长期施肥对水稻土碳氮矿化与团聚体稳定性的影响

Effects of Long-term Fertilization on Paddy Soil Carbon and Nitrogen Mineralization and Aggregates Stability

水稻土有机碳、氮矿化过程对水稻土质量和作物养分吸收具有重要的作用,但是它们对施肥措施的响应及其与土壤结构之间的关系尚不清楚。本研究基于红壤性水稻土长期施肥定位试验,分析了不施肥(CK)、施用常量化肥(NPK)、2倍化肥(NPK2)和常量化肥配施有机肥(NPKOM)等处理下水稻土碳氮矿化特征,并研究了其与土壤团聚体稳定性的关系。结果表明NPKOM处理显著提高了土壤有机碳和全氮含量(PV0.05),而单施化肥处理(NPK2和NPK)则同CK处理没有显著差异。土壤有机碳矿化速率、累积矿化量和矿化率均为NPKOM>NPK2>NPK>CK处理,其中NPKOM处理显著高于其他处理(PV0.05),而后3个处理间没有显著差异。土壤氮矿化速率、累积矿化量和矿化率同土壤碳矿化的规律一致,NPKOM、NPK2和NPK处理累积矿化氮量较CK处理分别提高110.0%、29.4%和8.8%,矿化率分别提高110.8%、25.6%和13.0%。单施化肥处理(NPK和NPK2)的平均质量直径(MWD)分别降低了 17.1%和15.5%,而NPKOM处理则增加了 19.4%。相关分析表明,土壤碳氮矿化主要取决于土壤有机碳氮含量,而与土壤团聚体水稳定性无直接关系。在今后研究中,应重点分析土壤孔隙结构与有机碳氮周转的关系。

Mineralization of soil organic carbon (SOC) and nitrogen (N) plays an important role in maintaining soil quality and providing nutrients for crop growth. However, the response of carbon (C) and N mineralization to fertilization strategies and their relationship with soil structure are not clear. In this study, the effects of different fertilization strategies on the mineralization of SOC and N of a paddy soil were analyzed based on a long-term field experiment. The relationship between carbon (C) and N mineralization and the water stability of soil aggregates was also studied. The field experiment had 4 fertilization treatments: no fertilizer (CK), chemical fertilizer (NPK), double chemical fertilizer (NPK2) and chemical fertilizer plus organic manure (NPKOM). Results showed that NPKOM treatment significantly increased SOC and total nitrogen (TN) contents compared to CK;however, no significant difference was found between the treatments of chemical fertilizers (NPK2 and NPK) and CK treatments. The mineralization rates, cumulative mineralization and mineralization ratio of SOC all showed the same trend as NPKOM>NPK2>NPK>CK, where NPKOM treatment was significantly higher than other treatments while there was no significant difference among NPK2, NPK and CK treatments. The mineralization rates, cumulative mineralization, and N mineralization ratio showed the same trends as SOC. Compared with CK treatment, NPKOM, NPK2 and NPK treatments increased N cumulative mineralization by 110.0%, 29.4% and 8.8% respectively, and increased N mineralization rate by 110.8%, 25.6% and 13% respectively. Compared to CK treatment, the mean weight diameter (MWD) of water-stable aggregates of NPK2 and NPK treatments decreased by 17.1% and 15.5%, respectively, while NPKOM treatment increased MWD by 19.4%. Correlation analysis shows that the mineralization of SOC and N mainly depended on SOC and N content, and was not correlated with the water stability of soil aggregates. Future research should focus on the effect of soil pore structure on the turnover of SOC and N.