两种外源性有机物料对设施土壤磷变化的影响

Effects of Two Organic Amendments on Phosphorus Transformation in Greenhouse Soil

采用室内强化模拟试验研究了90 d培养期内稻草和草炭2种外源性有机物料对设施菜地土壤磷素转化的影响。结果显示,与对照相比,添加量为2 g C·kg-1和4 g C·kg-1的稻草处理土壤微生物生物量磷分别增加111.1%~310.0%和197.7%~356.3%,草炭处理分别增加23.7%~54.6%和63.2%~157.1%;添加量为2 g C·kg-1和4 g C·kg-1的稻草处理土壤有效磷平均降低了15.0%和20.2%,草炭处理土壤有效磷与对照差异在前期(45 d)并不显著;土壤易解吸磷30 d后持续降低,培养结束时稻草和草炭处理土壤易解吸磷均值分别降低了21.3%和10.9%。以培养结束时各组分磷占全磷的比例来看,稻草和草炭均可促进土壤无机态的Al-P、Fe-P、O-P及有机态的MLOP、HROP等组分向有机态的LOP和MROP转化,土壤微生物生物量磷、有效磷和易解吸磷均与Fe-P呈显著线性相关。研究表明,添加稻草和草炭有利于设施土壤磷素的管理,且稻草的效果总体上比草炭的要好;Fe-P是调控设施土壤磷素周转与流失的重要形态。

Greenhouse soils are different from common agricultural soils in nutrient transformation, due to high temperature and moisture. In this study, the effects of rice straw and peat applications on the transformation of phosphorus(P) in a greenhouse vegetable soil were studied in a laboratory incubation. Dynamics of soil microbial biomass P(MBP), available P(Olsen-P) and readily desorption P(Ca Cl2-P) were examined during a 90-day experimental period. Inorganic P was fractionationed as aluminum(Al-P), ferric(Fe-P), calcium(Ca-P) and occluded P(O-P), while organic P as labile organic P(LOP), moderately labile organic P(MLOP), moderately resistant organic P(MROP)and highly resistant organic P(HROP). Compared to the control, soil MBP increased by 111.1%~310.0% and 197.7%~356.3% following rice straw amendments at 2 g C·kg-1and 4 g C·kg-1, respectively, while it increased by 23.7%~54.6% and 63.2% ~157.1% following peat additions at 2 g C·kg-1and 4 g C·kg-1peat, respectively. Soil Olsen-P decreased by average 15.0% and 20.2% after additions of rice straw at2 g C·kg-1and 4 g C·kg-1, respectively. However, peat additions did not significantly change soil Olsen-P until 45 days of incubation. Soil Ca Cl2-P kept declining after 30 days of incubation. After 90-day incubation, rice straw and peat reduced Ca Cl2-P by average 21.3% and10.9%, respectively, in comparison with the control. By comparing the percentages of each P fractions over total P at the end of incubation,rice straw and peat both enhanced the conversion of Al-P, Fe-P, O-P, LOP and HROP to LOP and MROP. The correlation coefficients between MBP, Olsen-P, Ca Cl2-P and Fe-P fractions were statistically significant at P <0.05. In conclusion, rice straw and peat amendments would help control P transformations in greenhouse soils, with rice straw more effective than peat. Fe-P may be a vital chemical fraction in regulating cycling, transformation and runoff of phosphorus in greenhouse soils.