林下养鸡年限对杨树人工林土壤磷素形态和生物有效性的影响

林下养殖是一种经济有效的林地空间利用方式,但长期高负载的林下养殖对林地土壤性状究竟产生何种影响,目前尚无定论.以不同林下养鸡年限(0年、1年、3年和5年)的美洲黑杨(Populus deltoides)人工林为对象,采用Hedley磷素分级法,分析其林地土壤的磷素组成和形态变化,探讨林下养鸡年限对土壤磷库特征及其生物有...

Effects of in-forest chicken-raising duration on soil phosphorus fractions and bio-availability in poplar plantations

In-forest raising is a cost-effective way to improve the comprehensive utilization of forest land.However,it is currently unclear what impact of long-term and high-load in-forest raising has on soil properties.In order to reveal the effects of chicken-raising duration on soil phosphorus pool and its bioavailability,this study used plantations of Populus deltoides under different in-forest chicken-raising duration(0,1,3,and 5 years)to analyze the changes in soil phosphorus fractions by Hedley phosphorus fractionation method.The results show that the contents of soil total phosphorus and the fractions of NaHCO₃-extracted inorganic and organic P(NaHCO₃-Pi and NaHCO₃-Po)and NaOH-extracted inorganic and organic P(NaOH-Pi and NaOH-Po)in 0-5 cm soil layer increased significantly with the extension of in-forest chicken-raising duration,even showing a 1.4-to-2.4-time increase in the plantations with 5-year in-forest chicken-raising than in the control plantation.However,no obvious changes of the four fractions were found in 5-10 cm soil layer.The contents of diluted HCl-extracted inorganic P(D.HCl-Pi)and concentrated HCl-extracted inorganic P(conc.HCl-Pi)in 0-10 cm soil layer decreased significantly after 1-year of chicken raising,and then increased with the extension of in-forest chicken-raising duration.The contents of concentrated HCl-extracted organic P(conc.HCl-Po)and the more chemically stable P(Residual-P)showed similar trends as D.HCl-Pi and conc.HCl-Pi,but no significant differences were found among different in-forest chicken-raising duration.The contents of soil total inorganic phosphorus in 0-10 cm soil layer decreased significantly after 1-year of chicken raising,and then increased with the extension of in-forest chicken-raising duration,while the contents of soil total organic phosphorus significantly increased.The contents of bio-available P(available P and labile P)in the topsoil increased with the extension of in-forest chicken-raising duration,and both were significantly aand positively correlated with the contents of NaOH-Pi and NaOH-Po,showing that the fractions of NaOH-P,especially NaOH-Po,was the most important potential source that could be transformed into bio-available fractions.Overall,the contents of phosphorus that are more easily decomposed and utilized in the soil obviously accumulate with the extension of in-forest chicken-raising duration,and the contents of phosphorus that are difficult to decompose do not change significantly.The supply level of available phosphorus or labile phosphorus in the topsoil of forest land is improved obviously with the extension of in-forest chicken-raising duration,and the bioavailability of soil phosphorus has continued to increase.