Abstract:

To study the decomposition characteristics of sorghum and maize residues and the functional diversity of microbial community in straw decomposition,under different residual types(sorghum stalk-leaves,maize stalk-leaves,sorghum root,maize root),soil type(cinnamon soil,yellow loam soil),nitrogen treatment(adjust C/N ratio,not adjusted),the culture experiment method was used to explore the decomposition characteristics of residues under different decomposition conditions,and to analyse the metabolic functional diversity of microbial community used the BIOLOG-ECO plates method in straw decomposition process.The results showed that the decomposition rate of sorghum and maize residues was faster in the early stage than the late stage.The residual dry matter degradation rate and CO₂ release rate had the following pattern of decomposition rate was shown,sorghum stalk-leaves>maize stalk-leaves>sorghum root>maize root,under the same soil and nitrogen treatment.According to the second experiment, the dry matter degradation rates of sorghum stalk-leaves and maize stalk-leaves were 55.50% and 48.00%,respectively,however,the dry matter degradation rate of sorghum root and maize root were 31.25% and 16.75%,respectively at 60 d of incubation,under the condition of cinnamon soil+N treatment.The degradation rate of hemicellulose and cellulose in root were lower than that in stalk-leaves,under the same soil and N treatment conditions,the decomposition of hemicelluloses and cellulose was decreased by 23.70,18.80 percentage point,in sorghum root treatment than sorghum stalk-leaves treatment at 90 d of incubation,under the condition of cinnamon soil+N treatment.The microbial metabolic activity of straw was the highest at 30 d and lowest at 90 d during decomposition.The metabolizable ability of microbial community of straw decomposition to amines and phenolic acids was lower on the 1st day of decomposition,and the metabolizable ability to carbohydrates,amino acids and polymers was significantly decreased on the 90th day,compared with 30 d.Collectively,the decomposition of sorghum residues was easier than maize,and adjusting C/N ratio could accelerate the decomposition of residue to a certain extent.The microbial metabolic diversity was the highest at 30 d under the experimental conditions.

Key words: Sorghum, Maize, Residues decomposition, Carbon mineralization, Cellulose, Hemicelluloses, BIOLOG-ECO