Wheat-maize Model Of Chemical Fertilizer Reduction On Soil Microbial And Soil Environment

Interaction relationships exist between the soil microbial community structure andsoil environment. The soil environment has an important impact on soil microbial quantity,type, and its dynamic development. Therefore, take soil microbial characteristics asbio-indicator, study on the inherent relationship of the reduction of soil fertilizer and soilbiological properties in Wheat-maize rotation mode, to provide a reference to determine areasonable soil fertility improving programs to improve soil ecological environment, topromote sustainable crop production.7treatments were set in the mode of wheat-maize: fertilizer fixed match high manure(NPK+HM); fertilizer fixed match medium manure(NPK+MM); fertilizer fixed match lowmanure(NPK+LM); fertilizer decrement30%match low manure(70%NPK+LM); fertilizerdecrement50%match medium manure(50%NPK+MM); fertilizer decrement70%matchhigh manure(30%NPK+HM);CK. The detailed study on the soil microbial biomass, soilmicroorganism, soil enzyme, soil respiration and soil moisture in the0～20cm and20～40cm soil profile during the wheat seedling stage, over-wintering stage, jointing stage, headingstage, filling stage, maturation stage and during maize seedling stage, jointing stage, largebelling stage tasseling stage, filling stage and autumn stage. The main results are as follows:1. Increased organic manure application can improve the soil microbial biomasscarbon and nitrogen content significantly in the wheat-maize cropping pattern. In wheat field,soil microbial biomass carbon and nitrogen content reached the top with NPK+HMtreatment, they were up to167.83mg/kg,51.82mg/kg, and increased by58.70%,107.97%,respectively; with chemical fertilizer reduction treatment, it reached the top by50%NPK+MM treatment, up to165.76mg/kg,46.99mg/kg, increased of56.74%,88.60%respectively to CK. In maize field, they were up to177.27mg/kg,50.66mg/kg with NPK+HMtreatment, increased by69.47%,64.82%, respectively by CK. With the chemical fertilizerreduction treatment, it reached the top with50%NPK+MM treatment, up to165.76mg/kg,46.99mg/kg, and increased by56.74%,88.60%respectively by CK.2. Diluting plate method was used to study on the soil microbe numbers. The resultsshowed that:increased application of organic fertilizer can significantly improve the number of soil bacteria, fungi, ray fungi, and azotobacter. In wheat field, soil microbialnumber reached the top with NPK+HM treatment, they were up to8.35×106indiv/g,0.22×10~4indiv/g,18.01×10~4indiv/g,15.72×10~4indiv/g, and increased by115.84%,177.56%,109.58%,89.85%, respectively; with chemical fertilizer reduction treatment, itreached the top by50%NPK+MM treatment, up to7.93×106indiv/g,0.19×10~4indiv/g,17.17×10~4indiv/g,15.07×10~4indiv/g, increased of105.55%,140.38%,99.86%,82.00%,respectively to CK. In maize field, they were up to8.76×106indiv/g,0.22×10~4indiv/g,18.61×10~4indiv/g,16.85×10~4indiv/g with NPK+HM treatment, increased by117.75%,148.32%,74.29%,59.40%, respectively by CK. With the chemical fertilizer reductiontreatment, it reached the top with50%NPK+MM treatment, up to8.45×106indiv/g,0.21×10~4indiv/g,17.93×10~4indiv/g,16.47×10~4indiv/g and increace by109.99%,131.03%,67.88%,55.66%,respectively by CK.3. Soil invertase,urease and catalase activity have increased with the advance of the cropgrowth period in the wheat-maize cropping pattern. In wheat field,soil invertase,urease and catalase activity reached the top with NPK+HM treatment, theywere up to12.72mg/g,0.49mg/g,5.57mL/g, and increased by84.19%,27.19%,103.12%,respectively;with chemical fertilizer reduction treatment, it reached the top by50%NPK+MMtreatment, up to12.28mg/g,0.47mg/g,5.24mL/g, increased of77.80%,22.21%,91.16%respectively to CK. In maize field, they were up to12.63mg/g,0.47mg/g,5.73mL/g withNPK+HM treatment, increased by125.11%,58.55%,76.66%, respectively by CK. With thechemical fertilizer reduction treatment, it reached the top with50%NPK+MM treatment, up to12.14mg/g,0.45mg/g,5.55mL/g,and increased by116.24%,50.25%,70.93%, respectivelyby CK. On the contrary, this study showed that soil polyphenol oxidase activity decreaseswith the increase of organic fertilizer application rate. The soil polyphenol oxidase activitywas highest in the treatment of only chemical fertilizers application. There were up to3.39mg/g,3.02mg/g in wheat field and maize field.4. Soil respiration was subjected to soil temperature, humidity and soil fertility status,and many other factors. Organic fertilizer can significantly improve the soil respiration. In thewheat field the treatment of NPK+HM which was the highest and increased by85.56%asagainst the control; in the treatment of chemical fertilizer reduction, the treatment of50%NPK+MM increased by77.78%. In the maize field the treatment of NPK+HM whichwas the highest and increased by94.18%as against the control; in the treatment of chemicalfertilizer reduction, the treatment of50%NPK+MM increased by40.97%.5. Fertilizer reduction has little effect on corn biomass in the same amount of organicfertilizer, the root,stem, leaves,husks and grain biomass those were treated with NPK+HM and50%NPK+MM were differ0.22g,1.12g,0.42g,3.89g,1.60g, comparedwith the other fertilizer reduction processing,50%NPK+MM treated with the corn biomasswith the NPK+HM is the closes.