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通过田间埋藏分解试验,比较了3种施氮量(0、120和240kg N·hm~(-2))处理的玉米根茬(R_0、R_(120)、R_(240))分别与杨凌塿土、长武黑垆土充分混合并埋藏分解一年后,根茬碳分解差异及其影响因素,并且利用碳稳定同位素δ~(13)C技术,研究了根茬碳分解对土壤有机碳的贡献。结果表明,杨凌地区水、热条件较好,试验期间降水量总和较长武高215mm;杨凌试验地15cm和45cm土层平均温度分别较长武高3.2℃和4.2℃。分解1年后,长武黑垆土中根茬残留碳较杨凌塿土高21%44%。根茬来源的土壤有机碳比例在塿土、黑垆土中分别为22.4%44.7%和27.4%38.3%。在黑垆土中根茬来源的土壤有机碳含量显著高于塿土,3种施氮量根茬来源的土壤有机碳含量差异未达显著水平。可见土壤深度、质地、施肥状况等影响有机残体还田腐解与土壤有机碳的更新,良好的水热条件能够促进玉米根茬残体分解,有利于新增耕地的快速培肥熟化,构建富含有机物质的耕作层,满足作物对养分的需求。
The field stubble decomposition experiments were conducted to compare the effects of three nitrogen fertilizer treatments (0, 120 and 240 kg N · hm -2) on root stalks (R_0, R_ (120) and R_ (240) Soil and Changwu black loam soil were fully mixed and buried for one year, the differences of carbon decomposition in root stubble and its influencing factors were studied. The carbon stable isotope δ 13 C technique was used to study the effects of root carbon decomposition on soil organic carbon contribution. The results showed that the water and heat conditions in Yangling were better, and the total precipitation during the experiment was 215mm higher. The average temperature of 15cm and 45cm soil layers in Yangling was 3.2 ℃ and 4.2 ℃, respectively. After 1 year decomposition, residual carbon in root stubble of Changwu black soil was 21% and 44% higher than that of Yangling stubborn soil. The proportion of soil organic carbon from root stubble was 22.4%, 44.7% and 27.4%, 38.3% respectively in loam and black soil. The soil organic carbon content of stubble in black soil was significantly higher than that in soil, and the difference of soil organic carbon content of three stubble sources was not significant. It can be seen that soil depth, texture and fertilization affect the decomposition of organic residues and the regeneration of soil organic carbon. Good hydrothermal conditions can promote the decomposition of corn stubble residues, which is good for rapid fertilization and maturation of newly-added cultivated land. Tillage layer rich in organic matter to meet the crop’s nutrient needs.