College of Agriculture and Environmental Sciences, Bahir Dar University, Bahir Dar, Ethiopia; Amhara Region Bureau of Agriculture, Bahir Dar, Ethiopia.
College of Agriculture and Environmental Sciences, Bahir Dar University, Bahir Dar, Ethiopia.
Sci Total Environ. 2021 Sep 10;786:147450. doi: 10.1016/j.scitotenv.2021.147450. Epub 2021 Apr 30.
Improving our understanding of how different land uses and management practices affect soil nutrient outflows in sub-Saharan Africa could aid in developing sustainable practices. The objective of this study was to analyse the variation in outflows of soil total nitrogen (TN) and available phosphorus (P) as influenced by land use types (cropland, grazing land, and bushland) and land management practices (soil bunds for cropland and exclosures for non-croplands) in the three contrasting agro-ecological zones of the Upper Blue Nile basin, Ethiopia. Field data were collected for TN and P outflows by water erosion (Eo), leaching (Lo), product harvest (Ho), and gaseous emissions (Go) from 18 runoff plots (30 m × 6 m) for two years (2018-2019). TN and P losses significantly varied (p < 0.05, p < 0.01) among agro-ecological zones, land use types, and management practices. Losses of TN ranged from 39.6 to 55.5 kg ha yr and those of P from 4.1 to 5.9 kg ha yr, with a total replacement cost of US$26-38 ha yr. Nutrient losses and cost generally increased from lowland (Dibatie) to midland (Aba Gerima) to highland (Guder), although the highland and midland sites did not differ significantly (p > 0.05) in nutrient losses. Cropland showed significantly higher TN and P losses than other land use types, but TN loss did not differ significantly between grazing and bushland. In all land use types at all sites, the magnitude of nutrient losses was Ho >Eo >Lo >Go. In plots with land management practices, TN and P losses associated with Eo, Lo, and Go were reduced on average by 44-76%, 9-47%, and 1%-36%, respectively. These practices were most effective to reduce Eo nutrient losses. Further study is required to analyzing the soil nutrient balance and identify priority areas for implementing mitigation measures.
提高我们对不同土地利用和管理实践如何影响撒哈拉以南非洲土壤养分流出的理解，可以帮助制定可持续的实践措施。本研究的目的是分析土地利用类型（耕地、放牧地和林地）和土地管理措施（耕地的土壤堤埂和非耕地的围栏）对埃塞俄比亚上蓝尼罗河流域三个截然不同的农业生态区土壤总氮（TN）和有效磷（P）流出量的影响。在两年（2018-2019 年）内，通过水蚀（Eo）、淋溶（Lo）、作物收获（Ho）和气体排放（Go）从 18 个径流场（30 m×6 m）收集了 TN 和 P 流出量的田间数据。TN 和 P 的损失在农业生态区、土地利用类型和管理措施之间存在显著差异（p < 0.05，p < 0.01）。TN 损失范围为 39.6 至 55.5 kg ha yr，P 损失范围为 4.1 至 5.9 kg ha yr，总替代成本为 26-38 美元 ha yr。养分损失和成本通常从低地（Dibatie）到中地（Aba Gerima）再到高地（Guder）增加，尽管高地和中地站点的养分损失没有显著差异（p > 0.05）。耕地的 TN 和 P 损失明显高于其他土地利用类型，但放牧地和林地之间的 TN 损失没有显著差异。在所有土地利用类型的所有地点，养分损失的幅度为 Ho >Eo >Lo >Go。在有土地管理措施的地块中，Eo、Lo 和 Go 相关的 TN 和 P 损失平均减少了 44-76%、9-47%和 1%-36%。这些措施对减少 Eo 养分损失最有效。需要进一步研究分析土壤养分平衡，并确定实施缓解措施的优先领域。
