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利用水稻土长期定位试验和室内培养方法,研究了不同施肥处理对水稻土溶解性有机碳(DOC)含量及其生物降解特性。结果表明,长期施用化肥对DOC含量无明显影响,而化肥配施秸秆和化肥配施猪粪显著增加水稻土DOC含量。不同施肥处理水稻土DOC降解率为17.97%~39.18%。化肥配施猪粪处理(C1+M)和化肥配施秸秆处理(C2+S)水稻土的DOC降解能力强于对照(CK)和单施化肥处理(C2和C3)。DOC降解符合双指数衰变模型,水稻土DOC分别由周转时间约为1天的易降解部分和周转时间约为0.61~2.28年的难降解部分组成。降解过程中DOC溶液中结构较复杂的芳环物质比例前期呈上升趋势,后期趋于稳定,与其中易降解组分的降解有关。DOC的降解率与UV280之间存在极显著的负相关关系(P<0.01)。
Using paddy soil long-term experiment and indoor culture method, the contents of dissolved organic carbon (DOC) and their biodegradability under different fertilization treatments in paddy soil were studied. The results showed that the long-term application of chemical fertilizers had no significant effect on the DOC content, while the chemical fertilizer application of straw and chemical fertilizer combined with pig manure significantly increased the DOC content in paddy soil. The DOC degradation rates of different fertilization paddy soils were 17.97% -39.18%. The biodegradation of DOC in pig manure (C1 + M) and chemical fertilizer application (C2 + S) was higher than that in CK and C2 and C3. DOC degradation accorded with the dual-exponential decay model. The DOC in paddy soil consisted of easily degradable part with turn-around time of about 1 day and refractory part with turn-around time of about 0.61 ~ 2.28 years respectively. In the process of degradation, the proportion of aromatic ring compounds with more complex structures in DOC solution increased in the early stage and stabilized in the later stage, which was related to the degradation of the easily degradable components. There was a significant negative correlation between the degradation rate of DOC and UV280 (P <0.01).