Effects Of Four Kinds Of Green Manures On Soil Nutrients Of Tobacco Field And Growth Characteristics Of Flue-cured Tobacco

In order to reduce the excessive dependence of tobacco production on chemical fertilizers and ensure the sustainable development of the flue-cured tobacco industry,four common green manures,rhynchopHylla(Melilotus suaveolens),alfalfa(Medicago sativa.),ryegrass(Lolium perenne L.),and wheat(Triticum aestivuml.)were used in this study.The characteristics of decomposing green manure and effects on soil nutrient content were studied.The field experiment was conducted to study the effects of different overturning time of green manureand appling with chemical fertilizers on the growth pHysiological characteristics and economic traits of flue-cured tobacco.The.results of the study are as follows:Decomposition characteristics of green manure and its effect on soil nutrient content:(1)The four green manures decomposed rapidly within 30 days after treatment,and the decomposing rate reached more than 50%,and the decay rate of alfalfa was higher than other green manures.(2)The decomposition rate of green manure is expressed as 10 g overturning volume>20 g overturning volume>30 g overturning volume,turning over on August 9>turning over on August 24>turning over on September 8.(3)All green manures significantly increased the content of soil available P and available K,and the soil pH value decreased significantly,but had no significant effect on soil organic matter and total P content.In addition,rhynchopHylla and alfalfa can significantly increase soil alkaline N and total nitrogen.It is better to use rhynchopHylla and alfalfa.Effects of overturning of green manure and appling with chemical fertilizers on growth pHysiological characteristics and economic traits of flue-cured tobacco:(1)The treatment which choosed green rhizome,alfalfa,ryegrass,and wheat as green manure increased the plant height,stem diameter,leaf area of the largest leaf,SPAD,net photosynthetic rate,transpiration rate,stomatal conductance,yield per mu of finest smoke,yield per mu of upper and middle smoke,yield per mu,and value per mu,while decreased the intercellular CO2 concentration.The effect was generally expressed as green manure + conventional fertilization,green manure+ reduction 30%>green manure>CK.The effect of alfalfa was better than the other three green manures.(2)The effect of grass rhinoceros + 30%reduction was better than grass rhinoceros + conventional fertilization,and the effect of the third batches of grass rhinoceros +reduction of 30%was better.The effect of Alfalfa + 30%reduction was better than alfalfa +conventional fertilization,and the effect of the second batch of alfalfa + 30%reduction was better.The effect of ryegrass + conventional fertilization was better than ryegrass + 30%reduction,and the effect of the second batch of ryegrass + conventional fertilization was better.The effect of wheat + conventional fertilization was better than ryegrass + 30%reduction,and the effect of the third batches of wheat + conventional fertilization was better.Therefore,it was recommended that alfalfa be used as green manure in the Heilongjiang tobacco area,and applied with chemical fertilizers.The overturning biomass of alfalfa should be 1890 g/m2,and the amount of chemical fertilizer should be 30%reduction on the basis of conventional fertilization.