Regulation Of The Availability Of Nitrogen And Phosphorus In Fertilizers By Adding Humic Acid

Humic acid combine with N/P fertilizer can increase crop yield and improve fertilizer utilization rate by promoting nutrient absorption,reducing N loss,slowing down P fixation,etc.,but its effect is closely related to the way of adding humic acid.Currently in humic acid add on humic acid fertilizer characteristics and application effects of the lack of system research,this article will therefore humic acid by physical mixing,melting（reaction）two add ways combined with nitrogen and phosphate fertilizer,the preparation of different humic acid fertilizers combination way,through the analysis of the structure,soil culture and corn cultivation test.In order to provide theoretical basis and data support for the selection,production and application of humic acid value-added fertilizer,the effects of humic acid addition methods on the structure of nitrogen and phosphate fertilizer,the transformation characteristics in flu-tidal soil,and the yield and nutrient utilization of maize are studied.The main results are as follows:（1）The structure of humic acid nitrogen and phosphate fertilizer is different with different adding methods.The fused humic acid urea contains more secondary amides than mixed humic acid urea.Reactive humic acid phosphate fertilizer contains more phosphate mono ester and phosphate diester than mixed humic acid phosphate fertilizer.（2）Humic acid can significantly slow down the hydrolysis of urea and reduce the volatilization of ammonia.Compared with the control urea,it can reduce the volatilization of ammonia by 6.7%～61.7%,and the effect increases with the increase of the amount of humic acid.When the addition amount of humic acid is 5%,the volatilization of ammonia can be reduced by 10.1%～14.3%by melting humic acid urea compared with mixing humic acid urea.Humic acid addition can affect soil urease activity,in which the urease activity increase in the melting humic acid urea treatment,but decrease in the mixed humic acid urea treatment.（3）Compared with the control urea,humic acid urea can increase corn grain yield by 4.9%～7.7%and N apparent use efficiency by 2.4～7.7 percentage points by increasing grain number per panicle,and the effect increase with the increase of humic acid supplemental level.Compared with mixed humic acid urea,melting humic acid urea can increase the apparent nitrogen use efficiency by 2.7-3.0 percentage points,but there is no significant difference in grain yield and fertilizer nitrogen use efficiency.（4）Humic acid can affect the conversion of phosphate fertilizer in soil,and its effect is related to soil temperature.At 15℃,adding humic acid could increase soil Ca₂-P content by 5.7%-30.4%and Ca₈-P content by 4.2%-29.4%,and the effect of reactive addition method is better.At 25℃,the addition of humic acid could increase soil available P by 6.3%～21.0%and decrease the content of Ca₂-P by2.4%～19.9%,and there is no significant difference between the two methods.（5）Compared with the control P fertilizer,humic acid P fertilizer could increase corn grain yield by2.8%～21.2%by increasing grain number per panicle,and humic acid P fertilizer with 5%humic acid content can also increase the apparent utilization rate of P fertilizer by 10.6～10.7 percentage points.When the supplemental amount of humic acid is 0.5%,the supplemental way of humic acid have no significant effect on maize grain yield and P fertilizer apparent utilization rate.When the supplemental amount of humic acid is 5%,the reaction humic acid phosphate fertilizer could significantly increase corn grain yield by 6.3%compared with the mixture of humic acid phosphate fertilizer,but there is no significant difference in the utilization rate of phosphorus fertilizer.