河谷平原水田土壤肥力特点与可持续管理*

以浙江省为例,探讨了南方河谷平原水田土壤肥力状况及其空间变化特点。因成土物质来自周围高度风化土壤及其质地偏砂,河谷平原水田土壤酸化明显,酸性及强酸性土壤的比例高达58.75%。土壤质地是导致河谷平原水田土壤肥力空间差异的关键因素,位于河流下游的泥质田和泥筋田质地较重,保肥性较强,土壤有机质、全氮积累明显,供钾能力较高,土壤酸化相对较弱；相反,位于河流上游及河沿的洪积泥砂田、泥砂田和培泥砂田土壤质地偏砂,其保肥性较弱,有机质、全氮较低,供钾能力较弱,土壤酸化明显。土壤有效磷空间异质明显,同时存在过度积磷与严重缺磷的现象。分析认为,在河谷平原水田土壤管理与施肥策略上应考虑土壤性状的空间差异,并重视磷和钾的测土配方施肥。

Soil Fertility Characteristics and Sustainable Management of Paddy Fields in River Valley Plains

Taking Zhejiang province as an example, the status and spatial variation of soil fertility of paddy fields in the southern valley plains were discussed. As the soil parent materials in the valley plains came from the highly weathered soil and the texture of most soils tended to sandy, the paddy soils in the valley plains were obviously acidified, and the proportion of acidic and strongly acidic soils in the regions was as high as 58.75%. Soil texture was the key factor that leads to the spatial difference of soil fertility in the valley plains. The pale fluviogenic loamy paddy soil and pale fluviogenic muddy paddy soil on depression located in the lower reaches of the river had heavy texture, strong fertility retention, obvious accumulation of soil organic matter and total nitrogen, high potassium supply capacity, and relatively weak soil acidification. On the contrary, the diluvial gritty loamy paddy soil, fluviogenic loamy paddy soil, and hale-percogenic loamy paddy soil located at the upstream and along the river had sandy texture, weak fertility retention, low organic matter and total nitrogen, weak potassium supply capacity and obvious soil acidification. The spatial heterogeneity of soil available phosphorus was obvious, and there were both excessive phosphorus accumulation and serious phosphorus deficiency. It was suggested that the spatial differences of soil properties should be considered in the management and fertilization strategy of paddy soils in the valley plains, and soil testing and formula fertilization would still be an important technology to maintain the balance of soil nutrients in the region.