烤烟/玉米套作中生物炭与氮肥配施对坡耕地水土流失的影响OA

[Objective]This study aims to clarify the synergistic soil and water conservation effect and specific roles of combined biochar and nitrogen fertilizer application in the flue-cured tobacco/silaga maize intercropping system on sloping farmland,in order to mitigate the risks of soil erosion and nitrogen loss exacerbated by high-intensity rainfall and high nitrogen input in this system.[Methods]A flue-cured tobacco(Yunyan 87)and silage maize(Zhongyan 335)intercropping system was used as the study system,and simulated rainfall experiments were conducted on plots with a slope of 10°.Two simulated rainfall events were conducted:the first after the initial harvest of flue-cured tobacco(before maize transplanting)and the second before the tasseling stage of maize.Each event applied three rainfall intensities(40,70,and 160 mm/h),each lasting for 30 minutes.The experimental design included three nitrogen(N)application levels:no nitrogen(N0:0 kg/hm2),half nitrogen(N1:52.5 kg/hm² for flue-cured tobacco+100 kg/hm² for maize),and conventional nitrogen(N2:105 kg/hm2 for flue-cured tobacco+200 kg/hm² for maize);and two biochar treatments:no biochar(B0:0％)and biochar addition(B1:3 kg per 100 kg of soil,equivalent to 3％).Parameters,including soil nitrogen content,soil erosion amount,runoff initiation time,runoff volume,and nitrogen loss in runoff,were measured for different treatments at various stages.[Results]Under different rainfall intensities,the treatments amended with biochar demonstrated significant improvements in soil and water conservation.The combined application of biochar and conventional nitrogen fertilizer(B1N2)significantly prolonged runoff initiation time(by 124.86％under the 160 mm/h rain intensity),reduced the runoff volume(by 46.58％to 62.85％across different intensities,with significant reductions at 40 and 70 mm/h),and significantly decreased soil erosion amount.Furthermore,the soil and water conservation effect was enhanced with increasing rainfall intensity.Biochar addition also improved soil nitrogen retention ability:the B1N2 treatment significantly reduced nitrate nitrogen concentration in runoff under 70 mm/h rainfall intensity,and increased soil total nitrogen content after the maturity of flue-cured tobacco and silage maize.Soil nitrate nitrogen and ammonium nitrogen contents were also significantly increased.Compared with the half nitrogen treatment without biochar(B0N1),the combination of biochar with half nitrogen fertilizer(B1N1)still significantly prolonged runoff initiation time(by 56.8％)and reduced the runoff volume(by 28.1％)under 40 mm/h rainfall intensity.However,the reduction in soil erosion was not significant under 160 mm/h.[Conclusion]The combined application of biochar and conventional nitrogen fertilizer significantly enhances soil and water conservation capacity,exhibiting the optimal effect.Although combining biochar with half nitrogen fertilizer is less effective,it still provides considerable soil and water conservation benefits.