Basal and topdressing application technology of phosphate fertilizer for high cotton yield and high phosphorous efficiency in Xinjiang

Objectives Different basal and topdressing ratios of phosphate fertilizer were attempted on cotton in Xinjiang Uygur Autonomous Region, in order to optimize the phosphate fertilization suitable for the widely extended fertigation under plastic mulching technology.

Methods Three treatments were set up including no phosphorus fertilizer, all phosphorus fertilizer basal applied, and basal plus fertigation. 50% of phosphorus was applied with drip irrigation in 2009 and 2010, and 35% in 2011. Phosphorus fertigation was conducted in bud stage and early flowering stage of cotton. All nitrogen was applied with drip irrigation and all potassium fertilizer was used as basal application. The cotton biomass, yield and phosphorus contents were determined in maturity stage of cotton.

Results The application of phosphorus fertilizer significantly increased the aboveground biomass of cotton. Compared with control, the biomass of leaf, stem, seed and fiber of cotton were significantly increased by 15%, 9%, 9% and 11% with basal treatment, and those of leaf, stem, shell, seed and fiber of cotton by 21%, 23%, 21%, 12% and 13% with fertigation treatment, respectively; the average seed cotton yield of 3 years was increased by 8% with basal treatment and 13% with fertigation, and the average yield of fertigation treatment was 5% higher than that of basal treatment. Phosphate application significantly increased phosphorus uptake of cotton. The use efficiency of phosphate fertilizer at basal treatment was 18%, and that at fertigation treatment was 23%. The yield increase and phosphate utilization rate of 35% phosphorus fertilizer was applied with drip irrigation were 18% and 24% respectively, and those were 11% and 22% in treatment with drip irrigation topdressing ratio of 50%.

Conclusions Application of phosphorus fertilizer could significantly increase the cotton aboveground biomass and yield, and increase the phosphorus absorption of cotton. The effect of phosphorus fertigation is better than that of all phosphate fertilizer basal applied. The yield increase effect of 65% phosphate fertilizer applied as basal and 35% as drip irrigation was better than that of drip irrigation topdressing ratio of 50% phosphate fertilizer.