长期增温试验对华北潮土区农田土壤有机碳库组分变化的影响机制

Stability improvement of soil organic carbon (SOC) pool is an important basis for sustainable development of farmland productivity. As the climate warming, and response SOC decomposition to warming is still unclear, and need long-term temperature study on field to reveal the mechanism of SOC decomposition to warming, which are the the current frontier issues of global change. Here, we used the conservation tillage and conventional tillage "winter wheat-summer corn" long-term field warming test (since 2010 early) as research platform which located in the fluvo-aquic soil in the North China Plain, carried out soil SOC component (labile and recalcitrant components, aggregates and the organic carbon distribution of each size of agrregates), and soil microbial physiological characteristics (5 species extracellular enzyme (β-glucosidase, chitinase, phospatase, cellobiohydrolase and Sulfatase) activities, enzyme dynamics and microbial communities) and long-term soil respiration, established temperature-tillage-SOC component, temperature-tillage-soil microbial physiological relationships to long-term warming, revealed the mechanism of long-term warming on soil SOC component, to find a tillage management measures to stability improvement soil organic carbon pool under warming.

农田土壤有机碳（SOC）库的稳定提升是农田生产力可持续发展的重要基础，受到耕作措施和气候变暖的显著影响，但还没有定论，需要长期的田间增温试验来揭示SOC响应的机制，目前相关内容是全球变化领域的前沿问题。本研究拟以华北潮土区免耕和翻耕“冬小麦-夏玉米”长期田间增温试验（2010年初至今）为研究平台，开展土壤SOC组分（活性及惰性组分、团聚体及各粒级团聚体有机碳分布）、土壤微生物生理特性（5种胞外酶（β-glucosidase, chitinase，phospatase, cellobiohydrolase, sulfatase）活性，酶动力学以及微生物种群）和长期土壤呼吸等观测分析，建立温度升高-耕作措施-SOC组分，温度升高-耕作措施-土壤微生物生理之间的长期响应关系，揭示长期增温条件下土壤SOC组分对温度升高响应的机制，为找出气候变暖条件下稳定提升土壤有机碳的农田管理措施提供依据和支持。

农田土壤有机碳（SOC）库的稳定提升是农田生产力可持续发展的重要基础，受到耕作措施和气候变暖的显著影响，但还没有定论，需要长期的田间增温试验来揭示SOC响应的机制，目前相关内容是全球变化领域的前沿问题。通过本项目的开展，获得以下主要结果：1）长期增温通过促进冬小麦生物量增加了华北农田土壤有机碳含量；2）免耕下增加的土壤有机碳主要分布在大团聚体（>0.25mm）中，翻耕下增加的碳分布在微团聚体中（<0.25mm）；3）土壤有机碳的增加主要通过根系生物量的增加形成，免耕下增加的根系分布在0-5cm土层，翻耕下增加的根系分布在5-15cm土层；4）长期增温促进了免耕下土壤胞外酶的活性，进而增强了其对活性底物的分解和利用；长期增温后土壤存在热适应性，即土壤有机碳库会持续分解增强；5）长期增温促进土壤中硝态氮和有机态氮的消耗，导致土壤氮含量降低，C/N比升高，有利于碳素的固持。综上本研究建立了温度升高-耕作措施-SOC组分，温度升高-耕作措施-土壤微生物生理之间的长期响应关系，揭示了长期增温条件下土壤SOC组分对温度升高响应的机制，为找出气候变暖条件下稳定提升土壤有机碳的农田管理措施提供依据和支持。