珠江三角洲耕地土壤质量演化及其机制

通过对代表性区域的调查研究,探讨了珠江三角洲耕地土壤质量演化的趋势及其形成机制.结果表明,与第二次土壤普查时期(1980)比较,珠江三角洲耕地土壤有机质全氮稳中有降,土壤速效氮(NO_3~--N)、速效磷含量显著增加,已达丰富水平,土壤速效钾含量有所增加、但仍偏低,土壤有效镁、硼、钼仍严重缺乏,部分土壤有效硅、锰缺乏;伴随大量水田改种蔬菜、水果等经济作物而产生的耕作制度变化、利用强度增加以及相应的化学氮、磷肥料过量投入、蔬菜地施用石灰等管理措施等,是导致珠江三角洲耕地土壤有机质下降和产生新的养分非均衡化的主要影响因素.

The cultivated land soil quality change and mechanism in the Pearl River Delta

The soil quality change and mechanism of cultivated land was studied by soil survey of typical region in the Pearl River Delta. The results showed that, comparing with the second generalsoil survey in 1980s, the content of soil organic matter and total nitrogen had no significant change but performed decrease trend; the available-N(NO_3~--N) and available-P increased obviously, es-pecially the accumulations of available-P adding up to very rich level; the available-K increased slightly, but being still at lower level; the available-Mg, available-B, and available-Mo were still seriously insufficient, some of the soils were poor in available-Si and available-Mn. It was indicated, along with the cropping system change, intensive continuous cultivation, the over fertilization and applying caustic lime in vegetable field for control of plant disease and insects, might be the main factors of the degrease of soil or-ganic matter and the presenting of news nutrient imhalance.