Preparation And Performance Evaluation Of Coated Zinc Fertilizer And Its Application To Maize

Zinc is an essential trace element for plant growth,and its application can promote crop growth and improve grain yield and quality.Corn is an important grain-feeding crop in China,but it is also one of the crops that are sensitive to zinc deficiency.The zinc fertilizers used in actual production are mainly inorganic zinc fertilizers such as zinc sulfate and zinc oxide,which are easily adsorbed and fixed by carbonates,iron and manganese oxides and organic matter in the soil after application,affecting the effectiveness of zinc and resulting in low utilization of zinc fertilizers.Controlled-release fertilizers can promote crop growth,improve crop yield and quality and fertilizer nutrient utilization compared with common fertilizers.Therefore,this study used polyurethane material to coat granular zinc fertilizer,exploring the relationship between the ratio of coating materials and the nutrient release performance of the fertilizer.Subsequently,soil culture experiments were conducted to study the migration and transformation of coated zinc fertilizer and ordinary zinc fertilizer in the soil.Finally,corn field experiments were conducted,with three zinc fertilizer rates of 10,20,and 30 kg/ha,and four treatments of uncoated zinc fertilizer and 3%,4%,and 5% coated zinc fertilizer were set under each fertilizer rate,Exploring the effects of not applying zinc fertilizer on soil physicochemical properties,maize growth and development,and fertilizer nutrient utilization efficiency,as compared to not applying zinc fertilizer.The main results were as follows:(1)The fertilizer-controlled release performance was better when the addition ratio of material A and material B was 4:6 and the addition ratio of material C was 0.5% in the film formulation.The nutrient release rate of coated zinc fertilizer was determined by conductivity and atomic absorption methods,respectively,which proved that conductivity method can be used for the determination of nutrient release rate of coated controlled-release zinc fertilizer,which is a fast and simple method.(2)Compared with uncoated zinc fertilizer,coated zinc fertilizer can reduce soil adsorption and fixation of zinc,improve the effectiveness of zinc in the soil and the nutrient utilization efficiency of zinc fertilizer.(3)Compared with no Zn application,Zn application treatment increased soil urease activity,and the highest urease activity was observed under CZ8(5% coating thickness Zn fertilizer with 20 kg/ha application rate)treatment;When the coating thickness is constant,the activity of alkaline phosphatase increases with the increase of controlled release zinc fertilizer application amount;Zinc application increased the available zinc content in the soil.(4)Compared with no zinc application,zinc application treatment relatively increased the zinc concentration and cumulative absorption of corn stems,leaves,bracts,and cobs during the mature stage,which can increase the fresh weight,dry weight,plant height,and stem diameter of corn plants,promoting their growth.Compared with CK,zinc application increased the grain yield of corn by 7.61%～23.23%,reaching its maximum value under CZ2(zinc fertilizer with 3% coating thickness and a fertilization amount of 20 kg/ha)treatment.Under the same fertilization amount,compared with uncoated zinc fertilizer,coated controlled-release zinc fertilizer improved the agronomic and agricultural physiological efficiency of zinc,reaching the maximum value under CZ1(3% coated zinc fertilizer with a fertilization amount of 10kg/ha)and CZ4(4% coated zinc fertilizer with a fertilization amount of 10kg/ha)treatments,respectively,and the utilization efficiency of zinc fertilizer decreased with the increase of coating thickness.