Management of Nitrogen and Phosphorous in Green Gram (Vigna radiata) by Foliar Supplementation of Urea Phosphate in Acidic Inceptisols

Abstract

Foliar fertilization is key to correct the diagnosis of plant nutrient deficiencies. Under certain situations, the foliar application is more economical and efficient than soil application. Foliar fertilization of crops sometimes adds to soil fertilization. It provides more rapid utilization of nutrients by stomata in less time, particularly in the daytime. Foliar application of urea phosphate (UP), acidic water-soluble fertilizer, along with blanket fertilizer doses can influence the photosynthetic activity as well as yield, nutrient use efficiency and economics of the crop green gram. A field experiment was conducted during 2015-2016 to study the present hypothesis. The experimental design was laid out in randomized block design (RBD) with 3 replications having 10 treatments. These treatments were T₁: control (no nutrient); T₂: 50% of the recommended dose of fertilizer (RDF) for N and P; T₃: 75% of RDF for N and P; T₄: 100% RDF for N and P; T₅: 50% of RDF for N and P + twice foliar spray (FS) of 1% UP; T₆: 50% of RDF for N and P + twice FS of 2% UP; T₇: 75% of RDF for N and P + twice FS of 1% UP; T₈: 75% of RDF for N and P + twice FS of 2% UP; T₉: 100% of RDF for N and P + twice FS of 1% UP; T₁₀: 100% of RDF for N and P + twice FS of 2% UP. The total chlorophyll content in green gram leaves at different growth stages due to different treatments varied from 2.57 to 4.01 mg g^-1 fresh weight. Irrespective of the treatments, an increasing trend of total chlorophyll content was observed up to 29 days of sowing and the highest content was observed with T₁₀ (4.01 mg g^-1 fresh weight). Yield attributes like grain (834.1 kg ha^-1) and straw (2535.4 kg ha^-1) yield were recorded highest with T₁₀ (100% of RDF + twice FS of 2% UP) whereas the lowest value was observed with T₁. Similarly, uptake of nutrients (N-55.5 kg ha^-1; P-8.6 kg ha^-1; and K-27.0 kg ha^-1) in green gram leaves at harvest stages were also recorded maximum in T₁₀. The highest nutrient use efficiency (16.3 kg of grain per total kg of nutrient) was recorded with T₂ whereas apparent nutrient recovery of N (97.5 %) and K (26.3%) were recorded highest with T₁₀. The highest cost of cultivation (Rs. 19025), gross income (Rs. 38370), net return (Rs. 19345) and benefit-cost ratio (2.02) was also observed with T₁₀ (100% of RDF for N and P + twice FS of 2% UP).