宁夏贺兰山东麓扬黄新灌区土壤质量的演变

为系统认识宁夏贺兰山东麓扬黄新灌区土地在利用变化背景下,土壤质量演变的一般规律,用空间换时间的田间取样方法,分别从利用方式、土壤分层、利用年限的角度构建数据体系.结果表明,相对未利用对照地,耕地土壤中有机碳和盐分发生表聚现象,园地20～60cm土层中有机碳和盐分明显富集;随利用年限的延长,早期耕地和园地表层中有机碳和盐分含量都呈现先降后升的格局,但后期变化趋势出现分异.园地和耕地表层土壤中wC/N,wC/P随利用年限的延长表现出近似的变化趋势,但后期土壤中wC/N开始趋近于未利用对照地,土壤中C-N循环并未发生实质性改变.耕地、园地各自具有其独特的土地退化防治价值,但是园地具有更突出的生态适宜性,耕地长期利用下的次生退化问题依然需要关注.

Succession of Soil Quality in New Irrigation Areas by Pumping Yellow River in Eastern of Helan Piedmont

To understand the succession of soil fertility in new irrigation areas by pumping Yellow River in eastern of Helan piedmont,investigated the soil quality of Yuanyi Village,based on the soil layers,land used years and modes.The results showed that the soil nutrients and salts in croplands(wheat and maize interplant) gathered in surface,compared with the wasteland.obviously occurred with gardens(grape) in layer of 20 to 60 cm.changes of soil physics-chemistry index shoewd falling-rising-falling patterns at the croplands from the second year to the 10th year,and as well as the gardens from the second year to the 8th year.However,there were different patterns along with land used years at different soil index.There were similar changed trends of C/N and C/P in soils of the croplands and gardens,but C/N approached the C/N in soils of wasteland at the end of land used years.It suggest that the soil ecological functions relating to soil fertility quality would not improved indeedly,both croplands and gardens had their ecological function to prevent land degradation.However,the gardens had more important ecological values,and the hypo-degradation by long-term croplands should be regarded in the future.