NOVELTY - Use method of straw decomposition agent of straw field, comprises e.g. digging a crop cultivation row or shallow ditch, spreading straw into ditch, uniformly spraying the straw decomposition agent, digging a second ditch for covering soil on the upper part of straw, and sequentially digging a ditch on a ditch, stacking the straw into small section or mechanical crushing the straw, irregularly spreading on ground, patting, spraying straw decomposition agent, plowing the straw on ground with mechanical or animal power, and using rainwater or irrigation water to maintain high soil moisture.    USE - The straw decomposition agent is useful for promoting root development and robust growth of crop.    ADVANTAGE - The straw decomposition agent: converts organic matter into microorganism fertilizer within a short time, can eliminate the pathogenic bacteria in the soil, reduces the diseases, improves the utilization rate of the fertilizer or farmyard manure in the soil, improves the crop yield and the product quality, does not exhibit toxic side effects, and is environmentally friendly.    DETAILED DESCRIPTION - Use method of straw decomposition agent of straw back field, comprises (a) digging a crop cultivation row or shallow ditch with a width of 40-50 cm and the depth of 30-40 cm after harvesting the crop, spreading straw into ditch, uniformly spraying the straw decomposition agent; (b) digging a second ditch for covering soil on the upper part of straw up to thickness of 10 cm, and sequentially digging a ditch on a ditch for sowing on the decomposed straw ditch on the second year; (c) stacking the straw into small section of 10-20 cm or mechanical crushing the straw and irregularly spreading on the ground, and lightly patting with a shovel; (d) spraying the straw decomposition agent, immediately plowing the straw on the ground with mechanical or animal power, and using rainwater or irrigation water to maintain high soil moisture; (e) stacking the straw into small section of 10-20 cm or mechanical crushing the straw, using a plastic thin film, and sealing to prevent water evaporation, stack temperature diffusion and nutrient volatilization; (f) adding an organic matter-decomposing inoculant agent liquid, carrying out material curing process, and maintaining the moisture content up to not less than 50%; (g) uniformly spreading wheat straw or rape shell on the field surface; (h) taking a base fertilizer according to high yield fertilizer application requirements, mixing 2 kg/acre base fertilizer with straw decomposition agent, immediately spraying on the straw field, manually or mechanically patting the straw or turning in the soil, and accelerating straw decomposition; (i) uniformly spreading wheat straw or rape shell on the field surface; (j) taking base fertilizer according to high yield fertilizer application requirements, mixing 2 kg/acre base fertilizer with straw decomposition agent, immediately spraying on the straw field, after spreading; and (k) using a reverse rotary cultivator or slurry rotary tillage machine for rice, turning wheat straw or rape shell by plowing to bury in soil, watering the field, leveling, seeding, planting or throwing seedling.