Energy use and Economic Analysis for Achieving Target Yield through Site Specific Nutrient Management in Soybean (Glycine max L.)- Chickpea Cropping System (Cicer arietinum L.) 

Soybean and chickpea are important kharif and rabi crops and the production are limited by nutrients and scarcity of moisture. Timely nutrient management practices play an important role in the successful cultivation of these crops. Existing fertilizer recommendation for soybean-chickpea system often consists of fixed rates and timing of N, P and K for vast areas of production. Such recommendations are constant over the years over large areas. But crop growth and crop need for supplemental nutrients are strongly influenced by crop growing conditions, crop and soil management and climate which can vary greatly among field, season and year. The SSNM (site specific nutrient management) approach does not significantly aim to either reduce or increase fertilizer use. Instead, it aims to apply nutrients at optimal rates and times in order to achieve high yield and high efficiency of nutrient use by the crop, leading to high cash value of the harvest per unit of fertilizer invested (Shankar and Umesh, 2008). Considering the fertilizer cost and availability, this limited resource needs to be saved for sustainable crop production through improving the nutrient use efficiency by site specific application.
       
Sustainable agricultural management technologies should be studied in terms of increased productivity, profitability, energy saving and efficiency of agricultural inputs usage by using efficiency indices and sustainable indicators. Comparison of different cropping systems with reference to land use and yield advantages is possible through various efficiency indices. The various cropping and farming systems practiced in an area have to be properly evaluated to decide their suitability and relative advantages. The comparisons can be made with reference to many factors viz., yield, monetary, water use efficiency, nutrient use efficiency, total dry matter production etc. Agricultural productivity is closely linked with the energy inputs. The measure of energy flow in crop production system provides a good indicator of the production of technological aspects of crop production systems in agriculture. Direct energy inputs to crop production system are derived from power sources like human, draught animals, engines, tractors, power tillers and electric motors etc., whereas indirect energy inputs are in the form of seeds, organic manures, fertilizers, pesticides and growth regulators etc.
       
Energy input-output relationships in cropping systems vary with the crops knitted in a sequence, type of soils, nature of tillage, operations, nature and amount of organic manures, chemical fertilizers, plant protection measures, yield level and biomass production (Devasenapathy et al., 2008). The energy input referred to the both renewable and non-renewable energy. Renewable energy constituted manual, animal/bullock, seed, manure etc., whereas non-renewable energy encompassed chemical fertilizers (NPK), tractor, diesel, electricity, lubricants, machinery and agro chemicals etc. Total physical output referred to both the grain and byproduct yield.
       
Generally, the production of a system depends not only on the efficiency of individual component crop of the system but also on how well these crops compliment with each other in time and space. Therefore, the overall productivity of soybean-chickpea system depended partly on the efficiency of soybean and chickpea.  Since two crops are included in cropping systems, it becomes very difficult to compare the economic produce of one crop with the other. Hence, soybean equivalent yield, input energy, output energy, energy efficiency, specific energy, net energy, energy productivity, energy intensity in physical terms and in economic terms, crop profitability, system profitability and relative economic efficiency suggested for such studies was made use. The study on refining the nutrient application through SSNM was conducted to study the response on soybean-chickpea genotypes to inorganic fertilizers based on energy indices.

The experiment was conduct at Agricultural Research Station, Janawada, Bidar as part of Ph.D. research work to study the influence of site specific nutrient management on soybean-chickpea in north eastern transitional zone of Karnataka during kharif and rabi seasons of 2014 and 2015. Survey was conducted in surrounding villages of experimental site with 25 farmers growing chickpea for their nutrient management. Based on their nutrient management practices, average quantity of fertilizers for farmer’s practice treatment was worked out. The amount of fertilizer for SSNM treatments was calculated by using the formulae (IPNI web site).
   
Where,  
T = Targeted yield (t ha^-1).
       
The composite soil samples from each treatment at 0-15 cm depth was collected and analyzed before the initiation of experiment during kharif and rabi seasons of 2014 and 2015. The nutrient statuses of soils are mentioned in the Table 1. Nutrient removal by soybean and chickpea crop per tonne seed yield were 75, 16.4, 39.0 and 46.3, 8.4, 49.6 NPK kg ha^-1 respectively (IPNI website) (Doberman et al., 2004). The nutrient ratings for soil available nutrient status are as below.
 
Nutrient rating                                             Quantity to be applied
 
Medium                                                    Exactly removal quantity
Low                                                                     30% more
High                                                                     30% less
 


       
The available soil nutrient status of the soil before sowing of soybean during rabi 2014 and 2015 were low in nitrogen, medium in phosphorous and high in potash. The calculated fertilizer doses for different target yield of soybean are given in the Table 1. 50% of nitrogen through urea and entire  quantity of phosphorus through DAP (Diammonium phosphate) and potassium through MOP (Murate of potash) were supplied at the time of sowing as a basal dose to each plot and remaining 50 per cent of nitrogen was applied at 30 days after sowing. The soil samples were analyzed by adopting standard procedures (Nitrogen - Subbaiah and Assija method (1956), Phosphorus - Olsen et al., (1954), Potassium - Jackson (1973).The soil was medium deep black, neutral in reaction.
       
The energy indices viz., were work out based on formula given by Devasenapathy et al., (2008). Input energy will be calculated for various inputs and management practices during crop cultivation and the output energy will be calculated from economic and byproduct yields (Table 2, 3 and 4).






       
Energy efficiency (MJ ha^-1) is cultural energy utilized through inputs and energy produced as products are calculated and expressed as Mega Joules. Energy efficiency (MJ ha^-1) was worked out by taking in account in the input and output energy for each treatment.  
       
Specific energy (MJ kg^-1) of the treatment can be calculated in terms of energy required to produce a kg of main product and expressed as MJ kg-1. 
   
       
Net energy (MJ ha^-1) can be calculated by deducting the energy input from the energy output of particular treatment or practice.
   
       
Energy productivity (kg MJ^-1) describes the quantity of physical output obtained for every unit of input and expressed as kg MJ^-1.
  
Energy intensity is the ratio between energy output and total physical output or cultivation expenses and expressed as MJ ha^-1 in physical terms or MJ Rs^-1 in economic terms.
 
In physical terms (MJ ha^-1) =
   
In economic terms (MJ Rs^-1) =
   
Crop profitability (Rs ha^-1day^-1) =
   
System profitability (Rs ha^-1 day^-1) =  
Relative economic efficiency (%)
 
It is a comparative measure of economic gains over the existing system. The following method is proposed for calculating the REE. It is expressed as percentage.
  Where,
DNR- Net income obtained under improved/diversified system. ENR- Net return obtained under existing system.
       
The experiment was laid out in randomized block design with the eleven treatment and three replications. The post popular cultivars of soybean and chickpea were JS 335, DSB 21 and JG 11, GBM 2 respectively used for the study. The data was analyzed statistically for test of significance following the procedure described by Gomez and Gomez (1984). The results have been discussed at the probability level of five per cent. The level of significance used in ‘F’ and ‘t’ test were p=0.05. Critical difference values were calculated whenever the ‘F’ test was significant.

Energy indices
 
Significantly higher energy efficiency, net energy, energy productivity, energy intensity in physical terms and economic terms, crop profitability, system profitability and relative economic efficiency were noticed in JS 335/JG 11 + target yield 3.0 t ha^-1 (5.28 MJ ha^-1, 1,71,039.00 MJ ha^-1, 0.40 kg MJ^-1, 13.29 MJ kg^-1 and 3.68 MJ Rs.^-1, 723.53 Rs.ha^-1 day^-1, 417.05 Rs.ha^-1 day^-1 and 2.75, respectively) compared to  JS 335/JG 11 + farmer’s practice (3.76 MJ ha^-1, 1,25,638.83 MJ ha^-1, 0.29 kg MJ^-1, 13.09 MJ kg^-1 and 3.20 MJ Rs^.-1, 397.21 Rs. ha^-1 day^-1, 228.90 Rs. ha^-1 day^-1 and 0.00, respectively) Table 5 ,6, 7 and Fig 1, 2, 3). The treatments which produce higher energy efficiency, net energy, energy productivity, energy intensity, crop profitability, system profitability and relative economic efficiency are economically beneficial, advisable and recommended for large scale adoption.












       
Specific energy follows opposite trend as that of energy efficiency, significantly lower specific energy was recorded in JS 335/JG 11 + target yield 3.0 t ha^-1 (7.05 MJ kg^-1) over JS 335/JG 11 + farmer’s practice ( 13.01 MJ kg^-1), but it was on par with  JS 335/JG 11 + target yield 3.0 t ha^-1(7.39 MJ kg^-1). Minimum energy required to produce a kg of seed was noticed in JS 335/JG 11 + target yield 3.0 t ha^-1 than JS 335/JG 11 + farmer’s practice. Thus, it may be concluded that site-specific nutrient management approach may break the yield barrier of soybean and chickpea by enhancing yield through judicious exploitation of available nutrients by plants. Nutrients applied to soybean crop have definite carry over beneficial effects on enhancing yield of succeeding chickpea crop. This indicates for a cautious and balanced use of nutrients for enhancing systems productivity and profitability without endangering soil and human health. The results can be correlated with findings of Mandal et al., (2002), Billore et al., (2009), Kirankumar et al., (2013), Mauriya et al., (2013), Walia et al., (2014) and Jain et al., (2015). These indices suggest that the target yield based on SSNM equation not only optimizes the soybean-chickpea system yield to the desired level but maintains the better soil health which is a prime factor for sustainable crop production and for large scale adaptation. The above findings suggest that SSNM technology may be the appropriate approach for optimum nutrient supply which improves the soil properties especially the soil health and productivity in a long run in comparison to other nutrient management technologies. The results indicated that the maximum potential yield of genotypes for both soybean and chickpea was achieved upto target yield of 3.0 t ha^-1.

Soybean equivalent yield and system profitability
 
Among the different target yield levels (Table 8 and Fig 4), the pooled data indicated that significantly higher soybean equivalent yield, gross return, net return and BC ratio were obtained in JS 335/JG 11 with target yield of 3.0 t ha^-1 (5683 kg ha^-1, Rs.2,09,623 ha^-1, Rs. 1,52,224 ha^-1 and 3.65 respectively ) compared to rest of the target yield levels but it was found to be on par with that of DSB 21/GBM 2 with target yield of 3.0 t ha^-1 (5465 kg ha^-1, Rs. 2,01,612 ha^-1, Rs.1,44,208 ha^-1 and 3.51 respectively), while significantly lower soybean equivalent yield was registered in the target yield treatments of DSB 21/GBM 2 with target yield of soybean/chickpea to 2.0 t ha^-1 (4383 kg ha^-1, Rs. 1,61,720 ha^-1, Rs. 1,10,010 ha^-1 and 3.13). Significantly lower soybean equivalent yield, gross return, net return and BC ratio were noticed in JS 335/JG 11 with farmer’s practice (3524 kg ha^-1, Rs. 1, 30,040 ha^-1, Rs. 83,548 ha^-1 and 2.80) among all the treatments. The cost of cultivation of soybean-chickpea cropping sequence was higher with JS 335/JG 11 + target yield 3.0 t ha^-1 (Rs.57,399 ha^-1) over JS 335/JG 11 + farmer’s practice (Rs.46,492 ha^-1). This may be due to higher cost of fertilizers resulted in increased cost of cultivation in soybean-chickpea cropping sequence. The higher gross returns observed in the above treatment was mainly attributed to significantly higher grain and straw yields obtained in the respective treatments. Significantly higher grain yield of preceding soybean coupled with higher market price for succeeding chickpea contribution for higher system net return. This might be due to higher grain, seed and straw yield of component crops (soybean-chickpea) due to different targeted yield levels. These results are in conformity with the findings of Mauriya et al., (2013), Honnalli and Chittapur (2014), Jain et al., (2015) and Shreeharshakumar and Gaddanakeri (2015).

The target yield based on SSNM equation not only optimizes the soybean- chickpea system yield to the desired level but maintains the better soil health which is a prime factor for sustainable crop production and for large scale adaptation by efficiently comparison with energy efficiency.