A systematic review of soil erosion in citrus orchards worldwide

Abstract

The rapid expansion of citrus orchards and their increased cultivation intensity have accelerated soil erosion, which has impeded the achievement of Sustainable Development Goals. In citrus orchards, the benefits of soil and water conservation measures for alleviating soil erosion have been widely tested at the plot scale. These studies provide crucial information, but they inevitably involve considerable uncertainty and cannot fully characterize the efficacy of soil and water conservation measures. Given the seriousness of soil erosion in citrus orchards and the uncertain factors in the efficiency of soil and water conservation measures, data published in the literature were collected. A meta-analysis of 346 plots (representing 4443 events) for runoff and 307 plots (representing 3596 events) for soil loss was conducted to evaluate the effectiveness of soil and water conservation measures in citrus orchards. This study aims to (i) summarize the level of soil erosion in citrus orchards worldwide, (ii) explore the influence of soil and water conservation measures on soil erosion control in citrus orchards and (iii) identify the trade-offs between runoff reduction and soil loss reduction. The results showed that the citrus orchards without soil and water conservation measures had a probability of approximately 80% of exceeding tolerable levels of soil loss. The effectiveness of soil and water conservation measures in reducing soil erosion decreased in the order biological measures + engineering measures > engineering measures > biological measures. The trade-off between runoff reduction and soil loss reduction showed that soil and water conservation measures provide better soil loss control than runoff control. Overall, besides considering the ecological benefits of soil and water conservation measures, decision maker should also consider the economic benefits to obtain an optimal citrus orchard management for farmers.