RESUMO
BACKGROUND: Sodic soils are harmful to agricultural and natural environments in Ethiopia's semi-arid and arid regions, leading to soil degradation and reduced productivity. This study investigated how amendment resources could help improve the chemical properties of sodic soils around the Abaya and Chamo Lakes in the South Ethiopia Rift Valley. METHODS: A factorial experiment was conducted to study the effects of gypsum (GYP) and farmyard manure (FYM) on sodic soil reclamation. The experiment had four levels of GYP (0, 50, 100, and 150%) and four levels of FYM (0, 10, 20, and 30 tons ha-1), with three replications. The pots were incubated for three months and leached for one month, after which soil samples were collected and analyzed for chemical properties. ANOVA was performed to determine the optimal amendment level for sodic soil reclamation. RESULTS: The study found that applying 10 ton FYM ha-1 and gypsum at 100% gypsum required (GR) rate resulted in a 99.8% decrease in exchangeable sodium percentages (ESP) compared to untreated composite sodic soil and a 1.31% reduction over the control (GYP 0% + FYM 0 ton ha-1). As a result, this leads to a decrease in soil electrical conductivity, exchangeable sodium (Ex. Na), and ESP values. The results were confirmed by the LSD test at 0.05. It is fascinating to see how different treatments can have such a significant impact on soil properties. The prediction models indicate that ESP's sodic soil treatment effect (R2 = 0.95) determines the optimal amendment level for displacing Ex. Na from the exchange site. The best estimator models for ESP using sodic soil treatment levels were ESP = 1.65-0.33 GYP for sole gypsum application and ESP = 1.65-0.33 GYP + 0.28 FYM for combined GYP and FYM application, respectively. CONCLUSION: The study found that combined GYP and FYM applications reduced ESP to less than 10% in agriculture, but further research is needed to determine their effectiveness at the field level.
RESUMO
Deficiency of phosphorus (P) and sulfur (S) is increasingly being reported in soils of Ethiopia. While some studies have shown significant response of wheat to P and S application, information on the response of wheat to P and S application interactively is conspicuously lacking. In this regard, we evaluated the response of wheat to P and S application interactively in the study area. A field experiment was conducted at two locations to determine the effects of P and S, on yield, uptake and P, S use efficiency of bread wheat. A factorial combination of four levels of P (0,11,22 and 44 kg h-1) and three levels S (0, 15 and 30 kg ha-1) laid out in Randomized Complete Block Design with three replications. Results revealed that interacted application of P and S at 22 and 15 kg ha-1 respectively increased grain yield of wheat by 40.1 % over control. The corresponding increase with straw was 53.4 % over control. Wheat yield obtained with combined application of P and S greater than single application of P or S indicating synergistic between them. The maximum grain N (56.3 kg ha-1), P (12.8 kg ha-1) and S (4.2 kg ha-1) uptakes were obtained due to combined application of P and S at 22 P and 15 S kg ha-1. Agronomic efficiencies of P and S decreased as the rates of P and S application increased. Combined fertilization of S and P is necessary in the study district and 15 kg S combined with 22 kg P ha-1 produced the highest yield. Thus, this treatment is found to be recommended for bread wheat production in Vertisols of the district. While, partial budget analysis result revealed that, combination of 22P and 15S kg ha-1 produced the highest MMR (54.9 %) and thus, this treatment is found to be economically feasible treatment for bread wheat production in study area of the district. We recommend further experiments on different combination of P with S in different agro-ecologies and soil types are required for confirmation of results and the residual effect of P and S on the following crop is needed to study the long-term effect of P and S.
