Effects of straw and biochar on NH3 volatilization and N2O emission from alkaline soils planted with cotton
The main objectives of this study were to investigate how straw and straw biochar influence soil ammonia(NH3)volatilization and nitrous oxide(N2O)emission after continuous addition for 5 years,and to ascertain a practical straw return practice for reducing N loss in alkaline cotton fields.On the basis of the equivalent carbon input,we established four treatments(straw incorporation,straw decomposition plus mulching,straw biochar incorporation,and a control treatment without straw or biochar),all of which involved application of the same amount of NPK fertilizers.The results revealed that compared with the control,straw biochar incorporation promoted a significant reduction in NH3 volatilization by 27.3%and N2O emission by 56.7%.These effects were mainly attributed to the significant inhibition of soil hydroxylamine reductase and nitrate reductase activities,and an increase in N uptake by cotton,as well as the strong adsorption capacity of biochar per se.Furthermore,compared with the control treatment,straw incorporation and straw decomposition plus mulching increased NH3 volatilization by 37.2%and 21.2%,respectively,but reduced N2O emissions by 17.1%and 38.3%,respectively.These contrasting effects can be ascribed to the fact that that these two straw returning practices promote a significant enhancement of soil organic N mineralization and hydroxylamine reductase activity,while inhibiting nitrate reductase activity.Redundancy analysis provided evidence to indicate that hydroxylamine reductase activity and N uptake by cotton were the main factors influencing the observed effects,explaining 64.8%and 20.1%of the variances in NH3 volatilization and N2O emission,respectively.On the basis of these findings,it appears that straw biochar incorporation has the best synthetic benefits in the reducing NH3 volatilization and N2O emission and is accordingly recommended as a practice for reducing N loss in alkaline soil planted with cotton.
万方数据
