Effect on growth attributes
Data presented in Table 1 reveals that the crop management treatments significantly influenced the growth attributes
viz., plant dry matter at 45 and 60 DAS, CGR and RGR. Whereas, the values for plant height, number of branches per plant, dry matter per plant at 30 DAS and RGR at 45-60 DAS were non significantly influenced. The treatment T
1: Full practice recorded significantly higher number of pods per plant (58 pods) and significantly higher dry matter at 45 DAS (8.13 g plant
-1) and at 60 DAS (14.46 g plant
-1) over the treatment T
4: Full practice excluding RDF and closely followed by treatment T6: Full practice - insecticide application and T7: Full practice - ridges and furrow sowing. The values for CGR at 30-45 DAS (0.337 g m
-2 day
-1) and at 45-60 DAS (0.421 g m
-2day
-1); and for RGR at 30-45 DAS (0.035 g m
-1day
-1) were significantly high in treatment T
1: Full practice over T
5: Full practice excluding weed management and rest of the treatments under study. Variation in the number of pods per plant, dry matter accumulation and growth rate due to different treatments might be attributed as positive assotiation with leaf area, number of leaves per plant and net assimilation rate of soybean plants
(Malek et al., 2012). The differences in total dry matter accumulation in genotypes reflect differences in photosynthetic production
(Bhattacharya, 2021).
Effect on seed yield and its attributes
The data on seed yield in various treatments was significantly different (Table 2). Soybean crop grown with T
1: full practice (3221 kg ha
-1) gave significantly higher seed yield over treatment T
4: full practice excludes RDF (2489 kg ha
-1) and T
5: full practice excludes weed management (2560 kg ha
-1) and was closely followed by rest of the treatments under study. Increase in seed yield under treatment T
1 over the T
4 was 22.72% and over T
5 it was 20.52%. Increment in seed yield due to full practice supported the essentiality of optimum cultivation practices required for obtaining the higher yield and evidenced the importance of individual cultivation practice to harvest maximum yield. Higher seed yield under treatment T
1: Full practice attributed to the maximum number of pods due to supply of all inputs and optimum management practices. Per cent decrease in yield under the treatments compared to full practice (T
1) presented in Fig 1. It showed decreasing order of an input/the management practice, which put forth the importance of an individual input/ the management practice for raising the soybean crop and obtaining optimum yield. Per cent increase in yield over full practice-RDF (T
4) was higher in all treatments except full practice - weed management (T
5) due to maximum yield loss. The results showed that the absence of RDF to supplement the nutrients, non removal of weeds that compete for resources and no insecticide application to manage the insect-pests contribute to maximum yield losses compared to rest of the crop management practices. Seed yield increase in soybean due to high input system was supported by the findings of
Marburger et al., (2016).
Economics of study
Economic evaluation of the different treatments presented in Table 3 showed that the crop management with full practice (T
1) gave maximum gross returns (₹ 1,09,501/- ha
-1), net returns (₹ 67,844/- ha
-1) and benefit: cost ratio (2.63:1) over full practice excluding RDF (T
4) and weed management (T
5); while these values in rest of the treatments were closely followed. Least net returns and benefit: cost ratio was observed with treatment T
5: full practice excluding weed management (₹ 49,125/- ha
-1 and 2.32:1) followed by T
4: full practice excluding RDF (₹ 50,239/- ha
-1 and 2.47:1). The increase in the yield due to full practice (T
1) showed 27.59% and 25.94% increase in net returns over full practice excluding weed management (T
5) and excluding RDF (T
4), respectively. The yield gap in terms of yield reduction per hectare determined over the treatment full practice was recorded maximum under T4: full practice excluding RDF (732 kg ha
-1) and T5: full practice excluding weed management (661 kg ha
-1) followed by T
6: full practice excluding insecticide application (351 kg ha
-1). However, the least yield gap was recorded under treatment T
2: full practice excluding seed treatment (152 kg ha
-1), which showed it has least effect on soybean seed yield than other management practices. The value of differential yield based on the yield gap per hectare was maximum in treatment T
4: full practice excluding RDF (₹ 24,888/- ha
-1) followed by T5: full practice excluding weed management (₹ 22,474/- ha
-1) while, it was least in T
2: full practice excluding seed treatment (₹ 5,168/- ha
-1). The differential cost per treatment determined over full practice was higher under T
4: full practice excluding RDF (₹ 7,282/- ha
-1) and T
5: full practice excluding weed management (₹ 3,750/- ha
-1) due to the absence of RDF and weed management. The incremental benefit: cost ratio determined considering the value of differential yield and differential cost was maximum in T
3: full practice excluding seed inoculation (59.84:1) and it was followed by T
2: full practice excluding seed treatment (20.67:1) than rest of the treatments. Higher incremental benefit: cost ratio with T
3: full practice excluding seed inoculation (59.84:1) and T
2: full practice excluding seed treatment (20.67:1) showed the highest factor productivity and was associated with a minimum cost of cultivation incurred on seed inoculation and seed treatment. The break-even yield determined based on the cost of cultivation and selling price of soybean varies from 948 kg ha
-1 to 1041 kg ha
-1. Overall an average soybean yield needed to break even was 984 kg ha
-1 to receive high returns under use of all the inputs of production,
i.
e. T
1: Full practice. However, the break-even cost per kilogram of soybean was maximum in treatment T
5: full practice excluding weed management (₹ 14.81/- kg
-1); it showed that more cost was incurred on the production of a kilogram of soybean per hectare. Whereas, least break-even cost was incurred in treatment T1: full practice (₹ 12.93/- kg
-1). Break-even analysis gives accurate future profitability from soybean production
(Billore et al., 2020).
Crop output efficiency
Output efficiency in terms of partial factor productivity (PFP) and agronomic efficiency (AE) of applied nutrients to soybean crop presented in Table 4. PFP in terms of kilogram of grain produced to the kilogram of nutrient applied (Nitrogen, phosphorus and potash) was maximum with treatment T
1: Full practice followed by T
2: full practice excluding seed treatment and T
3: Full practice excluding seed inoculation, while the values for PFP of N, P and K were least under treatment T
5: full practice excluding weed management. However, AE of the applied nutrients (N, P and K) to soybean was recorded maximum in T
1: full practice followed by T
2: full practice excluding seed treatment and T
3: full practice excluding seed inoculation. Least AE was recorded with treatment T
5: full practice excluding weed management. These results are in agreement with
McLaughlin et al., (2011), who reported that P fertilization increases nutrient use efficiency and partial factor productivity. PFP is a measure of efficiency that includes production per unit of nutrient applied
Rose et al., (2012). Yuan and Xu (2011) reported that PFP indicates how productive a crop in comparison to its nutrient input is. Similarly,
Mujeeb et al., (2010) reporeted that the application of all the organic and inorganic inputs significantly increased the agronomic efficiency of nutrients applied to the soils. The results of study revealed that soybean crop grown with all management practices comprising land preparation, seed treatment, seed inoculation, balanced nutrition, water, weed management, insect-pest and disease management gives optimum seed yield. An absenec of the factors of production significantly affects the growth, yield attributes, seed yield and the economic benefits from the soybean. Recommended dose of fertilizer and weed management are major factors contributing to soybean yield loss and attributed to maximum yield gaps compared to full practice.