垦殖对川西北高寒草地土壤中不同磷组分含量的影响

Effects of reclamation on the soil phosphorus fractions of alpine meadow in Northwest Sichuan

选择川西北高寒草地垦殖3和10年后的川贝母种植地为研究对象,以邻近未开垦天然草地土壤为对照,采用修正后的Hedley磷元素分级方法,探究垦殖对川西北高寒草地土壤磷组分含量变化的影响。结果表明,垦殖导致了高寒草地土壤全磷(TP)、水溶性磷(H_2O-Pi)、活性磷(NaHCO_3-P)、潜在活性磷(NaOH-P)、中稳性磷(Dil.HCl-Pi)、高稳性磷(Conc.HCl-P)含量显著下降,残余态磷(Residual-P)显著上升。其中0～20 cm土层变化最显著,垦殖10年后,土壤TP、H_2O-Pi、NaHCO_3-P、NaOH-P、Dil.HCl-Pi和Conc.HCl-P分别下降了16.48%、78.98%、57.43%、26.06%、16.38%、10.87%,而Residual-P增加了40.08%。其中H_2O-Pi、NaHCO_3-P和NaOH-P含量变化显著高于其他组分的磷,说明磷的活性越高损失越明显。垦殖过程中,土壤H_2O-Pi、NaHCO_3-P和NaOH-P占全磷比重显著下降,而Dil.HCl-Pi、Conc.HCl-P和Residual-P呈上升趋势。垦殖前3年,土壤全磷及各形态磷组分的年下降率显著高于垦殖3～10年,说明垦殖过程中磷的损失主要发生在垦殖前期。

Alpine grassland in northwest Sichuan, dominated by Fritillaria cirrhosa and subject to 3 or 10 years development, was compared with nearby uncultivated natural grassland (Control) to explore the effects of development on the soil phosphorus fractions. Soil phosphorus tests were performed using a modified Hedley method. It was found that after development the levels of total phosphorus (TP), water-soluble phosphorus (H 2O-Pi), active phosphorus (NaHCO 3-P), potentially active phosphorus (NaOH-P), stable phosphorus (Dil. HCl-Pi) and highly stable phosphorus (Conc. HCl-P) were significantly lower than those of Control plots, while residual phosphorus (Residual-P) levels were significantly increased. These changes were most pronounced in the 0-20 cm soil layer. After 10 years of development, the levels of TP, H 2O-Pi, NaHCO 3-P, NaOH-P, Dil. HCl-Pi and Conc. HCl-P decreased by 16.48%, 78.98%, 57.43%, 26.06%, 16.38%, and 10.87 % respectively, while Residual-P levels increased by 40.08%(P<0.05). H 2O-Pi, NaHCO 3-P and NaOH-P changed to a greater extent than the others, indicating the higher the activity, the greater the loss. With increased time under development, the ratios of H 2O-Pi, NaHCO 3-P, and NaOH-P to TP significantly decreased, while the ratios of Dil. HCl-Pi, Conc. HCl-P, and Residual-P to TP increased. In the early stages of development (0-3 years), TP and various phosphorus fractions changed faster than at the later stages (3-10 years), indicating that the losses of the various phosphorus fractions mainly occurred in the early stages of development (0-3 years).