Studies On Nitrogen Mineralization In Tobacco Growing Soils In Typical Tobacco Growing Areas And Effects Of Reducing Nitrogen Fertilizer In Flue-cured Tobacco Of Yunnan Dali

Nitrogen is an essential nutrient element for the growth of tobacco,and its main source is soil nitrogen supply,Soil nitrogen mineralization is one of the important factors to reflect the soil nitrogen supplying capacity.Soil factors play an important role in the formation of tobacco leaf quality and style characteristics.Now nitrogen dynamics in soils of tobacco-growing areas of different flavor types are not known,and they applying amounts of chemical fertilizers in early growing stage are more than enough which lead to nitrogen accumulation in soils.Then tobacco is hard to ripe,causing quality decrease of tobacco leaf.According to this production status,the experiments were conducted to control temperature(15?,28?,37?)and moisture content(50%,65%,80% of field moisture capacity)of soil,and do nitrogen mineralization experiment for soils from Dali,Yunnan province,Bijie,Guizhou province and Xuchang,Henan province,3 different ecological tobacco-growing area.The study aimed to explore the characteristics of nitrogen mineralization and its relationship with temperature and water in typical tobacco growing areas,so as to provide theoretical support for rational fertilization of flue-cured tobacco in different ecological areas.And according to Yunnan Dali area of nitrogen fertilizer was excessive,resulting in tobacco growth,maturity stage and difficulties,influence the quality of tobacco leaves,designed the reduction of nitrogen fertilizer during tobacco growth period,growth stage of spraying water soluble chitosan organic fertilizer to promote the advancement of nitrogen absorption of tobacco plant,study on the effect of improving tobacco quality test.The results are as follows:1.The experiment was conducted to study the changes of ammonium nitrogen,nitrate nitrogen,mineral nitrogen,available nitrogen and their responses to temperature and moisture in tobacco planted-soil.The results show that the content of ammonium nitrogen of the different tobacco planted-soil with the increase of culture time was increased rapidly,flat,downhill,eventually stabilize at a low level.The content of ammonium nitrogen increased with the increase of temperature in tobacco planted-soil in three tobacco growing areas.It showed that the higher the temperature,the stronger the ammonification.The ammonium nitrogen content of tobacco planted-soil was the highest under the 65% field water holding capacity in Yunnan and Henan,Xuchang.The 50% field capacity is the most suitable moisture content of tobacco planted-soil ammonification in Guizhou,Bijie.The content of nitrate nitrogen in tobacco plantedsoil in typical tobacco growing areas showed a rapid increase in the early stage,an increase in the medium term,after the gradual slowdown in the growth rate and eventually stabilized at a certain level.The whole process was "S" shape change,the nitrification rate showed a larger early stage,later decreased gradually,and finally stabilized at a lower level.The change of content of nitrate nitrogen with temperature in different tobacco growing areas showed that 37?>28?>15?.The content of nitrate nitrogen was different in different tobacco growing areas under different moisture content.The nitrate nitrogen content of tobacco growing soil in Yunnan Dali was the highest under 65% field capacity.The content of nitrate nitrogen of tobacco planted-soil in Guizhou,Bijie was significantly higher than that of the other two moisture conditions under the condition of field capacity of 50%.The content of nitrate nitrogen in tobacco growing soil in Henan Xuchang was the highest under 65% field capacity.The difference of nitrate nitrogen content in tobacco planted-soil showed that the effect of temperature and moisture on soil nitrification was obvious.The content of mineral nitrogen in different tobacco planted-soil showed a rapid increase in the early stage,and then decreased in the later stage,at the end of incubation,the largest tobacco soil mineral nitrogen content in plant of Yunnan Dali for 107.91mg/kg,the largest tobacco soil mineral nitrogen content in plant of Guizhou Bijie for 103.23mg/kg,the largest tobacco soil mineral nitrogen content in plant of Henan Xuchang for 72.76mg/kg.In the temperature range from 15 ?to 37?,the content of soil nitrogen and mineralization rate increased with the increase of incubation temperature,and there was a significant positive correlation between the mineralization and temperature of tobacco planted-soil.Soil mineral nitrogen content in three regions varies with water content differences,optimum moisture content of 65% field capacity for Yunnan Dali and Henan Xuchang tobacco planted-soil nitrogen mineralization,Guizhou Bijie tobacco soil mineralization suitable water content was 50% of field capacity.The change of available nitrogen content in different tobacco planted-soil and the content of mineral nitrogen in tobacco planting soil varied with the change of temperature and moisture content.Analysis of tobacco soil mineral nitrogen content differences suggest that the effects of incubation temperature on mineral nitrogen content had obvious interaction,in which the temperature contribution of mineral nitrogen content greater than the rate of moisture content of the contribution rate,the effect of temperature on mineral nitrogen content greate.At the end of indoor culture,the available nitrogen content was Yunnan Dali,Guizhou,Bijie,Henan tobacco planted-soil.It was concluded that the soil organic nitrogen mineralization in Yunnan Dali and Henan Xuchang was the highest at the temperature of 37 ?,65% field capacity,Guizhou Bijie tobacco planted-soil organic nitrogen mineralization suitable conditions for the temperature of 37?,50% field capacity.2.The study on the effect of reducing nitrogen and increasing nitrogen efficiency of Dali tobacco in Yunnan showed that the application of water soluble organic fertilizer to reduce the single leaf weight and leaf weight of flue cured tobacco could be reduced by reducing the application of 20% nitrogen fertilizer at the early growth stage.The contents of protein,nicotine and total nitrogen in tobacco leaves were decreased,and the contents of reducing sugar,total sugar and potassium were increased.,Increase the coordination of chemical composition of tobacco leaves.The content of neutral aroma components in tobacco leaves was increased by 8.23% ~ 18.04% compared with the normal nitrogen application rate.The sensory quality of tobacco increased by 5.03% ~ 5.86%,the proportion of superior tobacco increased by 15.04%,the output value increased by 9.07%.Therefore,after the application of 20% nitrogen fertilizer,the application of chitosan oligosaccharide organic water-soluble fertilizer can improve the quality of tobacco leaf and the economic benefits of tobacco.The comprehensive evaluation is good and has the value of popularization and application.