Growth and productivity of cowpea (Vigna unguiculata L.) as affected by different levels of nano DAP in north eastern dry zone of Karnataka

A field experiment was conducted at College of Agriculture, Bheemarayanagudi during kharif season 2023 with an objective to study the effect of nano DAP on growth and yield of cowpea (Vigna unguiculata L.). The soil was clayey in texture and experiment was laid out in randomized block design with three replications and comprised of seven treatments. The treatments comprise of rate of soil application of conventional (DAP) and foliar application of nano DAP fertilizers. Regional recommended N and K fertilizer rate is common for all the treatments. Results revealed that basal application of 100 per cent RDP + foliar spray of 4 ml l-1 of nano DAP had resulted in higher seed yield (1940 kg ha-1), however, it was statistically on par with application of 100 per cent RDP + 2ml l-1 nano DAP spray at 30 and 45 DAS (1890 kg ha-1), 75% per cent RDP + 4 ml l-1 nano DAP spray (1871 kg ha-1) and control treatment with RDF (1790 kg ha-1). Further, similar trend has been followed in case of stover yield, gross returns, net returns and B C ratio of cowpea production. These results confirms that we can replace about 25 per cent of conventional DAP fertilizer with nano DAP application of 4 ml l-1 at 30 and 45 DAS in increasing the P use efficiency and productivity of cowpea.