Effects Of Different Kinds Of Green Manure On Soil Enzyme Activity And Soil Nutrient Content In Flue-Cured Tobacco Field

Aims of this study were to explore the development of low-carbon flue-cured tobacco agriculture,reduce the excessive dependence of flue-cured tobacco fields on chemical fertilizers,build resource-saving and environment-friendly agriculture,and promote development of characteristic flue-cured tobacco leaves and sustainable development of flue-cured tobacco industry.In this experiment,four green manures were selected,including Rhododendron(annual)(Melilotus officinalis L.),alfalfa(Medicago sativa L.),ryegrass(Lolium perenne L.)and wheat(Triticumae stivum)-besed manures;This study was conducted in the experimental base of Mudanjiang Tobacco Science Research Institute,Fanjia Township,Ning’an,Mudanjiang City,Heilongjiang Province,2016-2017.The effects of ploughing patterns,different green manures,and flue-cured tobacco relay cropping with chemical fertilizers on soil enzyme activities and main soil nutrient contents of flue-cured tobacco fields were studied.The main results are shown as follows1.Effects of different green manures and chemical fertilizers on soil enzyme activities and nutrient contents in tobacco fields(1)In the treatment of only ploughing green manure back,the four green manures after ploughing treatment can increase activities of soil invertase,urease,neutral phosphatase and catalase.In general,the four enzyme activities increased with the delay of green manure rolling time in different growth periods of flue-cured tobacco.Therefore,the third batch of ploughing(September 8)had the best effect.Among them,alfalfa is better than other green manures.Compared to the control,the activity the four enzymes treated by alfalfa increased by 52.9%,136.2%,102.3%,and 66.9%,respectively.(2)Combined applications of green manure and chemical fertilizer can effectively increase activities of soil sucrase,urease,neutral phosphatase and catalase as well as contents of soil total nitrogen,total phosphorus,alkali nitrogen,available phosphorus,available potassium and organic matter.Overall,the third batch of plough showed better performances in the soil enzyme activity and nutrient content.The effects of Rhododendron(annual)combined with conventional fertilization were better than that of nitrogen reduction and fertilization;alfalfa combined with nitrogen reduction and fertilization better than conventional fertilization;ryegrass combined with conventional fertilization better than that of nitrogen reduction;wheat combined with conventional fertilization better than that of nitrogen reduction.Applications of alfalfa basedgreen manure can fertilize the soil,also reduce the use of fertilizer.2.Effects of different green manure and flue-cured tobacco relay cropping with nitrogen fertilizer on soil enzyme activity and nutrients in flue-cured tobacco fields:The green manures and flue-cured tobacco relay cropping with nitrogen and fertilization can increase the activities of invertase,urease,neutral phosphatase and catalase as well as the contents of total nitrogen,total phosphorus,alkali nitrogen,available phosphorus,available potassium and organic matter of the flue-cured tobacco soils,which mesns significant improvements in the soil fertility.The improved effect is listed in a decreasing order:green manure and flue-cured tobacco relay cropping+nitrogen reduction>conventional fertilization>green manure and flue-cured tobacco relay cropping+no fertilization>no green manure+no fertilization.Among them,the effects of alfalfa based green manure+nitrogen reduction were better than the other treatments,including green manure and flue-cured tobacco relay cropping+nitrogen reduction and flue-cured tobacco without relay cropping green manure+conventional fertilization.Compared to the control,the four enzyme activities under the treatment(alfalfa-based green manure and flue-cured tobacco relay cropping+nitrogen fertilizer)increased by 81.2%,80.9%,55.1%,and 17.1%,respectively.The contents of total nitrogen,total phosphorus,alkali nitrogen,available phosphorus,available potassium and organic matter of soils in the treatment increased by 109.1%,31.0%,34.5%,48.6%,82.2%and 38.8%,respectively.In summary,applying alfalfa-based green manure and 30%nitrogen reduction is a better fertilization pattern for flue-cured tobacco planting in Heilongjiang areas,with the soil characteristics of organic matter content of 2%to 3%and alkali-soluble nitrogen content of 90-120 mg·kg-1.