水保所知识产出(1956---)知识库

Understanding farmland ecosystem processes such as straw decomposition under nitrogen fertilization is critical for predicting
carbon and nitrogen cycles. Nitrogen fertilization significantly affects soil and straw quality, which may significantly affect
straw decomposition; however, comprehensive studies considering both factors are lacking. To evaluate the decomposabil-
ity of crop residues under nitrogen fertilization, we conducted three subexperiments involving straw decomposition in situ,
decomposition of the same straw in soils with different nitrogen fertilization regimes and decomposition of different straw
types in the same soil with nitrogen fertilization and investigated the changes in soil respiration and wheat straw physico-
chemical properties. Nitrogen fertilization promoted straw decomposition: 180 and 360 kg N ha −1  year −1 increased the weight
loss rate by 9.95% and 11.15%, respectively, but the difference between the two was not significant. The carbon emissions
under 360 kg N ha −1  year −1 were significantly higher than those under 180 kg N ha −1  year −1 . Straw chemical characteristics
exhibited different sensitivities to nitrogen fertilization; hemicellulose responded positively to 180 kg N ha −1  year −1 , while
carbon and cellulose had obvious responses to only 360 kg N ha −1  year −1 . The soil temperature, soil moisture, straw nitrogen
content, and straw C/N ratio were the main factors affecting decomposition. Excessive nitrogen fails to promote nutrient
return during straw decomposition and may also increase carbon emissions from farmland soil and aggravate the greenhouse
effect. This study provides a theoretical basis for understanding nutrient cycling in farmland ecosystems under reasonable
fertilization regimes and for improving farmland soil quality and nitrogen fertilization.