Study On The Coupling Effect Of Biochar And Humic Acid On The Increase Effect And Decrease Amount Of Chemical Fertilizer

That chemical fertilizers not used by crops can enter water through infiltration and soil loss,which is one of the main reasons for water eutrophication.Reducing the amount of chemical fertilizers can effectively reduce this agricultural non-point source pollution.Humic acid and biochar are both charcoal-rich products.Due to their huge surface area and adsorption properties,they can adsorb excess nitrogen and phosphorus in the soil.Studies have shown that applying biochar and humic acid to soil separately can increase nutrient use efficiency and increase crop yield,but whether the combined application of the two materials to soil can produce greater synergistic effects has not been studied.In this study,we analyzed the soil structure and properties,fertilizer utilization,nitrogen leaching effects,wheat growth and yield when biochar and humic acid were applied to soil at the same time for reveal the mechanism of biochar and humic acid on soil improvement and crop yield increase.The main results of the experiment are as follows:1.Soil culture experiments show that the application of biochar can effectively reduce the leaching of ammonium nitrogen and nitrate nitrogen.Compared with the control,it can reduce up to 26%and 37%,respectively.At 30 d of applying biochar to soil,the ammonium nitrogen content increased,the ammoniation intensity reached up to 2.4 and 4.6 times that of the control,and the apparent nitrification rate of the soil was reduced by 18%that of the control.At the 30 d of the single application of humic acid,the ammonium nitrogen content increased,the ammoniation intensity reached up to 2.2 and 4.1 times that of the control,and the apparent nitrification rate of the soil was reduced by 7%that of the control.At the 30 d of applying biochar and humic acid together,the ammonium nitrogen content increased,the ammoniation intensity reached up to 2.7 and 5.5 times that of the control,and the apparent nitrification rate of the soil was reduced by 31%that of the control.2.Wheat pot experiments showed that the two additives increased the residual ammonium nitrogen and nitrate nitrogen contents at different depths of the soil.The performance is most obvious under the high fertilizer condition.Among them,F2B3increased ammonium nitrogen of the shallow soil and deep soil to 288%and 91%,respecticely,and increased nitrate nitrogen of the shallow soil and deep soil to 63%and 40%,respectively.3.Wheat pot experiments showed that adding biochar to the soil alone can increase soil moisture content and reduce soil drought,and with the increase of biochar,the soil moisture content is continuously increasing;the effect of adding humic acid to the soil to increase soil moisture not obvious.B3F3 had the best effect in the combined treatment,and increased soil moisture content by 7.51%at the booting stage.4.Wheat pot experiments showed that the addition of biochar and humic acid alone can increase soil porosity and reduce bulk density.The effect of combined treatment was most obvious under the gradient of H2 fertilizer.The maximum soil bulk density decreased by 0.38 g/cm³,and the maximum soil porosity increased by14.33%.The addition of biochar to the soil can increase the soil pH,and the addition of humic acid reduces the pH.The treatment can balance the effects of biochar and humic acid on soil pH.5.Wheat pot experiments showed that addition of humic acid alonely contributed to increase the amount of>5 mm water-stable aggregates,reduced the amount of<0.25 mm water-stable aggregates,stablized the amount of 5⁰.25 mm water-stable aggregates.Addition of biochar alonely contributed to increase the amount of>5 mm and 2¹ mm water-stable aggregates,reduced the amount of<0.25 mm water-stable aggregates,stablized the amount of 5² mm and 1⁰.25 mm water-stable aggregates.Addition of humic acid and biochar contributed to increase the amount of>0.25 mm water-stable aggregates,reduced the amount of<0.25 mm water-stable aggregates.6.Potted wheat trials show that the addition of biochar and humic acid to the soil contributed to increase wheat production per mu by increasing photosynthetic intensity at the heading stage,spike numbers per mu and 1000-grain weight.Under normal fertilization condition,the treatment of B2F3 improves the wheat intensity of photosynthesis mostly significantly among all treatments in this study.The leaf net photosynthetic rate,stomata conductance,the intercellular CO₂ and the transpiration rate increased 81%,75%,43%and 13%,respectively,comparied with control treatment.Under the 25%,50%and 100%of normal fertilizer amount condition,addition of biochar and humic acid contributed to increaase wheat spike numbers per mu to 8%,8%and 3%,respectively,and increase 1000-grain weight to 6%,4%and4%,respectively,and increase production per mu to 49%,20%and 15%,respectively.