Comparison Of Sorghum And Corn Straw Decomposition Characteristics

Straw is an important source of organic fertilizer,which is rich in nitrogen,phosphorus and potassium.Decomposed straw is an important source of soil organic matter.This paper uses indoor culture experiments in soil microbes in Guizhou and Shanxi.The test has a total of 8 treatments: 1)cultivation of corn straw(G-Y)by Guizhou soil microbial extract,2)cultivation of sorghum straw(G-G)in Guizhou soil microbial extract,3)Guizhou soil microbial extract culture to regulate C/N corn straw(G-YN),4)Guizhou soil microbial extract culture to regulate C/N sorghum straw(G-GN),5)cultivation of corn straw(SY)by Shanxi soil microbial extract,6)cultivation of sorghum straw(S-G)in Shanxi soil microbial extract,7)Shanxi soil microbial extract culture to regulate C/N corn straw(S-YN),8)Shanxi soil microbial extract culture to regulate C/N sorghum straw(S-GN);adjusting straw with urea C/N=25:1.By analyzing structural changes during the decomposition of two straws inoculated with different soil microbial extracts,decomposition rate and response of straw residue microbial,compare the differences in the decomposing properties of two straws,exploring the microbial characteristics of straw residue during straw decomposing,provide theoretical basis for agricultural utilization of straw resources,main results and conclusions are as follows:(1)Using fourier transform spectrometer to analyze the functional group changes during the decomposing process of each treated sorghum and corn straw,the results showed that the functional groups changed significantly during the decomposing process of sorghum and corn straw: carbohydrate and sugar content is gradually reduced during the decomposition process,decomposition of soluble organic matter such as amino acids and organic acids,reduced levels of methyl,methylene and amide compounds,increased carboxyl content,decreased fat.Decomposed for 30 d,the absorption peak intensity of straws cultured in Guizhou soil microbial extracts was 2917,2850,1033 cm-1,which was greater than that of Shanxi soil microbial extracts.It shows that Guizhou soil promotes straw decomposition compared with Shanxi soil;the sorghum straw has an absorption peak at 2917,2850,1033,890 cm-1,and the absorption peak intensity decreases more than corn straw,indicates the reduction of carbohydrate content in sorghum straw and fatty decays faster than corn straw;after adjusting C/N,the absorption peaks of the two straws were 2917,2850,and 1457 cm-1,it is indicated that the regulation of C/N promotes the decomposition of straw.(2)Using the weight loss method to determine the rate of straw decomposing,the results showed that both sorghum and corn straw showed a tendency to be fast(30 d before culture)and slow(30 to 90 d).The sorghum and corn stalk decomposing rates of unregulated C/N ratio at the end of the culture were 60.50% and 49.38%,the decomposition rate of 30 d before culture was 53.93% and 51.40% of the total decomposition rate;the sorghum and corn stalk decomposing rates of the C/N ratio were 63.00% and 54.25%,the decomposition rate 30 d before the culture was 53.02% and 58.07% of the total decomposition rate.Compared with Shanxi soil,Guizhou soil promotes the decomposition of straw,but the difference is not significant.The decomposition of cellulose and lignin in sorghum and corn stalks is consistent with the trend of total decomposing rate.(3)Using BIOLOG ECO microplate method to study the utilization of microbes in carbon sources in straws during the decomposing process of sorghum and corn straw.The results showed that the highest utilization rate of carbohydrates and amino acids by microorganisms in each treated straw was observed after 30 days of decomposition,followed by lipids and acids,microorganisms and acids in straw are mainly used in decomposing for 90 d.Cluster analysis showed that after 30 days of decomposition,maize straw residue microorganisms of two soils without C/N have similar carbon source utilization capacity,further similarity with S-G treatment of C/N in Shanxi soil culture.At the end of the culture,cluster analysis of the ability of the residues of straw residues on carbon sources showed that G-G and G-YN,S-G and SYN,G-Y and S-Y,G-GN and S-GN were clustered together;further the first two get together again,the latter two groups get together;it shows that under the same extract culture,the utilization rate of carbon source of sorghum straw and corn straw C/N ratio is similar;the same C/N ratio of sorghum stalks and corn straw treated with different extracts was similar in carbon source utilization.