Sustainable Land Use by Organic and Integrated Farming Systems

Chapter 1.2

Sustainable Land Use by Organic and Integrated Farming Systems H.J. Reents, B. Küstermann and M. Kainz

1.2.1 Organic farming system in Scheyern Principles The design of organic farming systems and their cultivation measures are based on the knowledge of the structural elements and functional relationships in natural ecosystems. Existing relationships are supported and strengthened under the ecological approach with the target to make food production efficient. The design of the farming system in Scheyern mirrors various principles of natural ecosystems. Food cycles and mass fluxes were considered in crop rotation patterns and livestock keeping. The input of materials from industrial processes was avoided or kept on a very low level. Inputs, vital for growth, had to be provided by biological processes (e.g. N2 fixation, mobilisation of minerals). Means for the control of pathogens as well had to be of natural origin. Diversity schemes in crop production were designed to contribute to the conservation of regulatory cycles, especially with a view to pathogens and weeds. However, the Perspectives for Agroecosystem Management Edited by P. Schröder, J. Pfadenhauer and J.C. Munch Copyright © 2008 Elsevier B.V. All rights reserved.

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temporal and spatial dominance of some species (cash crops) may seem contradictory to this objective, but it is necessary for food production. A special criterion is the recognition of an intrinsic value of animals and thus the organisation of livestock keeping in a way that would safeguard their requirements. The mentioned principles of ecological farming were implemented by agronomic measures (Auerswald et al., 2000). Design and utilisation of agro-ecosystems were adapted to the tolerance and productivity of the given sites (natural, human and economic resources). Part of this adaptation was the establishment of crop rotations with an essential share of legumes, which brings atmospheric nitrogen into the system. The resulting N and C accumulation should help maintain or even raise the humus content in the soil. Above this, crop rotations combined with tillage were able to control weed infestation and plant health. To keep soil compression as low as possible, it was controlled by crop rotation and appropriate machinery (e.g. wheel load). Only farming systems with livestock and own forage production are able to fully implement the principle of nutrient cycling and exploit it with high flexibility. Stock management and feed composition were organised with attention to the natural behaviour of the animals and their feed preferences. Diseases and pests had to be handled exclusively by measures of system management or by substances issued from natural or biological processes. Purposeful farmscaping was to supplement the ecological measures on the operated area (Altenweger et al., 1998; Furchtsam et al., 1995, 1996; Gerl et al., 1999; Gerl and Kainz, 1997, 1998a, 1998b; Hofmann, 2005; Kainz et al., 2001, 2002; Reents et al., 1999; Weller et al., 2000; Weller and Kainz, 1999). Structural design of the organic farm in Scheyern The total area of the farm Scheyern was subdivided between the two farming systems with regard to the water catchment borders. Organic farming was executed on the more sandy and non-arable sites (grassland), as typical for the region (too steep or wet and close to waters). To follow the principles of site-specific farming with nutrient cycling, the grassland was used as pasture. Mother cow keeping with ‘baby beef ’ production was set up including grazing in summer and in-house feeding in the winter months. Keeping dairy cattle, which would have fit the farm structure much better, was not possible for organisational reasons. To implement the principle of nutrient cycling, livestock was of central importance. During the grazing period, a short cycle developed with the chain pasture–animal– dung–pasture. Nutrient export due to increasing stock numbers was relatively small; however, the behaviour of the animals led to a redistribution of matter within the grazed area. In arable farming, ruminant keeping requires forage legumes in the crop rotation as precondition for N and C

1.2.1 Organic farming system in Scheyern C and N input

19

farm border fodder

C and N

fodder

input

grassland

stable

manure

field

manure

C and N losses

C and N losses

Figure 1 C and N fluxes in the organic farm in Scheyern.

supply to the field. The wider mass flux on farm level included the production of forage on fields and grassland and its transport to the stable. Via the excreta output in the stable period in winter, when feed preserves were given, nutrients and organic matter were brought back to the cropping areas (Figure 1). Even when publications about organic farming often refer to this mass flux on farm level as closed mass cycle, additional matter is supplied by the plants (N2 by legumes, CO2 fixation, mineral mobilisation by plant roots), or losses occur in husbandry (weight gain of animals for the market, N and C loss from stable dung) and the soil (i.e. nitrate leaching, N2 by denitrification). Therefore, management measures had to be oriented on a long-term extension of the mass cycle without increasing losses, thus supporting and even improving the productivity of the farm. Crop rotation pattern After the decision had been taken in favour of a farming system with livestock keeping, the essential element for implementing ecological principles by management measures was the design of the crop rotation. The crop rotation pattern had to meet numerous demands which can be summarised as follows: It was necessary to provide the feed basis for livestock. The input of farmyard manure and the cultivation of legumes were the basis for corresponding yields of cash crops. The succession of root crops, cereals and green manure crops led to an alternation of humus degradation and accumulation. This alternation favoured soil conservation and

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plant diversity. Last but not least, the call for the provision of a broad variety of foodstuffs for the population was to be satisfied. In view of the outlined criteria, the following rotation pattern for the main crops was designed and implemented in the years 1992–1994: Lucerne-clover-grass mix–potato–wheat–sunflower–lupin–wheat–rye. This crop rotation presupposed an optimal N2 fixation on both legume fields, together with the grown catch crops. The lupin fields, however, had to be abandoned because of increasing development of anthracnosis, which lowered the productivity and favoured strong weed growth with additional volunteer sunflowers. So this crop rotation field was substituted in 1995 also with lucerne-clover-grass. Table 1 shows the final crop rotation (lucerneclover-grass mix–potato–wheat–sunflower–lucerne-clover-grass mix– wheat–rye) with an evaluation of the ecological and economic target values. The decisive criterion for evaluating the sustainability of arable farming is the nitrogen cycle (Figure 2) of the crop rotation in combination with livestock keeping. The main source of nitrogen supply was N2 fixation in the two rotation fields under lucerne-clover-grass. The fixed nitrogen was transferred to the stable via the N accumulated in the soil on the one hand and, to the larger extent, via the forage on the other; from there as solid and liquid manure to the subsequent crops in the rotation. The nitrogen fixed in catch crops was transferred to the subsequent crops in the rotation mainly via the humus pool in the soil. The nitrogen gain from the atmosphere was counter-effected by the export of N in cereals, potatoes and animal products sold on the market. In addition to this, losses occurred in the stable or during the spreading of organic fertiliser, mainly in gaseous state as NH3 and N2, or in the field in form of nitrate after intensive tillage. Both loss potentials can be reduced by improved management measures (Rühling et al., 2005). Tillage The objective of sustainable and soil-conserving management requires, in addition to crop rotation, soil preparation in such a way that the best preconditions are provided for both plant growth and soil conservation (Figure 3). The establishment of lucerne-clover-grass sown under rye or sunflowers allowed to omit one basic tillage operation to each crop. The purpose was to achieve a better biological structure of the soil. Earthworms had more time to create biopores and found an increased food supply in form of crop residues at the surface. For potatoes, wheat after clover-grass and winter rye, ploughing was carried out to a depth of 26–28 cm. Thus, the root layer was loosened and provided a maximum root–soil contact. Simultaneously, organic matter was incorporated into the soil (lucerne-clover-grass or stable manure), and

1.2.1 Organic farming system in Scheyern

21

Table 1 Crop rotation of the organic farm beginning in 1994/1995 and the agronomic, ecological and economic target values. Year

Main crop

Intercrop

1

Lucerne-clover-grass

2

Potatoes

Sowing of mustard into the potato crop, early August till harvest in September

3

Winter wheat

Legume mixture

4

Sunflowers

Undersown lucerneclover-grass

5

Lucerne-clover-grass

6

Winter wheat

7

Winter rye

Undersown lucerne-clover-grass

Target values Forage production, N2 fixation, weed control, humus formation, subsoil developing, soil conservation High sales revenue, reduction of deep-rooted weeds, nitrate uptake, soil and groundwater protection, easier harvesting Sales revenue, straw for bedding, weed control, N2 fixation, humus formation, soil conservation Sales revenue, K uptake from the subsoil, feedstuff (pressed cake), soil conservation, early yield of forage Forage, N2 fixation, humus formation, weed control, subsoil opening, soil conservation Sales revenue, straw for bedding Sales revenue, straw for bedding, weed control, nutrient decomposition, early and increased productivity of forage crops, soil conservation

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NH3

Clovergrass mix

NH3 Rye

Potatoes

UCr clovergrass

NO3 Wheat

Wheat

Intercrop

NO3

Sun flowers

Clovergrass mix

UCr clovergrass mix

N2fixing crop

N-transfer by manure

N-export by harvest

N transfer in soil

N-transfer by forage

N transfer in-house

Figure 2 Essential N fluxes within the crop rotation und at interfaces to livestock keeping in organic farming in Scheyern. Soil rest

Clovergrass mix Rye

Ploughing Potatoes

UCr clovergrass mix

Rotory cultivator

Ploughing

Wheat Wheat

Intercrop Ploughing

Ploughing Sunflowers Clovergrass mix

UCr clovergrass mix Soil rest

Figure 3 Tillage in the crop rotation.

1.2.1 Organic farming system in Scheyern

23

competitive weed growth was reduced. To avoid an incorporation of not picked up potatoes, which would occur as volunteers in the successive crop, soil preparation between potatoes and wheat was made with the rotovator without turning the soil up. Crop-related cultivation technologies – Lucerne-clover-grass Main targets of lucerne-clover-grass cultivation were forage yield and N2 fixation; secondary targets were weed regulation, humus formation, erosion control, and subsoil opening. The seed mixture of the three main components lucerne, clover and grass allowed to make use of their specific needs of growth and of the different ecological responses. Under the heterogeneous site conditions in Scheyern, this helped stabilise crop yields; with 17.6%, the variation coefficient was lower than in the other crops of the organic crop rotation. In drought periods, for example, particularly lucerne on sandy sites was still able to develop enough biomass, whereas for the other crops (except for some grass species), water supply was not sufficient. In wet periods and on wet sites, however, clover and most grasses grew better than lucerne. The lucerne-clover-grass mix was used as overwintering crop, usually sown under rye in spring. Undersowing was generally successful. Beginning in 1998, the forage mixture was already sown together with rye in autumn. This improved plant establishment, mainly of the grass component. In some years, however, rye tended to lodge, and the undersown crop developed excessively. This was favourable for lucerne-clover-grass, but outgrowth occurred in rye. After the harvest of rye cover, one or two cuts of the forage were taken, in the main harvest year even three. When the mixture was sown under sunflowers, the forage population developed weaker than under rye due to more shading and the later harvest of the sunflowers. No problems were recorded with the sunflowers. The forage crop could not be used in the sowing year because of the sunflower stalks; they had to be mulched in autumn or winter. Then the undersown crop used to grow better than in case of resowing in spring, when especially lucerne reached maturity rather late. When three cuts per year were taken on average, 79–131 dt DM ha⫺1 were harvested (mean level: 99 dt DM ha⫺1) (Table 2). With underseed, forage yields of 16 (minimum) to 53 (maximum) dt DM ha⫺1 or 30 dt DM ha⫺1 on average were achieved after the cereals had cleared the field, which demonstrates the importance of this cropping technology for the forage output. The lucerne-clover-grass mix was ploughed under as close as possible before the successive crop, that is, immediately before wheat sowing in autumn or before potato planting in winter or spring. For the purpose of site-specific tillage, operations on heavy soils with the tendency to lump formation were postponed to the winter (January), and on light soils with a tendency to leaching to spring.

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Table 2 Yields (dt ha⫺1) and coefficient of variation (CV) of the main crops in the organic farming system in Scheyern.

Average Median Maximum Minimum CV (%)

Lucerneclovergrass main crop

Lucerneclovergrass undersown

98.9 101.3 131.0 78.8 15.9

30.3 27.9 53.0 16.5 36.1

Potatoes Winter wheat

238.8 205.0 342.0 137.1 28.6

37.3 35.2 58.9 21.3 27.0

Spring wheat

Rye

Sunflower

31.5 33.4 35.6 25.0 14.5

37.7 36.9 65.8 28.5 26.7

26.9 26.0 33.0 19.8 18.1

Potatoes Main targets of potato cultivation were maximum yields and high revenues from the sale of seed potatoes; secondary target was controlling deep-rooted weeds. Potato varieties were selected according to the demand in the market, supported by own experience gathered in running projects on potato growing. The nutrient supply was guaranteed by the pre-crop lucerne-clover-grass, supplemented by about 300 dt ha⫺1 stable manure. The seed potatoes were pre-germinated and planted as early as possible, mostly not before the end of April. Weeds were regulated mechanically in two to four operations with a roller hoe. Depending on prognosis and infestation, Cu preparations were applied against late blight (Phytophthora infestans) and Bt (Bacillus thuringiensis) against the Colorado beetle. Since the production target were seed potatoes, the crops were routinely checked for virus attacks; seriously infested plants were eliminated. Till the year 2001, the foliage used to be cut at the end of July and beginning of August, to restrict the size of the seed tubers and to avoid P. infestans spores to be washed in. In addition to this, till 2001 mustard was intersown in order to absorb nitrate from the soil, to cover the ground and thus protect it from erosion, and also to suppress photophilic problem weeds such as common chickweed (Stellaria media), to crumble the soil and to produce green biomass. Harvesting took place not before early September to give the tubers enough time for developing sufficient firmness of the skin. After the machine harvest, the seed tubers were stored in pallet boxes in a computer-controlled storehouse and later, in the winter months, graded and bagged. Throughout the years, the yields varied between 167 and 342 dt DM ha⫺1 (maximum); the mean yield was 239 dt DM ha⫺1 (Table 2). Thus, they ranked on the level of the potato yields obtained in organic farms in the years 2000–2002 However, it must be remembered

1.2.1 Organic farming system in Scheyern

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that here seed potatoes were propagated, which requires that plant growth be stopped at a defined size of the tubers. The annual yield differences were caused mainly by the weather conditions. In wet and cool years, yields tended to be below average, and in warm and dry years above average. Wheat Main targets of wheat cultivation were high yields and sales revenues for seed propagation; secondary target was straw for animal bedding. Wheat varieties were selected according to demand, experience gathered in own experiments, rating in other tests and the ‘list of varieties’. Wheat occupied two positions in the crop rotation, after potatoes (root crop) and after annual lucerne-clover-grass. In some years, winter wheat had to be substituted by spring wheat due to inappropriate soil conditions at the moment of sowing (wetness). After potatoes, the field was worked with the cultivator (non-turning soil preparation, to let remaining potatoes freeze in the winter) and then wheat was sown. The lucerne-clover-grass mix as pre-crop was ploughed under just before sowing. Depending on sowing time and soil conditions, 350–420 germinable grains were sown per square metre. Weed control was performed with a spring tine weeder. One operation was scheduled in autumn and one or two in spring; the exact processing depended on the conditions in the given year. Intersowing white clover together with the last combing operation as done in the first years was given up in favour of an intensive mechanical control of couch grass after harvest. The yields of winter wheat varied between a minimum of 21.3 dt ha⫺1 in 1994 and a maximum of 58.9 dt ha⫺1 in 1996; averaging the years, a yield of 37.3 dt ha⫺1 was achieved (Table 2). Spring wheat, which was grown five times on different fields throughout the years, reached 31.5 dt ha⫺1 on average. Thus, yields corresponded to the level cited in the ‘agricultural reports of the federal government’. Since in organic farming, crop rotation is the decisive element for controlling the yielding capacity, it was especially interesting to compare wheat yields after different pre-crops. It turned out that the mean yields throughout the years were by 10% increased after lucerne-clover-grass compared with potatoes as pre-crop (Table 3); also was the variance slightly lower (CV). Thus, in single cases, lucerne-clover-grass can be regarded as the more favourable pre-crop, but its position in the crop rotation must finally be determined on the basis of the overall performance of the system. The production target ‘higher-than-average yields’ was reached in some years only; usually, the mean level of organic farming was reached. Seed material, however, brought higher prices than wheat as cash crop for consumers’ nutrition.

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H.J. Reents et al. Table 3 Wheat yields (dt ha⫺1) and coefficient of variation (CV) after the pre-crops potatoes and lucerneclover-grass in the years 1994–2004. Pre-crop potatoes

Pre-crop lucerne-clover-grass

36.1 33.9 57.9 18.1 32.9

40.0 37.7 61.9 23.9 28.5

maximum average median maximum minimum CV (%)

Rye Main targets of rye cultivation were high yields and sales revenues for seed propagation till 2001; secondary targets were straw as bedding material, cover crop for undersown lucerne-clover-grass, weed suppression, nutrient decomposition, and soil conservation. Varieties were selected according to demand and rating in comparative variety trials. The cultivation technology was elaborated step by step under the guidance of the research association for agro-ecosystems, the FAM. At the beginning, sowing was performed in early October, as usual in the region. The forage crop was undersown in spring. After some years of project running, sowing was moved up to the first decade in September with simultaneous intersowing of the undercrop. This method favoured the pre-winter development of rye and a reliable growth of the undercrop. There was, however, a higher risk of lodging. In 2004, yields were extraordinarily high (65.8 dt ha⫺1). In other years they ranked between 40.8 and 28.8 dt ha⫺1; the mean yield was 35 dt ha⫺1 and thus only slightly lower than in case of winter wheat (Table 2). Sunflowers Main targets of sunflower cultivation were oil yield for human nutrition and thus high sales revenues; secondary targets were flowering in the crop rotation, an aesthetic landscape effect and K uptake from the subsoil. Sunflower varieties were selected according to rating in the ‘list of varieties’. The seed rate was 7.5–8 grains m⫺2, sown by mid-April. In the beginning, the inter-row distance was 37.5 cm (uniform seed spacing), later 50 cm and finally 75 cm, to provide longer penetration of light and, resulting from this, a better development of the undercrop. Weed management shifted from two harrowing and two hoeing operations to harrowing before the emergence of the sunflowers with simultaneous intersowing of the undercrop. At the moment of emergence, field borders were treated

1.2.1 Organic farming system in Scheyern

27

with burnt lime to prevent slugs from immigrating. Dock plants were removed by hand. Grain yields varied between 19.8 and 33.0 dt ha⫺1, the mean was 26.9 dt ha⫺1 (Table 2). Livestock and grassland management The concept of organic farming in Scheyern, i.e. matter cycling, N supply and site-specific use of fields, could only be successful in combination with cattle husbandry. For breeding, a herd of Simmenthal cows was established. A German Angus bull was purchased for crossing to get calves with higher meat yield and meat quality. The calves were sold as baby beef with about 450 kg live weight. In the first years, as typical for the region, the animals were kept on pasture in summer and in-house in winter, where mainly silage from the own forage fields was fed. The housing system was an open stable with deep bedding for resting and a non-roofed paddock with feeding table. In the course of the FAM experiment, cattle keeping was adjusted to the possibilities offered by the system, which means increased forage output thanks to changes in the crop rotation (lupins replaced by a second lucerne-clover-grass field) allowed to raise stock numbers and to intensify feeding. In 1996, the animals were divided into two herds: (1) the herd of mother cows with their calves of 1/2 to 3/4 years, which in the vegetation period were kept exclusively on grazing and in winter in the stable, and (2) the herd of weaning calves which in summer were sent out to pasture for hours and in winter housed in a separate stable with deep bedding, paddock and outside feeding until they had gained the final fattening weight of 600 kg. On January 1, 1999, the herd of breeding cows included 29 cows, 1 heifer and 17 calves; the mean age of the cows was 7.8 years with a span from 3 to 13 years. By the end of 2000, 32 mother cows and 26 calves were kept. The herd of weaners for fattening comprised 45 animals. Feeding and grassland productivity In summer, the herd of breeding cows was kept on rotational grazing on 28 different meadows. Plant cuts not needed for grazing were preserved for winter feed in form of silage and hay. The grassland yields were determined on the basis of the forage cuts taken for ensiling and hay making on the one hand and animal performance (subsistence need and meat gain) on the other. With 68 and 74 dt DM ha⫺1, respectively, averaging the years (Table 4), yields ranked on the normal level of the site; the recorded deviations resulted mainly from varying precipitation. When we consider the yield level, it must be remembered that the grassland got no fertiliser, which means that plant regrowth was mainly stimulated by the share of legumes and on pasture by the return of nutrients in excreta and urine from the grazing animals.

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H.J. Reents et al. Table 4 Mean dry matter yields (dt DM ha⫺1) and coefficient of variation (CV) of grassland in the organic farming system.

Average Median Maximum Minimum CV (%)

Pasture

Meadow

62.2 61.8 71.7 48.2 9.0

64.9 67.5 84.7 47.1 20.2

1.2.2 Integrated farming system in Scheyern Principles Integrated farming comprises cropping methods and other agricultural production techniques which fulfil both ecological and economic demands. Suitable methods of agronomy and crop production are to be harmonised in compliance with site specifics. The farmer has to adjust his management measures concerning variety selection, crop rotation, cultivation technology, plant nutrition and plant protection to the natural environment. This also includes an optimal soil conservation, for example, by environment-friendly management systems and purposeful fertilisation and pest control. At the same time, it must be excluded that groundwater and surface waters as well as adjacent biotopes become polluted by matter input; typical landscape elements are to be safeguarded. The selection of pesticides depends on the degree of ecological tolerance and their application on economic considerations (http://www.bauernhof.net, 2006). Structural design of the integrated farming system in Scheyern The integrated farm was established as arable farming system with cattle fattening on a very limited grassland area. Farms of this type with all their typical problems such as handling of liquid manure or the cultivation of maize are frequent in the region. Integrated Farm Scheyern was established in view to reduce negative impacts on the environment and to find possibilities for the optimisation of the operational result with the goal of high yields. There was no cattle fattening within the farm boundaries; it was simulated by corresponding mass fluxes. Cattle fattening was assumed on the basis of feeding maize silage, farm-produced cereals and the external purchase of protein-supplemented feed. The animals were supposed to stand on slatten floors as common. This allowed storing the collected liquid manure up to 6 months before spreading it on the fields in

1.2.2 Integrated farming system in Scheyern

29

spring or summer. The roughly 25% maize in the crop rotation corresponded to 45 bulls per year and to a calculated output of liquid manure of about 18 m3 ha⫺1 a⫺1 arable land. Crop rotation in such a system has to satisfy the following demands: The forage output for cattle fattening should be sufficient and of high energy content. Good profit should be gained from other cash crops. Since mainly the row crops maize and potatoes were able to fulfil these two criteria, cultivation had to be oriented on soil and environment protection to the highest possible extent. Resulting from this, the following crop rotation was established (Table 5). The principles of the farm management design and the objective of the crop rotation were to be implemented by the following agronomic and cultural measures. For reducing erosion in winter wheat cropping, attention was paid to an optimal sowing time and to sufficient pre-winter development of the plants. Non-turning tillage should leave the straw on the ground as long as possible to reduce water flow-off. Prior to the row crops maize and potatoes with their high erosion potential, a cover crop had to provide a protective layer on the field in the juvenile phase of the crops. Fertilisation as well had to be adapted to the site-specific and agronomic conditions. Thanks to the preceding management measures in the former

Table 5 Crop rotation of the integrated farm and related agronomic, ecological and economic target values. Main crop

Intercrop

1

Maize

2

Wheat

Summer ridges for potatoes with Intersowing of mustard

3

Potatoes

4

Wheat

Intersowing of mustard in summer after clearing the potato foliage Mustard as undercrop

Target values Basic feed supply for cattle fattening, energy for the feed ration Sales revenue via yield and quality, erosion control in the potato crop of the following year ⫽ dam stability High sales revenues, soil conservation, nitrate uptake Sales revenue via yield and quality, erosion control in winter and spring, after maize sowing

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years and a good storage capacity of the soils, P and K were sufficiently available. Liming, however, was necessary. N fertilisation had to be coordinated with the system of reduced tillage, this involved partially higher N doses than in a system with ploughing. The continuously declining S immissions made sulphur supplies to wheat necessary. The application of fungicides had been planned in such a way that the given yield potential could be guaranteed. Spraying rates were reduced by combining them with liquid fertilisers. Residual weed plants were tolerated if problematic species (cleavers, creeping thistle) were thoroughly controlled. The technological objective was a largely soil-conserving passage on the ground, executed by the combination of different machine operations with wheels as broad as possible and low pressure of the tyres (Altenweger et al., 1998; Furchtsam et al., 1995, 1996; Gerl et al., 1999; Gerl and Kainz, 1997, 1998a, 1998b; Hofmann, 2005; Kainz et al., 2001, 2002; Reents et al., 1999; Weller et al., 2000; Weller and Kainz, 1999). Crop-related cultivation technologies – Wheat Main targets of wheat cultivation were high yields and revenues from seed propagation. Varieties were selected according to demand and rated according to ‘list if varieties’. Tillage for wheat sowing was guided by the idea of soil conservation with pre-crop–related decision of the single measures (Table 6). The basic implements were cultivator, rotary harrow and seed drill. Desirable was a sowing date (first decade of October) that allowed the plants in most years to reach EC 23 in autumn. Thus, the soil surface Table 6 Cultivation of winter wheat after different pre-crops.

Tillage

Criteria of tillage

Ground coverage

After potatoes

After maize

Directly before wheat sowing, in case of early potatoes directly after harvest Loosening wheel tracks without turning the soil, maximum depth 10–12 cm, levelling Intersowing mustard into the ridges before harvest left plant residues on the ground surface (maximum 20% ground coverage).

Directly before wheat sowing

Loosening wheel tracks without turning the soil, levelling Mais stubble mulching, remaining stalks should be incorporated (Fusarium re-infection), ground coverage by root residues

1.2.2 Integrated farming system in Scheyern

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became rather resistant against erosion, and overwintering was more successful with a prolonged tillering phase and better ear differentiation. In years, when the weather conditions did not allow sowing in autumn, spring wheat was grown. The seeding rate varied depending on the date between 250 and 320 (400) germinable kernels per square metre, this quantity was increased by 10% when poor emergence was expected. Besides the current demand on the market, the following criteria were important for variety selection: (1) broad resistance spectrum, especially to Fusarium and ear diseases and (2) yield components: single-ear type, rather long and stable. From 1993 to 1997, Atlantis and then Petrus were grown. The exceeding of threshold values was rather likely for Septoria tritici and Drechslera tritici-repentis. The seed material was dressed with a preparation that acted also against dwarf bunt. Liquid cattle manure, an all-nutrient fertiliser produced by the farm system, had to be integrated into the fertilisation scheme despite its difficult handling. Particular attention was paid to spreading the liquid manure at lowest ammonia loss and towards the highest possible use efficiency of the crop. According to the management scheme, 22 m3 ha⫺1 had to be applied to wheat. The spreading required a ground with good trafficability in order to carry the corresponding axle loads. Frosty days were avoided to evade damages of the wheat plants by cauterisation. In the late stage of tillering, nitrogen was to be provided via liquid manure. After spreading, cool and moist weather was desirable to keep NH3 emissions low. Liquid manuring involved the risk of covering the weed plants up, which might reduce the efficiency of herbicide applications within a space of up to 3 weeks. By the time, the following approach turned out to be optimal: The first N dosis was given as mineral fertiliser by about mid-March, the second as ammonium-urea solution together with herbicides (reduced application rate), and roughly 1 week later liquid manure, but not later than to EC 30, distributed by a 15 m drag hose spreader. The ammonium N contained in the liquid manure was used by the crop to 100%; the total nitrogen appeared in the balance sheet to 100% after the deduction of losses (model calculations). Mineral fertiliser to wheat was given mainly in form of nitrogen (Table 7). Plant protection measures were sometimes combined with the application of low Mg or Mn doses, depending on the weather situation. The dosage of N fertiliser was determined in view of the expected removal. In the juvenile stage (to EC 30), fertilisation was carried out very carefully to avoid excess inputs which might lead to uncontrollable plant growth. As from EC 31, dosage was oriented on the site- and weather-specific yield optimum. Uptakes of 120–200 kg N ha-1 by the plants required a supply of 130–190 kg N ha⫺1. Active agents were used which could control the existing weed flora and, combined with AU fertilisation, tolerated reduced application rates. On some subfields, cleavers (Galium aparine), creeping thistle (Cirsium

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Table 7 Mean N rates to winter wheat on the example 1999, (kg N ha⫺1).

First N Second N Third N Fourth N Total

Stage

Fertiliser type

kg N per hectare

Early vegetation Tillering EC 31/32 EC 39

AU solution Liquid manure AU solution AU solution

40 33 50 50 173

arvense) and, beginning in 2000, bindweed (Convolvulus arvensis) in their later growth stages were fought, depending on the need. To a certain degree, grass weeds (wind grass) and other weeds were generally tolerated. The cultivated crops were comparatively stable, medium high with a long distance between flag leaf and spike. Nevertheless, lodging resistance was stabilised with CCC, and side shooting was supported. As common, 0.5 l ha⫺1 CCC was applied to EC 21–25 and 0.3 l ha⫺1 to EC 30–31. The second dose of 0.3 l ha⫺1 CCC was applied irrespective of temperature. It should retard the main shoot and induce a uniform development of side shoots. The grain moisture content at harvest was always below 15.5%. Between 1993 and 2004, wheat yielded 69.6 dt ha⫺1 on average with a range from 40 to 88 dt ha⫺1 (Table 8). When we ignore the low yield in 2003, which was caused by the special long summer drought, the yield trend throughout the test period was rising. Besides enriched experience and knowledge on farm management, a certain adjustment of the site to non-ploughing soil-conserving tillage may also have attributed to this trend. In the integrated system as well, wheat was sown after two different pre-crops, potatoes and maize. A 10-year comparison showed that the mean wheat yields after potatoes exceeded those after maize by 10%; the yield stability as well was increased (Table 8). Extreme levels in the crop rotation were recorded after maize. The reasons for the superiority of potatoes as precrop might be the good aeration and mixing of the soil during the tuber harvest despite rather soil-conserving seedbed preparation. Deficiencies of maize are the increased production of high-C root and plant residues, less soil aeration by and after harvest and a higher pressure of fungi on the subsequent wheat population. Straw was regarded as valuable humus resource (⬎50% of the humus supply). It was chopped (⬍8 cm) by the combine in the field and left there. As cover material or after shallow incorporation, it helped reduce erosion and offered food for earthworms, thus contributing to a favourable soil structure. Despite these measures, straw manuring could not compensate the humus balance. Soil preparation before mustard sowing as pre-crop

1.2.2 Integrated farming system in Scheyern

33

Table 8 Wheat yields in the period 1994–2004 (dt ha⫺1) and coefficient of variation (CV), differentiated for the pre-crops potatoes and maize.

Average Median Maximum Minimum CV (%)

Pre-crop potatoes

Pre-crop maize

76.0 75.9 89.2 61.0 12.2

68.4 65.9 97.0 51.3 19.5

was performed with a cultivator by not later than August 20, to guarantee sufficient plant development before the winter. Maize Main targets of maize cultivation were high mass and energy yield for bull feeding. In some years, silage maize was substituted by grain maize for experimental reasons. Then, the main target was maximum grain yields. Secondary target was soil and groundwater conservation. Varieties were selected according to the ‘list of varieties’. Maize as row crop in the Tertiary Hills with slopy fields and partially high percentage of silt in the soils involved a high risk of erosion. Above this, necessary herbicide applications in the early growth stages represented a serious danger of xenobiotics input into surface water and groundwater. Therefore, ‘soil and groundwater conserving cultivation’ as secondary target was a special criterion for the cultivation technology. Soil preparation for maize sowing already took place in the summer of the preceding year and included a shallow incorporation of straw and one passage of the cultivator (see the subsection ‘Wheat’). After this, the mustard stand was established whose main purpose was to protect the soil: root development in autumn, ground coverage and protection against erosion under maize in spring. Maize was sown into the (frost-killed) intercrop without additional soil preparation using a slotted precision drill (for example, from F.A. Becker, Kleine). Soil preparation and sowing technique were aimed at reaching ⬎50% soil coverage. The frosted mustard plants formed the upper layer, below which residues of the wheat straw from the preceding year were present. The target could not be reached in all years because the mustard plants had not always reached the required length in autumn. Sowing was performed at a soil temperature of ⬎8⬚C in a depth of 5 cm, in moist soil rather shallow, in dry soil 4–5 cm deep. The seed material had been dressed with Thiram and Mesurol (against frit fly

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and phytophagic pests). In view of the defined targets, variety selection required special attention of certain growth characters influencing yield formation (total DM, MJ NEL ha⫺1), stable resistance and share of cobs. The fact that the crop rotation included two wheat links made resistance to Fusarium a further important criterion in the variety selection. Our approach was based on the assumption that maize removes from the soil about 220–250 kg N and 50–60 kg P. In some years, about 30 m3 manure ha⫺1 were given to the pre-crop before maize (this is equal to 90 kg total N). In the following spring, about 120 kg N was given as mineral fertiliser. There were also years when no liquid manure was given to the pre-crop at all. In such cases, liquid manure was spread in maize up to a plant height of 60 cm using a high-clearance tractor. Under the normally growing mustard pre-crop, shatter grain and unsown weeds emerged, which made it necessary to apply a total herbicide in spring. The general goal was to keep the populations free of weeds from the 3-leaf to the 10-leaf stage. Mechanical measures were not used. Control measures against fungus attack and insects were not necessary. Harvesting took place with self-driven choppers which blow the chopped material to accompanying trailers. The resulting soil compaction had to be considered in soil preparation for wheat. Initially, it was planned to grow silage maize for bull fattening. Because of the fact that these bulls were not kept in the regarded farm, in some years different reasons led to the change in the production target in favour of grain maize (experiments, production technique). Grain maize yielded from 70 to 111 dt ha⫺1 with 87 dt ha⫺1 on average. The yields of silage maize varied over the regarded period from 737 to 327 dt ha⫺1 with a mean yield of 493 dt ha⫺1 (Table 9). It becomes evident that the yields of silage maize varied much more than the grain yields; nevertheless, the former were clearly rising throughout the regarded period, which, similar to the situation in cereal growing, can be explained by the adaptation of the site to improved agronomic aspects. Potatoes Main targets of potato cultivation were high sales revenues from high yields and seed production. Secondary target was soil and groundwater conservation. Varieties were selected according to demand. The local conditions for potato growing are difficult in Scheyern because of the very high erodibility on the slopy areas. On some fields, clay levels are far too high for potatoes. Therefore, the guiding principle in all activities was consequent soil conservation. The risk of potato cropping in slopy regions is erosion. Planting potatoes parallel to the slope may reduce erosion at the beginning. In case of strong rainfall, however, ridges may break and favour gully erosion. Therefore, the cultivation technology was aimed at building the ridges as stable as possible and thus to clearly reduce the risk of erosion. To reach the above-described target, ridging was

1.2.2 Integrated farming system in Scheyern

35

begun already in the summer of the preceding year. After a phase of optimisation, the set task was implemented on the basis of the following scheme. Tillage and ridging were performed with a ridge-forming cultivator developed in Scheyern which loosens the soil to a depth of 22 cm in the first operation; then large-size discs throw up the dams which are shaped by special dam-shaping blades. In a second step, mustard seeds were distributed over the ridges by a sowing equipment attached on the ridging cultivator. The cultivator tines moving over the ridge were turned upward, and the space between the dams was loosened a second time. Initially, the green mustard plants favoured the protection of the dams in autumn and early winter; they supported aggregate formation by the roots and then the uptake of nitrate for the purpose of no groundwater contamination. After mustard had been killed by frost, the plant residues served as protection against erosion. Risks of this approach were partially non-uniform emergence of the mustard seedlings and germination of shatter grain. Under favourable weather conditions in autumn, crops might reach a height of 130 cm; the plants were killed by freezing not later than in December. The seed potatoes were planted with a fully automatic potato planter with a special tandem control which had been adjusted to this purpose. Because of the preformed ridges, higher ground clearance was necessary. Before the drop tube, a disc coulter had to be attached to cut off plant residues and to open the dam. Other than on a usual potato planter, the covering discs had to have a larger diameter because of the pre-shaped ridges. It was important to not destroy the dam bottom which had formed a rather stable connection with the remaining soil on the surface; thus, the risk of erosion was lowered, particularly, the danger of dam ruptures (Gerl and Kainz, 1998c, 1999; Kainz et al., 1999; Seuser et al., 1999). After planting the tubers, the ridges were interspersed with coarse, but high-porous lumps. When the potatoes broke through, ridging was performed with a roller hoe. At that moment, the residues of the cover crop mustard had already dried and began to rot; therefore, the cover was carefully chopped and incorporated into the soil, which decreased the remaining mustard biomass on the surface to 10–20%. Much higher coverage was left by the overwintering cover crop bird rape because it developed much more and heavily lignified biomass which as well was degraded not before April. Herbicide treatment with a soil-active means took place immediately after ridging, when the soil was covered to less than 20% by fine-structured material. Higher coverage rates partially shielded the soil off and prevented a reliable effect of soil-applied preparations. In such cases, foliar treatment post emergence was used (for example, Metribuzin and Rimsulfuron). The decisive fungal pests in potato growing were P. infestans and Alternaria solani. The control of P. infestans was executed according to the program SYMPHYT. As first step systemic pesticides were applied (for example, Metalaxyl-M), followed by

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Table 9 Yields of the main corps (dt ha⫺1) of the integrated farming system.

Average Max Min CV (%)

Potatoes

Winter wheat

Spring wheat

Grain maize

Silage maize

368.1 500.0 276.5 19.7

69.6 88.2 39.8 18.7

53.0 70.7 36.6 28.7

86.8 111.6 70.0 16.2

493.3 737.0 327.5 27.1

contact herbicides (for example, Fluazinam). Attention was paid to a reliable effectiveness against A. solani in July and August because without control this disease had caused considerable damage (addition of maneb). The leaves of food potatoes were mulched by mid-September. For maturing, the tubers remained in the soil for another 3 weeks. For seed production, the crop was desiccated, when the starch content had reached at least 11% and first signs of maturity became visible, accompanied by a corresponding size of the seed tubers. Desiccation was executed as early as possible to exclude virus infections of the tubers. The yield range of 276–500 dt ha⫺1 in the years 1993–2004 (Table 9), goes back do to the weather and site conditions on the one hand (different fields) and to the different production targets (here not allocated) on the other.

1.2.3 Discussion The established farming systems in Scheyern are built up by their own principles. The interaction of the different farm sections – plant production with the differentiated crop rotation, grassland and livestock – is of utmost importance for the success of the organic farming system. Cycles of matter and nutrients could be arranged in a way resulting in a sufficient N supply to the arable crops and good yields from livestock and fields. Inside the integrated farming system, the nitrogen supply can be assured by import of mineral fertiliser, so nitrogen fixation by legumes was not necessary and the feeding of the livestock could built upon maize. For this reason the methods of soil conservation – non-turning tillage, direct seeding – became more important. The achievement of objectives in the two farming systems can be followed by different parameters. The food for livestock in the organic farming system was provided by grassland and the fodder legumes as a part of the crop rotation. The yield level of these legumes and the grassland were

1.2.3 Discussion

37

on the regional level over the investigation period of 10 years and did not show any trend. After the change from lupin to a second field of lucerneclover-grass, the fodder volume increased and the livestock could be increased also. For this reason a higher amount of manure was available for the crops. The potatoes benefited from this in a specific way. The averaged yield over 10 years of 238 dt ha⫺1 exceeded significantly the yield of organic farms in Germany. In the same period we achieved a trend of increasing yields of 7.3 dt ha⫺1 a⫺1 and reached largely the goals for this crop. The yields of the two grain crops wheat and rye were similar to yield level and trends in organic farming in Germany; for wheat we got a rate of ⫹0.7 dt ha⫺1 year⫺1 in the investigated period. For rye the rate was lower if the outstanding yield of 65 dt ha⫺1 in 2004 was not taken into consideration. For the sunflowers the goals could not be reached completely. The averaged yield of 27 dt ha⫺1 was high level for organic farming but there was a negative trend of ⫺1.0 dt ha⫺1 a⫺1. One of the reasons was the immigration of the slug pest Arion lusitanicus, which damaged plants in the early growing stage in some years. But most important was that plant space was changed from 37 cm ⫻ 37 cm to at last 75 cm ⫻ 18 cm, what was favourable for the management. Within the integrated farming system, the potatoes, winter wheat and corn yielded on a regional typically level or in some years also a little higher. During the 10-year period, all crops showed a positive trend of the yields. The silage maize had a significant higher yield of 493 dt ha⫺1 than the region and an increasing rate of 24.3 dt ha⫺1 year⫺1. The main reasons for this success have been the cultivation techniques and the advancements in plant breeding. It is remarkable that these results could be achieved at a very high level of soil conservation. The different measures like not-turning tillage, direct seeding and cover plants reduced the soil erosion significantly (Fiener and Auerswald, 2006; Huber et al., 2005). The leaching of nitrate and pesticides could be decreased, too. The results of the two farming systems at the research station in Scheyern have shown that the goals verbalised at the beginning of the project could be achieved. The yields reached the region typical level or even better, and at the same time, the environmental achievement was improved significantly. Acknowledgements The scientific activities of the FAM Munich Research Network on Agroecosystems were financially supported by the German Federal Ministry of Education and Research (BMBF 0339370). Overhead costs of Research Station Scheyern are funded by the Bavarian State Ministry for Science, Research and the Arts.

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