不同形态磷在砂土中的移动性研究(英文)

预测土壤中磷的长期淋洗性需要了解土壤特性和不同形态磷的行为.本研究用模拟试验评估了不同磷负荷砂质土壤中不同形态磷的移动性.分别从浙江省衢州市和温州市采集具不同磷含量的蔬菜地土壤,每一地点分别采集2个深度的土壤(0～10 cm和10～30 cm),表层土壤(0～10 cm)通过添加不同量的磷酸盐、CaCO和无定形氧化铁,形成研究需要的不同磷含量和不同磷形态的系列土壤样品;淋洗柱长30 cm,由10 cm经培养处理的表层(0～10 cm)土壤和未经培养处理的亚表层土壤(10～30cm)构成,每一淋洗土柱连续经历12个循环的0.002 mol?L-1CaCl2溶液淋洗,收集的淋洗液用于分析钼酸反应总磷(TRP)、可溶态钼酸反应磷(DRP)和颗粒态钼酸反应磷(RPP);试验结束后鉴定土壤中水溶态磷、MehlichⅢ-P和磷的化学形态变化.结果表明:添加无定形氧化铁和碳酸钙可显著改变砂土中磷的形态,降低土壤磷的有效性;无定形态氧化铁在降低土壤磷有效性方面的作用大于碳酸钙;淋洗液中磷的形态主要为DRP,颗粒态磷占总磷的比例为1.2%～39.8%;TRP和DRP的损失与培养处理后表土中磷含量存在显著的相关.相关分析和淋洗试验后土壤中磷形态变化结果都表明:表土柱中淋移的磷主要来源于水溶性磷(H2O-P)和NaHCO3-P,与NaOH-P、HCl-P和残余磷的相关不明显;从表土淋失的磷有27.1%～54.2%被淋出土体,其余下移至10～30 cm土层中.研究结果还表明,添加无定形氧化铁可增加土柱中颗粒态磷的迁移.

Mobility of different forms of phosphorus in sandy soils

Predication of the long-term leaching of phosphorus (P) in the soil requires information of soil characteristics and behavior of P forms.This study assessed the mobility of different P forms in sandy soils that have been intensively loaded with P.Two sandy soils with different P concentration were collected at two depths (0-10 cm and 10-30 cm) from the vegetable farms in Quzhou and Wenzhou,Zhejiang Province,China.The surface soils (0-10 cm) were spiked with P (in form of KH2PO4) and amended with CaCO3 or amorphous iron oxide to obtain soil samples with different P concentration and P forms.A series of 30 cm length leaching column containing 10 cm of amended surface soils varying forms of P above 20 cm of non-amended subsoil were constructed.The soil columns were consecutively leached by 0.002 mol·L-1 CaCl2 for 12 cycles.Column leachates were collected for measurement of concentration of total reactive P (TRP),dissolved reactive P (DRP),and reactive particulate P (RPP).Changes of water soluble P,Mehlich Ⅲ-P,and P fractions in the leached soils were characterized.The results showed that addition of amorphous iron oxide and CaCO3 to soils could significantly change P forms in sandy soils,and decrease soil P availability.Amorphous iron oxide was more effective for decreasing soil P availability than CaCO3.Forms of P in leachate presented mainly for DRP,and particulate P ratio of total P ranged from 1.2% to 39.8%.The loss of the TRP and DRP were significantly correlated to P accumulation in surface soils.Both correlation analysis and changes of P forms in the soils before and after leaching indicated that P leached from the soil columns were mainly originated from H2O-P and NaHCO3-P.Twenty-seven point one percent-54.2% of the P lost from surface soils was leached out from the columns,and the remainder was downward moved into 10-30 cm soils.Addition of iron oxide to sandy soils could enhance the downward transfer of particulate P in columns.