Assessment And Practical Application Of Soil Fertility Restoration In Eroded Red Soil Region Of South China Based On Catastrophe Theory

Currently, Soil degradation has become one of the ten major environmental problems, and suppression of soil degradation and restoration of degraded soil have become the key measures to achieve ecological restoration. In this study, adhering to the basic principles of soil and ecology restoration and introducing the catastrophe theory, Zhuxi basin in the Southern eroded red soil and Laiyoukeng of the experimental plot were taken as the study area. Through combining a series of surveys including soil fertility restoration assessment, validation, restoration measure adjustment and practical application, which were conducted by field survey, located observation, laboratory analysis, farmer interviews, data research and other methods, the study is designed to provide new theoretical basis and technical guidance for the ecological restoration and reconstruction of degraded ecosystem in red eroded soil of South China. According to the assessment results of soil fertility restoration in the Zhuxi basin using the catastrophe model, the soil fertility after restoration measures were significantly improved, further facilitating the catastrophe. Among the 89 soil samples, catastrophic soil samples and stable soil samples accounted for 26 (29.21%) and 63 (70.79%), respectively. The catastrophic direction of 26 catastrophic soil samples was upward to the leaves. For the four ecological restoration measures, the highest catastrophe proportion among soil sampling sites was those with low-quality forest improvement (LQFI), followed by arbor-bush-herb mixed plantation (ABHMP), orchard improvement (01) and closing measures (CM), and all of these proportions proved to be higher than those without restoration measures. Two methods were used to validate the assessment.1) Farmer instigation, where the assessment of farmers on soil fertility restoration was in line with the proportions of catastrophic soil sampling sites in four restoration measures and contrary to average â–³, confirming the reliability of catastrophe theory in assessing soil fertility restoration after restoration measures; and 2) calculation of runoff volume and sediment volume values in runoff plots, which showed that LQFI and ABHMP played a more effectively role in reducing runoff and sediment than OI and CM, thus verifying the reliability of assessment. Then, using the catastrophe model, the soil fertility restoration was regionalized into three types, i.e., "soil fertility capable of self-development", "soil fertility possible for self-development" and "soil fertility unable for self-development". All soil sampling sites, whose least effective vegetation cover were more than 1, were distributed in the soil fertility stable region for lower leaves, indicating the needs for other measures, such as fertilizers or engineering measures. According to calculation, the saved funds can be up to 18.35 million RMB by taking the restoration measures of safe exit in the study area, proving the practical and economic significance of our study findings. Consequently, suggestions for the practical application of study findings were then proposed, including giving full play of self-development ability, timely intervention of human interference, effective use of interference patterns, timely exit of human interference and emphasis on the water conservation function of Dicranopteris Dichotoma.