Effect of straw-derived carbon on carbon component of the low fertility soil at different nitrogen application rates

• Main Authors: HE Zhen-chao, SU Yao, YU Man, CHEN Xi-jing, WAN Mei-xia, SHEN A-lin
• Format: Article
• Language: zho
• Published: Agro-Environmental Protection Institute, Ministry of Agriculture 2019-05-01
• Series: Journal of Agricultural Resources and Environment
• Subjects: straw-derived carbon, dissolved organic carbon(DOC), microbial biomass carbon(MBC), particulate organic carbon(POC), stable isotope labeling, ¹³C
• Online Access: http://www.aed.org.cn/nyzyyhjxb/html/2019/3/20190307.htm
• ISSN: 2095-6819; 2095-6819

In order to study the effects of straw C on the contents of dissolved organic carbon (DOC), microbial biomass carbon (MBC)and particulate organic carbon (POC)in low-fertility soil at different nitrogen application rates, ¹³C-labeled wheat straw was mixed with low fertility soils in the carborundum tube at different nitrogen application rates (0, 120, 240 kg·hm^-2, pure nitrogen content). Soils were sampled periodically to analyze carbon component contents and its relative δ¹³C value. Straw C transformation rate and contribution to soil C pool was also calculated. The results showed that straw C was transformed rapidly within the first 7 days, thereafter the decomposition rate slowed down and was dependent on transformation to POC. Compared with DOC, straw C preferred transforming into MBC and POC, with the transformation rate of 0.12%~0.38%, 4.01%~6.25% and 4.74%~9.54% on 60 d after straw addition, respectively. Soil DOC, MBC, and POC contents were increased significantly by straw addition, with 0.29%~15.01%, 13.20%~32.85% and 33.62%~59.69% of respective carbon derived from straw, respectively. Compared with 0, 240 kg·hm^-2 application rates, 120 kg hm^-2 could increase the active and slow organic C pool of the experimental soil simultaneously. All results suggest that straw return with moderate nitrogen application is more conducive to both soil fertility improvement and C sequestration of low fertility soil.