Effects of Organic Substitution of Chemical Fertilizer on Nitrogen Transformation Related Enzyme Activities in Black Soil
[Objective]Organic substitution of chemical fertilizer is one of the most widely used methods to increase nitrogen use efficiency.Enzymes are the major driving force of nitrogen(N)transformation after N is inputted into the soil.Thus,studying the effects of organic substitution of chemical fertilizer on N transformation-related enzymes in the soil is meaningful for increasing N use efficiency.[Methods]This study took National Long-term Location Monitoring Base on Black Soil Fertility and Fertilizer Efficiency as a research platform.The activities of soil urease,catalase,polyphenol oxidase,nitrate reductase and nitrite reductase were determined during the maize growth period.A total of 4 treatments were involved in this study:no fertilizer application(CK),only chemical application(NPK),straw partly replaced chemical fertilizer application(NPKS),organic manure partly replaced chemical application(NPKM).[Results]NPKS and NPKM enhanced activities of soil urease,catalase,nitrate reductase and nitrite reductase during maize growth period.The specific trend was NPKM>NPKS>NPK>CK.In contrast with NPK treatment,NPKM and NPKS averagely increased activities of urease by 29 and 21.9%,catalase by 2.7%and 2.2%,nitrate reductase by 39.8%and 24.1%,nitrite reductase by 8.4%and 6.1%.NPKS and NPKM exhibited opposite effects on polyphenol oxidase in contrast with NPK.NPKS averagely increased polyphenol oxidase activity by 15.9%.While,NPKM decreased polyphenol oxidase activities by 9.3%during the maize growth period.The activities of soil urease,catalase,polyphenol oxidase and nitrate reductase all exhibited a trend of initially increasing and then decreasing during the maize growth period,while nitrite reductase activities were increased gradually.[Conclusion]Organic substitution of chemical fertilizer enhanced the activities of N transformation related enzymes in soil.
Black soilChemical fertilizerOrganic fertilizerLong-term locationEnzyme activity