Understanding spatial patterns of soils for sustainable agriculture in northern Ethiopia’s tropical mountains

Abstract

Knowledge of the geographical distribution of soils is indispensable for policy and decision makers to achieve the goal of increasing agricultural production and reduce poverty, particularly in the Global South. A study was conducted to better understand the soilscapes of the Giba catchment (900–3300 m a.s.l.; 5133 km2) in northern Ethiopia, so as to sustain soil use and management. To characterise the chemical and physical properties of the different benchmark soils and to classify them in line with the World Reference Base of Soil Resources, 141 soil profile pits and 1381 soil augerings at representative sites were analysed. The dominant soil units identified are Leptosol and bare rock (19% coverage), Vertic Cambisol (14%), Regosol and Cambisol (10%), Skeletic/Leptic Cambisol and Regosol (9%), Rendzic Leptosol (7%), Calcaric/Calcic Vertisol (6%), Chromic Luvisol (6%) and Chromic/Pellic Vertisol (5%). Together these eight soil units cover almost 75% of the catchment. Topography and parent material are the major influencing factors that explain the soil distribution. Besides these two factors, land cover that is strongly impacted by human activities, may not be overlooked. Our soil suitability study shows that currently, after thousands of years of agricultural land use, a new dynamic equilibrium has come into existence in the soilscape, in which ca. 40% of the catchment is very suitable, and 25% is moderately suitable for agricultural production. In view of such large suitable areas, the Giba catchment has a good agricultural potential if soil erosion rates can be controlled, soil fertility (particularly nitrogen) increased, available water optimally used, and henceforth crop yields increased.

Potentialities and limitations of Planosols with distinct depths of diagnostic horizon

“…Organic carbon contents in both profiles were lower than 10 g kg -1 (Table 3). Low contents of organic carbon are consistent with the semiarid conditions, which result in low supply of organic residues to the soil and favor the rapid decomposition of organic matter (Oliveira et al, 2003;Sampaio et al, 2010;Nyssen et al, 2019). P2 had higher carbon content than P1, and both profiles showed a reduction in carbon in subsurface, except for the horizons Btf1 of P1 and 2Btf2 of P2 (Table 3).…”

“…The increase of CEC in the subsurface horizons of the two profiles is related to the increasing clay contents in subsurface (Table 2). Increase in CEC with depth in Planosol was observed by Nyssen et al (2019), who associated it with the increase in clay content.…”

Estimation of Current Water Use over the Complex Topography of the Nile Basin Headwaters: The Case of Ghba Subbasin, Ethiopia

“…e landscape is characterized by highlands and hills in the north and north-eastern and highlands in the central part of the catchment [14]. e central highlands are divided by numerous rivers that flow towards the southwestern part of the subbasin and joins the main Tekeze River at Chemey [15]. e altitude varies from 3,300 meter above seas level (m.a.s.l.)…”

“…At the subbasin outlet [16]. e mean elevation of the catchment is 2144 m, with a standard deviation of 361 m indicating that the topography is very rugged [15].…”

Cause and cost of onsite nutrient loss replacement in the highlands of Ethiopia and implication of Soil and Water Conservation measures

“…According to (Food and Agriculture of the United Nations [62] classifi cation system Nitisols, Luvisols, and Vertisols; Cambisols, Regosols and Leptosols are the major soil types in Highland of Ethiopia [61,[63][64][65] The study area soils are characterized with shallow, moderate to very deep in depth and clay loam to clay texture.…”