腐植酸基质缓释尿素对氮素淋失和氨挥发的阻控OA北大核心CSTPCD

[Objectives]Matrix slow-release nitrogen fertilizer increases nitrogen use efficiency through preventing urea from quick release and hydrolysis in soil.Humic acid contains large amount of functional groups,and has been proved of preserving nutrient from leaching when applied into soil.So we replaced part of the loss control additives with humic acid for modification of nitrogen release and ammonia volatilization of loss control urea.[Methods]Six nitrogen fertilizers were chosen as test materials,including:common urea(U),three matrix slow-release urea products with high,medium and low ratio of loss control additives(LU1,LU2,and LU3),the matrix slow-release urea containing medium rate of loss control additives and equal rate of humic acid(HLU),and the HLU added with anti-setting agent(HLUA).All the fertilizers were buried in soil for leaching and ammonia volatilization monitoring experiment.The soils were leaching for 15 days,and the contents of total nitrogen,nitrate nitrogen and ammonium nitrogen in the leachate were analyzed.During the leaching period,ammonia tube method was used to monitor ammonia volatilization rate.Fourier transform infrared spectroscopy(FTIR),nuclear magnetic resonance(NMR),X-ray photoelectron spectroscopy(XPS),thermogravimetric analysis(TG),and specific surface area adsorption(BET)were used to characterize the chemical structure,pore structure and thermal properties of the loss control additives and the tested fertilizers.[Results]Compared with urea(U),the total soluble N in the leachates of LU1,LU2,LU3,HLU,and HLUA were decreased by 24.5%,32.2%,34.9%,31.5%,and 32.2%,respectively,and the cumulative ammonia volatilization decreased by 13.1%,24.3%and 27.1%,28.0%,and 29.5%,respectively.Higher rate of loss control additives in matrix slow-release fertilizers showed declining nitrogen leaching and ammonia volatilization amount,and HLU and HLUA treatments were tested similar nitrogen leaching and ammonia volatilization amount with LU2.According to energy and structure analysis results,the loss control additives was composed of attapulgite and polymer,and the main component of the anti-coagulating agent was nano-carbon powder.Both attapulgite and humic acid formed intermolecular hydrogen bonds with urea,and the intramolecular hydrogen bonds of them were similar in strength and thermal stability.Nano-carbon did not form any bonds with the urea,and did not show any impact on the intramolecular hydrogen bond strength and thermal stability.[Conclusions]The humic acid-matrix slow release urea,which is prepared by adding humic acid,control loss additives and anti-coagulation agent into urea,is low in nitrogen leaching risk and ammonia volatilization loss,and its good stick-resistance characteristics made it suitable for procession and storage,so is a multifunctional slow-release fertilizer.