宁夏灌区不同种植年限及方式温室土壤磷素的变化特点

Soil Phosphorus Content Variations in Greenhouse Soils with Different Growing Manners in Different Growing Times in Ningxia Irrigating Regions

根据宁夏灌区温室的分布状况，采集了不同种植年限和不同种植方式温室表层（0-20cm）和剖面（0～120cm）土壤，分析了土壤全磷和速效磷含量的变化特点．结果表明，温室表层土壤全磷含量随种植年限的延长呈曲线增加，但在连作条件下6a以后呈下降趋势；表层以下层次全磷含量与大田土壤基本一致；轮作土壤全磷含量高于连作土壤，所有温室土壤全磷含量明显高于大田土壤．土壤表层速效磷含量随种植年限的延长也呈增加趋势，种植9a时出现高峰值，之后逐渐下降；表层以下层次速效磷含量与大田土壤基本一致，但温室土壤整个剖面的速效磷含量明显高于大田土壤；连作土壤速效磷含量高于轮作土壤．相关分析表明，不论轮作还是连作，温室土壤表层磷素含量及其累积量明显高于下层，表层出现磷素富集现象，在今后确定施磷量时应重点予以考虑．

Based on the distribution locations of the greenhouses in Ningxia irrigating regions, the soil samples of both the top soil（0-20 cm） and the profiles（0-120 cm） were collected at random for different greenhouses and various planting years. The contents of total P and available P for the greenhouse soils were determined to study the variation of the greenhouse soil P with different growing ages and planting manners of Ningxia. The results showed that the total P contents increased with the planting years in the form of parabolas, but after 6 years of cultivation it began to reduce in the continuous cropping. The contents of the total P in subsoil were similar to that of the farmland soils. The contents of soil total P under rotation were higher than that of continuous cropping. The contents of total P in all greenhouse soils were higher than that of farmland soils. The contents of soil available P also increased with planting ages in the first 9 years, and then they were tend to decrease. The contents of soil available P in subsoil were similar to that of farmland soils. But the contents of available P in all soil profiles（0-120 cm） in the greenhouse soils were higher than that of farmland soils. Compared with the contents of total P, the contents of soil available P of continuous cropping were higher than that of crop rotation. Both contents and accumulated rates of soil phosphorus had a very significant differences between the topsoil and the subsoil. It was true that the soil phosphorus is enrichment in the greenhouse topsoils, therefore it should be considered as the rational fertilization for the greenhouse soils in the future.