Effect Of Adding Methods Of Zinc In Nitrogen/Phosphorus Fertilizer On The Availability Of Nutrients In Fertilizer

Zinc is one of the necessary trace elements for the growth and development of plants.Zinc absorpted by plants is mainly from soil.However,about half of the cultivated land shows a zinc deficiency in China.In practice,soil application and foliar spraying are the common methods used to supplement the zinc nutrient in soil and crops.When zinc fertilizer applied to soil,the uneven application and easy fixation by the soil will happen,leading to the decrease of the zinc availability.In order to conqure these problems,the combination of zinc and bulk chemical fertilizer is attempted.However,at present,there is still a lack of research on the effect of zinc addition ratio,the combination process,and the combination product on the bioavailability of zinc.In this study,0.5 and 5 parts by weight of zinc sulfate heptahydrate were combined with 99.5 and 95 parts by weight of urea or phosphate fertilizer to prepare zinc-containing urea or phosphate fertilizer,respectively.The soil cultivation experiment and soil column cultivation experiment were conducted to study the effects of zinc-containing urea and zinc-containing phosphate fertilizer on maize growth,yield and nutrient absorption and utilization,and the availability of zinc,nitrogen and phosphorus nutrients.This study clarified the best combination of zinc,nitrogen and phosphate fertilizers,and provided a scientific basis and technical support for the efficient combination of zinc,nitrogen and phosphate fertilizers and the production of zinc-containing fertilizers.The main results were as follows:（1）Zinc-containing urea prepared by physical mixing and melting mixing of zinc and urea delayed the hydrolysis of urea,increased the content of soil NO₃^--N,NH₄⁺-N and mineral nitrogen in the late period of cultivation.It also reduced the fixation of zinc and increased the effective zinc content of the soil,and the melting mixing of zinc and urea performed the best.Compared with physical mixing,fertilizer prepared by melt mixing with 0.5%and 5%addition amount of zinc with urea could increase soil availiable zinc content by 10.91%and 12.66%,respectively.（2）Compared with ordinary urea,zinc-containing urea prepared by melting mixing could significantly promote maize growth,increase crop yield,and promote maize nutrient absorption.The aboveground biomass and grain yield of maize applied with zinc-containing urea prepared by melting process were higher than that with ordinary urea by 7.86%and 6.35%,respectively.Zinc-containing urea prepared by melting process could also increase fertilizer utilization,and the nitrogen utilization rate was increased by 2.81%,and the loss rate was reduced by 5.19%than that ordinary urea.Zinc-containing urea prepared by melting mixing could also increase the residual amount of fertilizer nitrogen and available zinc content in 0-30 cm soil layer,which was beneficial to the nutrient utilization for subsequent crops.The combined application of zinc and urea increased the cumulative amount of zinc in maize kernels,and the zinc-containing urea prepared by melting mixing had a better performance than that prepared by physical mixing process.Compared with the addition of 5%,adding0.5%zinc and urea by melt mixing could increase the accumulation of zinc in maize kernels by 46.82%.（3）Zinc-containing phosphate fertilizer prepared by physical mixing and reaction mixing could reduce the fixation of zinc and increase the effective zinc content of the soil.The zinc-containing phosphate fertilizer prepared by reaction mixing performed better than that by physical mixing.Compared with physical mixing,zinc-containing phosphate fertilizer prepared by reaction mixing with0.5%and 5%addition amount of zinc with phosphate could increase the effective zinc content by 21.13%and 7.37%,respectively.Zinc-containing phosphate fertilizer prepared by reaction mixing could reduce the fixation of phosphorus and zinc in the soil,and increase the content of soil available phosphorus and available zinc.Compared with the 5%addition ratio,the reaction mixing of zinc with 0.5%addition and phosphate fertilizer could reduce the the fixation rate of phosphorus by 3.03%on average in soil.（4）Compared with ordinary phosphate fertilizer,the combination of zinc and phosphate fertilizer could significantly promote the growth of maize and increase the crop yield.The aboveground biomass and grain yield of maize applied with zinc-containing phosphate fertilizer were higher than that with ordinary phosphate fertilizer by 15.18%and 7.70%,respectively.Compared with ordinary phosphate fertilizer,the zinc-containing phosphate fertilizer prepared by reaction mixing process could increase the absorption of phosphorus by maize.The effect of reaction mixing to combine 0.5%zinc with phosphate fertilizer showed the best performace,which increased the total phosphorus uptake of grain by 16.67%,and the apparent utilization rate,agronomic efficiency and partial productivity of phosphate fertilizer were repectively increased by 2.78%-7.33%,14.57%-41.91%and 3.58%-11.64%,compared with other treatments.Compared with physical mixing,the reaction mixing of zinc and phosphate fertilizer significantly increased the zinc accumulation and zinc fertilizer utilization rate in maize shoots by 26.04%and 7.94%,respectively.Zinc-containing phosphate fertilizer prepared by reaction mixing process could also significantly increase the effective zinc content in 0-30 cm soil layer,which was50.09%higher than that treated with the zinc-containing phosphate fertilizer prepared by the process of physical mixing on average.Compared with 5%addition,the reaction mixing of zinc with 0.5%addition of phosphate fertilizer significantly increased maize grain yield,number of ears,grain phosphorus absorption and apparent utilization rate of phosphate fertilizer.