Study On The Characteristics Of Carbon And Nitrogen Mineralization Of Maize Stalk In Lime Concretion Black Soil

This study analysis the release disciplinarian and release amount of C,N,P,K after straw returning during the entire wheat growing period, in lime concretion black soil on the north of the Huai River of Anhui Province ,by using the soil incubation experiment,from the view of various temperatures and different C/N ratios(different maize straw addition). ANOVA showed that different temperatures and different maize straw addition and both interaction have significant effects on the contents of soil organic carbon (SOC), organic nitrogen, available phosphorus (P) and availablepotassium (K) during maize straw composting process. The main results are as follows:1 A laboratory aerobic incubation test was conducted under constant temperature and moisture to study different temperatures and different C/N ratios(different maize straw addition) effects on organic matter decomposition during grinding straw returning. The results showed that temperature affected the SOC mineralization significantly , soil organic C cumulative mineralization increased with the temperature rising under the control and the same maize straw addition. The Q10 values in the low temperature( <20℃) will be greater than that in the warmer stage ( >20℃), which indicates that soil organic C cumulative mineralization showed more tendency for thermosensitivity under lower temperature.The soil organic C cumulative mineralization and diurnal changes of SOC increased with the increasing of straw addition ,while under the same condition of incubation temperature.The results was analyzed with non-linear regression procedure of SPSS software indicated that the first-order kinetic model could significantly fit the experimental data. The Potentially mineralized C (C0) are not significantly changed under the different temperature, while under the same condition of incubation temperature ,Co would be increased with the increasing of straw addition.2 The processes and characteristics of nitrogen mineralization were studied with an interval leached aerial incubation at various temperatures (10℃,20℃and30℃) and different C/N ratios.The results showed that soil nitrogen net mineralized amount increased as the extension of incubation time under different treatments, while under the same C/N ratios condition it is raised with the temperature rising. The result was analyzed with non-linear regression procedure of SPSS software indicated that three models (one-pool model,two-pool model and special model)could primely fit the experimental data. The soil nitrogen mineralization potential No and nitrogen mineralization rate constant ko was calculated from one-pool model ,and affected by different temperatures and C/N ratios. The nitrogen mineralization potential No increased with the increasing of temperature,while under the same condition of incubation temperature ,No would be increased with the increasing of C/N ratios.There were close relationships between ko and C/N ratios, while under the same temperature condition the C/N ratios increased but ko decreased.Both the two-pool model and special model fitted the the experimental data better than one-pool model signified that it would be more reasonable and practical to divided the organic nitrogen pool into easily decomposable plant materials Na and resistant plant materials Nr. Nr was deeply affected by temperature, and its value decreased from higher temperature to lower temperature.3 The dynamic changes were studied in soil available P and available K under the condition of different temperatures and different maize straw addition using the method of the laboratory aerobic incubation test was conducted under constant temperature and moisture. The results showed that the content of available P in soil at first increased, then decreased as the extension of incubation time under different treatments;and the content of available K in soil slowly increased during incubation time. Temperature had a higher significant effect on the contents of available P and available K in soil.During the early stage of incubation, the content of available P in soil rised along with the temperature rised from 10℃to 30℃,whereas at the later stage the available P of soil will be released slowly at higher temperature,and at the same time obviously improve plant availability and efficiency of soil P. The content of available K in soil increased with the increasing of temperature,while under the control and the same straw addition. The content of available P and efficiency of soil P in treatmentⅢare significantly higher than those of the control, treatmentⅠand treatmentⅡrespectively, under the same temperature. The content of available K in soil increased with the increasing of straw addition ,while under the same condition of incubation temperature.