半干旱地区不同土壤团聚体中微生物量磷的分布特征

Distribution Characteristics of Microbial Biomass Phosphorus in Different Soil Aggregates in Semi-arid Area

从半干旱地区采集了7个不同利用方式的土壤样品,利用干筛法获得了不同粒径的土壤团聚体,研究了微生物量磷、速效磷、有机磷及其组分在团聚体中的分布特征。结果表明,土壤微生物量磷、有机磷分别为5.86～12.24mg·kg-1和0.12～0.35g·kg-1,灌溉耕地最高、退化草地最低,二者在大团聚体(>2mm)中的含量皆高于小团聚体(<2mm);土壤速效磷含量则相反,在小团聚体中较高。有机磷分组研究显示,大团聚体的中等稳定性和稳定性有机磷含量较高,活性和中等活性有机磷含量则在>2mm或<0.5mm团聚体中较高。结果表明土壤大团聚体可能是磷转化的库,小团聚体是土壤磷供给的源。微生物量磷与各种形态的土壤磷都显著相关。

Seven soils with different land use types were collected from semi-arid area and treated by dry-sieving. Distribution of microbial biomass P (MBP), available P (AP), organic P (OP), labile organic P (LOP), moderately labile organic P (MLOP), moderately resistant organic P (MROP) and highly resistant organic P (HROP) were studied. The results showed that the content of MBP and OP in whole soil and aggregates were 5.86-12.24 mg·kg-1, 0.12-0.35 g·kg-1, the irrigated arable soil and the grassland soil had the highest and lowest value, respectively. The amounts of MBP and OP in large aggregates (>2 mm) were higher than in small aggregates (<2 mm), and the AP in small aggregates was higher than in large aggregates. The result also showed that large aggregates had higher content of MROP and HROP, large and small aggregates were both rich in LOP and MLOP. These results suggest that the large aggregates may be the pool of soil P transformation, and the small aggregates are the source of soil available P. There were significant correlation between MBP and different types of soil phosphorous.