桂西北典型环境移民迁入区土壤养分特征分析

在桂西北典型环境移民迁入区,分析了5种土地利用方式表层(0-20 cm)土壤有机质(SOM)、全量养分和速效养分的变化特征.结果表明,根据变异系数(Cv)大小,除速效磷(AP)为强变异外Cv＞1.0),其余土壤养分都为中等变异(0.1＜Cv＜1.0).整体而言,移民迁入区SOM、全氮(TN)含量处于较高水平,速效氮(AN)、速效磷(AP)含量处于中等水平,全磷(TP)、速效钾(AK)处于偏低水平,而全钾(TK)处于低水平.土地利用方式是影响土壤养分的主要因素.灌丛和荒草地的SOM,TN,AN处于较高水平,果园和旱地则处于中等水平;次生林SOM处于较高水平,TN处于中等水平,而AN处于偏低水平.除旱地和果园AP含量处于中等水平外,不同利用方式土壤的TP,TK,AP,AK含量处于低或偏低水平.由于采取了较好的水土保持措施,移民后较大规模的土地利用变化没有导致明显的土壤退化,但需要增加磷钾肥的施用量.

Soil Nutrient Characteristics in Typical Immigrant Region of Northwest Guangxi Province

Five typicalland use types were chosen in the representative environmental immigrant region of Northwest Guangxi, China. Soil organic matter (SOM) and total and available nutrient contents were analyzed in the surface soil layer (0) 20cm). Results showed that in terms of the coefficient of the variation (C_V) of soil nutrients, the contents of SOM, total N(TN), total P(TP), total K(TK), available N(AN),and available K(AK) had a moderate variability(0.1V1.0), except that available P(AP) content had a high variability(C_V1.0). In general, SOM and TN contents were in a higher level, AN and AP contents were in a moderate level, TP and AK contents were in a low level, and TK content was in a lower level.Land use had an important effect on the change in soil nut rients. SOM,TN, and AN contents had a high level in shrubland and grassland and a moderate level in dry land and or char dland. SOM, TN, and AN co ntents had a high, moderate, and low levels in seco ndary forest land, respectively. TP, TK, A P, and AK contents had low and lower levels in five land use types except that AP had a moderate level in dry land and orchar dland. Land use change after immigration did not lead to obv io us soil deg radat ion due to effective soil and water conserv ation measures, but P and K nutrients were increased.