Assessment of the impacts of toposequence on soil properties and quality in Tula, Gombe State, Nigeria

Soil erosion and a decline in fertility are influenced by insidious topography, which results in the problem of food insecurity in developing countries. Tula is a slope terrain, thus, prone to soil degradation due to continuous cultivation, hence the need to assess soil variability and quality to guide on suitable management practices to adopt across the slope classes. Hence, this study was conceived to assess the effect of toposequence on soil properties and quality in Tula, Gombe state Nigeria. Three slope classes were selected (upper, middle and lower slope). Soil samples were collected from each slope class at depths of 0–15 cm and 15–30 cm and analysed for soil physical and chemical properties using standard procedures. The results show that the soil texture varies from loamy sandy to sandy. The bulk density ranges from 1.02 to 1.12 mg.cm−3 and were rated medium at <1.6 mg.cm−3. Soils on the lower slope were significantly (p < 0.05) higher in soil pH. The soils were generally slightly acidic to neutral. Soil organic carbon was medium in the upper and lower slopes (>10 mg.kg−1), while the middle slope was low. The exchangeable bases were rated medium to high across the slope. The soils in the upper slope were of high quality (17 = SQ1), soils in the lower slope were moderate in quality (22 = SQ2) due to low effective cation exchange capacity, and soils in the middle slope were poor in quality (26 = SQ3) due to low soil nutrients. The implication to farmers is that crop grown on upper and lower slope will grow better than those on middle slope due to variations in nutrients. The middle slope was more afflicted by denudation processes because its steep slopes favour erosion. In conclusion, our data show that soil nutrient and quality varies across slope classes and different management practices should be adopted based on slope classes for sustainable crop production. Farmers are therefore advised to add more organic manure and crop residues as well as practice terrace farming on the middle slope for sustainability.