Study On The Model And Effect Evaluation Of Microbial Enhanced In Situ Returning Of Sugarcane Leaves To Field Technology

Sugarcane is the largest sugar raw material in China,accounting for 90%of the country’s total sugar production,among which Yunnan province is the second sucrose producing province.Cane leaf returning is the most effective way to improve the utilization rate of cane leaf resources,but also can improve soil fertility,improve structure,increase crop yield and other aspects of the effect.However,due to the existence of cellulose,hemicellulose and lignin in sugarcane leaves,the low degradation degree of sugarcane leaves in natural conditions and the high cost of sugarcane leaves returning to field,the technology of sugarcane leaves returning to field can not be widely used.In this study,the sugarcane leaves with high content of cellulose,hemicellulose and lignin were used as decomposing materials,and the pure culture experiment was conducted to explore the effect of different strains on the decomposing sugarcane leaves.At the same time,the simulated soil culture experiment was conducted to explore the influence of adjusting C/N to optimize the decomposing conditions on the cane leaves of different strains.Field tests were conducted to explore the effects of cane leaf decomposing fungus species on cane leaf nutrient release,soil sample nutrient and organic matter,cane agronomic traits and malleability in actual production.Economic benefits of cane leaf in-situ returning to field were evaluated through the analysis of yield and yield to investment ratio of each treatment of cane,and a new technical model of simple,efficient and green cane leaf in-situ returning to field was constructed.And provide theoretical support for other straw returning to the field.The main experimental results are as follows:1.Adjusting C/N to optimize decomposing conditions can effectively accelerate the process of bacterial agent decomposing cane leaves.In the simulated soil culture experiment,the optimal decomposing conditions were adjusted by C/N and simultaneously inoculated with P.flavoris and VT-1000.The dry matter accumulation reduction rate,cellulose degradation rate,semi-fiber degradation rate and lignin degradation rate reached 46.78%,56.12%,46.86%and 56.82%,respectively.2.In situ decomposition of sugarcane leaves to field can effectively promote the decomposition process of sugarcane leaves and significantly promote the release of nitrogen,phosphorus and potassium nutrients in sugarcane leaves.On the 192nd day of field experiment,the dry matter accumulation reduction rate,cellulose,hemicellulose degradation rate and lignin degradation rate of cane leaves were 90.75%,90.98%,90.85%and 91.67%,respectively,after being inoculated with P.flavus and VT-1000.The nitrogen,phosphorus and potassium nutrients in cane leaves were released continuously.On the 192nd day,the release rates were 85.73%,92.45%and 92.59%,respectively.3.Cane leaf in situ decomposition and returning to field could significantly increase soil alkali-hydrolyzed nitrogen content,and was beneficial to increasing soil available phosphorus,available potassium and organic matter content.Soil cane leaves were decomposed in situ to return to the field,and soil alkali-hydrolyzed nitrogen,available phosphorus and available potassium increased by 2.68-16.11 mg/kg,0.83-2.93 mg/kg and6.01-16.86 mg/kg,respectively.Compared with the original soil,the organic matter content of soil inoculated with P.flavoris and VT-1000 was increased by 1.06 g/kg.4.In situ decomposition of cane leaves to field had a positive effect on plant height and stem diameter of sugarcane,and significantly increased the effective stem number and yield of sugarcane,and effectively increased the yield and yield ratio of sugarcane.The effective stem number of sugarcane could be increased by 0.61-1.89 104plant/hm~2 when cane leaves were decomposed in situ and returned to the field.Compared with no fertilization and no inoculation,the yield of 70%fertilizer treatment with P.chrysospora and VT-1000 inoculated agent increased by 30.09 t/hm~2,respectively,and the yield to investment ratio reached 6.32.A technical model of cane leaves in situ decomposition and return to the field was formed:the cane leaves after harvesting were concentrated in the cane ditch,C/N was adjusted to25:1 by urea,and the mixing ratio was 1 according to 2‰of cane leaves dry matter weight:The sugarcane land can be covered with a full film after the sugarcane leaves are evenly sprayed.The mulching film of the sugarcane land can be removed in the middle period of soil cultivation(72 days after returning to the field).Cane leaf in situ decomposition and return technology,can reduce 30%fertilizer application,can increase the income of10568.47 yuan/hm~2.