降雨强度对黄绵土坡地磷流失特征影响试验研究

坡地磷(P)的流失是导致土壤质量退化与水环境恶化的重要原因,探讨降雨特征对土壤P流失的影响机理对于坡地养分管理和环境保护具有重要的科学意义。该文以黄绵土(质地为粉质壤土)为试验材料,通过室内模拟降雨试验研究了雨强对坡地P随径流流失的影响。结果表明：施肥条件下坡地径流中溶解态磷(DP)含量达到0.18 mg/L以上。相同雨量时,径流中DP含量随雨强的增大而降低,泥沙浸提态磷(SEP)与全磷(STP)的含量与流失量以小雨强(0.91 mm/min)时为最大。坡面产流过程中DP、SEP及STP含量的变化均表现为“低－高－低”的变化趋势,其变化与径流含沙量呈正相关,而累积流失量则表现为加速增加的趋势。黄绵土坡地径流中不同形态P的含量随雨强的增大而降低,而总的流失量受雨强与产流过程等多种因素影响。

Experimental study on the impacts of rainfall intensity on phosphorus loss from loessial slope land

Phosphorus (P) loss from slope land is an important factor for soil degradation and water environmental worsening. It is very significant to study the mechanisms of rainfall characteristics affecting soil P loss for slope nutrients management and environmental protection. Impacts of rainfall intensities on P loss from loessial slope land were studied using loessial soil with texture of silty loam and through simulated laboratory rainfall experiments. Results show that Dissolved P(DP) contents in the slope runoff are above 0.18 mg/L. DP contents in runoff significantly decrease with increase of rainfall intensity at the same rainfall amount. The contents and loss amounts of Sediment Extractable P(SEP) and Sediment Total P(STP) are all the greatest under the smallest rainfall intensity 0.91 mm/min. Changes in DP, SEP, and STP contents all show a similar "low-high-low" tendency and are positively related to sediment concentration during runoff process, while the accumulative amounts increase with accelerative rates. Contents for different P forms in the runoff from loessial slope land decreases with increase of rainfall intensities. However, the loss amounts for different P forms are affected by multiple factors including rainfall intensity and runoff process.