An assessment of productivity potential, biological feasibility and economic viability of castor based relay intercropping system in Rainfed Alfisols of Karnataka

A field experiment was conducted at the Zonal Agricultural Research Station (ZARS), University of Agricultural Sciences, GKVK, Bengaluru during the kharif and rabi season of 2022-23 and 2023-24 to evaluate the feasibility of a castor-based relay intercropping system under rainfed alfisols of Karnataka. The experiment followed a split-plot design, comprising four main plot treatments involving different crop geometries combined with fingermillet intercropping, four subplot treatments consisting of various relay intercropping system and seven treatments under sole cropping for comparison. The study results revealed that the wider paired row planting of castor (60-240 cm x 45 cm) combined with fingermillet intercropping significantly outperformed other cropping geometries. This system recorded the highest pooled values dry matter accumulation (145.26 g plant-1), seed yield (1442 kg ha-1), stalk yield (4417 kg ha-1), castor equivalent yield (2868 kg ha-1), land equivalent ratio (1.88), rain water use efficiency (3.97 kg ha-mm-1), system profitability (₹ 452.25 ha-day-1) and net return per rupee invested (₹ 2.08 Re-1) compared to narrow paired row planting (45-240 cm x 30 cm) and skipped row planting systems (120 cm x 60 cm and 90 cm x 60 cm). Interestingly, fingermillet grain and straw yield was significantly higher under skipped row planting of castor than in other geometries. In terms of relay intercropping, fieldbean relay intercropping has outperformed with significantly higher dry matter accumulation (26.41 g plant-1) than compared to sorghum (25.40 g plant-1), horsegram (24.16 g plant-1) and cowpea (22.58 g plant-1) relay intercropping system. However, in castor based relay intercropping system paired row planting of castor (60-240 cm x 45 cm) with fingermillet intercropping followed by fieldbean relay intercropping recorded the higher seed yield (1446 kg ha-1), stalk yield (2636 kg ha-1), castor equivalent yield (2881 kg ha-1), land equivalent ratio (1.89) rain water use efficiency (3.98 kg ha-mm-1), system profitability (₹ 459.98 ha-day-1) and net return per rupee invested (₹ 2.17 Re-1) surpassing all other relay intercropping combinations.