Grazing by livestock and cultivation have been considered as two important causes of soil erosion and nutrient export. However, there has been limited evidence that grazing or cultivation matters to soil erosion and nutrient export in Ethiopia. Hence, this study was conducted in the Galesa watershed in Ethiopia to examine the effects of grazing and cultivation on runoff, soil loss, and nutrient export. Daily values of runoff, soil erosion, and nutrient outflow were measured for three consecutive years following standard procedures. Independent t test was performed to check if the means of runoff, soil loss, and nutrient loss from grazing and cultivated lands were significantly different. Moreover, repeated analysis of variance (ANOVA) was used to test if mean values of runoff, soil loss, and nutrient export varied significantly over the study years. Although the average annual runoff depth was 7.8% higher in grazing land (GL), soil erosion was significantly lower (39%) in GL as compared to cultivated land (CL). Similarly, sediment and runoff-associated annual losses of total nitrogen (N), available phosphorus (P), exchangeable potassium (K), and organic carbon (OC) were low in the GL treatments. Lowest losses of total N (9.30 kg ha−1 year−1), available P (0.83 kg ha−1 year−1), and exchangeable K (1.84 kg ha−1 year−1) were recorded in GL treatment. Likewise, lowest losses of sediment-associated total N (32.8 kg ha−1 year−1), available P (0.39 kg ha−1 year−1), exchangeable K (0.23 kg ha−1 year−1), and soil organic carbon (630 kg ha−1 year−1) were recorded from GL over the 3 years of experimentation. Our results indicate that cultivation increased soil erosion as compared to grazing. Although there were significant reductions in soil erosion and nutrient export from grazing lands compared with cultivated lands, the absolute losses were still high. This implies the need for grazing land management using appropriate physical and biological erosion control measures to increase productivity and reduce soil erosion as well as nutrient export.

中文翻译：

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放牧和耕作对埃塞俄比亚中部高地径流，土壤侵蚀和土壤养分输出的影响

牲畜放牧和耕种被认为是土壤侵蚀和养分输出的两个重要原因。但是，只有有限的证据表明，在埃塞俄比亚，放牧或耕种对土壤侵蚀和养分出口至关重要。因此，这项研究是在埃塞俄比亚的加莱萨流域进行的，目的是研究放牧和耕作对径流，土壤流失和养分输出的影响。按照标准程序连续三年测量径流量，土壤侵蚀和养分流出的每日值。进行了独立的t检验，以检查牧场和耕地的径流，土壤流失和养分流失的方式是否存在显着差异。此外，使用方差重复分析（ANOVA）来检验径流，土壤流失，在研究年份中，养分出口和营养出口差异很大。尽管放牧地（GL）的年平均径流深度增加了7.8％，但与耕地（CL）相比，GL的土壤侵蚀显着降低（39％）。同样，在GL处理中，与沉积物和径流相关的总氮（N），有效磷（P），可交换钾（K）和有机碳（OC）的年度损失较低。在GL处理中，总氮损失最低（9.30 kg ha-1年-1），可用P（0.83 kg ha-1年-1）和可交换K（1.84 kg ha-1年-1）的损失最低。同样，与沉积物相关的总氮（32.8 kg ha-1年-1），可利用的P（0.39 kg ha-1年-1），可交换的K（0.23 kg ha-1年-1）和土壤有机质损失最低在3年的实验中，GL记录了630千克ha-1年-1的碳。我们的结果表明，与放牧相比，耕作增加了土壤侵蚀。尽管与耕地相比，放牧地的土壤侵蚀和养分输出显着减少，但绝对损失仍然很高。这意味着需要采用适当的物理和生物侵蚀控制措施来管理牧场，以提高生产力，减少土壤侵蚀以及养分输出。