棉杆来源碳在农田土壤的固碳量和固碳机制差异研究

The biochar, compost and straw from plant are effective way to increase soil organic carbon (SOC). However, the differences of carbon (C) sequestration in agricultural soil and mechanism of them is not clear. The cotton is widely planted in the Yellow River Delta. The effective use of cotton straw that is a kind of agricultural wast material is in accordance with the national profit and the sustainable development of agriculture. In this program, the incubation of 30, 90, 180 and 360 days and field experiment for two years are conducted. The dynamics of soil humic substances including humic acid (HA), fulvic acid (FA) and humin (HU) are going to be analyzed by δ13C method when the biochar, compost and straw derived from cotton straw (BCS) input into soil in order to study the mechanism of BCS sequestration in soil. In addition, the integrative analysis of the dynamic differences of chemical characteristics of HA, FA and HU among different treatments will be investigated by 13C nuclear magnetic resonance (NMR) spectra and Fourier transform infrared (FTIR) spectroscopy. The differences of C sequestration from BCS and mechanism are studied by quantity and quality analysis, separately. The study can provide some new scientific materials for sustainable and stable improving C sequestration in agricultural soil and better use of cotton straw.

秸秆生物质炭、秸秆堆肥、秸秆还田是增加土壤有机碳的有效措施。然而，这三种形式的秸秆来源碳在农田土壤固碳量及机制差异尚不清楚。黄河三角洲地区种植了大面积的棉花，棉杆作为一种农业废弃物的高效利用既符合国家利益也有利于农业的可持续发展。本项目拟通过室内培养30、90、180和360天，以及连续两年的田间试验，采用δ13C方法分析不同棉杆来源碳（棉杆生物质炭、棉杆堆肥和棉杆）添加到土壤中后，棉杆来源碳在土壤腐殖物质（胡敏酸、富里酸和胡敏素）中含量的动态变化，研究棉杆来源碳在土壤固碳过程中固定量的动态变化规律。同时采用13C核磁共振波谱、傅里叶变换红外光谱相互印证，综合分析不同处理间土壤胡敏酸、富里酸和胡敏素的化学结构特征的动态变化差异。分别从定量分析和定性分析两个角度探讨不同形式棉杆来源碳在土壤中的固定量和固定机制差异。为高效利用棉杆，持久稳定的增加农田土壤固碳量提供理论依据。

本研究通过室内培养试验和田间试验探究了秸秆来源碳（作物秸秆、秸秆堆肥、秸秆生物质炭）在土壤中的固碳机理。13C同位素示踪研究结果表明，土壤原有有机碳的50.84%、41.03% 和38.55%分别被棉杆生物质炭、棉杆堆肥和棉杆替代，秸秆来源碳主要固定在土壤胡敏素组分中；13C核磁共振和红外光谱研究结果表明，添加秸秆有利于土壤有机碳中碳水化合物的形成，添加秸秆堆肥有利于土壤有机碳中的烷基碳形成，而添加秸秆生物质炭有利于土壤有机碳的芳香碳含量增加。从碳的稳定性来看，添加秸秆生物质炭土壤有机碳化学结构最稳定，其次是秸秆堆肥，再次是秸秆。胡敏素化学结构特征的稳定性将影响到土壤有机碳的稳定性。在施用生物质炭的同时配施有机肥更有利于土壤固碳。