长期外源有机物料添加对川中丘陵区农田土壤养分和有机碳组分的影响

有机肥和秸秆等有机物料添加是调控土壤肥力的重要手段，可促进农田土壤有机碳的数量和质量发生变化。研究选取盐亭紫色土农业生态试验站长期（16a）6种不同施肥处理试验小区，探究两种形式的外源有机物料（猪粪堆肥和秸秆还田）添加对土壤有机碳及总氮、总磷、硝态氮和速效磷养分含量的影响，并基于固态13C核磁共振波谱技术(13C-NMR)分析其对土壤有机碳化学组分的影响。研究发现，添加有机物料可显著增加0~30 cm土壤有机碳和各养分含量；猪粪堆肥施用对土壤总磷、速效磷和硝态氮含量的影响大于秸秆还田。结果还表明两种有机物料添加改变了耕层土壤有机碳化学组成及其稳定性，有机物料添加增加了0~10 cm表层土壤有机碳中烷氧基碳和羧基碳的比例，降低了烷基碳的比例，同时降低了10~20 cm土层羧基碳比例，增加了烷基碳比例。本研究可为区域旱耕地有机碳库稳定性及其碳汇功能评估提供科学依据。

Effects of Exogenous Organic Materials on Soil Nutrients and Organic Carbon Components in Hilly Region of Central Sichuan, China

The addition of organic materials such as organic fertilizer and straw is key management strategy to improve soil fertility by regulating both quantity and quality of soil organic carbon. This study selected 6 different fertilization treatment plots in Yanting Purple Soil Agro-Ecological Experimental Station for a long period (16a) to explore the effects of two forms of exogenous organic materials (pig manure composting and straw returning) on the contents of soil organic carbon, total nitrogen, total phosphorus, nitrate nitrogen and available phosphorus. Based on 13C nuclear magnetic resonance spectroscopy (13C-NMR), soil organic carbon components was analyzed. The results showed that organic materials addition significantly increased the contents of soil organic carbon and nutrients in 0-30 cm soil. The effects of pig manure compost application on the contents of total phosphorus, available phosphorus and nitrate nitrogen in soil were greater than those of straw returning. Results also found both pig manure and straw addition caused changes of soil organic carbon components of tilled soil (0-20 cm). Organic material addition increased the proportion of alkoxy carbon and carboxyl carbon and decreased the proportion of alkyl carbon at 0-10 cm depth, while the proportion of carboxyl carbon at 10-20 cm soil layer was decreased, and the proportion of alkyl carbon was increased. This work could provide a base for accurate evaluation of soil organic carbon stability and sinks of upland cropland in the region.