Conservation and Conventional Vegetable Cultivation Increase Soil Organic Matter and Nutrients in the Ethiopian Highlands

Abstract

Agriculture in Africa is adversely affected by the loss of soil fertility. Conservation agriculture (CA) was introduced to curb the loss of soil fertility and water shortages and improve crop productivity. However, information on how CA practices enhance soil quality and nutrients is scarce in the sub-Saharan Africa context. The objective of this study was to investigate the effects of CA and conventional tillage (CT) on soil organic matter and nutrients under irrigated and rainfed vegetable on-farm production systems. During the dry and wet monsoon phases in the northern Ethiopian Highlands, a four-year experiment with CA and CT was carried out on ten vegetable farms under rainfed and irrigated conditions. Although the increase in concentration of organic matter in CA was generally slightly greater than in CT, the difference was not significant. The average organic matter content in the top 30 cm for both treatments increased significantly by 0.5% a−1 from 3% to almost 5%. The increase was not significant for the 30–60 cm depth. The total nitrogen and available phosphorus concentrations increased proportionally to the organic matter content. Consequently, the extended growing season, applying fertilizers and livestock manure, and not removing the crop residue increased the nutrient content in both CA and CT. The increase in CA was slightly greater because the soil was not tilled, and hay was applied as a surface cover. Although CA increased soil fertility, widespread adoption will depend on socioeconomic factors that determine hay availability as a soil cover relative to other competitive uses.

Intercropped Maize and Cowpea Increased the Land Equivalent Ratio and Enhanced Crop Access to More Nitrogen and Phosphorus Compared to Cultivation as Sole Crops

“…To counter the trend of soil fertility loss, which can jeopardize the food security of small-scale farmers, it is usually recommended to use organic amendments and adopt practices that increase the amount of crop residues left on the soil [7,8]. If crop residues are not removed from the field, they can enhance soil organic matter and nutrient cycling, particularly important in acidic tropical soils with a sandy texture [9][10][11]. Intercropping practices can also benefit soil fertility, being seen as very important for regions of the world where farmers have limited access to industrial fertilizers, and, not requiring external inputs, they are easy to implement [1,2].…”

Heavy metal pollution and risk assessment of tailings in one low-grade copper sulfide mine

“…The pH was measured using a pH meter (PHS-3C, Ramag, China) at a 2.5:1 water-to-tailings ratio. The cation exchange capacity was estimated at pH equal to seven by ammonium acetate exchange method (Belay et al, 2022). The mineral phase of the tailings was determined by X-ray diffraction spectroscopy (X'Per Powder, PANalytical, Netherlands) scanning from 10 °to 80 °at a scan speed of 1 °/min.…”

Physiological and Molecular Approaches for Developing Thermotolerance in Vegetable Crops: A Growth, Yield and Sustenance Perspective

“…Similarly, improved yields of tomato, cucumber and bitter guard were observed under conservation agriculture (Paudel et al, 2020 ). Conservation agricultural practices in vegetable production systems has shown to increase soil organic matter and nutrients (Belay et al, 2022 ). Irrigation increases soil moisture, decreasing soil temperature (by 2°) compared to non-irrigated soil (Lobell and Bonfils, 2008 ).…”