Comparative economic analysis of inter-crop based conservation bench terrace and conventional systems in a sub-humid climate of India

Resources, Conservation and Recycling 98 (2015) 30–40

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Comparative economic analysis of inter-crop based conservation bench terrace and conventional systems in a sub-humid climate of India V.N. Sharda a,∗ , Pradeep Dogra b , D.R. Sena b a

Agricultural Scientists Recruitment Board, Pusa, New Delhi 110 012, India Indian Institute of Soil and Water Conservation (Formerly Central Soil & Water Conservation Research & Training Institute), 218, Kaulagarh Road, Dehradun 248 195, Uttarkahand, India b

a r t i c l e

i n f o

Article history: Received 26 February 2015 Accepted 4 March 2015 Keywords: Conservation bench terrace Economic efficiency Energy use efficiency Sloping border Water harvesting

a b s t r a c t Economic performance of two land configuration systems, namely conservation bench terrace (CBT) and conventional (sloping borders), were evaluated through an experimental study conducted during 1997–2005 in a sub-humid climate of India. Energy use efficiencies of the two systems were also evaluated. The two systems were cultivated with maize + cowpea in rainy season followed by wheat + mustard in dry winter season. For CBT, an additional intervention of rice cultivation was done during rainy season in its recipient area. Mathematical relationships were established between seasonal and effective rainfalls as well as between effective rainfall and crop equivalent yields. These relationships were then utilized for evaluating economic efficiency of various combinations of the two inter-crop based land configuration systems. Excess runoff from the combinations was considered as rainwater harvested into a common tank for recycling as supplemental irrigation during intervening dry spells in the rainy season and the remaining during dry winter season. In this way, the best combination for inter-crop based systems adoptable to a region experiencing rainfall uncertainty i.e. regular intervening dry spells was identified. Sensitivity analysis was carried out to analyze response of the combinations to changes in economic parameters. Based on the analysis of experimental data, net present value of CBT system was observed to be 56% higher than the conventional system due to higher average crop equivalent yields. Net energy return, energy ratio and energy profitability of CBT system were higher by more than 100% as compared to conventional system, thus indicating better energy use efficiency. Benefit–cost analysis of the system combinations under different rainfall probabilities suggested that a combination with higher proportion of CBT will be more remunerative. However, the 75:25 (CBT:conventional) combination was observed to be the best for minimizing risks associated with erratic rainfall at all probability levels. Sensitivity analysis of various combinations indicated that CBT predominant combinations will be least affected by changes in considered economic parameters. From the study, it was concluded that adoption of 75:25 (CBT:conventional) combination can be recommended for sustaining crop productivity by generating sufficient runoff for harvesting and its subsequent recycling as supplemental irrigation during both seasons on mildly sloping lands in sub-humid climates. © 2015 Elsevier B.V. All rights reserved.

1. Introduction Efficient management of water is an essential pre-requisite for higher agricultural productivity that leads to augmentation and sustenance of production. Globally, 78% of increase in total crop

∗ Corresponding author at: Agricultural Scientists Recruitment Board, Pusa, New Delhi 110 012, India. Tel.: +91 1125841168. E-mail addresses: [email protected] (V.N. Sharda), [email protected] (P. Dogra), drsena [email protected] (D.R. Sena). http://dx.doi.org/10.1016/j.resconrec.2015.03.004 0921-3449/© 2015 Elsevier B.V. All rights reserved.

production during 1961–1999 was due to boost in agricultural productivity (Bruinsma, 2003). It was partly attributed to expansion of irrigated areas (FAO, 2007) which increased from 142 to 271 million ha during 1961–1999 (Bruinsma, 2003). It is still challengingly increasing due to population growth and rising income levels, which have augmented demand for water intensive agricultural commodities (Molden, 2007; Falkenmark, 2007; De Fraiture and Wichelns, 2010). In India, agriculture sector is the largest (85%) consumer of water (Datt and Nischal, 2010), and more than 80% of total future water demand projections are for use by this sector (Chopra et al., 2003). Gross irrigation water demand in 1990 was 460 km3 ,

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which is expected to reach 628 km3 under low growth scenario and 807 km3 under high growth scenario by 2050 (NCIWRD, 1999). Whatever the estimates, total water availability is fixed for its ever increasing second largest population. Consequently, it is heading towards chronic blue water (water available in rivers, lakes, wetlands and aquifers) shortage (<1700 m3 per capita per year) to meet its food water requirements by 2050 (Rockström et al., 2009). Water shortages seem inevitable with unabated irrigation as well as industrial and domestic water demand growth. Further aggravation in future due to excessive pollution, over exploitation or climate change impacts is unavoidable. Addressing the problem through supply side infrastructure-intensive solutions encompass challenging externalities. Evaluation of proposed river linking programme of India with five criteria distilled from diverse criteria indicated poor scoring in all criteria (Gupta and van der Zaag, 2008). Instead, a demand driven approach that conserves water for enhancing localized supply and entails its judicious use is required to tackle India’s steadily worsening water-related problems (Datt and Nischal, 2010). More so, as water and land are best managed locally (Chopra et al., 2003). Green water resources (i.e. infield rainfall, naturally infiltrated rainwater and harvested local runoff) can keep India potentially self-sufficient [total (i.e. blue plus green) water availability >1300 m3 per capita per year] till 2050 if green water is carefully managed (Rockström et al., 2009). Further, adaptation to changed local water resources conditions is as important as availability of freshwater resources (Pandey et al., 2011). In rainfed areas, rainwater harvesting can generate locally available water resource, which can be self managed by farmers. The potential of supplemental irrigation from locally stored surface runoff in small reservoirs to global cropland areas to increase crop evapo-transpiration (or green water flow) ranges from 9.5% to 18% of total green water flux from all cropland area. Supplemental irrigation of existing cropland areas from a medium variant of reservoir capacity can increase cereal production by ∼50% in Africa and Asia (Wisser et al., 2010). In terms of transpiration efficiency (i.e. green water use over availability), India has an enormous potential to boost food production (Rockström et al., 2009). Utilization of harvested rainwater for supplemental irrigation in Indian rainfed areas has reported yield increase by 119–485%, depending upon crop and soil conditions (Samra and Sharda, 2006). Positive impacts of supplemental irrigation from on-farm water harvesting structures, on enhancing crop productivity and their economic viability have been well reported across different agro-ecological regions of India (Samra et al., 2002; Sharda and Ojasvi, 2005; Yadav et al., 2006; Arya and Yadav, 2006; Narayan and Biswas, 2012; Pande et al., 2012). Rainfed agriculture has tremendous potential to augment food production, if substantial investments in water harvesting, agricultural research, supporting institutions and rural infrastructure are made (De Fraiture and Wichelns, 2010). Dichotomy between irrigated and rainfed agriculture is now reduced as they are difficult to separate (Rockström and Barron, 2007). Irrigated agriculture is partly dependent on infiltrated rain, and rainfed agriculture is being increasingly supported by supplementary irrigation for dry spell mitigation. Therefore, future development solutions would be found as techno-feasible tradeoff between two extremes of purely irrigated and purely rainfed agriculture (Falkenmark, 2007). System innovations along these lines are solutions to achieve productivity rise, as reported for southern and sub Saharan Africa, where to offset impact of dry spells, four different system innovations indicated significant scope to increase maize grain yields with little available rainfall (Makurira et al., 2011). Rainwater use efficiency can be significantly improved through runoff water harvesting structures and appropriate water conservation measures across the slope. There are several best management practices for conserving rainwater which otherwise

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results into inevitable runoff causing soil erosion. It further leads to loss of fertility, lowering of water holding capacity and disruption in nutrient cycle of the soil (Sharda, 2011). Among structural measures, the conservation bench terrace (CBT) system is an innovative land configuration measure that harvests rainwater generated as surface runoff from a sloping donor catchment (left in its natural slope) and impounds runoff on leveled portion of the same land (recipient area). The two components of CBT system, i.e. donor and recipient areas are used for cultivation of crops having diverse water requirements. Runoff in excess of impoundment can be stored and recycled for providing supplemental irrigation during intervening dry spells or providing initial life saving irrigation to winter crop. CBT system has been hydrologically evaluated on mildly sloping lands (<4%) under varying soil, crop and climatic conditions for water conservation, erosion control and enhancing crop productivity in arid, semi-arid and sub-humid climates of the world (Hauser, 1968; Michelson, 1968; Black, 1968; Cox, 1968). In India, the CBT system was extensively tested for rainfed areas in semi-arid regions at Bellary (Sastry et al., 1975) and Kota (Prakash and Verma, 1984), and in sub-humid region at Dehradun (Bhushan, 1979; Sharda et al., 2002, 2003). At Dehradun, a 3:1 mono-crop based CBT system, comprising of sole maize in rainy season followed by sole wheat in winter season with rice during rainy season in the recipient area of CBT system was found effective in improving productivity by over 19% in terms of maize equivalent yields as compared to conventional system (sloping border) (Sharda et al., 2002). With an aim to further economize the system and reduce runoff and soil loss, an experiment on inter-crop based CBT system comprising of maize + cowpea in rainy season followed by wheat + mustard in dry winter season with rice during rainy season in recipient area of CBT system was conducted during 1997–2005. The conventional and CBT systems were evaluated in terms of runoff, soil erosion, and crop productivity. CBT system was observed to be effective in reducing runoff and soil loss drastically by about 80% and 88%, respectively as compared to conventional system. An additional yield gain of 18% was observed over the conventional system in terms of maize equivalent yields (Sharda et al., 2013). Although a number of studies have been conducted to evaluate the CBT system hydrologically, its economic assessment, in terms of tangible and intangible benefits, still have not been adequately reported or compared with conventional system. In a sole attempt to characterize the economics of CBT system, Sharda and Dhyani (2004) observed that CBT system exhibited 58% higher net present value compared to conventional system. However, economics of CBT system over the conventional system for inter-cropping system vis-a-vis mono-cropping system have not been evaluated as yet. Economic evaluation of CBT and conventional systems cultivated with different cropping systems in a given agro-climatic region can help in selecting an appropriate cropping system which can provide higher profitability besides resources conservation. Further, to make cultivation of cropping systems adoptable in a region having regular intervening dry spells, suitable combinations of the two systems in areal units, i.e. CBT (for water conservation and productivity) and conventional (for surface runoff generation for harvesting and recycling as supplemental irrigation), need to be economically assessed for evolving alternatives conforming to a targeted production and economic goals while considering uncertainty in rainfall incidences. The present study, therefore, is focussed towards addressing the above issues by analysing the tangible (crop yield) and intangible (soil loss) benefits of inter-crop based CBT and conventional systems. The inter-crop based systems were also compared with the mono-crop based systems considering all economic measures of benefit cost analysis. Attempt has also been made to establish an ideal quotient in areal units involving the two systems for utilizing trade off between water resource

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conservation and water availability for supplemental irrigation under contingent rainfall uncertainty. While doing so, crop productivity goal was kept at a reasonably remunerative level. Energy use efficiency of both the systems was also estimated and compared to showcase the additional benefits of the CBT system over the conventional system in terms of its energy footprint.

level (Appendix II). Using these PDFs, the exceedance probabilities were estimated to undertake the sensitivity analysis for the combinations of land configuration (CBT or conventional) systems in conjunction with the respective cropping system as discussed elsewhere in the manuscript. 2.3. Estimation of effective rainfall

2. Material and methods 2.1. Experimental framework The study was undertaken at Selakui Research Farm of the Indian Institute of Soil and Water Conservation (formerly Central Soil and Water Conservation Research and Training Institute), Dehradun (India). It is located at 30◦ 21 18.90 N latitude, 77◦ 52 38.00 E longitude, and 540 m elevation above the mean sea level in lower hills of north-western Himalayas. The site receives about 1650 mm average annual rainfall, most (>80%) of which occurs during monsoon season from mid-June to mid-September. Experimental data were collected during 1997/98–2005/06. Three plots of 50 m × 20 m size, each with donor (having 2% slope) and recipient (level bench) areas in a ratio of 3:1 were constructed for the CBT system. Runoff water from donor area was collected in the recipient area of CBT system to an impoundment depth of 20 cm. Excess runoff over the impoundment depth was drained through a rectangular weir having crest length equal to width of the plot. Three plots of same size were also constructed at 2% slope to represent conventional system of cultivation (sloping borders with no level bench and depth of impoundment at lower end) for comparing the efficacy of CBT system. Plan and sectional elevation of CBT and conventional systems are presented in Fig. 1. Excess runoff from the two types of land configuration systems was stored in an open-top brick masonry tank of 30 m × 15 m × 2.5 m size. The water stored in the tank was pumped out for providing supplemental irrigation, whenever required. In the CBT system, maize was intercropped with cowpea in the ratio of 1:1 in donor area while rice was grown in the recipient area during rainy (kharif) season (June–September). It was followed by wheat intercropped with mustard in the ratio of 8:1 in the entire CBT system during dry winter (rabi) season (November–April). This cropping pattern was repeated for 9 years (1997/98–2005/06). In the conventional system, maize + cowpea (1:1) followed by wheat + mustard (8:1) were cultivated in kharif and rabi seasons, respectively. Recommended package of practices for cultivation of study crops were uniformly adopted in the two systems during the experimental period. Other experimental details have been described by Sharda et al. (2013). Data of runoff and soil loss was collected event-wise for majority of events during the study period. Rainfall, runoff and soil loss data for the two systems are presented in Appendix I. 2.2. Probability of seasonal rainfall The seasonal rainfall concurrent to cropping season windows e.g. kharif (maize + cowpea and paddy) and rabi (wheat + mustard), as per the cropping systems, was used in this study for economic analysis of different combinations of the two systems. The rainfall amounts during the crop season window were recorded and aggregated. The seasonal rainfalls thus estimated were used to determine the probability of their occurrence employing a best fit probability distribution function (PDF). A set of PDF was tested to determine the best fit functions that reasonably represent the seasonal rainfall exceedance probabilities. It was observed that the cumulative generalized Cauchy distribution and cumulative Fisher–Tippet Type-III distribution functions best matched the seasonal rainfall series with all the data conforming to 95% confidence

Water production functions for rainfed maize + cowpea and rice cropping system in kharif and wheat + mustard cropping system in rabi were developed by correlating runoff excess rainfall (effective rainfall) to equivalent yield of the cropping systems assuming that all other factors of crop production are identical. Runoff was estimated on daily basis by employing the SCS curve number method and using the optimized SCS parameters derived from the majority of the observed rainfall and runoff events pairs as per procedure outlined by Sharda et al. (2013). Daily estimated runoff values were aggregated over each season to estimate seasonal values of runoff. The procedure was adopted for each of the seasons corresponding to the cropping systems windows for the period from 1997/98 to 2005/06, and seasonal rainfall and estimated effective rainfall were correlated. The parameters of the linear equation fitted between estimated effective rainfall and seasonal crop rainfall along with statistical parameters for both CBT and conventional systems are presented in Appendix III. As evident, the additional storage due to CBT in kharif season has least effect on effective rainfall due to the fact that rainfall in kharif season is generally sufficient to meet the crop water requirements in effective root zone depth of the crop. In rabi season, the difference is, however, more pronounced as reduced seasonal rainfall resulted in higher soil moisture storage and lesser runoff in the CBT system. 2.4. Water production function To develop a water production function, the equivalent yield of crops in a given cropping system was correlated with effective rainfall i.e. runoff excess rainfall. The production function was conceptualized from trend analysis of the curve relating yield with effective rainfall. A nonlinear relationship was observed to fit well, thereby indicating that the yield increased with increase in effective rainfall until a threshold value is reached, beyond which the yield declined. The following equation was observed to describe this trend reasonably well: Y = Ymax e

−(Reff(mm)−Reff thresh) 2c 2

(1)

This equation has an effective rainfall threshold value “Reff thresh” corresponding to a maximum attainable yield “Ymax ” beyond which the equivalent yield starts declining. Table 1 presents the coefficients corresponding to this trend as per Eq. (1) along with statistical performance of the fitting.Water production functions for kharif and rabi seasons, in terms of maize and wheat equivalent yields vis-à-vis the effective rainfall, are presented in Fig. 2a and b. In either case, the relationship follows a trend similar to the one as hypothesized. However, in kharif season, additional rice crop has shifted the peak of the curve towards higher effective rainfall zone as rice has higher water requirements. However, in case of wheat equivalent yields during the rabi season, since both the systems have same crops, the peak was attained concurrently with same effective rainfall though the peak in CBT system was higher which is attributed to better soil moisture regime. 2.5. Economic analysis Economics of cropping sequences of CBT and conventional systems was analyzed based upon observed data collected during

V.N. Sharda et al. / Resources, Conservation and Recycling 98 (2015) 30–40

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Fig. 1. Plan and sectional elevation of CBT and conventional systems (after Sharda et al., 2013).

9 years period. Primary data of inputs utilized (seeds, fertilizers, chemicals, human labor and machinery) and outputs produced (maize, rice and wheat grain/straw; cowpea and mustard grains) were systematically collected during the cropping seasons following a well-designed monitoring mechanism. For working out individual economics of the two systems, all inputs and outputs were converted into their respective monetary value based on average price of each input/output over 9 years study period to account for yearly price fluctuations. Wherever available, government prices (minimum support prices) were considered; otherwise, local farmgate prices were utilized. Following this procedure, year wise total cost and total returns per hectare from all crops in each of the seasons were calculated for each land configuration system. They were utilized along with cost of constructing and maintaining the tank (2% of initial cost every year) as well as recurring cost of pumping water for irrigation to attain a certain yield goal for benefit–cost analysis (BCA) of each system at a discount rate of 10% considering tank life of 25 years. Year wise net returns per hectare from all the crops in a season from each system were calculated by deducting the estimated total cost from the respective total returns in a year.

2.5.1. Considering soil loss Estimation of environmental cost due to soil erosion for inclusion in the cost of cultivation is a challenging task due to complexity involved in its valuation in monetary terms. Following Dogra et al. (2002) and Ghosh et al. (2015), as a proxy, soil loss incidental to net returns earned at constant prices i.e. net returns per tonne of soil loss were estimated on yearly basis for each land configuration system. It was estimated by dividing the net returns per hectare by corresponding per hectare soil loss. The quantum of soil loss, which was measured on an annual basis during the study period (1997/98–2005/06), was actually used to account for any intangible monetary losses caused by it. 2.5.2. Combinations of CBT and conventional systems Different proportions of the two land configuration systems were proposed in areal units and economically analyzed for cultivation of inter-cropping systems in a region experiencing regular intervening dry spells. Potential of CBT system to yield higher annual crop production with least runoff and soil loss, and of conventional system to generate sufficient runoff that can be harvested and recycled for supplemental irrigation during intervening

Table 1 Statistical performance of fitted equation between effective rainfall and yield for CBT and conventional systems during kharif (rainy) and rabi (winter) seasons. Cropping system and land configuration system

Season

Equivalent yield of crop

Ymax a (q ha−1 )

Reff threshb (mm)

c

R-sq

Maize + cowpea (1:1) and rice (CBT) Maize + cowpea (1:1) (conventional) Wheat + mustard (8:1) (CBT) Wheat + mustard (8:1) (conventional)

Kharif Kharif Rabi Rabi

Maize Maize Wheat Wheat

35.87 29.86 41.72 34.87

1214.78 1031.81 131.30 131.30

352.55 342.18 124.78 104.00

0.870 0.675 0.300 0.343

a b

Ymax = maximum attainable yield. Reff thresh = effective rainfall threshold value.

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Fig. 2. Water production functions for conventional and CBT Systems during (a) kharif and (b) rabi seasons.

drought periods in the rainy season as well as during dry winter season were effectively utilized. Benefit–cost analysis (BCA) of combinations of CBT and conventional systems was undertaken by considering five probable combinations under three rainfall probabilities of exceedance (30%, 50% and 70%) as follows: (1) (2) (3) (4) (5)

Pure CBT (100% area under CBT system). 75% area under CBT and 25% under conventional system. 50% area under CBT and 50% under conventional system. 25% area under CBT and 75% under conventional system. Pure conventional (100% area under conventional system).

A systematic procedure was adopted for economic analysis of the combinations. Firstly, at a given rainfall probability of exceedance, maize equivalent yield (MEY, 100 kg ha−1 ) of cultivated kharif (rainy) season crops was estimated for each system of a combination. For this, following established regression relationships were utilized, in this order: a. between probability of exceedance and rainfall amount (mm) in kharif season (Section 2.2), b. between kharif season’s rainfall and effective rainfall (mm) amounts for a given land configuration system (Section 2.3), and c. between kharif season’s effective rainfall for a given land configuration system and MEY (Section 2.4). Secondly, runoff (mm) was estimated for each system at a given probability of exceedance as the difference between kharif season’s rainfall and corresponding effective rainfall. The runoff estimated for a given system in kharif season was multiplied by total area (ha)

under the system for estimating the runoff volume (ha m) available from the system for storing in the tank. The probability analysis is associated with uncertainty in rainfall that implies the risk in adopting a particular technology which in our case, is an areal unit ratio of inter-crop based CBT and conventional systems. However, relationship of yield and runoff excess effective rainfall (aggregated daily values over the cropping season) was observed to be a non-linear relationship with both kharif and rabi inter-cropping systems. It was observed to significantly conform to a non-linear function with reasonably acceptable statistical performance as already discussed (Section 2.4). The function was conceptualized keeping in view the yield boundaries which suggests that the crop yield responds positively to an increase in rainfall upto a threshold value (pertaining to highest crop yield) and declines thereafter with increase in rainfall. This trend allowed us to decide the amount of irrigation (water pumped from tank) that is required to attain the maximum yield, when the seasonal rainfall corresponding to a probability level falls short of the threshold rainfall value for which the yield is maximum. If, for any probability, the seasonal rainfall exceeds the threshold limit, then irrigation was not applied and the less than maximum crop yield due to the excess rainfall (beyond the threshold limit) was accounted for in the economic analysis. The total runoff volume (ha m) from a combination of two systems was assumed to be stored in a common tank and deemed as available water (supply) to meet the combined irrigation requirement. If available quantity of stored runoff water in the tank was sufficient to meet the kharif irrigation requirement of a combination for achieving the maximum MEY of either/both land configuration systems, then the required quantity was utilized from stored water for irrigating kharif crops cultivated in either/both systems. The remaining water in the tank stored during kharif season was utilized for irrigating rabi (winter) crops cultivated in the two land configuration systems. For rabi (winter) crops also, the above procedure was adopted. As runoff from a relatively dry rabi season is not timely available to meet initial water requirements of main rabi crop i.e. wheat, rabi season runoff was not considered for storage and supplemental irrigation of wheat and mustard crops. Only water left in the tank after harvesting the preceding kharif season crops was considered for irrigating rabi crops. Generally, the recommended depth of dugout pond/tank varies from 2 to 4 m (Sharda and Dhyani, 2004). Therefore, the depth required for construction of an open-top brick masonry tank was fixed at 2.7 m for storing runoff from a system combination during kharif season. For economic analysis of system combinations at different rainfall probabilities, a unit land area of 1 ha was considered. Out of the unit area, the area required for construction of the tank of fixed depth of 2.7 m but variable surface area, as per total volume of runoff from a system combination, was considered as unavailable for cultivation. The tank surface area was subject to a maximum of 500 m2 to ensure that no more than 5% area is lost from cultivation for tank construction out of total area of 1 ha. Therefore, maximum storage limit was fixed at 1350 m3 . The remaining area available for cultivation was apportioned between the two systems as per a given combination for both seasons. Further, in CBT system, irrespective of its proportion in a system combination, a further 1% of its cultivable area was considered as lost for bund construction to impound runoff in the level bench for rice cultivation. Under Dehradun valley conditions, studies have indicated that water harvested during kharif season can be effectively utilized during rabi wheat crop for providing life saving irrigation at (A) pre-sowing and (B) crown root initiation (CRI) stages, depending upon water availability (Singh et al., 1981). For attaining maximum wheat equivalent yield (WEY) from either/both land configuration systems, available water in the tank was utilized for irrigation at

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pre-sowing and CRI stages after accounting for seepage and evaporation losses. Based on a study reported on brick lined tank (Sharda et al., 1986), average storage losses (seepage + evaporation) during October 1–November 15 (date of application of pre-sowing irrigation), when the tank is full to its capacity, were 1.1 cm/day. From pre-sowing irrigation to CRI stage, the losses were 0.5 cm/day, as the water storage during this period is mostly less than half of tank’s capacity. For BCA, a linear relationship was assumed between actual cost of construction and capacity of the tank (Sharda and Dhyani, 2004). Further, 2% of this cost (taken as initial investment) as well as that of impoundment bund was taken as average annual maintenance cost. The BCA was done at a discount rate of 10% considering tank life of 25 years for every combination of land configuration systems at different rainfall probabilities. Sensitivity analysis of values of economic measures utilized for evaluating the combinations under different rainfall probabilities was done with tank life reduced to 20 years. Similar analysis was also done with increase in tank cost and/or reduction in output prices by 10%. Sensitivity analysis was also undertaken with different values of discount rate to study the resilience of the combinations to changes in the BCA parameters. 2.6. Energy input–output analysis For assessing and comparing the efficiency of the intense production systems adopted for the study on two different land configuration systems in terms of energy estimates, the inputs and outputs of individual crops in a cropping system were converted from physical to energy values based on published conversion coefficients (Table 2). The following energy input, output and efficiency measures were estimated: Input energy (MJ ha−1 ) = energy equivalents for all inputs summed to provide an estimate for total energy input. Output energy (MJ ha−1 ) = energy equivalents of biomass crop yield as sum of yields of grain and by-products (straw). Energy output from the product (grain) was calculated by multiplying the amount of production and its corresponding energy equivalent. Energy output from the by-product was estimated by multiplying the amount of by-product and its corresponding equivalent. Net energy return (MJ ha−1 ) = difference between the gross output energy produced and the gross energy required (input energy) to produce it. Energy ratio = output energy (MJ ha−1 )/input energy (MJ ha−1 ) Energy profitability = net energy return (MJ ha−1 )/input energy (MJ ha−1 ) productivity (kg MJ−1 ) = crop economic yield Energy (kg ha−1 )/input energy (MJ ha−1 ) Energy intensiveness (MJ INR−1 ) = input energy (MJ ha−1 )/cost of cultivation (INR ha−1 ) 3. Results and discussion 3.1. Economic analysis of experimental data Benefit–cost analysis (BCA) of inter-crop based CBT system during 9 years period was done at a discount rate of 10% with tank life of 25 years. The results indicated that inter-crop based CBT system was profitable as it had a benefit–cost ratio (BCR) of 1.21:1 with internal rate of return (IRR) of 18.7%. The IRR value was almost double of the considered discount rate of 10% (Table 3). The intercrop based conventional system was also found to be profitable (BCR 1.14:1; IRR 15.8%) under similar set of BCA parameters. A comparison of the two inter-crop based systems indicated that CBT system was more profitable than conventional system in terms of

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all BCA estimates. In addition to higher BCR (by 6%) and IRR estimates, the CBT system could provide 56% higher net present value (NPV) of INR 56,725 ha−1 compared to that from conventional system with 3 years shorter payback period (PBP). The MEY and WEY of CBT system were reported to be on an average higher by 12% and 17%, respectively over the conventional system (Sharda et al., 2013), thus leading to higher returns. These findings are similar to the ones reported by Sharda and Dhyani (2004) for the mono-crop based systems where the superiority of CBT system over the conventional system was clearly established in terms of all the BCA parameters. For a meaningful comparison of land configuration systems cultivated with two different cropping systems (inter-cropping and mono-cropping) during two different time frames, the results of economic analysis based on mono-cropping system (1987/88–1994/95) were re-estimated with averages of respective input and output prices of 1997/98–2005/06. This nullified the effect of price variations among the two periods. The comparison indicated that for the two land configurations, inter-cropping system was more profitable than mono-cropping system. It is significantly so in terms of NPV and IRR (Table 3). It is ascribed to higher outputs from inter-cropping system, both during kharif (43%) and rabi (46%) seasons (Sharda et al., 2013). Year-wise crop yield data of the two land configuration systems during these periods are reported in Appendix IV. Interestingly, even mono-crop based CBT system was observed to be more profitable than the inter-crop based conventional system in terms of PBP by two years, and slightly better in terms of BCR and IRR.

3.2. Economic analysis considering soil loss Soil loss incidental to net returns earned was taken into account as a proxy for environmental cost of cultivating the two land configuration systems. CBT system yielded higher average net returns per tonne of soil loss (INR 29,003 t−1 ) as compared to only INR 1291 t−1 from conventional system. It is ascribed to a very low average soil loss of 0.9 t ha−1 resulting from CBT system as compared to a significantly higher soil loss of 7.4 t ha−1 from conventional system. It resulted into significantly higher average net returns of INR 10,588 ha−1 from the former as compared to INR 7878 ha−1 from the latter. This indicates that the CBT system not only provided higher monetary returns but these returns were also at a lower environmental cost incurred in terms of soil loss. In fact, in 2002/03, the CBT system incurred zero soil loss as compared to conventional system (6.7 t ha−1 ) though returns from the two (INR 9615 t−1 and INR 8034 t−1 , respectively) were not significantly different.

3.3. Energy input–output relationships Analysis of energy use efficiency in cultivation of intense cropping systems on the two land configuration systems indicated that 257,399 MJ ha−1 of net energy return was generated annually from CBT system as compared to 112,038 MJ ha−1 from conventional system. Net energy return from CBT system was, therefore, 125% higher than that of conventional system. It is attributed to significantly higher energy output (106%) of crops in CBT system as compared to that in conventional system though the energy input of the cropping systems was almost equal (Table 4). Consequently, the energy ratio and energy profitability were also significantly (107% and 127%, respectively) higher in the CBT system. Further, higher economic crop yield from CBT also resulted in higher energy productivity by 20% over conventional system. The CBT system also has advantage of 11% lower energy intensiveness inspite of having higher cost of cultivation. It is ascribed to lower absolute value of

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Table 2 Energy equivalents of inputs and outputs in agricultural production. Input/output

Particulars

Unit

Energy equivalent (MJ unit−1 )

Seed/grain

Maize Cowpea Rice Wheat Mustard

kg kg kg kg kg

15.10 13.52 14.70 14.70 22.72

Human labor

Adult male

man-h

Chemical fertilizer

Urea (N) DAP (P2 O5 ) MOP (K2 O)

kg kg kg

60.60 11.10 6.70

Chemicals

Superior Zinc sulphate Liquid

kg kg ml

120.00 20.90 0.102

Farm machinery Crop straw

Cultivator Dry mass

h kg

3.135 12.50

1.96

Sources: Chaudhary et al. (2006), Nassiri and Singh (2009), Tuti et al. (2012).

Table 3 Economic analysis of conventional and CBT systems with different cropping systems (discount rate – 10%; tank life – 25 years). Economic evaluation measure

CBT (1997–2005) with inter-cropping

Conventional (1997–2005) with inter-cropping

CBT (1987–1994) with mono-croppinga

Conventional (1987–1994) with mono-croppinga

Net present value (INR ha−1 ) Benefit:cost ratio Pay-back period (years) Internal rate of return (%)

56,725 1.21:1 10 18.7

36,370 1.14:1 13 15.8

26,392 1.15:1 11 16.0

14,441 1.09:1 14 13.5

Note: INR (Indian Rupee) 1 USD = INR 60.8090. a Re-estimated from input–output data of experiment reported in Sharda et al. (2002) and Sharda and Dhyani (2004).

input energy in the CBT system than its cost of cultivation while it was just the opposite in case of conventional system. 3.4. Economic analysis considering different combinations and rainfall uncertainty Under different probabilities of exceedance of runoff producing rainfall events, distinct combinations of CBT and conventional systems were considered to utilize tradeoff between water conservation and water availability (as runoff) possible from the two systems, respectively. This will enable cultivation of inter-crops on these systems in a region experiencing regular intervening dry spells. Therefore, advantages of the two systems (CBT for water conservation and productivity; conventional for harvesting surface runoff and its recycling for supplemental irrigation) need to be effectively utilized. Benefit–cost analysis of these combinations was done to identify the best combination for all probabilities of exceedance to address rainfall uncertainty. Within any single probability level, values of NPV, BCR and IRR showed decline in profitability with increase in area under conventional system across the combinations (Table 5). PBP also exhibited

decline in profitability, because it increased with increase in area under conventional system. It is mainly attributed to increase in runoff volume with increase in area under conventional system, as this system generates higher runoff compared to CBT system. Increase in runoff will warrant larger size of the tank to store excess runoff up to fixed storage limit (1350 m3 ) thus adding to cost of tank construction. Further, gross returns will decrease due to lesser area under CBT system, as the conventional system has lower productivity than CBT system, thus causing fall in profitability. Therefore, inter-crop based sole CBT system was observed to be most promising among all combinations and under all probability levels. Among different probability levels, values of BCR and NPV (Table 5) at 50% probability were observed to be higher or equal to that at other probabilities, except for 100:0 combination of CBT and conventional systems, where NPV was higher at 30% probability level. However, IRRs of all the combinations at 50% probability were observed to be equal or higher than that at 30% probability level. Similarly, PBPs at 50% probability were observed to be equal or lower than that at 30% probability. It is thus inferred that with increase in rainfall volume (as probability of exceedance falls from 70% to 50%), the profitability of any combination of CBT and

Table 4 Energy input–output relationships of inter-cropping systems cultivated in CBT and conventional systems based on means over 1997/98–2005/06. Energy measure

Unit

Energy input Energy output Net energy return Energy ratio Energy profitability Energy productivity Energy intensivenessa

MJ ha−1 MJ ha−1 MJ ha−1 Ratio Ratio kg MJ−1 MJ INR−1

Note: INR (Indian Rupee) 1 USD = INR 60.8090. a At constant input prices – averages of prices of inputs from 1997/98 to 2005/06.

CBT 21,229 281,750 257,399 11.6 10.6 0.32 1.07

Conventional 21,369 136,994 112,038 5.5 4.5 0.26 1.23

V.N. Sharda et al. / Resources, Conservation and Recycling 98 (2015) 30–40

37

Table 5 Economic analysis of different combinations of CBT and conventional systems under different rainfall probabilities (discount rate – 10%; tank life – 25 years). Probability of exceedance

30%

Economic evaluation measure

0:100

25:75

50:50

75:25

100:0

)

37,337 (30,541) 1.13 (1.11) 10 (10) 17.5 (17.0)

43,776 (36,384) 1.15 (1.13) 9 (9) 18.4 (18.0)

50,214 (42,227) 1.17 (1.15) 9 (9) 19.3 (18.9)

92,111 (82,989) 1.33 (1.32) 5 (5) 36.6 (36.6)

135,575 (125,272) 1.53 (1.52) 2 (2) 120.8 (120.8)

NPV (INR ha−1 )

37,337 (30,541) 1.13 (1.11) 10 (10) 17.5 (17.0)

43,776 (36,384) 1.15 (1.13) 9 (9) 18.4 (18.0)

54,391 (46,341) 1.19 (1.17) 8 (8) 20.6 (20.2)

93,747 (84,676) 1.34 (1.33) 5 (5) 38.7 (38.7)

132,287 (122,237) 1.52 (1.51) 2 (2) 121.0 (121.0)

23,179 (17,261) 1.08 (1.06) 13 (13) 14.6 (14.0)

33,157 (26,425) 1.12 (1.10) 11 (11) 16.4 (15.8)

52,567 (44,881) 1.18 (1.16) 8 (8) 20.8 (20.5)

83,793 (75,488) 1.31 (1.29) 5 (5) 36.5 (36.5)

116,852 (107,807) 1.46 (1.45) 3 (3) 102.4 (102.4)

−1

NPV (INR ha BCR PBP (years) IRR (%)

50%

BCR PBP (years) IRR (%) 70%

Ratio of CBT and conventional systems

NPV (INR ha−1 ) BCR PBP (years) IRR (%)

Note: NPV – net present value; BCR – benefit:cost ratio; PBP – pay-back period; IRR – internal rate of return (%); INR (Indian Rupee) 1 USD = INR 60.8090. Figures in parentheses are with tank life of 20 years.

runoff for harvesting and recycling under erratic and deficient rainfall conditions at all probability levels. Between the two, the 75:25 combination is preferred due to its significantly higher profitability compared to the 50:50 combination of CBT and conventional systems. These results are in consonance with the earlier study conducted by Sharda and Dhyani (2004) wherein 75:25 combination (along with 50:50 combination) was found to be promising when water harvesting and recycling is aimed at.

3.5. Sensitivity analysis of combinations

Fig. 3. Benefit–cost ratio values of different combinations of CBT and conventional systems under different probabilities of exceedance of rainfall (discount rate – 10%; tank life – 25 years).

conventional systems tends to increase. However, with further increase in rainfall volume (as probability declines from 50% to 30%), the profitability of all combinations is likely to remain the same or fall. Among different combinations of CBT and conventional systems, the 75:25 and 50:50 combinations were observed to have least variability among BCA measures estimated at different probability levels. It is clearly evident in Fig. 3, where the BCR graphic lines are clustered for these two combinations. However, there is a significant difference in the values of BCA measures in case of pure CBT and pure conventional systems. Therefore, though the sole inter-crop based CBT system was observed to be most profitable among all combinations, particularly at 50% level of probability, the 75:25 and 50:50 combinations can be safely recommended to minimize the risks associated with generation of insufficient

3.5.1. Reduced tank life Sensitivity analysis of values of economic measures utilized for evaluating the five combinations of CBT and conventional systems under different rainfall probabilities when tank life is reduced from 25 years to 20 years indicated that NPV reduced significantly by 8–26% (Table 5). The reduction was observed to decrease with increase in proportion of CBT system in a combination for a given probability of exceedance. It is attributed to higher returns from CBT system, which can minimize the negative impact of reduced tank life. With increase in probability of exceedance, reduction in NPV increased for 0:100 and 25:75 combinations of CBT and conventional systems. For other combinations, reductions were insignificant across the probabilities. On the whole, the reduction approached or equalled the highest value (26%) as the proportion of conventional system in a given combination and the probability of exceedance increased. Among the different combinations of CBT and conventional systems, the lowest reduction in NPV value was registered in case of 100:0 combination (8%) irrespective of probability of exceedance, which was slightly better than 75:25 combination (10%). For other economic evaluation criteria, reduction in tank life to 20 years had little or no impact under various combinations or probabilities of exceedance. Therefore, even with reduction in availability of the harvested water due to reduction in tank life from 25 years to 20 years, combinations with higher CBT

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V.N. Sharda et al. / Resources, Conservation and Recycling 98 (2015) 30–40

Table 6 Net present value (INR ha−1 ) for different combinations of CBT and conventional systems considering different rainfall probabilities and sensitivity parameters (discount rate – 10%; tank life – 25 years). Sensitivity parameter

Ratio of CBT and conventional systems 0:100

30% probability of exceedance Tank cost 10% higher Output prices 10% lower Tank cost 10% higher and output prices 10% lower 50% probability of exceedance Tank cost 10% higher Output prices 10% lower Tank cost 10% higher and output prices 10% lower 70% probability of exceedance Tank cost 10% higher Output prices 10% lower Tank cost 10% higher and output prices 10% lower

25:75

50:50

75:25

100:0

29,140 5661 −2536

35,579 10,627 2430

42,018 15,593 7396

87,170 55,262 50,322

134,009 96,409 94,842

29,140 5661 −2536

35,579 10,627 2430

46,579 19,684 11,872

89,105 56,991 52,349

130,816 93,530 92,059

14,982 −7081 −15,278

24,960 1070 −7127

45,244 18,464 11,140

79,441 48,281 43,930

115,473 79,717 78,338

proportion (100:0 and 75:25) will suffer from lowest reduction in NPV, irrespective of the rainfall probabilities. 3.5.2. Changes in economic estimation parameters Sensitivity analysis with 10% increase in cost of tank construction indicated that there would be significant reduction in NPV if proportion of conventional system in a given combination is high (22–35% in 0:100 compared to only 1% in 100:0) (Table 6). It is mainly attributed to lower returns from conventional system as compared to CBT system. Increase in cost of tank construction becomes unaffordable if the combination has higher proportional of conventional system. Among the three probabilities, the reduction was observed to be highest in case of 70% rainfall probability for 0:100 (35%) and 25:75 (25%) combinations. For other probabilities and combinations, the difference in reduction was either insignificant or nil. From 100:0 to up to 50:50 combinations of the two systems, the reductions will vary only if probability of exceedance is equal to or more than 70%. Therefore, escalation in cost of tank construction by 10% will have least adverse effect on NPV, if proportion of CBT is higher in the combinations. As compared to 10% increase in cost of tank construction, the impact of 10% reduction in prices of outputs was observed to be much higher ranging from 29% to 97%, and even resulting in loss (131%) in case of 0:100 combination at 70% probability of exceedance. This indicates that the combinations are more sensitive to prices of outputs and their quantities as compared to cost of tank construction. However, both the sensitivity tested parameters exhibited a similar trend for different proportions of conventional and CBT systems in the combinations and the probabilities of exceedance. On the whole, a high impact would be realized for 100:0 and 75:25 combinations, but relatively lesser than that for other combinations, if output prices deflate by 10%. When changes in the two parameters were considered simultaneously for the sensitivity analysis, there was an additive effect of the two on reduction of NPVs ranging from 30% to 166%. No change was observed in the reduction trend pertaining to proportion of conventional and CBT systems in the combinations as well as change in probability of exceedance. Among different combinations of CBT and conventional systems, the lowest reduction in NPV value was observed in case of 100:0 combination (30–33% depending upon probability of exceedance), which was observed to be better than the 75:25 combination (44–48% depending upon probability of exceedance). Therefore, simultaneous increase in tank cost and reduction in output prices will jointly cause significant reduction of NPVs, with least effect in case of 100:0 and 75:25 combinations. 3.5.3. Changes in discount rates The resilience of different combinations of the two land configuration systems evaluated in terms of changes in discount rate

Fig. 4. Net present value (INR ha−1 ) as affected by discount rates under different combinations of CBT and conventional systems at 50% rainfall probability of exceedance (tank life – 25 years).

indicated that at lower rainfall probability (upto 50%), all the NPVs were positive except for 0:100 combination at 18% discount rate (Fig. 4). At higher probability (70%), the 0:100 combination was observed to be negative not only at 18% but also at 16% discount rate, while 25:75 combination was negative at only 18% discount rate. The remaining NPVs at 70% rainfall probability were positive. The highest positive NPVs were observed in case of 100:0 combination followed by 75:25 combination for a given rainfall probability and/or discount rate. Therefore, it can be inferred that resilience to increase in discount rate above 10% is highest in combinations having higher proportion of CBT (100:0 and 75:25) at all rainfall probability levels as they have highest NPV value in spite of reduction in it. The reduction will be more pronounced (33–146%), even leading to a negative NPV, if the probability of exceedance is high (≥70%) and proportion of conventional system is higher in the combination. 4. Conclusions In this study, economic and energy use aspects of inter-crop based conservation bench terrace (CBT) and conventional (sloping border) land configuration systems were analyzed through a nine years experimental study conducted in a sub-humid climate of India. The analysis revealed that the CBT system was more remunerative than the conventional system with higher net present value (NPV) (56%) and benefit–cost ratio (BCR) (6%), and 3 years lesser pay-back period (PBP) due to 18% higher maize equivalent yield of all crops together. Taking into account the incurred soil loss as an environmental cost resulting from the two inter-cropped

V.N. Sharda et al. / Resources, Conservation and Recycling 98 (2015) 30–40

systems, the CBT system proved to be more cost-effective than the conventional system as the former could provide average net returns of INR 29,003 per tonne of soil loss as against only INR 1291 from the latter. The energy use efficiency of CBT system was significantly better than that of conventional system as CBT system had higher energy parameter values of output (106%), net returns (125%), profitability (127%), and productivity (20%). The inter-crop based systems are more profitable than the mono-crop based systems considering all economic measures of benefit cost analysis. The additional cost of cultivation incurred for inter-cropping is well compensated by higher outputs (by 43% in rainy and 46% in dry winter season) of the inter-crop based systems. Regression relationships evolved for estimation of seasonal and effective rainfalls, and crop equivalent yields were utilized for economic and sensitivity analyses of five different combinations of the two systems provided with supplemental irrigation to achieve maximum potential crop equivalent yields from the systems. The combinations having higher proportion of CBT system were observed to be more profitable at all rainfall probabilities. At 50% probability of exceedance, any combination of the two systems was observed to be equally or more promising as compared to lower (30%) or higher (70%) probabilities of exceedance. Among the five combinations tested, the 75:25 and 50:50 combinations of CBT and conventional systems were observed to be the best for minimizing risks associated with inter-cropping cultivation under erratic and deficient rainfall conditions at all probability levels. However, 75:25 combination is more preferable due to higher net returns over the 50:50 combination. The resilience of profitability of 75:25 combination of CBT and conventional systems in terms of NPV to reduction in tank life by 5 years (i.e. reduced water availability), escalation in tank construction cost by 10%, reduction in output prices by 10% and increase in discount rate (i.e. increase in capital cost) is higher than other combinations having higher proportion of conventional system, irrespective of probability of exceedance. The inter-crop based CBT system being more remunerative in terms of income, energy and environmental benefits can, therefore, be recommended over the conventional system on mildly sloping lands (2–6% slope) in the sub-humid climates. If water harvesting and recycling is essential to sustain crop productivity and mitigating ill-impacts of rainfall uncertainty on water availability in a region, a combination of CBT and conventional systems, with higher proportion of CBT system (75:25) is found to be most remunerative among all combinations. Moreover, the returns from this system are least affected (after 100:0 combination) by reduction in life of water harvesting tank, increase in cost of tank construction and decrease in the prices of crop outputs at all rainfall probabilities of exceedance.

Acknowledgements The authors thankfully acknowledge the services rendered by Mr. U.C. Tiwari, Technical Officer, for collecting and compiling the field data, and the support provided by scientists and staff of IISWC (formerly CSWCRTI), Dehradun during the study period, under the Research Project File (RPF) No. 3(II)/DD-D/95/HE. The financial support provided by IISWC (ICAR) for this study is also duly acknowledged.

Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.resconrec. 2015.03.004.

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