Studies on residual effect of green manuring and different organic sources of nutrients on growth and yield of cowpea in maize-cowpea cropping sequence

Abstract

A field experiment was conducted at research and demonstration block of Research Institute on Organic Farming, UAS, GKVK, Bengaluru during 2022-23 and 2023-24 to study the effect of green manuring and different organic sources of nutrients on growth and yield of maize in maize-cowpea cropping sequence. The experiment was laid out in a split plot design with three replications. The experiment consists of 18 treatment combinations which consisted of two main plots i.e. with and without In situ incorporation of sunhemp as a green manure crop and nine subplots comprising three levels of N equivalent and four organic sources of nutrients. The soil of experimental site was red sandy loam having medium organic carbon (0.64%), medium in available N (291.2 kg ha-1), medium in available P2O5 (26.24 kg ha-1) and medium in available K2O (228.3 kg ha-1) content. The experimental results indicated that In situ incorporation of green manure along with the integrated application of 25% N equivalent FYM + 25% N equivalent poultry manure + 25% N equivalent vermicompost + 25% N equivalent jeevamrutha for maize crop resulted in significantly higher plant height (56.76 cm), leaf area (1550 cm2 plant-1), total dry matter accumulation (23.84 g plant-1), grain yield (1386 kg ha-1), haulm yield (2903 kg ha-1) and B:C ratio (2.37). This was followed by the combination of green manuring with 50% N equivalent FYM + 50% N equivalent poultry manure which resulted in higher plant height (53.55 cm), leaf area (1499 cm2 plant-1), total dry matter accumulation (20.96 g plant-1), grain yield (1283 kg ha-1), haulm yield (2705 kg ha-1) and B:C ratio (2.17) of residual crop cowpea. This combination was found to be significantly superior over other treatments in the studies.