四川紫色土退化及其防治

PURPLE SOIL DEGRADATION AND ITS CONTROL IN SICHUAN PROVINCE

四川紫色土的物理性退化、构造性退化,以及营养性退化中的氮素贫化、有效磷缺乏和有机质贫化等都比较严重。这主要受母质、生态和侵蚀等因素的影响。防治紫色土退化的措施有:重建紫色土生态保护系统,改土培肥以增强土壤“体质”和实施保护性耕作等。划分出四川紫色土退化防治区,并分区提出了防治途径。

Based on classification and gradation of the degraded purple soils according to the Index System to Evaluate the Purple Soil Degradation in Sichuan Province,the present situation of the purple soil degradation was assessed. By means of frequent and statistical analyses,the trendency of the results by comparison with the two ways was quite accordant.The results determined by statistical analysis showed that the area of the physical , constitutional degradation,the deficiency of organic matter, nitrogen,and available phosphorus in the purple soils in Sichuan Province, respectively, reaches 150. 5, 116. 9, 144. 7, 217. 0, 166. 8 (×10~4 ha),and is 37. 1, 28. 8, 35. 6, 53. 4, 41. 1(%) of the total area of the cultivated purple soils. All those demonstrated that the degradation of the purple soils in Sichuan Province is rather serious.The purple soil degradation in the province is influenced by the properties of bedrocks and parent materials,the constraints of soil substance circulation and soil erosion,etc. The practices of rebuilding the ecological protective system of the purple soils,ameliorating soils,and improving soil fertility to enforce the ability of soil reaction on degradation,renovating the traditional tillage system,and protectively tilling can be taken to guard from and control the purple soil degradation.According to the types and distribution of the purple soil degradation ,the distribution area of the purple soils in Sichuan Province was divided into 6 subregions of controlling soil degradation, i. e. the northern , central, southern, eastern, western subregions of Sichuan Basin and the subre-gion of Panzhihua-Xichang. In accordance with the characteristics of the subregions and principal types of the purple soil degradation, the basic countermeasures of controlling degradation of the subrgions had been proposed.