The paper deals with the effect of MAP and DAP on zinc adsorbed by loess soil and the biological effect of MAP and DAP.The results show that the zinc-adsorption diagrams of loessial soil was similao to chat of Tucson loam in steeps obtained by Udo,E.J.The amount of zinc adsorbed by soil was effected by pH of different equilibrium Zn solutions of soil.The amount of zinc adsorbed by the parent material was higher than those by argillic horizon and rusEy dark loessial soil.MAP and DAP application had an important effect on the model of zinc adsorbed by soil.The amount of zinc adsorbed by soil was decreased by MAP application.Hovveverr the amount of zinc adsorbed by soil was increased by DAP application.The effects of MAP and DAP were specially obvious in the loessial soils with lower contents of O.M.and clay.The pH in two different system was a leading factor to control zinc adsorbed by soil,but the change of pH was affected by phosphate form.The results show that MAP could promote the adsorption of zinc by plant the interaction between zinc and phosphous,but DAP could decrease the amount of zinc adsorbed by plant and weaken the interaction between zinc and phosphate.Therefore,the zinc fertilizer applied togather with MAP is more beneficial than with DAP in the loessial soils deficient in zinc and phosphorus.