/ha (red diesel price of 15 p/l) as a result of the changes in cultivations, and also taking into account the crops grown and reduced pesticide and fertiliser applications. There were also some differences in the amount of energy use associated with the fertiliser and pesticides themselves, such that reductions at each site in terms of fertiliser and pesticide use are reflected in the overall energy used. At individual sites, however, and
Fig. 1. Total energy use (excluding harvesting) per hectare, all sites, all years, all crops—mean values.
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Fig. 2. Total energy use (excluding harvesting) per hectare, all sites, all years, all crops—mean percentage change integrated to conventional.
for a range of crops there are differences in chemical amounts applied and therefore energy used in some cases favouring the integrated system and in other cases favouring the conventional system. For example, with respect to cereals, and in particular wheat, there was frequently little difference between the amount of fertiliser used at any of the sites. This was also, to some extent, determined by the cereal variety grown. For example, quality wheat and barley were grown on the integrated systems at Boxworth and Pathhead, respectively. This suggests the potential need for greater applications of fertiliser and therefore increased energy use. However, in the case of the Pathhead barley crop this was a spring variety which, along with the introduction of spring oilseed rape in the integrated system, allowed reductions in fertiliser use and therefore energy use to be attained. Spring crops were also incorporated on the integrated system at a number of other sites (HM and LH) with some sites also opting for a switch in crop type away from oilseed crops to pulses (HM and LH). This again allowed for reductions in fertiliser use. Energy use in relation to pesticides was also dependent on the crops grown. Incorporating spring crops within the integrated rotation (HM, LH and PH) allowed reductions in pesticide use and therefore also
energy use. However, reductions were not achieved where potatoes were grown in the rotation (SW, HM and LH) nor where reduced cultivation on the integrated system led to later problems with weed growth as this led to the need for either mechanical weeding or greater use of pesticides. Figs. 3 and 4 illustrate the typical sector inputs in total energy use per hectare for two crops, winter wheat at Boxworth and potatoes at High Mowthorpe. The Boxworth example has been chosen as it demonstrates the difference in energy inputs in the cultivation and crop establishment operations between the two systems. Only two passes were used on the integrated system, the first was a cultivator drill unit followed by simple harrowing. In contrast, there were five passes on the conventional system, including a plough, power harrow, tined cultivator, seed drill and separate light harrow. The figure also illustrates the relativity of seed, fertiliser and pesticide energy inputs against operation energy inputs. In the case of Boxworth, the reduced cultivations led to a serious weed problem resulting in the increased use of herbicides, reflected in the higher energy use in pesticides and spraying. The example also highlights the lack of difference in energy use associated with fertiliser. This reflects the decision of the site leader to grow
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Fig. 3. Total energy use at Boxworth—example of input sectors for one field of winter wheat in 1 year.
quality wheat and high yielding varieties in order to maintain profit margins. The High Mowthorpe example, Fig. 4, is included as a comparison and highlights the difficulties of achieving input reductions with a potato crop. The only reduction achieved is that related to pesticides. At High Mowthorpe this was as a result of reductions in herbicide used, considered a risky decision which in some years did not pay off. Considering all the sites individually, the greatest energy reductions on the integrated system were achieved as a result of reduced cultivations, either through the adoption of non-inversion tillage, such as at Boxworth, and/or the switch to spring cropping, such as at Pathhead. At Boxworth the frequency of non-inversion tillage on the integrated system was over 50% despite the requirement to contain weeds. At Pathhead the reductions in energy use result from the switch to spring cropping in more than one phase of the rotation. It is worth noting that the reduction
in energy use at Pathhead was achieved without the adoption of non-inversion tillage. Substantial reductions in energy use were also achieved at Lower Hope. This reflects the reduced cultivations on the integrated system, although not as substantial as those at Boxworth, in combination with a switch to a spring crop in one phase of the rotation. Set against this is the production of potatoes in one phase of the rotation where it is difficult to reduce energy use in any way. A limited reduction in energy use is also realised at High Mowthorpe and Manydown. In the case of High Mowthorpe, the site manager again faced the problem of reducing inputs in the potato phase of the rotation, but was able to make some reduction, first, as a result of reducing cultivations despite the requirement to contain weeds, and second, switching from a winter oilseed crop to spring beans to reduce the agrochemical input. At the Manydown site reductions in energy input were achieved through small
Fig. 4. Total energy use at High Mowthorpe—example of input sectors for one field of potatoes in 1 year.
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Fig. 5. Total energy (excluding harvesting) per kilogram yield, all years, all crops, by site.
differences in the amounts of fertiliser and pesticides used. Non-inversion tillage was not adopted in the integrated system and there was also no difference between the two systems in terms of the type of crops grown. Finally, the negligible increase in energy input in the integrated system at Sacrewell is a reflection of using the same rotation in the conventional and integrated systems including the production of potatoes in one phase and is in spite of the adoption of non-inversion tillage on the integrated system. 4.2. Energy use in relation to output The results discussed so far have focused on inputs only, with no account taken of crop yields. It is therefore appropriate to examine whether the variation in inputs is reflected in yield. The yields at all sites for all crops were recorded, and for the purpose of this analysis all yields were standardised for relevant moisture contents. The yields of all crops were then considered against energy inputs, again excluding harvesting. The mean values for energy used per kilogram of output are given in Fig. 5. This shows that, overall, there was very little difference in energy values between the conventional and integrated systems when considered on energy input to kilogram of crop yield basis. Slight increases in energy use on the integrated system, however, were seen at Boxworth and High Mowthorpe. This is probably related to the lower mean yields at these sites, where in one phase of the rotation it is the yields of different crops being compared. At Boxworth, there is a winter oilseed rape versus linseed phase where there is a
substantial difference in yield between the two crops which affects the overall picture. At High Mowthorpe there is a winter oilseed rape versus spring bean phase where the beans were low yielding. However, at Lower Hope which has a similar rotation, and despite a bean crop failure in 1 year, this did not lead to increased energy use in relation to output on the integrated system. This is perhaps a reflection of the greater difference between the two systems at Lower Hope in terms of the use of non-inversion tillage, with limited use on the conventional system and more substantial use on the integrated system. Where the rotations incorporate the same crop within both systems (SW, MD and PH) there is little difference between the two in terms of energy use in relation to output. At Sacrewell, the reduction in energy use on the integrated system could again, as with Lower Hope, be a reflection of the adoption of non-inversion tillage in that system as it is not used within the conventional system. At Manydown and Pathhead, where there is a negligible difference in energy use in relation to output, non-inversion tillage is not used in either system for reasons stated earlier.
5. Discussion The above analysis highlights the potential for energy inputs to be reduced on integrated farming systems, in comparison to conventional farming systems, through reductions in cultivations and agrochemical inputs. The operations associated with cultivations and the application of chemicals in agricultural systems are often perceived as being detrimental to the
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environment, and the reduction in their use alongside a corresponding reduction in energy use is likely to be considered beneficial. However, the energy input to output ratio of the two types of system, when considering the mean levels recorded on all sites, suggests there is little difference overall, with the reduction in energy input reflected by a reduction in crop yield. This generalisation, however, must be treated with some caution as findings from individual sites within the experimental project suggest that there might be some potential, through the adoption of more integrated farming practices, for reductions in energy use without corresponding crop yield reductions. In relation to this suggestion, it is the adoption or greater use of minimum, including non-inversion, tillage that appears to yield the greater savings in energy use, although it should be recognised that, for individual farms, reduced cultivations may not always be possible. This is particularly the case where these reduced cultivations lead to difficulties associated with crop establishment and increased weed problems. However, in certain cases, reduced cultivations may prove beneficial in reducing or preventing weed establishment and growth. Furthermore, many “mainstream” farmers are currently adopting or seriously considering the use of minimal tillage systems primarily as a mechanism for reducing costs and/or increasing workrates. In energy terms and also in financial terms, this change needs balancing against any subsequent increase in pesticide usage. As regards fertilisers, which generally have a high energy cost, the differences between the two systems in many instances was not found to be significant. Despite the exclusion of harvesting and subsequent operations from the energy use calculation, consideration was given to the differences in the two systems being compared. In terms of harvesting, there was insufficient data to judge whether harvesting time was significantly different between the two systems studied. Some minor problems with weed growth were reported in the integrated system but not on all sites nor in all years. Some records, again not representing a significant number of sites and plots, suggested that there could have been a slight increase in the amount of drying required for crops from the integrated plots. This could have been due to increased weed populations and possible lodging. It was indicated that this might have resulted in crops being harvested at 1.5–2%
higher moisture content on occasions, but no conclusive evidence was found for this. However, a calculation based on the same approach as for other inputs was made to consider the energy used in harvesting, transport to store, drier use and fuel to dry crops by an additional 3% moisture content, i.e. from 17 to 14%. This suggested that this would add another 5150 MJ/ha to the figures for total energy use in the integrated system. Clearly, the analysis of energy use should also take account of financial information, as that is likely to be of more direct importance to farmers in their decision making. Thus, the costs associated with the operation and inputs and the revenues received for the crops produced need to be compared. This is of particular interest where the difference between the two systems is as a result of a switch from one crop or crop variety to another, and where there is the potential to obtain a greater return from that change, whilst at the same time reducing overall energy use. In this respect, reduced yields in the integrated system may be offset by higher crop prices although this was not the case for the switches from winter oilseed rape to linseed and spring beans (BW, HM and LH). However, where crop varieties on the integrated system were changed with the emphasis on growing better quality crops (BW and PH), financial margins were improved or maintained (see Ogilvy, 2000; Keatinge et al., 1999; Park et al., 1997, 1999). Although energy input in relation to output was similar in both systems, overall energy use was reduced on the integrated system.
6. Conclusions Energy use is now seen as one of the key indicators of sustainable development and was listed in both the UK Governments “Quality of Life Counts” and “Pilot Agricultural Indicators” (DETR, 2000; MAFF, 2000). As agriculture currently accounts for about 5% of national energy consumption, reductions due to changes in farming systems could have an effect on national energy usage. The evidence presented here suggests that integrated arable systems, when compared with conventional farming systems on a per hectare basis, have the potential to reduce overall energy consumption by about 8%, although there was inevitable variation in this measure between the sites studied. Much
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of this saving resulted from reduced cultivation activity, in particular the use of minimal tillage systems. However, when energy use comparisons are made by weight of output, there is little difference between the two systems because of the generally lower yields per hectare under the integrated systems. Thus, initially, at a national level, it appears that a wide-spread adoption of IAFS would mean a reduction in energy use, but it would also result in less overall output. However, if national output was to be maintained under a regime of IAFS, it is clear that a larger area would have to be cultivated using more energy, with the probable result of a neutral energy effect. Furthermore, the surplus land at a national level under the current mainly conventional system, set-aside land, has an increasing value in environmental terms or as a land resource for the generation of bio-energy. In addition, in this series of experiments, the IAFS plots are very much the exception to a “conventional” cropping rule and it could be argued that they might be benefiting from the generally high level of weed and pest control in the surrounding countryside. Although as yet unproven, a significant shift to IAFS at a national level, may lead to a greater pesticide burden in the countryside generally and therefore make it increasingly difficult to maintain the lower levels of pesticide usage associated with the IAFS in this experiment. Overall, it has to be said that this analysis of energy use in integrated arable farming systems does not provide conclusive evidence that the introduction of such systems reduce energy input. However, it has been demonstrated that the systems and their associated practices, particularly the use of minimum tillage, have the potential to reduce energy use although this may mean an increased complexity in making management decisions and creating an increased risk of fluctuations in output. There is also a suggestion that part of the reason for the emergence of this somewhat confused picture is a result of the compounding of a number of factors, inevitable in this type of rotational systems multi-site project. UK arable farmers have been under severe financial pressure for several years (DEFRA et al., 2002). As a result, many have been adopting some integrated techniques (such as less cultivation, more precise fertilisation and the use of reduced dose pesticides) as a mechanism for reducing their costs of production.
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Some of these farmers, for instance, those who have undertaken a LEAF audit, will have considered their energy use in more detail. However, many farmers will not have undertaken a vigorous energy analysis of their cropping operations and, whilst agricultural ‘red’ diesel continues to carry its current fuel tax exemption, the message to farmers concerning the importance of energy saving on farms will remain confusing. Acknowledgements The authors would like to thank those involved in the LINK-IFS Project, particularly the six site leaders for their help in the provision and analyses of data. We are grateful for valuable comments from David Pimental on an earlier draft of this paper. Nevertheless, the opinions expressed here, and conclusions reached, are solely the responsibility of the authors. Financial support from the LINK sponsors, MAFF, SOAEFD, HGCA, Zeneca and BAA, and the MAFF Open Contracting Scheme is also gratefully acknowledged. Appendix A. See Tables A.1–A.4. Table A.1 Frequency of use of non-inversion tillage at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional (%)
Integrated (%)
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
0 28 25 5 0 0
35 56 35 28 0 0
Table A.2 Annual fertiliser nitrogen use (kg N/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
115 148 151 155 144 166
117 117 121 120 129 121
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Table A.3 Pesticide use (units/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
42.55 30.75 40.56 35.20 33.26 24.79
24.54 19.71 31.08 20.17 29.58 15.18
Note: A unit of pesticide is the maximum amount, in grams, of an active ingredient recommended for arable crops.
Table A.4 Average winter wheat yields (t/ha) at the LINK Integrated Farming Systems experimental sites for the conventional and integrated systems, 1993–1997 Site
Conventional
Integrated
Sacrewell Boxworth High Mowthorpe Lower Hope Manydown Pathhead
8.14 9.34 8.15 9.41 7.62 9.17
6.91 8.09 7.45 8.55 7.24 8.96
References Boller, E.F., Malavolta, C., Jorg, E. (Eds.), 1997. Guidelines for integrated production of arable crops in Europe. IOBC Technical Guideline 111, first ed. IOBC/WPRS Bull. 20 (5). Bonny, S., 1993. Is agriculture using more and more energy? A French case study. Agric. Syst. 43, 51–66. Butterworth, W., Nix, J.S., 1983. Farm Mechanisation for Profit. Granada Publishing, St. Albans. Dalgaard, T., Halberg, N., Porter, J.R., 2001. A model for fossil energy use in Danish agriculture used to compare organic and conventional farming. Agric. Ecosyst. Environ. 87, 51–65. DEFRA, SEERAD, DARD, NAWAD, 2002. Agriculture in the United Kingdom 2001. The Stationery Office, London. Department of Energy, 1991. Digest of United Kingdom Energy Statistics. HMSO, UK. DETR, 2000. Quality of Life Counts. Government Statistical Service, London. DLG, 1996–1998. OECD Tractor Test Reports—Various. Germany. Donaldson, J.V.G., Hutcheon, J.A., Jordan, V.W.L., Osborne, N.J., 1994. Evaluation of energy usage for machinery operations in the development of more environmentally benign farming systems. Aspects Appl. Biol. 40, 87–91. El Titi, A., Boller, E.F., Gendrier, J.P., 1993. Integrated production: principles and technical guidelines. IOBC/WPRS Bull. 16 (1).
Fluck, R.C., 1979. Energy productivity: a measure of energy utilisation in agricultural systems. Agric. Syst. 4, 29–37. Helsel, Z.R. (Ed.), 1987. Energy in Plant Nutrition and Pest Control. University of Missouri, Columbia, USA. Higginbotham, S., Noble, L., Joice, R., 1996. The profitability of integrated crop management, organic and conventional regimes. Aspects Appl. Biol. 47, 327–333. Holland, J.M., Frampton, G.K., Cilgi, T., Wratten, S.D., 1994. Arable acronyms analysed—a review of integrated farming systems research in Western Europe. Annals Appl. Biol. 125, 399–438. Jordan, V.W.L., Hutcheon, J.A., 1996. Multifunctional crop rotation: the contributions and interactions for integrated crop protection and nutrient management in sustainable cropping systems. Aspects Appl. Biol. 47, 301–308. Keatinge, J.D.H., Park, J.R., Bailey, A.P., Rehman, T., Tranter, R.B., Yates, C.M., 1999. Assessment of the financial and economic impacts demonstrated by low-input, integrated farm system experiments. Report Prepared for Ministry of Agriculture, Fisheries and Food (under reference CSA 2935). Department of Agriculture, The University of Reading. Konyar, K., 2001. Assessing the role of US agriculture in reducing greenhouse gas emissions and generating additional environmental benefits. Ecol. Econ. 38, 85–103. Lampkin, N.H., 1990. Organic Farming. Farming Press, Ipswich. Leach, G., 1976. Energy and Food Production. IPC Science and Technology Press, Guildford. Leake, A.R., 1996. The effect of cropping sequences and rotational management: an economic comparison of conventional, integrated and organic systems. Aspects Appl. Biol. 47, 185– 194. Loake, C., 2001. Energy accounting and well-being—examining UK organic and conventional farming systems through a human energy perspective. Agric. Syst. 70, 275–294. MAFF, 2000. Towards Sustainable Agriculture: A Set of Pilot Indicators. HMSO, London. Nix, J.S., 1996. Farm Management Pocketbook, 27th ed. Wye College, University of London, London. Ogilvy, S. (Ed.), 1993. LINK Project, Integrated Farming Systems. Annual Interim Report 1993. Ogilvy, S.E., 1996. LINK IFS—an integrated approach to crop husbandry. Aspects Appl. Biol. 47, 335–342. Ogilvy, S.E. (Ed.), 2000. LINK Integrated Farming Systems (A Field-Scale Comparison of Farming Systems), vol. 1 (Experimental Work; Project Report No. 173). HGCA, London. Ogilvy, S.E., Turley, D.B., Cook, S.K., Fisher, N.M., Holland, J., Prew, R.D., Spink, J., 1994. Integrated farming—putting together systems for farm use. Aspects Appl. Biol. 40, 53–60. Panesar, B.S., Fluck, R.C., 1993. Energy productivity of a production system: analysis and measurement. Agric. Syst. 43, 415–437. Park, J.R., Seaton, R., 1996. Integrative research and sustainable agriculture. Agric. Syst. 50, 81–100. Park, J.R., Farmer, D.P., Bailey, A.P., Keatinge, J.D.H., Rehman, T., Tranter, R.B., 1997. Integrated arable farming systems and their potential uptake in the UK. Farm Manage. 9, 483–494.
A.P. Bailey et al. / Agriculture, Ecosystems and Environment 97 (2003) 241–253 Park, J.R., Bailey, A.P., Yates, C.M., Keatinge, J.D.H., Rehman, T., Tranter, R.B., 1999. Do integrated arable farming systems provide a more sustainable form of agricultural production in the UK? Farm Manage. 10, 379–391. Pervanchon, F., Bockstaller, C., Girardin, P., 2002. Assessment of energy use in arable farming systems by means of an agro-ecological indicator: the energy indicator. Agric. Syst. 72, 149–172. Pimental, D., Hurd, L.E., Belloti, A.C., Forster, M.J., Oka, I.N., Sholes, O.O., Whitman, R.J., 1973. Food production and the energy crisis. Science 182, 443–449. Swanton, C.J., Murphy, S.D., Hume, D.J., Clements, D.R., 1996. Recent improvements in the energy efficiency of agriculture: case studies from Ontario, Canada. Agric. Syst. 52, 399–418. Taylor, A.E.B., O’Callaghan, P.W., Probert, S.D., 1993. Energy audit of an English farm. Appl. Energy 44, 315–335. Vereijken, P., 1992. A methodic way to more sustainable farming systems. Neth. J. Agric. Sci. 40, 209–223.
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Vereijken, P., 1994. Designing Prototypes. 1. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and associated countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO, p. 87. Vereijken, P., 1995. Designing and Testing Prototypes. 2. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and associated countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO, p. 90. Vereijken, P., 1996. Testing and Improving Prototypes. 3. Progress Reports of Research Network on Integrated and Ecological Arable Farming Systems for EU and Associated Countries (Concerted Action AIR 3-CT920755). Wageningen AB-DLO. Vereijken, P., 1997. A methodical way of prototyping integrated and ecological arable farming systems (I/EAFS) in interaction with pilot farms. Eur. J. Agronom. 7, 235–250.