Abstract
Nitrogen(N)plays a key role in crop growth and production;however,data are lacking especially regarding the interaction of biochar,grass cover,and irrigation on N leaching in saturated soil profiles.Eighteen soil columns with 20-cm diameter and 60-cm height were designed to characterize the effects of different grass cover and biochar combinations,i.e.,bare soil+0％biochar(control,CK),perennial ryegrass+0％biochar(C1),Festuca arundinacea+0％biochar(C2),perennial ryegrass+1％biochar(C3),perennial ryegrass+2％biochar(C4),perennial ryegrass+3％biochar(C5),F.arundinacea+1％biochar(C6),F.arundinacea+2％biochar(C7),and F.arundinacea+3％biochar(C8),on periodic irrigation infiltration and N leaching in homogeneous loess soils from July to December 2020.Leachates in CK were 10.2％-35.3％higher than those in C1 and C2.Both perennial ryegrass and F.arundinacea decreased the volumes of leachates and delayed the leaching process in the 1％,2％,and 3％biochar treatments,and the vertical leaching rate decreased with biochar addition.The N leaching losses were concentrated in the first few leaching tests,and both total N(TN)and nitrate(NO3-)-N concentrations in CK and C1-C8 decreased with increasing leaching test times.Biochar addition(1％,2％,and 3％)could further reduce the leaching risk of NO3--N and the NO3--N loss decreased with biochar addition.However,compared to 1％biochar,2％biochar promoted the leaching of TN under both grass cover types.The N leaching losses in CK,C1,C2,C3,C4,C6,and C7 were primarily in the form of NO3--N.Among these treatments,CK,C1,and C2 had the highest cumulative leaching fractions NO3--N(＞90％),followed by those in C3,C4,C6,and C7(＞80％).The cumulative leaching fraction of NO3--N decreased with increasing leaching test times and biochar addition,and 3％biochar addition(i.e.,C5 and C8)reduced it to approximately 50％.The one-dimensional advective-dispersive-reactive transport equation can be used as an effective numerical approach to simulate and predict NO3--N leaching in saturated homogeneous soils.Understanding the effects of different biochar and grass combinations on N leaching can help us design environmentally friendly interventions to manage irrigated farming ecosystems and reduce N leaching into groundwater.
基金项目
国家自然科学基金(52070158)
国家自然科学基金(42277073)
国家自然科学基金(51679206)
National Fund for Studying Abroad,China(201706305014)
维普
万方数据