Effects Of Returning Decomposed Straw To Field On Soil Characteristics And Growth Of Flue-cured Tobacco In Luoyang Tobacco-growing Area

Due to the excessive use of chemical fertilizers and long-term continuous cropping,soil degradation has become increasingly serious,affecting the sustainable development of tobacco production.Straw returning is one of the effective ways to improve soil and has been widely used.Returning straw to the field can not only reduce the pollution caused by straw burning,but also improve soil quality,which is of great significance for promoting sustainable agricultural development.Therefore,field experiments were conducted in Ruyang County,Luoyang City,Henan Province in 2017,and pot experiments were conducted in Henan Agricultural University Science and Education Park in 2018 to study the growth and development of flue-cured tobacco and soil characteristics of rotten straw returned to the field,so as to provide reference for soil improvement in tobacco areas.Straw returning provided organic substances for the above-ground part of tobacco plants,promoted the growth and development of tobacco plants,and promoted the development of root system.90 days after transplantation,there were significant differences in root volume among treatments.The overall trend was T3>T2>T1>CK.The positive effect of straw returning on root system directly promoted the growth of tobacco plant height,stem circumference,effective leaf number,maximum leaf length and leaf width.At 60 days after transplanting,the growth of T3 was faster than CK,and the average effective leaf number was 16.6 pieces,which was 1.11 times of CK.The net photosynthetic rate and transpiration rate of tobacco plants were significantly higher than those of the control,and the net photosynthetic rate increased with the increase of the amount of straw returned to the field.The accumulation of dry matter in tobacco plants increased with the increase of straw returning.After straw returning to the field,the quality of tobacco leaves was significantly improved.The content of total sugar,reducing sugar and chlorine in flue-cured tobacco leaves was increased by straw returning.The yield and output value of flue-cured tobacco leaves were increased.The proportion of upper and middle tobacco leaves was increased,and the yield and quality of flue-cured tobacco leaves were also significantly improved.The application of decomposed straw in Loess cinnamon soil increased with the increase of straw returned to the field,and most of the indicators of soil carbon pool quality,such as total organic carbon,soluble organic carbon,microbial biomass carbon and microbial biomass nitrogen content,and soil carbon pool activity index increased significantly,especially carbon pool management index.Returning decomposed straw to the field has significant effect on improving the carbon pool management index of different active components in soil.45 days after transplanting,the carbon pool management index of active organic carbon increased by 82.41%,160.75%and 189.63%,respectively,and the organic carbon content of different active components can be increased in varying degrees.In pot experiment,with the extension of incubation period,the more straw was added,the higher the content of soluble organic carbon was,which was consistent with the field experiment results,indicating that straw returning could promote the cultivation of soil carbon pool.Field experiment and pot simulation test showed that the effects of straw returning on soil fertility,soil respiration rate,the number of three major bacteria and enzyme activity were similar.Compared with the control,the addition of straw significantly increased the number of soil bacteria,fungi and actinomycetes,and significantly increased the activities of catalase,invertase and urease.Straw returning promoted soil respiration rate,and with the increase of straw amount,soil respiration increased.60 days after transplanting,treatment T3 reached 7.58?mol·m-2·s-1.Decomposed straw returning also increased soil nutrients of tobacco planting to varying degrees,improved soil fertilizer supply capacity,and increased soil available phosphorus and potassium content.Under the experimental conditions,the effect of conventional fertilization combined with straw returning 12 000 kg/hm2 was the best in Luoyang tobacco area.