复配改良剂调控强酸性茶园土壤酸度的关键过程与机制

Strongly acidic soil (i.e. pH<4.5) is detrimental for tea quality and production. Use of organic and inorganic amendments are effective to both enhance the liming performance of amendments and reduce the risk on soil acidity control. However, different rates of organic and inorganic amendments and various chemical components of organic amendment may result in reverse effect on acidity control, in which the mechanism involved is not clear. The proposed research is to investigate the components of organic amendment and application rates of combined amendments on soil C and N transformation and their effects on soil pH change in strongly acidic tea garden soils in southern China. The suppressed soil nitrification processed is also explored using 15N isotope-tracer technology. The correlation between soil acidity, ammonia , phosphorus contents and the change of AOA and AOB abundance and community is also studied in order to investigate the determined factor and the adaption mechanism of microbial on accelerating soil acidification. The results of this research are expected to prove deep insights into the amelioration of acid soil and resistance in the acceleration of soil acidification. The sustainable development of tea garden ecosystems is also be expected to benefit from the proposed research.

强酸性茶园土壤(pH<4.5)严重降低茶叶的产量与品质。有机与无机改良剂复配能够增强改良剂的调控能力减少调控风险，但会因复配改良剂配比和有机物料组分差异而出现相反的调控效果，其机制尚不清楚。本项目拟以南方典型强酸性茶园土壤为研究对象，通过对不同复配改良剂调控强酸性茶园土壤酸度研究，阐明不同改良剂组分与配比条件下，茶园土壤碳、氮转化规律及其对土壤酸度变化的反馈；并结合15N同位素示踪技术，明确复配改良剂阻控土壤复酸的关键过程与主控因素；同时建立土壤酸度、铵态氮、营养元素磷与土壤酸化关键功能菌群氨氧化细菌与古菌群落组成与丰度变化之间的内在关系，探究酸度调控下氨氧化菌群群落结构的响应特征，阐明土壤加速复酸的发生条件与驱动机制，最终提出在茶园土壤酸度调控的基础上减缓土壤复酸的农艺措施，为完善强酸性土壤的改良和维持茶园生态系统的健康稳定提供科学依据。

强酸性茶园土壤(pH<4.5)严重降低茶叶的产量与品质。有机与无机改良剂复配能够增强改良剂的调控能力减少调控风险，但会因复配改良剂配比和有机物料组分差异而出现相反的调控效果，其机制尚不清楚。项目通过碱渣或碱渣与有机肥(猪粪、菜籽饼)共施的方法，研究不同改良剂复配对土壤酸度以及底层土壤酸度的调控效果。研究发现复配改良剂特别是碱渣与高碳氮比有机物料复配能够有效降低各地底层土壤酸度、交换性酸、Al饱和度，并增加盐基离子饱和度。生物炭的添加能够有效的降低强酸性土壤的交换性酸和铝饱和度，提高土壤的交换性盐基离子含量与pH值。生物炭调节土壤酸度的能力不仅与其灰化碱含量相关，而且与其所施加的土壤环境有关。生物炭释放的碱量在不同土壤类型环境下因矿化程度存在差异。生物炭添加后，有机阴离子的脱羧作用、氮转化过程以及离子的吸附解析作用共同作用于土壤pH的变化，最终pH的变化是上述生化过程作用的结果，因此，生物炭提高土壤pH的能力并不因其添加量的增大而显著增大。改良剂对于酸性土壤群落结构与酶活的改变，是土壤碳结构变化、营养元素与土壤pH共同作用的结果，而非单一的酸度调控。长期施用有机物料会增加烷基碳（alkyl-C）含量和烷基碳键与含氧烷基碳（O-alkyl C）的比例。微生物群落结构与烷基碳、羧基碳以及酮基碳具有显著相关性，而酶活与烷基碳和酮基碳有显著相关性。上述研究结果以期为完善强酸性土壤的改良和维持茶园生态系统的健康稳定提供科学依据。