Effects Of Nectarine Planting Patterns On Soil Organic Carbon Fractions And Its Stability In Southern Yunnan

The fragile ecological environment and serious land degradation in southern Yunnan not only pose a great challenge to the stability of the ecosystem,but also potentially affect the sequestration of soil organic carbon.As an important measure of land degradation control project,economic orchard can alleviate the contradiction between human and land,improve the ecological environment and bring certain economic benefits to the local area.In order to explore the effects of nectarine planting patterns on soil organic carbon fractions and their stability,this study took different nectarine planting patterns,single nectarine and nectarine pumpkin interplanting in Kaiyuan city,Yunnan Province as the research object,and secondary forest as the control to analyze the soil organic carbon,permanganate oxidizable carbon,particulate organic carbon and mineral-associated organic carbon in 0-40 cm soil layer.Meanwhile,we took the secondary forest as the reference soil calculated carbon pool management index.Fourier infrared spectroscopy was used to measure the infrared spectral characteristics of organic carbon fractions in different planting patterns,and to explore the structural changes of soil organic carbon and its fractions.Based on soil organic carbon fractions,carbon pool management index,chemical structure of soil organic carbon,and soil physicochemical properties,we analyzed the stability mechanism of soil organic carbon and its fractions.The main results are as follows:(1)The soil organic carbon content of secondary forest,single nectarine and nectarine pumpkin interplanting were 8.03-29.52 g/kg,3.96-14.69 g/kg and 4.78-14.25g/kg respectively,which decreased with the increase of soil depth.There were significant differences in the distribution proportion of organic carbon fractions between different planting partterns(P<0.05).The distribution proportion of active organic carbon of nectarine pumpkin interplanting was less than that of single nectarine,which had high organic carbon stability.The carbon pool management index of single nectarine and nectarine pumpkin interplanting increased and then decreased with the soil layer.Nectarine planting changed the soil organic carbon pool.Compared with the control,the carbon pool management index of the two planting patterns decreased to varying degrees,and the carbon pool of nectarine pumpkin Interplanting was relatively stable.(2)Under different nectarine planting patterns,the component of soil organic carbon did not change,but the molecular structure changed.Polysaccharides account for a large proportion in organic carbon,followed by alcohols,phenols,aromatics and aliphatics.The infrared spectrum of soil organic carbon was similar with that of mineral-associated organic carbon.The relative content of phenolic hydroxyl alcohol and phenolic in particulate organic carbon was higher.Mineral-associated organic carbon had higher hydrophobicity with chemical stability.Compared with single nectarine,nectarine pumpkin interplanting had a higher content of soil alcohol phenol and aliphatic compounds,increase the hydrophobicity of organic carbon and the proportion of stable structure combined with minerals,increase the chemical stability of soil,and is more conducive to the long-term accumulation of organic carbon.(3)The results of correlation analysis,principal component analysis and redundancy analysis showed that particulate organic carbon was more sensitive to the change of soil organic carbon than other organic carbon fractions.Sand and p H were the main environmental factors affecting soil organic carbon fractions under different nectarine planting patterns and different soil depths.In conclusion,nectarine pumpkin interplanting is a better planting pattern,which is beneficial to the storage of organic carbon in the orchard.Improving the understanding of soil organic carbon fractions and their stability under different planting patterns of nectarine can provide theoretical basis and practical guidance for optimizing planting patterns of nectarine and improving the carbon sequestration potential of agricultural soil.