Yield response and economic analysis of fertilizer application in maize    grown in North China

【Objectives】Varied crop yield responses resulted from different soil types, and different nutrient management practices affect crop profitability. The study on yield responses and economic benefits from fertilizer N, P and K application, and the changes of economic benefits under projected yield responses, fertilizer application rates and different maize prices would provide reference for scientific and economical fertilization for maize in Northern China.【Methods】Three hundred and seventy three field experiments were conducted in seven provinces in North China from 2010 to 2012 to explore the yield response and economics of fertilizer N, P and K application on maize. Experiments included Nutrient Expert fertilizer recommendation based on yield response and agronomic efficiency, and series of omission plots including minus N, minus P and minus K treatment, and farmers practices as the control. Value to cost ratio (VCR) from fertilizer N, P and K was calculated based on yields, prices of maize and fertilizers, as compared with farmers practice.【Results】Results obtained indicated that great variation existed in yield responses to fertilizer N, P and K. The yield responses to N application were 3040, 2314, 2324, 981, 2139, 1184 and 1244 kg/ha, those to P application were 1463, 1216, 1425, 635, 944, 376 and 620 kg/ha, and those to K application were 1454, 1063, 1532, 877, 910, 383 and 592 kg/ha, for Heilongjiang, Jilin, Liaoning, Hebei, Henan, Shandong and Shanxi Province respectively. The yield responses to N, P and K application ranged from 341-7900 kg/ha,11-5381 kg/ha and 9-4097 kg/ha,respectively, with average of 1889, 954 and 973 kg/ha. The responses suggest that the yields are limited first by N, followed by K, and P had the minor effect. Economic analysis demonstrates that the VCR of applied N, P and K in maize were 2.8, 7.8 and 4.6 respectively suggesting that 2.8, 7.8 and 4.6 times of return with unit capital input on fertilizer N, P and K. Economic assessment based on projected cost of fertilizer and maize also show VCRs increase with increase of yield response although the fertilizer rate increases. Grain yield and economic benefits from Nutrient Expert based fertilizer recommendation with N-P2O5-K2O of 157-56-67 kg/ha are 10255 kg/ha and 18903 yuan/ha,those from farmers practice are 9996 kg/ha and 18154 yuan/ha with N-P2O5-K2O of 225-61-47 kg/ha at the same sites. Nutrient Expert recommendation achieve 748 yuan/ha more benefit than farmers practice, 1/3 of which is from saved cost from efficient use of fertilizers, and 2/3 from yield increase.【Conclusions】 The highest yield response is obtained to N, followed by K and lowest to P fertilizer in the maize production areas in North China. However, the highest profitability from fertilizer application was from P, followed by K and lowest from N considering unit fertilizer prices. Compared with farmers practice, Nutrient Expert recommended N-P2O5-K2O fertilizer of 157-56-67 kg/ha is the rate of both high grain yield and economic benefit for maize in Northern China.