8Jones GD,Lutz JA.Yield of wheat and soybeans and oil and protein content of soybean as affected by fertility treatments and deep placement of limestone.Agronomy Journal,1971,63:931～934
9Ham GE,Nelson WW,Evans SD,et al.Influence of fertilizer placement on yield response of soybeans.Agronomy Journal,1973,65:81～84
10Poole WD,Randal GW,Ham GE.Foliar fertilization of soybean:Ⅰ.Effect of fertilizer sources,rates and frequency of application.Agronomy Journal,1983,75:195～200
