Indices for measuring system efficiency of American cotton and legume intercropping in additive series of 1:1 ratio at rainfed vertisols

Abstract Background and Aims Cotton (Gossypium hirsutum L.) is grown at wide-row spacing and offers an opportunity to intercrop. We hypothesized that including a legume may improve the soil fertility and the system productivity. However, less is known about intercropping legume on rainfed vertisols. Methods During initial two years (2015–2017) field experiments were conducted for identifying efficient nitrogen (N) fixing legume [Blackgram (Bg), green gram (Gg), cowpea (Cp), soybean (Sb), cluster bean (Cb), pigeon pea (Pp), dolichos (Dc) and groundnut (Gn)] with high-density planting system (HDPS). Based on these results, a further study for three years (2018–2020) was conducted with the short, medium and long duration of shortlisted legumes to determine economic and operational feasibility. Results Legume intercrops reduced the seed cotton yield. However, cotton equivalent yield results showed that productivity of the cotton + cotton (Cc) and sole cotton (Cs), is lower (63, 30%) than legume intercropped cotton (CLi) excluding pigeon pea (Pp). The positive and higher values of land equivalent ratio (1.40–1.78) indicated the benefits of intercropping systems than of Pp (0.74 − 0.69) or Cs (1.00). Legumes also improved the area time equivalent ratio of 14–28% and 97% of land use efficiency than Cs. No competition and aggressivity was exhibited between legume intercrops and cotton. Conclusion These indices suggest that pigeon pea, dolichos and cotton are not suitable for intercropping in additive series with HDPS at the existing row spacing (1:1). Further, the indices with Bt-cultivars ensure the facilitative robustness of legume intercropping technology for sustainable production under rainfed areas.