Physiographic characteristics of agricultural lands and farmers’ soil fertility management practices in Wolaita zone, Southern Ethiopia

Abstract

Background: Understanding the landscape features of agricultural lands and soil management practices is pertinent to verify the potential and limitations of the soil resources; and devise relevant land management strategies. However, information is lacking in Wolaita, Southern Ethiopia. Thus, this study aimed at investigating the physiographic characteristics of agricultural lands, farmers' soil fertility management practices and their influences on soil fertility and crop productivity was conducted. The survey involved 789 randomly sampled agricultural lands. Soil sample as well as data on slope, topography, land use, crop rotation, fallowing, cropping intensity, crop residue management, fertilizer use and farmers' estimated crop yield were collected and evaluated. Results:The result indicated that agriculture has been practiced under diverse slope positions (1-58%). This significantly influenced most of soil physico-chemical properties in which an increase in soil bulk density, and decrease in available phosphorous, exchangeable calcium, extractable boron, copper, iron and zinc with an increase in slope positions were recorded. Furthermore, continuous cultivation without any fallow periods and complete crop residue removal (96%) were common practices. Fertilizer use was not sufficient. The average use (kg ha −1 ) was 30 and 9 for diammonium phosphate (DAP) and urea, respectively, and about 89% of study area received manure below 1.5 t ha −1 . All these limitations made farmers to experience lower crop yield than the national average estimates. Conclusion:Based on the result, it is possible to conclude that the following soil management interventions such as soil conservation, application of sufficient organic and inorganic fertilizers are recommended to restore the soil fertility and improve crop productivity.

Farmers’ soil knowledge, fertility management logic and its linkage with scientifically analyzed soil properties in southern Ethiopia

“…The lower P content might be ascribed to the combined effects of intensive cultivation, lower P and organic fertilizer application, and lower pH values. Lower P content on cultivated soils was also reported in the literature [4,5,[37][38][39].…”

“…The yield gap is emanated from very poor crop residue maintenance, inadequate compensation of plant nutrients and continuous cropping [4,5]. Consequently, it resulted in the presence of multi-nutrient deficiencies including N, P, S, B and Cu.…”

“…The lower S in all soil types could be linked to lower soil OC, crop uptake and non-use of S fertilizers. In Ethiopia, different researchers also reported the lower available S content in cultivated soils [4,5,35,40].…”

“…Farmers preferably apply FYM or homeleft wastes to enset, coffee and root and tubers crops, while mineral fertilizers are used for tef, maize, wheat, haricot bean and potato. Fertilizer-allocation practices by farmers in Wolaita area specifically to the study area are also briefly indicated in [5].…”

“…In the complex physiographic conditions like Wolaita [5], tailoring soil fertility management recommendations to specific soil types has been a crucial problem. Few studies in the area reported that farmers have a broader knowledge of their soils [8,23].…”