Effect Of Different Rice Straw Addition Methods On Nitrogen Supplying Capacity And Activity Of Enzyme In Coastal Saline Paddy Soil

At present,saline paddy soil in northern China has become an important production base for high-quality and high-yield rice.However,in recent years,a large number of chemical fertilizers have been applied to reduce soil fertility with ignoring the organic fertilizer and straw returned,and it has also seriously polluted groundwater and rivers and lakes,causing agricultural non-point source pollution.Therefore,the study on the straw returned methods of coastal saline soils is very important for both production and environment.In this paper,the coastal saline paddy soil in Liaoning Province is selected,and the biochar made of rice straw,decomposed rice straw,and rice straw is added to the soil and the indoor long-term flooded culture at constant 25°C is performed.Remove after 30,60,90,and180 days as test soil.The effect of three different rice straw addition methods on the physicochemical properties,nitrogen supplying capacity and enzyme activity in coastal saline paddy soil are studied to develop scientific and reasonable fertilization.Measures provide a theoretical reference.Research indicates:(1)During the flooding period,the contents of organic carbon in the saline-salted paddy soils treated with Z(Straw),F(Decomposed Straw),and S(Straw biochar)are significantly higher than those of CK(P < 0.05),and the organic carbon in paddy soils treated with S is the highest content.With the increase of culture time,the soil organic carbon content gradually decrease.(2)90 days after the cultivation,the amount of nitrogen mineralization in coastal saline soil increase with the increase of cultivation time.The addition of different rice straws promote the soil nitrogen mineralization to varying degrees.The amount of soil nitrogen mineralization is related to the organic matter contained in the soil.At the same incubation time,there is a significant difference in soil nitrogen supply capacity among the four treatments.Among them,the soil nitrogen supply capacity of the S treatment is significantly higher than that of other treatments at the 90 th day of the cultivation.(3)90 days after the cultivation,the microbial biomass nitrogen of the four different treated soils changes little,but decrease significantly after 180 days.The MBN content of the soils with different rice straws gradually decrease with the culture time.The changes of MBNof different treated soils showed consistency with time.(4)The addition of different rice straws can significantly increase the enzyme activity of the soil,in which the protease,urease and sucrase have the same change,which is significantly higher than that of CK,and the soil enzyme activity of S is higher than that of Z and F.The activity of catalase in soil treated with CK was lower than that of Z,F and S treatments.Except that the treatment of F was slightly higher than that of treatment Z at 180 days,it is expressed as CK < S < F < Z at other times.In summary,the addition of different rice straws can promote the mineralization of nitrogen in coastal saline soils,enhance soil nitrogen supply capacity and microbial activity.The results in this paper can provide a scientific reference for measures about rice straw returned.