云南坡耕地红壤地表径流氮磷流失特征定位监测

选取南方典型坡耕地红壤为试验区,采用田间小区试验方法,在自然降雨条件下,于2008-2010年连续3a对不同农业管理方式下地表径流及氮磷流失特征进行田间实地监测.结果表明,试验区域干湿季极其分明,3a平均降雨量为838.6 mm,主要集中在5月到10月,坡耕地红壤地表径流、养分流失时间、流失量与降雨量之间具有显著的相关性,在常规施肥处理下径流量和氮磷流失量之间呈极其显著的指数相关性,相关系数分别为R=0.8974**和R=0.5297**.坡耕地红壤地表径流量、径流系数及氮磷流失量变化规律一致,不施肥条件下,总氮、总磷流失量最大,优化施肥、揭膜、横坡垄作及秸秆覆盖等农艺措施能降低氮、磷流失量,尤其是横坡垄作种植,相对于顺坡垄作氮、磷流失总量降低了2/3左有.不同处理之间径流中各种形态氮磷含量无显著差异,说明不同农业措施主要通过地表径流流失量而影响坡耕地地表径流氮磷流失量的多少.坡耕地红壤地表径流氮磷流失以颗粒态为主,TDN占TN比例年均为24.58％,TDP占TP的比例年均为7％,TN流失量是TP的3倍左右；优化施肥和揭膜条件下可溶性氮磷所占比例增加,横坡垄作和秸秆覆盖条件下降低.在可溶性氮素中,NO3-N、NH3-N占TN的比例年均分别为8.41％、12.65％,但是2009、2010年NH3-N均小于NO3-N.因此,关于坡耕地地表径流不同流失氮素形态的影响因素较多,目前研究结果不确定,且年际之间差异较大,尚需要进一步研究.

The Monitoring of Nitrogen and Phosphorus Loss by Surface Runoff in Sloping Red Soil Fields of Yunan Province,China

The field plot experiment was carried out to monitor the surface runoff and the loss of N and P under different agronomic measures in a piece of typical southern red-soil-sloping land at Jiuxian Town,Qujing City,Yunnan Province from 2008 to 2010.The results showed that the dry and wet season was well marked and three-year average rainfall in the test area was 838.6 mm,mainly occurred from May to October.There was a significant correlation between the rainfall and the amount and time of nutrients loss by soil runoff:and an extremely significant exponential correlation between the nitrogen loss,phosphorus loss and runoff amount under conventional fertilization treatment,the correlation coefficients were R=0.897 4**and R=0.529 7**separately.Among all treatments,the amount of surface runoff and the loss of N and P was the greatest under non-fertilization.Other treatments,such as optimizing fertilization,covered film opening,slope ridge and straw mulching,significantly reduced the loss of nitrogen and phosphorus by runoff.Especially cross-slope ridge planting decreased the amount of loss by two-thirds than that of longitudinal ridge.There were no significant differences in various forms of N and P content among the different treatments.It means that nitrogen and phosphorus loss,affected by different agronomic measure,were largely depend on the amount of surface runoff.The particulate N and P were the dominate forms in the total loss of N and P by runoff,in which the annual average percentage of TDN / TN was 24.58% and TDP/TP was 7%.The TN loss was about three times than that of the TP.The proportion of soluble nitrogen and phosphorus increased in the conditions of optimize fertilization and removing mulching film,and reduced under cross-slop ridge and straw mulch treatments.In the loss of soluble N,the annual average percentage of NO 3-N/TN and NH 3-N/TN were 8.41% and 12.65% separately,but the loss of NH 3-N was less than NO 3-N both in 2009 and 2010.Therefore,the forms of nitrogen loss were affected by many factors in surface runoff on sloping land,the study results uncertainty at present,and the difference larger between inter-annual,still needed to be studied further.