| Due to the fragile ecological environment in Shanxi Province and the great disturbance of soil caused by engineering reclamation after the destruction of coal mining,the soil fertility of the coal reclamation area is low.Therefore,it is of great significance to improve the soil fertility of the coal reclamation area.Fertilization can improve soil fertility.Organic fertilizers play a major role in improving soil fertility.China is rich in organic resources.Returning organic materials to the field is an important source of soil organic carbon,which is of great significance for fertilizing and improving farmland soil.The role of different organic fertilizers is different,so it is of great significance to study the decomposition characteristics of various organic materials.In the field,a nylon mesh bag landfill test of organic materials was set up on the soil in early stage of reclamation,the soil in ten-year stage of reclamation and the soil in thirty-year stage of reclamation,to investigate the decomposition characteristics of organic materials on the soil under different reclamation years in the core-mining area,and organic materials.The main results of the study on the impact of soil in the core-mining area are as follows:1.The overall change trend of the decomposition of organic materials on the three kinds of reclaimed soil is the same: the fastest decomposition rate of pig manure,followed by straw,compost,biogas residue,and biochar basically do not decompose;but organic materials The decay of the crops showed a stage difference: the stalks decayed earlier in the soil in ten-year of reclamation or in thirty-year of reclamation than the rate in early stage of the reclamation,but the difference between manure and compost was not significant.The humification coefficient of straw is 0.47-0.51,the variation between soil and materials is small;the humification coefficient of manure is 0.47-0.74,the variation between soil is small,but the variation between materials is large;The humification coefficient of compost,biogas residue and biochar is 0.87-0.92,and the variation between soil and materials is small.The first-order kinetic accumulated temperature equation can well simulate the decomposition process of straw and manure.Organic materials can be divided into easily decomposable carbon pools and stable carbon pools.The division of each carbon pool component is the embodiment of the nature of organic materials.Manure varies greatly;for the same material,there is little variation between different soils.2.Organic materials are returned to the field through the input of carbon,which increases the soil microbial carbon and nitrogen,and improves the soil carbon and nitrogen retention capacity.After the organic materials were returned to the field,the soil microbial biomass carbon and nitrogen increased first and then decreased with time,and reached the maximum value in about 218 days.Organic materials returned to the field all increased the soil microbial biomass carbon and nitrogen,but showed differences between different materials and soil: the size of the microbial biomass carbon and nitrogen between the materials showed a trend of straw> manure> compost,but the increase rate was different;The amount of carbon and nitrogen is expressed as in the soil in ten-year of reclamation,in the soil in thirty-year of reclamation >in the soil in early stage of reclamation,but the increase rate shows the opposite trend.3.In the initial reclamation or ten-year of soil or reclamation,the return of organic materials to the field(except for biochar)has increased SMBC / SMBN.In thirty-year of reclamation,the SMBC / SMBN of cattle manure or biogas residue or biochar returned to the field decreased slightly,and the SMBC / SMBN of wheat straw or corn stover or pig manure or compost returned significantly increased.On the three reclamation years of soil,the overall change trend of soil microbial entropy after the return of organic materials to the field was similar: wheat straw,corn stalk,pig manure,and cow dung treatment all significantly increased the soil microbial entropy.Microbial entropy has no obvious effect,and the treatment of biogas residue and biochar reduces the soil microbial entropy.4.Returning organic materials to the field can increase the content of easily oxidized organic carbon in the soil,and can contribute to the storage of carbon in the soil;with the increase of the reclamation period,the amount of oxidized organic carbon in the reclaimed soil is increasing.The difference is not large,and the increase range varies greatly;in the soil of the same reclamation period,the size of soil oxidizable organic carbon is roughly: compost> pig manure,wheat,corn,cow dung> biogas residue> biochar.Therefore,returning organic materials to the reclaimed soil can improve soil activity.In summary,the rate of decomposition of organic materials in the soil in ten-year of reclamation or in thirty-year of reclamation is faster than the rate of decomposition in the early stage of reclamation,but the difference between different organic materials is significant: the rate of straw decomposition is fast than fertilizer.The first-order kinetic accumulated temperature equation can well simulate the decomposition process of straw and manure,but different organic materials have significant differences.Organic materials returned to the field can increase the soil microbial biomass carbon and oxidizable organic carbon content,showing significant differences between different materials and different soil. |
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