通过室内培养模拟试验，研究了农田棕壤可溶性氮(可溶性无机氮，DIN；可溶性有机氮，DON；可溶性全氮，DTN)含量、微生物生物量氮(MBN)含量和净氮矿化速率(NNMR)对不同冻融温度和冻融频数的响应。结果表明：冻结温度和冻融频数是影响农田棕壤氮素转化过程的主要因子。随着冻结温度降低，土壤NO₃^– -N、NH₄⁺ -N、DIN、DON、DTN和NNMR均显著增加，而MBN先降低后增加。随着冻融频数增加，土壤NO₃^– -N、NH₄⁺ -N、DIN和DTN均显著增加，这与NNMR的变化趋势正好相反；MBN则呈现降低–增加–降低的变化趋势，这与DON的变化正好相反。可见，冻融交替显著促进非生长季农田棕壤的氮素转化，增加土壤无机氮含量，提高土壤供氮能力。

With a laboratory simulation experiment, the responses of soil dissolved nitrogen (Dissolved inorganic nitrogen, DIN; Dissolved organic nitrogen, DON; Dissolved total nitrogen, DTN) content, microbial biomass nitrogen (MBN) content and net nitrogen mineralization rate (NNMR) to different freezing-thawing temperatures and freezing-thawing frequencies were studied in a farmland brown soil. The results showed that freezing temperature and freezing-thawing frequency were the major factors affecting N transformation process of farmland brown soil. With freezing temperature decreasing, NO₃^– -N,NH₄⁺ -N, DIN, DON, DTN and NNMR all significantly increased, but MBN first decreased then increased. With freezing-thawing frequency increasing, NO₃^– -N, NH₄⁺ -N, DIN and DTN all significantly increased being contrary to the changes of NNMR, and MBN showed a trend of decrease-increase-decrease being contrary to the changes of DON. Therefore, it was preliminarily concluded that freezing-thawing cycle significantly promoted N transformation of farmland brown soil during no growth season, and further increased soil DIN content and soil N supply capacity.

S153.6

辽宁省农业领域青年科技创新人才培养计划项目(2014018)、国家自然青年科学基金项目(41301253)和辽宁省博士启动基金项目(20121145)资助