Productivity and nutrient status of coconut (Cocos nucifera) as influenced by integrated nutrient management with vermicomposted coconut leaves

Abstract

A long-term field investigation was carried out during 2001 to 2010 at Vittal (Karnataka) in a 22 year old coconut garden under laterite soil to study the impact of inorganic fertilizer substitutions by vermicompost (VC) on productivity and profitability of coconut (Cocos nucifera L.). The treatments, viz. recommended inorganic fertilizer (500 g N, 320 g P and 1200 g K/palm/year), 25% of N in the form of VC (9.6 kg/palm) + 75% of NPK, 50% N in the form of VC (19.2 kg/palm) + 50% of NPK, 75% in the form of VC (28.8 kg/palm) + 25% NPK and 100% N in the form of VC alone (38.5 kg/palm) were imposed in randomized block design. Annual leaf production did not differ significantly among the treatments; however, integrated treatments resulted in higher number of leaves (12 no.). Six years pooled data on nut yield indicated that, application of vermicompost in combination with inorganic fertilizer either at 25% of N + 75% NPK (64.5 nuts/palm/year) or 50% of N + 50% NPK (66.2 nuts/palm/year) resulted in significantly higher nut yield. There was improvement in the nutrient status of coconut leaves with integrated nutrient management practices compared to inorganic or organic manure alone application. The soil organic carbon build up was observed with application of 50% N or more in the form of vermicompost compared to the other treatments. Microbial population in respect of fungi and phosphate solubilizes were higher when vermicompost was applied.