Effect Of Green Manure And Straw Returning On Planting Tobacco Soil Organic Matter

In terms of the current situation including soil compaction,soil fertility and soil organic matter content decline in some planting tobacco soil of Hunan Province,long term field positioning experiments,used green manure growed in winter(rape,vicia sativa and ryegrass)and the late evening straw returning to the planting tobacco soil before tobacco transplanted,were conducted in Lanshan,Jianghua,Fenghuang and Huayuan in 2015 to 2017,to determine the effect of green manure and straw returning on the organic matter content ang composition and organic nitrogen mineralization of planting tobacco soil,and to compare the impact of different organic materials,in order to provide an alternative way to increase the soil fertility and promote the production of high-quality tobacco.The main results shows as follows:1.Green manure and straw returning on planting tobacco soil could in a certain degree to increase the organic matter content.The soil organic matter content of straw and rape returning in Lanshan increased by 1.87% and 1.91%,and 4.08% and 5.10% respectively compared with that of CK in Jianghua.The vicia sativa and ryegrass returning in Fenghuang increased by 2.68% and 0.64% compared with CK.,the effect of Huayuan green manure returning was not obvious.In addition,although the soil organic matter content and effect in rape returning was higher and better than that of straw returning,the effect of vicia sativa returning was better than that of ryegrass,but the statistical analysis shows that the effect of green manure and straw returning to increse soil organic matter content was not significant.So it can be seen that the increase of organic matter content in planting tobacco soil may be a long-term process and a gradual accumulation process.2.Green manure and straw returning could increase WSS content.The straw and rape returning in Lanshan and Jianghua were increased by 3.41%,10.23% and 18.18%,11.36%;and the vicia sativa returning in the Fenghuang and Huayuan has a great improvement,it increased by 14.29% and 20%.Green manure and straw returning has different degree effects on the contents of HA,FA and HM,but there was little change in general.In conclusion,green manure and straw returning could in a certain degree to affect humus components,but the effect was not significant in the short term.3.Green manure and straw returning could increase the high active organic matter content in planting tobacco soil.The straw and rape returning in Lanshan and Jianghua were increased by 14.19%,15.48% and 30.45%,13.58%,and the vicia sativa and ryegrass returning in the Fenghuang and Huayuan were increased by 40.54%,37.84% and 49.18%,50.82% compared with the original soil.It could increase the medium active organic matter content in planting tobacco soil.The straw and rape returning in Lanshan has increased by 19.22% and 14.23%,the straw returning in Jianghua has increased by 5.43%,the effect of straw returning was better than rape returning;and the vicia sativa and ryegrass returning in Fenghuang and Huayuan were increased by 34.07%,17.04% and 25.64%,20.32%,the effect of vicia sativa returning was better than ryegrass returning.It could increase the active organic matter content in planting tobacco soil.The straw and rape returning in Lanshan and Jianghua were increased by 27.78%,31.21% and 16.23%,9.42%,Fenghuang and Huayuan showed ryegrass > vicia sativa >CK,and continuous returning showed better results.4.Green manure and straw returning could effectively increase the proportion of water stable agglomerates >0.25 mm,MWD and GMD in planting tobacco soil,it improved the quantity composition of soil aggregates and improved the stability of soil structure.The proportion of >0.25 mm aggregates in straw and rape returning in Lanshan and Jianghua were increased by 38.63%,37.20% and 44.27%,49.59% compared with the original soil,respectively.The increase of straw returning in Lanshan and therape returning in Jianghua were larger;Fenghuang and Huayuan showed ryegrass > vicia sativa,the ryegrass returning in Fenghuang increased by 9.51%,and the vicia sativa returning in Huayuan increased by 1.43% and 10.57%?MWD and GMD increased to varying degrees,and the trend of change was the same as that of >0.25 mm water stable aggregates.It could reduce the soil bulk density and increase the water holding capacity,the effect of rape and ryegrass returning was better than straw and vicia sativa returning.The cation exchange capacity in the soil could be increased in a certain extent,there were different degrees of difference between returning treatment.5.Green manure and straw returning could increase organic matter content in agglomerates.The straw and rape returning in Lanshan has improved the accumulation of organic matter in different particle sizes of soil aggregates,showed as rape returning> straw returning > CK,the effect of rape returning was remarkable,but the effect of Jiang Hua's different treatments was not obvious.The green manure returning in Fenghuang and Huayuan increased the organic matter content in >0.25 mm aggregates mainly.Compared with the original soil,the vicia sativa and ryegrass returning in Fenghuang has increased the organic matter content in >2 mm soil aggregates by 6.68% and 3.56%,and has increased it in 2-0.25 mm by 23.64% and 13.93%;the organic matter content in >2 mm aggregates was only the vicia sativa has increased by 3.30% in Huayuan.In 2-0.25 mm,the vicia sativa and ryegrass returning has increased by 2.50% and 2.56% respectively,the effect of vicia sativa returning was better.6.Green manure and straw returning could increase the content of mineralized nitrogen in planting tobacco soil.Compared with the original soil,the straw and rape returning in Lanshan and Jianghua has increased by 65.97%,70.73% and 96.12%,57.86% respectively,Lanshan and Jianghua showed different degrees of improvement,the rape returning in Lanshan and straw returning in Jianghua showed better results.Fenghuang and Huayuan showed ryegrass > vicia sativa,and the vicia sativa and ryegrass returning in Fenghuang and Huayuan has increased by 26.54%,52.86% and 59.70%,57.39% respectively.Correlation analysis showed that the soil organic matter and its components and differtent components were expressed positively correlation,and organic matter and its components were significantly positively correlated with mineralized nitrogen.The regression analysis showed that besides active organic matter,organic matter,water soluble substance,humic acid,fulvic acid,Humin,high active organic matter and medium active organic matter had a good linear regression model with mineralized nitrogen.