紫色土丘陵区坡耕地退耕对水土流失的影响及其效益评价

 认识退耕对水土流失的影响,对耕地利用结构的调整和评价退耕还林还草的水土保持效益具有重要的科学意义。在中国科学院盐亭紫色土农业生态试验站通过2年(2003—2004年)的小区试验,观测了紫色土坡耕地种作物(小麦-玉米)、饲草(黑麦草)、果树(枇杷)和“果树+饲草”这4种模式的水土流失状况,并用层次分析法等对其水土保持效益进行了综合评价。观测结果表明:坡耕地退耕种草和种“果树+饲草”这2种模式,较作物模式显著减少水土流失超过30％,其中“果树+饲草”模式的侵蚀量减少60％以上。同时发现,退耕地如果只种果树,水土流失量反而多于种作物地,揭示了控制水土流失的关键之一是提高地表盖度。效益分析结果表明,4种模式水土保持综合效益的大小次序是:“果树+饲草”>饲草>作物>果树。

Influence and its benefits evaluation of removal lands from cultivation to afforestation and grassland in slope farmland on soil erosion in hilly region of purple soil

It' s important to understand the influence of removal lands from cultivation to afforestation and grassland on soil erosion for farmland use structure adjustment and benefits evaluation of soil and water conservation of those lands. The soil erosion of four types of farmland plot of planting crops (wheat-corn), grasses (ryegrass), fruit trees(loquat), and fruit trees + grasses, were investigated for two years (2003-2004) at Yanting purple soil agriculture experimental station of Chinese Academy of Sciences, and its comprehensive evaluation of soil and water conservation was also made by hierarchy analysis process. The observation results showed that the removal slope farmland used as types of fruit trees and grasses significantly decreased soil erosion by over 30% comparing with crop type, and especially as type of "fruit trees + grasses" by over 60% . Besides, the amount of soil erosion of only planting fruit trees was more than that of planting crops. Therefore, one of key countermeasures of controlling soil erosion is to increase the land coverage. Benefits analysis results showed the rank of its comprehensive benefits is " fruit trees + grasses' type > grasses type > crops type > fruit trees type.