Effect of different modified biochar treatments on nitrogen loss and rice yield in paddy fields
In order to further explore the potential of biochar in rice ecosystems for efficiency,fertilizer savings and emission reduction,six treatments of maize stover biochar(B),acidified biochar(BpH),nitrogen-loaded biochar(BNH4),iron-modified biochar(BFe)and calcium-modified biochar(BCa)were set up in a 2-year experiment using no biochar as the control(CK)to study the cation exchange capacity(CEC)of the biochar,the oxygen-containing functional groups,as well as rice yield,nitrogen extraction,ammonia volatilization,nitrogen leaching and soil nitrogen residues under their treatments were investigated.The results showed that BpH,BNH4 and BFe significantly increased the CEC of biochar(53.9%,29.6%and 28.2%)compared with B.All four modified treatments significantly increased the concentration of oxygenated functional groups,such as-COOH,-OH,C=O,and O-H,to enhance the nitrogen uptake capacity of biochar.The cumulative ammonia volatilization ranged from 9.1 to 19.9kg/hm(2021)and 8.49 to 13.7kg/hm(2022)over the whole reproductive period,and except for BNH4,which had a significant ammonia reducing effect(44.6%),B,BpH,BCa,and BFe had no significant effect on ammonia volatilization in the first year;whereas,BCa,BNH4,and BFe all significantly reduced ammonia volatilization by 33.5%,37.5%and 37.8%,respectively,compared to CK.The four modified biochars reduced nitrogen leaching by 19.0%and 35.2%(BpH),15.0%and 21.0%(BCa),11.3%and 28.7%(BNH4),and 12.6%and 29.0%(BFe)compared to CK in 2consecutive years.B had no significant effect on yield in year 1effect in year 1,but significantly increased yield(8.8%)after 1year of aging;BpH and BNH4were both effective for 2consecutive years,increasing yield by 19.7%and 12.2%(2021),and 11.49%and 5.8%(2022),respectively.BpH,BCa,and BNH4significantly reduced reactive nitrogen emissions in 2 years,with reductions of 23.4%,21.8%and 42.3%(2021)and 23.5%,30.5%and 35.5%(2022);BFe 2a had a mixed effect,with a 25.9%enhancement in year 1and a 35.6%reduction in year 2.There were no significant differences in soil mineralized N residuals between biochar treatments in year 1;however,BCa,BNH4,and BFe showed significant efficiency gains in year 2.When considering yield increases,reactive nitrogen reduction and mineralised nitrogen sustainability simultaneously,the best results for BpH and BNH4combined were achieved during the two-year trial,reducing ammonia volatilisation by 23.4%and 42.3%(2021),23.5%and 35.5%(2022),NH4+-N leaching by 18.9%and 10.6%(2021),35.4%and 29.0%(2022),NO3--N leaching 15.6%and 14.7%(2021),24.5%and 23.4%(2022),nitrogen accumulation 1.1%and 13.4%(2021),14.8%and 4.3%(2022)and mineralised nitrogen residues 1.3%and 15.0%(2021),12.2%and 17.9%(2022),and finally 19.7%and 12.2%(2021),11.5%and 5.7%(2022)rice yield increase,compared to CK.
different modified biocharsurface waterammonia volatilizationleaching lossrice yieldnitrogen destination
万方数据
维普
