Effects of various anionic zinc fertilizers on the rice nutrition and zinc forms in soil

Pot experiment was carried out to study the effects of 3 kinds of anionic zinc fertilizers on the growth,nutrient uptake of rice and zinc forms in soil.The results indicate that the yield is more benefitly increased by Zn(NO₃)₂ ,or by a combined application of Zn(NO₃)₂ and ZnSO₄ than ZnSO₄,ZnCl₂.The Zn content of various forms in provided soil is in the order of Ex-Zn and OM-Zn＜CAB-Zn＜COFe-Zn＜AOFe-Zn＜OMn-Zn ＜mineral Zn.Total Zn content in 3 forms of Ex-Zn and OM-Zn and OMn-Zn（i.e.available Zn）is 9.2mg/kg and 9.6% of the total soil Zn.The mineral Zn is the native form in paddy soil,and its content is 69.3mg/kg and 72.0%of the total soil Zn.The contents of CAB-Zn,AOFe-Zn and OMn-Zn are increased by rice planting,the Zn contents of various forms in soil are in the order of Ex-Zn and OM-Zn＜COFe-Zn＜CAB-Zn＜AOFe-Zn＜OMn-Zn＜mineral Zn.Total Zn content in 3 forms of Ex-Zn and OM-Zn and OMn-Zn is 10.5mg/kg and occupies 11.2% of the total soil Zn.The mineral Zn is still the native form in paddy soil,but the content is decreased by 4.2 mg/kg and 2.7% of the total soil Zn.The amount of total Zn uptake,the total soil Zn,the content of OMn-Zn and COFe-Zn are enhanced by application of zinc fertilizer and the content of available soil Zn（i.e. Ex-Zn,OM-Zn and OMn-Zn）is increased by 12.7%～103.8%.