The Study Of Humic Acid On Raising N And P Fertilizer Efficiency And Reducing Application Rates

Humic acid synergistic fertilizer plays an important role in improving crop yield and reducing fertilizer application.In this study,we use the effect of humic acid on nitrogen and phosphorus fertilizers to make a series of humic acid ureas?HAU?and humic acid phosphate fertilizers?HAP?by adding different proportions of humic acid synergist to urea and monoammonium phosphate.Potted plant experiments and culture experiment were conducted to study the effects of HAU and HAP on the yield and nutrient uptake of wheat and maize,and study the mechanism of synergistic effect of humic acid on nitrogen and phosphate fertilizer.We also want to research the feasibility of reducing the application rates of fertilizer through the synergistic effect of humic acid.The main findings are as follows:1?Study on fertilizer efficiency and transformation of HAUUnder the same N application rate,compared with the U treatment,the grain yields of the HAU treatments of wheat and maize were increased by 9.71%¹6.76%and 6.32%¹7.32%,respectively,and the increases were enhanced with the increase of HA adding proportions under the HA adding proportions ranging from 1%to 20%.HAU mainly enhanced grain weight to increase grain yield.The HAU treatments could increase the N uptakes and accelerate the transshipment of fertilizer N,and the fertilizer N uptakes of wheat and maize grain were increased by 11.90%to 28.57%and 16.78%to 25.87%,The HAU treatments could also increase the N apparent efficiency and ¹⁵N use efficiency.The fertilizer N total residues of the HAU treatments of wheat and maize were higher than that of the U treatment by3.70%²8.53%and 5.21%¹0.14%in 0⁹0 cm soil layer,while the ¹⁵N loss rates were decreased.Under the same fertilizer application rate,wheat grain yield of HAU treatments are still significantly higher than that of U treatment and maize grain yield are similar to U treatment while the N application rate was reduced by 20%.In the culture experiment,humic acid can inhibit urease activity in the early stage,slow down the decomposition of urea in the soil and reduce the accumulation of ammonium nitrogen in the soil.compared with U treatment,HAU treatments reduce the ammonia volatilization of urea by 3.07%²3.35%.The nitrogen leaching rate was significantly reduced by 6.67%¹9.72%,and decreased with the increase of humic acid adding proportions.2?Study on fertilizer efficiency and transformation of HAPUnder the same P₂O₅ application rate,compared with the P treatment,the grain yields of the HAP treatments of wheat and maize were increased by 9.60%¹5.78%and 4.54%¹3.54%under the HA adding proportions ranging from 1%to 20%.HAP mainly enhanced grain per spike to increase grain yield.The results showed that HAP treatment could promote the P₂O₅ uptake and improve the P apparent efficiency,agronomic efficiency,partial fertilizer productivity.The content of available phosphorus in0³0 cm soil layer was increased.The reduction of the P₂O₅ application rate can lead to the decrease of the grain yields of HAP treatments under the same fertilizer application rate,the grain yield of wheat and maize was not significantly reduced compared with the P treatment while the P₂O₅ application rate was reduced by 20%.Humic acid can increase the available phosphorus content in the soil,the available phosphorus content was higher than that of U treatment by 6.75%²1.13%.With the culture the content of available phosphorus decreased gradually,the available phosphorus content is proportional to the amount of humic acid added in the early soil.Compared with P treatment,HAP treatments could increase the content of Ca₂-P,Ca₈-P and Al-P in soil,and decrease Fe-P content.There was no significant effect on soil O-P and Ca10-P in short term.