Li Xiu-Zhi, Han Bang-Shuai, Yang Fan, Hu Cong-Yue, Han Guang-Zhong, Huang Lai-Ming
Special Agricultural Resources in Tuojiang River Basin Sharing and Service Platform of Sichuan Province, College of Geography and Resources Science, Neijiang Normal University, Neijiang, Sichuan, 641112, China.
Environment, Geology and Natural Resource, Ball State University, Muncie, IN, 47306, USA.
J Environ Manage. 2022 Jul 15;314:115122. doi: 10.1016/j.jenvman.2022.115122. Epub 2022 Apr 23.
Rural land use patterns in southern China centered on household grain crop production have observed significant changes in the past few decades, profoundly affecting the release and fixation of carbon and nitrogen in the paddy soil of the region. This study selected different land use patterns developed in purple paddy soil on a decadal time scale, examined the changing rate of soil carbon and nitrogen of the purple paddy soil after abandonment, dry-farming, and fish-farming, and revealed the impact of land use changes on the balance of soil carbon and nitrogen. Results showed that the loss rates of soil organic carbon, readily oxidizable organic carbon and total nitrogen at the initial stage of dry-farming were most considerable, followed by abandonment and fish-farming. An average of 11.95-13.94 g kg soil organic carbon loss and 0.90-1.03 g kg total nitrogen loss of the cultivation horizon were observed when purple paddy soil was abandoned and dry farmed. In comparison, the net release of soil organic carbon and total nitrogen after fish-farming were 6.64 and -0.23 g kg. The changes of land use of rural area driven by rising labor cost and market demand have been inducing a continuous decline in soil C:N and significantly reducing the purple paddy soil's carbon sequestration ability. The promotion of no-tillage management, increase of organic manure application, and avoidance of over-use of nitrogen fertilizer in dryland farming need to be further considered to meet the dual pressures of China's resource constraints and carbon neutrality goals. A regression model may predict the changes in soil carbon after the change of paddy soil utilization, which provides a pathway for predicting changes in farmland carbon sequestration potential and carbon storage caused by changes in paddy soil utilization in the future.
在过去几十年中，中国南方以家庭粮食作物生产为中心的农村土地利用模式发生了显著变化，深刻影响了该地区稻田土壤中碳和氮的释放与固定。本研究选择了在紫色稻田土壤上以十年为时间尺度发展起来的不同土地利用模式，研究了紫色稻田土壤在撂荒、旱作和养鱼后土壤碳和氮的变化速率，并揭示了土地利用变化对土壤碳氮平衡的影响。结果表明，旱作初期土壤有机碳、易氧化有机碳和全氮的损失率最为显著，其次是撂荒和养鱼。紫色稻田土壤撂荒和旱作时，耕作层土壤有机碳平均损失11.95 - 13.94 g/kg，全氮损失0.90 - 1.03 g/kg。相比之下，养鱼后土壤有机碳和全氮的净释放量分别为6.64和 -0.23 g/kg。劳动力成本上升和市场需求驱动的农村土地利用变化，导致土壤碳氮比持续下降，显著降低了紫色稻田土壤的碳固存能力。为应对中国资源约束和碳中和目标的双重压力，需要进一步考虑推广免耕管理、增加有机肥施用量以及避免旱地过度施用氮肥。回归模型可以预测稻田土壤利用变化后土壤碳的变化，为未来预测稻田土壤利用变化引起的农田碳固存潜力和碳储量变化提供了一条途径。
