Assessment of primary macronutrient deficiency of maize (Zea mays L.) through nutrient omission trials in Omo Nadda district, southwestern Ethiopia

Abstract

Maize (Zea mays L.) is a crucial staple crop in Ethiopia, widely cultivated and consumed across various regions. Despite the ongoing efforts to increase production, maize yields in some areas remain below their potential due to persistent nutrient deficiencies and improper fertilizer application practices. To address this challenge, a study was conducted in 2023 in the Nitisols of Omo Nada District, Southwestern Ethiopia, to identify the key nutrients limiting maize yields and assess the effect of nutrient omission on maize production. The study employed a randomized complete block design with four farmer groups serving as replicates. Various nutrient omission treatments were applied, including control (no amendment), PK (−N), NK (−P), NP (−K), nitrogen, phosphorus, and potassium (NPK), and NPK + lime. Maize growth parameters, yield, yield components, and agronomic efficiencies were carefully monitored and analyzed using SAS 9.3 software. The results showed that the application of 120 kg N ha⁻¹ + 46 kg P ha⁻¹ and 120-46-50 NPK ha⁻¹ produced significantly higher grain yields—(9.7 tonne ha⁻¹) and total biomass including stover (11.66 tonne ha⁻¹). The exclusion of nitrogen (N) and phosphorus (P) in comparison to NPK resulted in significant yield losses of 5.76 tonne ha-1 (59.38%) and 3.93 tonne ha⁻¹ (40.52%), respectively. Furthermore, the addition of lime to NPK treatment increased grain yield by 10.93% compared to NPK alone. The grain yield reductions followed the order: control > PK > NK > NP > NPK > NPK + lime. The maximum agronomic efficiencies for nitrogen (68.39), phosphorus (178.42), and potassium (164.15) were achieved with the NPK + lime treatment. In conclusion, nitrogen and phosphorus were the critical nutrients limiting maize yields on Nitisols in southwestern Ethiopia. By adopting a nutrient management strategy that addresses both N and P nutrient deficiencies and soil acidity, farmers can improve maize production and achieve sustainable crop yields in the region.