植茶年限对土壤团聚体氮、磷、钾含量变化的影响

摘要

采用野外调查和室内分析相结合的方法，研究了植茶年限对土壤团聚体氮、磷、钾含量变化的影响。结果表明，1）土壤团聚体速效钾含量随粒径的减小先升高后降低，在0.50.25 mm粒径中较高，为38.5270.32 mg/kg；全磷、全钾和碱解氮含量在各粒径中分布较均匀，其变异系数分别为2.77％11.58％、0.82％3.72％和5.98％10.62％；而全氮和有效磷含量则集中在＜0.25 mm粒径的团聚体中，分别为0.400.98 g/kg和8.5329.32 mg/kg。2）随着植茶年限的增加，各粒径团聚体全氮、碱解氮、全磷和有效磷含量逐渐升高，而速效钾含量则有所降低，全钾含量变化不明显。3）不同粒径土壤团聚体对土壤氮、磷、钾含量的贡献率有45％72％来自＞5 mm的团聚体，随着植茶年限的增加，＞5 mm的团聚体对土壤养分的贡献率先升高后降低，在植茶23年和31年时较高，为60％72％。不同粒径团聚体对土壤氮、磷、钾的保持和供应能力存在明显差异，长期植茶有利于土壤团聚体全氮、碱解氮、全磷和有效磷的积累，但速效钾含量却逐年降低，故在茶园的生产管理中，需平衡施用氮、钾肥，植茶23年后应增施有机肥料，以促进土壤大团聚体含量的增加，提高茶园土壤的保肥和供肥能力。%Through field investigation and laboratory analysis , effects of ages of tea plantations on changes of nitrogen , phosphorus and potassium contents in soil aggregates were studied .Results show that the contents of soil available K are increased first and then decreased with the increase of particle sizes of soil aggregates , and higher values which are from 38.52 to 70.32 mg/kg are found in 0.5-0.25 mm particle size .The distributions of total P and total K and available N are relatively even in soil aggregates of all particle sizes , and their coefficients of variation are 2.77%-11.58%, 0.82%-3.72%and 5.98%-10.62%separately .However , the contents of total N and available P are increased with decrease of particle sizes of the soil aggregates , and higher values(0.40-0.98 g/kg and 8.53-29.32 mg/kg) are found in <0.25 mm particle size.Along with rising ages of the tea plantations the contents of total N and total P and available N and P present increasing trends in soil aggregates of all particle sizes.However, the contents of available K display decreasing trends , and the contents of total K show no significant changes .The contribution rates of nitrogen , phosphorus and potassium contents in soil aggregates ( >5 mm) are 45%-72%.Along with rising ages of the tea plantations , the contribution rates of >5 mm aggregates nutrient contents present increasing first and then decreasing trends , and higher values are found in tea plantations with ages of 23 and 31 years ( 60%-72%) .The nitrogen , phosphorus and potassium retaining capacities and supplying capacities are significantly different in soil aggregates with different particle sizes .Long-term cultivation of tea is beneficial to soil aggregates total N and P and available N and P accumulations .However , the contents of available K are decreased year by year , and the contribution rates of >5 mm aggregates nutrient contents are found to be higher in tea plantations with ages of 23 and 31 years, and declined somewhat afterwards .Therefore, in management of tea gardens , it is essential to adopt balanced application of nitrogen and potassium fertilizers , and in tea plantations which are older than 23 years, to use organic manure in addition , so as to promote the increase of soil aggregates content and improve the capacity of tea garden soil fertilizer conservation and fertilizer supply .