Yu Wei Jia, Li Xue Song, Chen Zhu Jun, Zhou Jian Bin
College of Nature Resources and Environment, Northwest A&F University, Yangling 712100, Shaanxi, China.
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2018 Aug;29(8):2493-2500. doi: 10.13287/j.1001-9332.201808.009.
The application of nitrogen (N) fertilizer results in decreases of soil pH, but its effects on CO emission from soils with different inorganic carbon contents remain unclear. An closed-jar incubation experiment was conducted to examine the effects of N fertilizer and nitrification inhibitor (DCD) on soil pH and CO emissions from three soil types with different contents of soil inorganic carbon (SIC), including paddy soil (PS), lime concretion black soil (CS), and eum-orthic anthrosols (AS). There were three treatments for each soil type, including control (N), 0.2 g·kg N fertilizer (N), and its combination with DCD (N). Soil pH, contents of mineral N (NH, NO), and CO emissions were measured. The results showed that N fertilizer addition significantly reduced soil pH and increased soil CO cumulative emissions in each type of soil. Compared to control, the CO cumulative emissions after 49 days incubation from the three soil types were enhanced by 39.4%, 23.4%, and 71.8% for PS, CS, AS soils, respectively. The soil pH of N for three soil types were significantly higher than N after 49 days incubation, indicating that DCD application inhibited soil nitrification process. There were no significant differences in the mean CO cumulative emissions of PS and CS soils between N and N treatments; however, N treatment significantly reduced cumulative CO emissions from AS soil by 12.5%. Soil inorganic carbon can effectively buffer soil acidification caused by N fertilizer addition. The CO emission in calcareous soil following N addition is not only derived from the mineralization of soil organic carbon, but also from the dissolution of inorganic carbon. Given the large differences in soil inorganic carbon content in different regions of China, the problem of soil acidification and soil inorganic carbon pool consumption caused by long-term large amount of N fertilizer inputs deserve more attention.
施用氮肥会导致土壤pH值下降，但其对不同无机碳含量土壤中CO排放的影响尚不清楚。开展了一项密闭罐培养实验，以研究氮肥和硝化抑制剂（双氰胺，DCD）对三种不同土壤无机碳（SIC）含量的土壤类型（包括水稻土（PS）、石灰性黑土（CS）和潮土（AS））的土壤pH值和CO排放的影响。每种土壤类型设置三个处理，包括对照（N）、0.2 g·kg氮肥（N）及其与DCD的组合（N）。测定了土壤pH值、矿质氮（NH、NO）含量和CO排放量。结果表明，添加氮肥显著降低了各土壤类型的土壤pH值，并增加了土壤CO累积排放量。与对照相比，三种土壤类型在培养49天后的CO累积排放量，PS土、CS土和AS土分别提高了39.4%、23.4%和71.8%。三种土壤类型的N处理在培养49天后的土壤pH值显著高于N处理，表明施用DCD抑制了土壤硝化过程。PS土和CS土在N和N处理之间的平均CO累积排放量没有显著差异；然而，N处理使AS土的CO累积排放量显著降低了12.5%。土壤无机碳可以有效缓冲氮肥添加引起的土壤酸化。添加氮肥后石灰性土壤中的CO排放不仅源于土壤有机碳的矿化，还源于无机碳的溶解。鉴于中国不同地区土壤无机碳含量差异较大，长期大量施用氮肥导致的土壤酸化和土壤无机碳库消耗问题值得更多关注。
