In order to increase mulberry leaf yield and production efficiency in hilly areas of Sichuan Province through scientific fertilization,＂3414＂,a quadratic regression design for modern fertilization,was employed to simulate the regression relationship between mulberry leaf yield and major fertilizer elements including nitrogen（N）,phosphor（P） and potassium（K） among which mulberry leaf yield was the objective function and N,P and K were the regulatory factors to fertilization level.As a result,7 types of ternary,binary and monadic quadratic fertilizer effect functions of N,P and K fertilizer elements were established.The weight of fertilizer factors in the optimal mulberry leaf yield obtained by various types of functions was in decreasing order of KPKPNPKNKNNP,and the weight of fertilizer factors in the ratio of leaf yield to input was in decreasing order of K〉PK〉NPK〉P〉NK〉NP〉N.To be specific,the ternary quadratic fertilizer effect function（Y=20 313＋0.25X1＋43.48 X2＋34.47X3-0.01X1^2-0.14X2^2-0.06X3^2＋0.05X1X2＋0.02X1X3-0.07X2X3,in which X1,X2 and X3 indicate the fertilizer factors N,P and K,respectively） was a model containing all factors,thereby being a recommended fertilization program for mulberry field.Single factor effect analysis indicated that K fertilizer had the highest influence on mulberry leaf yield and ratio of leaf yield to input.Therefore,among all the simulation functions,the monadic quadratic fertilizer effect function of K fertilizer factor（Y=25 002.27＋44.728X3-0.084X32） leads to the optimal leaf yield and maximum ratio of leaf yield to input.By using the optimal fertilization program with 600 kg/hm2 N,210 kg/hm2 P2O5 and 254.33 kg/hm2 K2O,the optimal economic leaf yield obtained is 30 945.00 kg/hm2,the cost of fertilizer input is 4 403.65 yuan/hm2,and the ratio of leaf yield to input is as high as 17.57.After verification by production practices,the recommended fertilization indicators in the optimal mulberry fertilization program can provide reference
