土地利用方式对土壤团聚体磷组分及磷库管理指数的影响

Effects of land use types on the phosphorus component of soil aggregates and phosphorus pool management index

冀西北坝上地区是京津冀重要水源地。该区域水土保持能力受土地利用方式影响较大。为探究不同土地利用方式下土壤团聚体结构对磷素的稳定作用,采集马铃薯地、燕麦地、青贮玉米地、露地等地、草地、林地和大棚菜地7种土地利用类型的土壤,利用干筛法进行团聚体分级,分析不同团聚体中磷形态的分布规律及磷库管理指数变化。结果表明:冀西北土壤团聚体总磷质量分数为211.72~441.94 mg/kg,主要分布在≥0.25~0.50 mm团聚体;水溶性总磷质量分数为267.68~421.83 mg/kg,主要分布在≥1.00~2.00 mm团聚体。土壤团聚体磷库管理指数为79.00~153.00,≥0.50~1.00 mm团聚体最高。马铃薯地提高≥0.25~0.50 mm团聚体水溶性磷质量分数和≥0.50~1.00 mm团聚体总磷质量分数及比例,提高<0.25 mm团聚体磷库管理指数。燕麦地促进磷向≥5.00 mm团聚体中分布及提高其磷库管理指数。青贮玉米地和林地促进土壤总磷向≥1.00~2.00 mm团聚体分布,提高≥0.50~1.00 mm团聚体磷库管理指数。草地提高≥0.50~1.00 mm团聚体磷库管理指数。菜地增加≥5.00 mm团聚体总磷质量分数及比例,大棚菜地提高<0.25 mm团聚体磷库管理指数,露地菜地提高≥0.50~1.00 mm团聚体磷库管理指数。大团聚体能增加土壤磷素的供给能力,因此冀西北坝上地区应采用增施有机肥、轮作种植归还率较高的作物、控制马铃薯种植、增加饲草种植等措施,促进磷向大团聚体分布,减少磷素流失,提高京津冀水源保护地生态效益。

[Background]The Bashang region in the Northwest Hebei is an important water source in Beijing-Tianjin-Hebei.The soil and water conservation capacity of this region is greatly affected by land use types.This work is to explore the stability mechanism of soil aggregate structure on phosphorus under different land use types.[Methods]Soil samples from 7 land use types,i.e.,potato field,oat field,silage corn field,open vegetable field,grassland,woodland and greenhouse vegetable field were collected.Then the soil aggregates were classified by dry sieving method to analyze the distribution law of phosphorus forms and the change of phosphorus pool management index(PPMI)in different soil aggregates.The result data were processes by Excel 2007 and SPSS 20.[Results]The content of total phosphorus(TP)in Northwest Hebei ranged from 211.72 to 441.94 mg/kg,mainly distributed in the aggregates of≥0.25-0.50 mm,and water-soluble total phosphorus(WSTP)content ranged from 267.68-421.83 mg/kg,mainly distributed in the aggregates of≥1.00-2.00 mm.The phosphorus pool management index(PPMI)of soil aggregates ranged from 79 to 153,with the highest value of 0.50 to 1.00 mm aggregates.The contents of water-soluble phosphorus of≥0.25-0.50 mm,the TP content and proportion of≥0.50-1.00 mm,and the PPMI of<0.25 mm increased in the potato field.The oat field promoted the distribution of phosphorus to the aggregate of≥5.00 mm and increased PPMI.The distribution of soil TP to≥1.00-2.00 mm aggregate were promoted,and the PPMI of the≥0.50-1.00 mm soil aggregates increased in the silage corn field and forest land.The management index of aggregate phosphorus pool≥0.50-1.00 mm was improved in the grassland.The TP content and proportion of aggregates≥5.00 mm in the vegetable field,the PPMI of<0.25 mm in the greenhouse vegetable field,and the PPMI of≥0.50-1.00 mm aggregate increased in the open vegetable field.[Conclusions]Large soil aggregates can increase the supply capacity of soil phosphorus holding capacity.Therefore,in the Bashang region of Northwest Hebei,the methods of adding organic fertilizer,rotating crops with high return rate,controlling potato planting,and increasing forage grass planting should be used to promote the distribution of phosphorus to the big aggregate and deduce the loss of phosphorus,thus improving the ecological benefits of the Beijing-Tianjin-Hebei water source area.