粉垄耕作对甘蔗土壤碳固定和温室气体排放的影响及机制

Unreasonable tillage induced losses of soil organic carbon, led to decrease soil quality and increase greenhouse effect. Deep vertical rotary tillage(DVRT) was a new type of tillage technology. DVRT has a good ability to maintain higher production of 33 kinds of field crops in 22 provinces. However, there still exist a few comparisons between conventional tillage and DVRT systems for soil organic carbon sequestration and greenhouse gas emissions, and also sparse information concerning the mechanism of DVRT on C sequestration and C emission reduction. The project taking the sugarcane field under long-term（2010-2018） different tillage patterns(DVRT40cm、rotary tillage20cm) and under short-term different tillage patterns （ploughing depth with 35cm +rotary tillage20cm、rotary tillage20cm、DVRT20cm、DVRT30cm、DVRT40cm、DVRT50cm）as the research object, using the method of combining soil organic matter aggregate and density separation methods, static chambers-gas chromatograph, phospholipid fatty acid analysis(PLFA),nuclear magnetic resonances (NMR) techniques, evaluating and confirming the long-term and short-term effect of tillage patterns on C sequestration and C emission reduction by calculating the variation of CO2, CH4 and emission and SOC status together with its fraction dynamics of sugarcane field in different soil layers.And evaluating the effect of tillage patterns on soil microbial community structure, enzyme activity and the chemical structures of soil organic matter and soil organic carbon fractions.The reasonable DVRT depth will be elucidated.And especially revealing the process and physical, chemical, and biochemical mechanisms of soil organic matter stabilization under different tillage patterns.Results from this study can be used to promote development of soil carbon sequestration technology and improve the fertility of sugarcane field in South China.

不适宜的耕作措施易引起土壤有机碳的大量损失，导致土壤质量下降和温室效应加剧。粉垄耕作是一种新型耕作技术，在全国22个省区33种作物上增产效果显著，但对粉垄耕作的土壤固碳减排效果及其机理的研究甚少。本项目以广西长期（2010-2018年）粉垄耕作和旋耕方式下的蔗地及短期不同粉垄耕作深度(20cm、30cm、40cm、50cm)和常耕（翻耕+旋耕、旋耕）方式下的蔗地为研究对象，运用有机碳团聚体密度联合分组、静态暗箱-气相色谱、磷脂脂肪酸及13C核磁共振等技术，比较不同耕作方式下不同土层有机碳及其组分含量，土壤CO2、CH4和N2O通量，土壤微生物群落结构、酶活性及有机碳组分结构特征，探明粉垄耕作下土壤有机碳的转化趋势，确证粉垄耕作对蔗地土壤固碳减排的长期和短期效果，提出蔗地合理粉垄耕作深度，揭示粉垄耕作下土壤固碳减排的影响机制，为推动发展华南蔗区粉垄耕作技术及提高土壤质量研究提供科学依据。

本项目分析了旋耕20cm（XG20）、深翻35cm+旋耕20cm（SF35XG20）、粉垄30cm（FL30）、粉垄45cm（FL45）、粉垄60cm（FL60）5种耕作方式对甘蔗地土壤有机质含量及其组分、有机碳化学分析结构、土壤微生物群落组成、土壤温室气体CO2排放通量等的影响。项目主要研究结果如下： .1）SF35XG20、FL30、FL45和FL60较XG20处理显著降低0-20cm和20-40cm土层土壤有机碳含量。FL30、FL45和FL60三个粉垄处理显著降低2~0.25mm大颗粒团聚体的百分比，同时增加土有机碳脂化度，可能与粉垄耕作增加土壤扰动，加快土壤有机碳暴露，进而加速其矿化有关。.2）随着耕作年限的延长，粉垄耕作对土壤微生物群落组成的影响越明显，其中FL45深度对土壤微生物脂肪酸总含量增幅最大，显著改变土壤微生物群落组成。 .3）SF35XG20、FL30、FL45、FL60四个处理的4年平均CO2累积排放量较XG20处理略有增加，但差异不显著。综合考虑甘蔗增产效果、微生物群落组成变化、土壤CO2排放累积量，粉垄耕作45cm处理是较为适宜的粉垄耕作深度。.4）发表论文3篇，其中一级中文核心 2 篇。出版专著2部，授权专利 9件和软件著作权1件。