黄土丘陵区不同退耕模式对土壤物理性状影响研究—以甘肃定西市为例

甘肃定西全面实施退耕还林近10年来，取得了显著的成效。本文以退耕还林重点地区定西市安定区为例，通过采集、实地调查取样和实验室分析，对比研究了不同退耕植被类型地与对照地（农田和天然草地）的土壤物理性状的变化情况。包括土壤的含水量、容重、土壤孔隙度、土壤水稳性团聚体结构。研究结果表明：天然草地和柽柳的含水量最高，分别为13.44%和13.52%。农田和山杏的含水量最低为8.01%和8.2%。0～60cm不同土层中柠条的容重最小且变化不大，农田的上下变化最大。在20～60cm退耕还林地的孔隙度均高于天然草地和农田，天然草地和农田非毛管孔隙度小且上下变化大，不利于土壤入渗。刺槐、柠条、柽柳的水稳性团聚体的含量最多，分别是农田的3.4、2.8和2.4倍。退耕还林以后，林地的土壤物理性状得到明显的改善，与农田和天然草地相比，刺槐，柠条的改良效果最好。因此对退耕还林地区进行植被恢复过程中，要深入了解当地的土壤环境特征，做到因地制宜，适地适树。

Research of the Effect on the Physical Properties of Different"Conversion of Farmland to Forest"Practices--Take Dingxi City of Gansu Province as An Example

The full implementation of Gansu Dingxi forests the past 10 years, has achieved remarkable results. In this paper, key areas of returning farmland to forest stability Dingxi City area as an example, through the collection, field surveys, sampling and laboratory analysis, comparative study of different vegetation types with returning control to (agricultural land and natural grassland) of soil physical properties changes. Including soil water content, bulk density, soil porosity, soil water-stable aggregates structure. The results show that: the natural grassland and highest water content of Tamarix were 13.44% and 13.52%. Apricot of farmland and water content as low as 8.01% and 8.2% respectively. 0-60cm soil layer in different caragana little change in bulk density and the smallest, the largest changes in upper and lower fields. 20-60cm in returning farmland to forests and the porosity is higher than the natural grassland and agricultural land, natural grassland and farmland non-capillary porosity changes in small and large up and down is not conducive to soil infiltration. Robinia pseudoacacia, Caragana, Tamaricaceae of water-stable aggregates the content of most agricultural fields were 3.4,2.8 and 2.4 times. After returning farmland to forest, woodland soil physical properties have been significantly improved, and agricultural land and natural grassland as compared to black locust, improved Peashrub best. Therefore, returning farmland to forest areas during the recovery process of vegetation to the soil depth understanding of local environmental characteristics, so the light of local conditions, appropriate and suitable tree.