UV-B辐射促进红壤水稻土中碳氮转化

以母质相同而有机质含量不同的两种水稻土(高有机质土,HO;低有机质土,LO)为对象,研究了三种强度的紫外(UV-B)辐射对两种土壤碳、氮转化的影响。结果表明:随着UV-B辐射强度的增加,土壤有机碳(TOC)含量降低,而可溶性有机碳(DOC)含量增加;UV-B辐射促进了土壤有机碳的降解和硝态氮的增加。在高强度的UV-B(2.83 W·m~(-2))辐射处理96 h后,LO和HO土壤的TOC含量分别减少了9.89%和10.16%,而DOC含量分别提高了39.24%和50.50%;同样辐射条件下,LO和HO土壤NO_3~--N含量分别比接受辐射前增加了74.48%和81.87%。因此,在农业生产中为了保护土壤碳库,减少氮素损失,应尽量避免地表裸露以降低UV-B辐射对土壤碳、氮转化的影响。

UV-B radiation facilitates the transformation of carbon and nitrogen in red paddy soils

Two red paddy soils developed out of the same parental material with contrasting content of soil organic matter were selected to study the effects of UV-B radiation on soil carbon and nitrogen transformation. Results showed that soil total organic carbon(TOC) content decreased while dissolved organic carbon(DOC) content increased with increasing UV-B radiation level. UV-B radiation facilitated soil organic carbon decomposition and increased soil nitrate. Exposed to the strongest UV-B radiation(2.83 W·m^-2) for 96 h caused that TOC decreased by 9.89% and 10.16%, DOC increased by 39.24% and 50.50%, and NO₃^--N increased by 74.48% and 81.87% in soils with low and high content of organic matter, respectively. Therefore, in order to protect the carbon pool and reduce nitrogen lose in the agricultural practice, the soil surface should avoid exposing to UV-B radiation as much as possible.