Verification of Soil Test Crop Response Based Phosphorus Recommendation on Bread Wheat (Triticum aestivum L.) in Leka-Dulacha District, Eastern Wollega Zone, Western Ethiopia

Abstract

Bread wheat is a major cereal crop cultivated in Ethiopia. Owing to soil fertility depletion, particularly phosphorus (P) deficiency in high-rainfall areas, wheat productivity remains suboptimal in the study area. This study was conducted to verify soil test crop response-based phosphorus fertiliser recommendations for bread wheat in Leka-Dulacha District, extrapolated from the adjacent Jima-Arjo District. A field experiment was laid out in a randomised complete block design with three treatments: control, farmers’ practice, and soil test crop response-based P fertiliser recommendation, each replicated three times. The initial soils at the experimental sites were very strongly acidic, with pH values ranging from 4.55 to 4.99, low available P ranging from 3.95 to 12.14 mg kg⁻¹ soil, and moderate organic carbon and total nitrogen contents. The soil test crop response-based P fertiliser recommendation significantly (p ≤ 0.001) increased plant height, spike length, number of seeds per spike, number of effective tillers, biomass yield, and grain yield. The reported grain yield reached 29,300 kg ha⁻¹, representing a 74.41% increase over farmers’ practice. Economic analysis showed the highest net benefit of ETB 126,487 ha⁻¹ and a marginal rate of return of 449.00% under the soil test crop response-based recommendation. These results indicate that extrapolating the calibrated phosphorus recommendation from Jima-Arjo to Leka-Dulacha was agronomically effective and economically profitable under the study conditions.