长期施肥对酸性土壤磷形态及有效性的影响

为明确长期施肥对集约化果园土壤磷形态、分布特征及其有效性的影响，本研究对琯溪蜜柚主产区29个果园的土壤进行调查研究，采用张守敬和Jackson的酸性土壤无机磷分级方法，研究蜜柚果园土壤磷素累积对土壤磷形态及有效性的影响。结果表明：在集约化蜜柚果园中，土壤磷素累积丰富，随树龄增加土壤速效磷含量上升显著，且土壤磷形态在不同土层存在显著性差异；当全磷含量≤0.5 g/kg时，土壤磷形态主要以有机磷、铁磷为主，随着全磷含量的上升，铝磷含量、占比均显著上升；多元线性回归和逐步回归分析结果表明本试验中铝磷与速效磷相关性最好。果园土壤已经形成一个巨大的磷库，且有效性较高，可适当减少磷肥投入，降低土壤磷含量，减少经济成本，提高生态效益。

Effects of Long-term Fertilization on Phosphorus Forms and Availability in Acid Soils

In order to understand the effect of long-term fertilization on the forms, distribution and availability of phosphorus in orchard soils, 87 soils samples of Guanxi pomelo orchards were chosen in the present study to investigate the effect of soil phosphorus accumulation on soil phosphorus form and availability, by using Chang and Jackson''s inorganic phosphorus forms method in acidic soil. The results showed that soil phosphorus accumulation was abundant in intensive pomelo orchard planting system, and the soil available phosphorus content increased significantly with the increase of tree age. In addition, there were significant differences in phosphorus fractions among different soil layers. When soil total phosphorus content was less than 0.5 g/kg, the main forms of phosphorus were organic phosphorus and iron phosphorus, but with the increase of soil total phosphorus accumulation, aluminum phosphorus ratio and content increased significantly accordingly. Multiple linear regression and stepwise regression analysis in the present study demonstrated that higher and significant correlation between aluminum phosphorus and available phosphorus. In conclusion, orchard soil has formed a huge phosphorus pool with high efficiency, reducing phosphorus input in an appropriately way could effectively reduce soil phosphorus content, reduce economic costs and improve ecological benefits.