Effects of different N, P and K treatments on yield, nutrient accumulation and utilization and economic benefit of cassava

In 2010 and 2011, using cassava cultivar, SC205, as material and the 3414 experimental design, an experiment was carried out to study the effects of different application amounts of nitrogen, phosphorus and potassium on cassava yield, nutrient accumulation and utilization and economic benefit. And through multiple regressions, the equation of the fertilizer efficiency for upland red soils in Jiangxi province was established. The results show that the yields of the fertilization treatments are significantly higher than those of the treatments without fertilization, the yield of the nitrogen deficiency treatment is significantly lower than those of the phosphorus and potassium deficiency treatments, and the effects on the yield is NK2OP2O5 Cassava yield, fresh root starch content, fresh biomass, nutrient harvest index and economic benefit of the N2P2K2 treatment are the highest among the fertilization treatments. The outputinput ratio of the N2P2K0 treatment is the highest, the ratio of the N1P2K1 treatment is secondly and the ratio of the N2P2K3 treatment is the smallest. The order of plant total nutrient accumulation is K2ONP2O5 The average nutrients (potassium, nitrogen and phosphorus) requirements for 100 kg fresh root are 1.00, 0.91 and 0.11 kg, and the average harvest indexes are 0.53, 0.33 and 0.46, respectively. The correlation analysis shows that the cassava yield has an extremely significantly positive correlation with nitrogen application amount and a significantly positive correlation with the potassium application amount, while the yield has an insignificantly correlation with phosphorus application amount. Under the condition of this experiment, the fitting results of the developed quadratic equations in three variables show that the application amounts of nitrogen, phosphorus and potassium and the ratio of output to input for the economic optimum yield are 205.37 kg/ha, 65.43 kg/ha, 311.30 kg/ha and 6.23, respectively.