降雨与作物种植方式对赤红壤坡面土壤侵蚀特征的影响

Effects of rainfall and cropping patterns on the soil erosion characteristics of lateritic red soil slope

基于野外原位观测资料,以荒地为对照处理,探讨轮作和间作种植方式对赤红壤坡面土壤侵蚀特征的影响。结果表明:2017年研究区侵蚀性降雨在年内分布较为分散,高强度侵蚀性降雨主要分布在1—6月。降雨历时、降雨量与坡面径流量、侵蚀量均呈显著正相关关系,最大30 min降雨强度仅显著影响一定处理下坡面径流量和侵蚀量。不同降雨等级下,轮作坡耕地坡面侵蚀量和径流系数均显著高于荒地,而侵蚀量仅在>20~40 mm降雨等级下显著高于间作坡耕地。轮作坡耕地处理下坡面年径流深及年侵蚀量均最大,荒地处理下最小。轮作坡耕地各月径流量分布与侵蚀性降雨量分布特征基本一致,但侵蚀量的变化与侵蚀性降雨分布存在较大不同。各月坡面径流量和侵蚀量均表现为轮作坡耕地>间作坡耕地>荒地。其余处理下坡面产流输沙变化与侵蚀性降雨的年内分布基本一致。轮作坡耕地坡面侵蚀主要源自1—6月的高强度降雨,其余处理下坡面侵蚀量随次降雨变化波动相对较小。

[Background]Cropping pattern is an important factor that has significant impact on soil erosion characteristics.Soil erosion under farmland,which is a typical phenomenon in red soil region of South China,can cause decline of soil quantity and destroys local ecological environment.To provide the basis for effective prevention and control of soil erosion in different regions,soil erosion characteristics of lateritic red soil under different cropping patterns was explored in the middle area of Guangxi Zhuang Autonomous Region.[Methods]In this study,by using natural rainfall experience,rainfalls and sediment yields were observed in 2017 at Mu Mianlu watershed in Nama county,Nanning city,Guangxi Zhuang Autonomous Region in 3 different treatments of crop rotation,intercropping treatment and abandoned land.Rainfall characteristics were measured by using tipping-bucket rain gauge.The runoff,runoff coefficient and sediment yield were analyzed according to individual rainfall level.[Results]1)Rainfall was dispersed in 2017,and mainly happened in March to August,which was amount 88.2%of the total rainfall amount(1457.9 mm).Total erosive rainfall was 1082.2 mm,and the main rainfall class was≤40 mm rainfall one.The high erosive rainfall events were mainly occurred in January to June.2)Runoff and sediment yield under crop rotation were significant higher than those under abandoned land in most rainfall classes,while only significant higher than those under intercropping treatment in>20-40 mm rainfall class.Runoffs and sediment yields were all significantly related to rainfall amount and rainfall duration for all treatments,and maximum rainfall intensity in 30 min was significantly related to the runoff and sediment yield under crop rotation treatment.3)Runoffs and sediment yields under crop rotation were 1.6,2.3 and 2.9,7.6 times of those under the intercropping treatment and abandoned land.Runoffs were in the order of crop rotation>intercropping>abandoned land among all the months of having erosive rainfall events.Sediment yields under the crop rotation and intercropping treatments mainly happened in March,May and July.For crop rotation and intercropping treatments,sediment yields varied with changing of rainfall characteristics for individual rainfall events,and most of them were contributed by several erosive rainfall events that mainly happened in January to June.[Conclusions]Overall,crop rotation pattern had the largest runoff and sediment yield compared with the other two treatments among the whole year.Both cropping pattern and rainfall distribution had significant effects on runoff and sediment yield,especially under rotation cropping pattern.Sediment yield of crop rotation pattern was mainly contributed by several high erosive rainfalls during January to June.Therefore,considering the agricultural management and ecological benefit,the intercropping pattern should be selected in sloping land in lateritic red soil region.