Study On The Release Characteristics And Effect Of Humic Acid-urea Formaldehyde Slow-release Nitrogen Fertilizer In Bucharee Soil

The climate of Hainan has a cleardry and rainy season.The rainfall in the rainy season is concentrated and the rainfall is large.The soil is mainly laterite,and the laterite is acidic and the cation exchange capacity is low.The application of fertilizers in China has increased year by year,but the utilization rate of nitrogen fertilizers has been maintained at a relatively low level.The utilization rate of nitrogen fertilizers in farmland is only 30%-35%.Compared with other regions,the special environmental characteristics of Hainan Province make the nitrogen fertilizers in farmland more vulnerable to leaching.This will not only cause serious loss of nutrient resources,but also increase the burden on the ecological environment.At present,studies have shown that slow-release nitrogen fertilizer has a significant slow release and increasing effect.To improve the utilization of fertilizers in hot areas,provide basis for rational fertilization in laterite in hot areas.In this study,infrared spectroscopy(IR),thermogravimetric analysis,differential scanning calorimetry(TG+DSC),and X-ray diffraction pattern analysis(XRD)were used to study the structural characteristics of slow-release nitrogen fertilizers;soil column leaching tests and indoor culture experiments were performed.To study the release characteristics of slow-release nitrogen fertilizers in laterite of hot brick area,and to study the biological effects of slow-release fertilizers through pot experiments and field micro-zone experiments.This experiment was carried out in the Rubber Research Institute of the Chinese Academy of Tropical Agricultural Sciences from September 2016 to February 2018.The release characteristics and effects of slow release nitrogen fertilizer on laterite soil in gneiss parent material in hot zone were studied.The results of the study are as follows:1.In the infrared spectrum of humic acid-urea-aldehyde slow-release nitrogen fertilizer(NF),the stretching peak of aliphatic CH in humic acid appeared at 2956cm-1,and the characteristic peak of Urea appeared at 545cm-1;the endothermic melting decomposition peak of urea.At 137.76 ?,the endothermic peak appeared at 105.16 ? for humic acid,and the endothermic peak appeared at 108.77 ? for humic-urea-aldehyde slow-release nitrogen fertilizer.The humic acid-urea-aldehyde slow-release nitrogen fertilizer is a new phase formed by urea and humic acid under the action of aldehyde cross-linking agents,and the structure of the new phase has undergone qualitative changes,and the structure of the humic-urea-aldehyde slow-release nitrogen fertilizer is more stable.Thermal stability is higher.2.Compared with common urea,slow-release fertilizer can effectively reduce the nitrogen leaching of fertilizer nitrogen in laterite,and the nitrogen release rate of slow-release nitrogen fertilizer reduces by 27.75%.The slow-release nitrogen fertilizer is used in indoor constant temperature culture.The content of nitrate nitrogen in slow-release nitrogen fertilizer treatment soil was lower than that of urea treatment,and the ammonium nitrogen content in the slow-release nitrogen fertilizer treatment soil was significantly lower than that of urea treatment during the whole culture period.At the end of the experiment,the conditions were 25 ?,30?,and 35?.Under the slow-release nitrogen fertilizer treatment,the ammonium nitrogen content was 47%,44%,and 46%lower than that of urea treatment,respectively.Under constant temperature and constant temperature culture conditions,the nitrogen release rate of slow-release nitrogen fertilizer was significantly lower than that of urea,and the slow-release nitrogen fertilizer at 35 ? The supply of nitrogen is the largest,and the supply of nitrogen is the smallest at 25 ?.Under the same constant temperature,the supply of urea is the largest,the supply of nitrogen for sustained release nitrogen is the smallest,and it reaches a significant level with urea and humic acid.3.Effects of slow-release nitrogen fertilizer on biological effects of maize.The results showed that the slow-release nitrogen fertilizer had the highest nitrogen accumulation in corn kernels.Compared with common urea,the nitrogen agronomic efficiency of sustained-release nitrogen fertilizer increased by 4.88%.Compared with single application of urea,the root length of maize with application of slow-release nitrogen fertilizer increased by 28.56%,the root volume increased by 6.93%,the root surface area increased by 6.88%,and the root mean diameter increased by 4.06%.Significant increase in production,compared with urea alone,slow-release nitrogen fertilizer increased production by 25.48%.In summary:Compared with urea,slow-release nitrogen fertilizer can significantly reduce the leaching loss of nitrogen in laterite;it can effectively slow down the nitrogen supply rate of fertilizer nitrogen to crops,and reduce fertilizer nitrogen nitrogen in laterite.The accumulation of nitrate and nitrate reduces the risk of fertilizer loss.Slow-release nitrogen fertilizer can increase the nitrogen utilization rate of fertilizer to maize,promote the growth and development of maize root system,and have a significant effect on increasing the yield of corn in the field.