Effects of Phosphate Fertilizer Application Methods on Cotton Aboveground Biomass, Yield and Phosphorous Efficiency in Drip Irrigation and Plastic Mulch Field

Phosphorus deficiency has become a limiting fact for getting high yield in cotton field in Xinjiang, China. Field plot experiments were conducted from 2009 to 2011. It had 3 treatments that were no phosphorus, phosphorus as basal, and phosphorus split application (50% phosphorus as basal and 50% phosphorus as drip irrigation fertilizer in 2009 and 2010, and 65% phosphorus as basal and 35% phosphorus as drip irrigation fertilizer in 2011). Topdressing phosphorus was used in bud and early flowering stage of cotton with water droplets. Same dosage and use method of nitrogen and potassium were arranged in different treatment of every experiment. Nitrogen was splited application following with drip water in cotton growth period. Potassium was as basal fertilizer. The results showed as follow: application of phosphorus significantly increased aboveground biomass of cotton. All phosphorus as basal significantly increased 14.72%, 9.47% and 10.74% biomass of leaf, seed and fiber of cotton than those of no phosphorus, respectively. phosphorus split application significantly increased 20.58%, 22.57%, 21.16%, 11.85% and 13.46% biomass of leaf, stem, shell, seed and fiber of cotton than those of no phosphorus, respectively. Compared with no phosphorus, applying phosphorus could significantly improved cotton yield. Average yield of 3 years of phosphorus as basal increased by 8.38%, and the average yield of 3 years of phosphorus split application increased by 13.27%. The average yield of phosphorus split application increased by 4.89% than phosphorus as basal. Phosphorus application significantly increased phosphorus uptake of cotton. Recovery use efficiency of phosphorus at phosphorus as basal treatment was 19.20%, agronomic efficiency was 0.92 kg/kg, and phosphate partial productivity was 12.45 kg/kg. Recovery use efficiency of phosphorus at phosphorus split application treatment was 23.54%, agronomic efficiency was 1.46 kg/kg, and phosphate partial productivity was 12.99 kg/kg. Phosphate fertilizer split application could increase the phosphorous efficiency.