Effects Of Different Location Of Straw Incorporation On Soil Water Dynamics,Soil Enzymes,Microbial C And N

Relying on the 23.8% of the national total grain output,the black soil region in Northeast China has been developed as the biggest commodity grain base..The main source of water in agricultural system is rainfall with average annual rainfall is 400 ~ 700 mm.Due to the distribution of rainfall is extremely uneven,the seasonal drought happened.Therefore,how to rationally allocate,use and make full use of water resources and improve the efficiency of water use are the most important problem in agricultural production.Northeast China as a major maize producing areas in China,with a considerable amount of straw resources,and thus how to rational use of straw and how to make straw play a positive effect in agricultural production and soil improvement for great exploration and research value.In order to find out the characteristics of black soil for adapt to the regional climate of straw to field,the effect of straw incorporation on soil moisture,physical properties,enzyme activity and biomass C and N were studied in this study.The conclusions as follows:D0,0-35 cm soil layer(D1),20-35 cm soil layer(D2),0-35cm(D3)soil layer mixed with four levels,the amount of straw application were(S1),12000(S2),9000(S3),6000(S4),the application method is artificial mixing,the whole test is set to 7 processing D0T2,D1S2,D2S2,D3S2,D2S1,D2S3,D2S4,three replicates.First of all,the straw affected the content of soil surface water,and increased the capacity of the soil water storage.On the other hand,it can reduce the evaporation of the soil surface.The soil moisture content of D1S2 is 6.5%-14.7% higher than that of the other treatments during the observation period from June 19 to July 29.The soil water content of D0S1 treated 0-15 cm soil layer is 5.5%-7.6% higher than that of other treatments from July 29 to August 31.In the second,the depth of different straws had different effect on the soils water distribution in soil profile.It directly affected the physical properties of the surface soil and water content,and had the influence on the deep water content with a certain lag.The soil water content of D0S1 and D2S1 was significantly higher than that of other treatments,while the soil water content of D2S1 and D1S2 treated in > 20 cm soil layer is higher.Straw return also affected soil moisture infiltration.It would change the porosity of the soil,affected the formation of soil aggregates,which would affect the soil microbial and animal activities,so that in the background of straw return to the field,with the increase in straw application rate stabilized infiltration rate increases as well.Straw incorporation depth could reduce the soil bulk density,improve the soil physicalstructure,increase the soil organic matter,the same amount of incorporation with the field to increase the depth of field,enzyme activity and microbial carbon,nitrogen are significantly increased in 0-20 cm soil.The enzyme activity and the microbial biomass reached the maximum.While the maize stalks were increased with the depth of soil,the soil permeability was deteriorated,the decomposition rate of straw decay was slow,and the nutrient contained in the straw was not released sufficiently,and the enzyme activity and microbial biomass were decreased.The results with different treatments showed that D1T2> D2T2> D3T2,but the surface covered with D0S2 treatment with slightly different.As the straw in the same depth,the amount of organic matter and nutrient in the soil can be increased with the straw incorporation amount.However,when the amount of straw incorporation is too large in the soil,too much straw will affect the permeability and water permeability of the soil.So that soil enzymes and microbial biomass would decrease.The results showed that the soil enzyme and microbial biomass C and nitrogen increased with the increase of straw returning rate,and the soil enzyme activity and microbial carbon and nitrogen reached the peak at 12000 kg/ha,and then decreased.The results of all the test are D1S2>D1S1>D1S3>D1S4.Therefore,different straw returning treatments had significantly effect on soil water change,soil enzyme activity and microbial biomass C and nitrogen.Appropriate depth and amount of straw incorporation to the soil can optimize the soil physical properties,improve soil enzyme activity,and increase the microbial carbon and nitrogen.