长期施肥和耕作下紫色土坡耕地径流TN和TP流失特征

Characteristics of Runoff-related Total Nitrogen and Phosphorus Losses Under Long-term Fertilization and Cultivation on Purple Soil Sloping Croplands

为探究长期施肥和耕作对坡耕地径流率及随径流流失的氮、磷元素的影响,在紫色土坡耕地设置5个处理:顺坡耕作无施肥(CK)、顺坡耕作有机肥与化肥配施(T1)、顺坡耕作单施化肥(T2)、顺坡耕作单施化肥增量(T3)和横坡垄作单施化肥(T4),分析了2008~2019年间共104场侵蚀性降雨事件下,各处理的径流率,总氮(TN)、总磷(TP)流失浓度及其流失率的变化特征.结果表明,各施肥处理间径流率差异不显著(P>0.05),但均低于CK(P<0.05).CK处理的TN流失浓度显著高于其他施肥处理(P<0.05),T2、T3和T4处理间TN流失浓度差异不显著(P>0.05),但均显著高于T1(P<0.05).T1、T2和T3处理的TP流失浓度显著高于CK(P<0.05),但T4处理的TP流失浓度显著低于CK(P<0.05).各施肥处理间TN流失率差异不显著(P>0.05),但均显著低于CK(P<0.05);各顺坡耕作处理间TP流失率差异不显著(P>0.05),但均显著高于横坡耕作(P<0.05).CK、T1及T2处理下,径流率与TN、TP流失浓度间的关系不显著,在T3处理下上述关系表现为显著的线性负相关(P<0.05),在T4处理下则为显著的线性正相关(P<0.05).研究结果可为紫色土区坡耕地农业面源污染防治提供科学指导.

To elucidate the effects of long-term fertilization and cultivation on runoff rates and runoff-related nitrogen(N)and phosphorus(P)losses,the following five treatments were established on sloping purple soil cropland:(1)no fertilizer with downslope tillage(CK),(2)combined application of manure and fertilizer with downslope tillage(T1),(3)chemical fertilizers with downslope tillage(T2),(4)chemical fertilizer with increasing fertilization with downslope tillage(T3),and(5)chemical fertilizer with contour tillage(T4).The runoff rate,runoff-related total N(TN),and total P(TP)concentrations and their loss rates from 104 erosive rainfall events were determined for the period 2008-2019.Results showed that although runoff rates were not significantly different among the fertilization treatments(P>0.05),runoff was markedly lower in fertilization treatments than in the CK treatment(P<0.05).Runoff-related TN concentrations were significantly higher in the CK compared to the fertilization treatments(P<0.05),while there were no significant differences among the T2,T3,and T4 treatments,which had higher concentrations than the T1 treatment.Runoff-related TP concentrations were significantly higher from the T1,T2,and T3 treatments than the CK treatment(P<0.05),and were significantly lower in the T4 than the CK treatment(P<0.05).TN loss rates were not significantly different among the fertilization treatments(P>0.05),but were all lower than the CK treatment(P<0.05).Furthermore,TP loss rates were not significantly different among the downslope treatments(P>0.05),but were all higher than the contour treatment(P<0.05).Runoff rates showed no significant relationships with TN and TP concentrations in the CK,T1,and T2 treatments but were significantly negatively linearly correlated in T3(P<0.05)and significantly positively linearly correlated in T4(P<0.05).These results potentially provide scientific guidance for the prevention and control of agricultural non-point source pollution on sloping croplands in the purple soil area.