On-farm evaluation of fertilizer application and conservation tillage on productivity of cotton + pigeonpea strip intercropping on rainfed Vertisols of central India

Cotton + pigeonpea strip intercropping is a traditional cropping system in central India. On-farm trials were conducted on five farms each on medium deep soils (MDS) and deep soils (DS) during 2001-2002 and 2002-2003 on Vertisols under rainfed conditions to evaluate the effect of technological interventions on cotton + pigeonpea system. The interventions (applying recommended dose of fertilizer (RDF), conservation tillage (CT) with in situ green manure + RDF (CT1) and CT1 + zinc sulphate (CT2)) were compared with the farmers' practice (FP). Cotton (Gossypium hirsutum L.) and pigeonpea (Cajanus cajan (L.) Millsp.) were sown in 6:2 row ratio at a spacing of 0.75 m × 0.75 m on MDS and 0.90 m × 0.90 m on DS. Mean seed cotton yield was significantly greater in 2001-2002 (809 kg ha−1) compared to 2002-2003 (508 kg ha−1), while the reverse was true for pigeonpea grain yield. Averaged over years, seed cotton yield did not differ between locations (MDS versus DS). However, in 2001-2002 seed cotton yield was significantly greater on DS (855 kg ha−1) than on MDS (764 kg ha−1). Seed cotton yield increased by 114 with application of RDF, while the contributions for CT and Zn application were 51 and 76, respectively. Seed cotton yield increase in plots with interventions was because of more and heavier bolls (2.66-2.75 g) retained per plant than the FP (2.39 g). Pigeonpea grain yield was 80 kg ha−1 higher on DS than on MDS. For the interventions, yield followed the trend: CT2 ≥ CT1 ≥ RDF > FP, suggesting the need to apply fertilizers to pigeonpea. Fibre quality was better in the cotton grown on DS than on MDS. Marginal benefit:cost ratio (MBC) was the greatest for the RDF (3.08) followed by CT2 (1.71) and CT1 (1.41). Considering the farmer's low-income and high-risk nature of rainfed farming, investment on herbicide (US$ 37 ha−1) could be a deterrent to adopting CT.