Fertigation Effects on Productivity, and Soil and Plant Nutrition of Coconut (Cocos nucifera L.) in the Eastern Indo-Gangetic Plains of South Asia

Abstract

Fertigation has the potential to reduce extra chemical load by improving nutrient and water use efficiency of coconut (Cocos nucifera L.), but studies demonstrating the fertilizer reduction through drip irrigation in comparison to conventional ring basin method are rare in the Eastern Indo-Gangetic Plains (IGP) of South Asia. A long-term field experiment was conducted during 2007–2013 in West Bengal, India, to study the effect of fertigation on coconut var. DXT. The experiment was laid out in a randomised complete block design (RCBD) with six treatments (control–no fertilizers and water applied with drip irrigation; 25%, 50%, 75% and 100% of the recommended dose of fertilizer (RDF), each applied with drip irrigation; and 100% of the RDF and water applied with ring basin method of irrigation (i.e., conventional method)). Nuts yield was significantly higher for 75% of RDF (24.44 t ha −1  year −1 ) followed by 100% of RDF, each drip irrigation (23.79 t ha −1  year −1 ) compared to control (21.89 t ha −1  year −1 ). Copra yield was significantly higher for 75% of RDF (3.19 t ha −1 ) compared to 100% of RDF (3.12 t ha −1 ) and no fertilizer (1.87 t ha −1 ). Nitrogen (N), phosphorus (P) and potassium (K) contents of soil increased by 4.9%, 10.4% and 9.4%, respectively, with 75% of RDF applied through drip irrigation. Microbial population showed inverse relationship with amount of fertilizer application. The most water-use efficient fertigation treatment was 75% RDF (13.48 kg copra m −3 ) followed by 100% RDF (13.18 kg copra m −3 ) with drip irrigation as compared to conventional way soil application of fertilizers through ring basin method of irrigation (4.23 kg copra m −3 ). Role of N on yield variability was most prominent by both available soil N status (R 2  = 0.49**) and leaf N concentration (R 2  = 0.51**). The study indicated that there is a great scope for reducing the N, P and K fertilizers by up to 25% of the present RDFs for coconut when applied through drip irrigation compared to ring basin method of irrigation for its higher productivity and profitability through efficient use of nutrients and water in the Eastern IGP of South Asia.