Establishing Fertilization Recommendation Index of Soybean in Black Soil Region of Heilongjiang Province

In order to explore the fertilizer recommendation of soybean cropping system in the black soil area of the Northeast China,Heilongjiang Province,fertilization index system were established according to the‘3414’fertilizer trails which carried out in many locations for many years.The results showed as follows:(1) Soil fertility level were divided 5 grades of low,relatively low,middle,relatively high and high,based on the relative soybean seed yield of 75%,80%,85% and 90% for available nitrogen,and 75%,85%,90% and 95% for available phosphorus and potassium,respectively.(2) The optimum amount of fertilization of different fertility grades from low to high were 41.7-43.4,36.3-41.7,28.4-36.3,26.1-28.4 and 0-26.1 kg.ha-1 for N,51.0-62.0,47.7-51.0,38.9-47.7,33.9-38.9 and 0-33.9 kg.ha-1 for P2O5,55.4-64.1,51.2-55.4,43.2-51.2,35.4-43.2 and 0-35.4 kg.ha-1 for K2O.(3) The increase income of different fertility grades were 1 270.61 387.6,681.9-1 270.6,357.3-681.9,279.9-357.3,0-279.9 yuan.ha-1for pure N;856.9-1 101.3,729.3-856.9,347.6729.3,221.2-347.6 and 0-221.2 yuan.ha-1 for P2O5;and 444.1-739.5,382.1-444.1,266.2-382.1,184.6-266.2 and 0-184.6 yuan.ha-1 for K2O.(4) The agronomic efficiency of the optimum recommended fertilizer rate were 9.5-9.9,6.3-9.5,4.7-6.3,4.2-4.7 and 0-4.2 for N;6.1-6.3,5.6-6.1,3.9-5.6,3.3-3.9 and 0-3.3 for P2O5;and 4.0-4.9,3.8-4.0,3.43.8,3.2-3.4 and 0-3.2 for K2O.