Effect Of Eps Agents On Soil Water And Fertilizer Conservation And Crop Growth

The water resource shortage in the north of our country,the arid and semi-arid region is large,long-term single agricultural planting patterns cause the decline of soil fertility,cultivated land gradually degraded.When soil degradation occurred,the soil layer gradually thinning,moister fertilizer gas heat of soil regulating function decreased,affecting crop root growth and development,and the decline in soil fertility directly affect crop yield.When organic nutrients in the soil are close to exhaustion,will not only hinder the plant growth and soil microbial quantity will subsequently decreased significantly,the relations of soil-plant-microbe have entered a vicious circle,open the anti soil forming process,along with wind erosion,exacerbated by the continued loss of surface soil and soil desertification,and ultimately the formation of desertification.The use of water retaining agent and soil artificial biological crust is an important measure to improve soil structure and increase crop yield in arid and semi arid regions,as well as in desertification area.This paper separated two strains from the soil samples in wengniute desert and the desertification soil samples in Gansu Guo jia town Duan Po Cun,among them,the strain NM03 secrete extracellular polysaccharide including 2 components,molecular weight was 1.13×108KDa and1.12×107KDa,accounting for 91.4% and 8.6% respectively,under the shear rate of 6 r/min,the fermentation broth viscosity of strain reached 37900 m Pa.s.extracellular polysaccharide molecular weight of strain GS01 was 1.06×108KDa,under the shear rate of 6 r/min,the fermentation broth viscosity reached 32200 m Pa.s.The two strains synthesis extracellular polysaccharide(EPS)products which have water retention ability and also can form biologica crusts in soil surface,made these strains fermentation broth into bacterium agents,spraying on the surface of the soil,with water and fertilizer retention ability and crop growth promotion effect.Specific research results are as follows:1.NM03-EPS agents have water retention effect on sand,loam and clay,compared with control,the water retention rates of sand,loam and clay increased 46.2%,92.5% and 7.3%,after the application of bacterium agent in 12 days.By simulating the leaching of rainfall,the results show that NM03-EPS bacterium agents has good fertilizer retention effect in sand,loam and clay,and can reduce the leaching loss of soil fertilizer.Comparaed with control,ammonium nitrogen,phosphorus and potassium of clay leaching reduced by 83.3%,61.1%and 75.0%,in loam leaching reduced by 68.6%,41.2%,50.0%,in sand leaching reduced by17.3%,47.4% and 14.3%.Pot experiment showed that biological crusts in soil surface formed by NM03-EPS agent will not affect the emergence of corn and cotton,and Promote thegrowth of maize and cotton seedlings,the effect on cotton seedlings was more obvious,Comparaed with control,these indexes like plant height,fresh weight above ground,dry weight above ground,root fresh weight,root dry weight and so on were improved in the growth of cotton seedlings in different soil texture.2.The fermentation broth of the strain GS01 was diluted 5 times,GS01-EPS bacterium agent made by diluted fermentation broth had some role in water conservation in different soil texture,but the data of the second round 12 days water retention test was lower than that of the first round,which showed that the EPS synthesized by strain GS01 has poor anti degradation effect in soil.In nutrient retention capacity,GS01-EPS agents and NM03-EPS agents showed a significant difference,the effect of NM03-EPS microbial inoculum was better in the fertilizer retetion of clay and loam;For sand fertilizer retetion,the effect of GS01-EPS bacterium agent is better,compared with the control,ammonium nitrogen,phosphorus and potassium leaching reduced by 36.1%,96.5% and 36.3%.Compared with the corn seedling,GS01-EPS agents has more significant growth promoting effect in clay,loam and sand,fresh weight above ground of cotton seedling than the chemical water retaining agents treatment group increased by 86.4%,12.6% and 34.4%,respectively,dry weight above ground than the control group increased by 98.1%,9.8% and 22.0%,respectively.3.Through protoplast fusion breeding technology,we screened fusion strain 0102 fused by strain NM03 and GS01,at the same fermentation condition,the fermentation liquid viscosity of strain 0102 can reach 42000 m Pa.s strains,which respectively increased by10.8% and 30.4% than that of parent strain NM03 and GS01.The results of gel permeation chromatography showed that the extracellular polysaccharide molecular weight of Fusion bacteria was 1.83×108KDa.0102-EPS agents sprayed on the soil surface has some water and fertilizer retention capacity and has the promoting effect in the growth of corn and cotton.4.At the end of the retention of water fertilizer and crop growth experiment,we can still isolate live NM03,GS01 and 0102 strains,which illustrate that the three EPS synthetic bacteria have strong resistance and adaptability to the soil environment,applied the EPS bacterium agent in drought and desertification soil surface,it will contribute to the recovery of soil fertility and the growth of crops such as corn,cotton and so on.