Potassium fertilization enhances teff [ Eragrostis tef (Zuccagni) Trotter] productivity across contrasting soils in Omo‐Nada, southwestern Ethiopia

Abstract Potassium (K) is an essential macronutrient vital for plant growth and crop production. However, the misconception that K fertilization is unnecessary has long persisted in Ethiopia. Hence, a field experiment was conducted during the 2021 and 2022 cropping seasons on Nitisol and Cambisol soils to evaluate the response of teff [ Eragrostis tef (Zuccagni) Trotter] to different K fertilizer rates in terms of yield, nutrient concentration, uptake, and use efficiency. The K rates (0, 60, 120, and 180 kg K ha −1 ) were applied as muriate of potash (KCl) in a randomized complete block design with three replications. Results showed that K application significantly ( p < 0.01) increased teff grain yield on both soils. The application of 120 kg K ha −1 produced yield gains of 39.4% and 36.7% over the control on Nitisol and Cambisol, respectively. The highest mean straw nitrogen (N) concentration (6.63 g kg −1 ) on Nitisol was recorded in the control plot, while the lowest was recorded with an application of 180 kg K ha −1 . On Cambisol, plant N, phosphorus (P), and K uptakes were significantly ( p < 0.05) higher, with maximum values of 74.7, 31.9, and 95.4 kg ha −1 , respectively, under 120 kg K ha −1 . On Nitisol, only N uptake was significantly affected, reaching 61.3 kg ha −1 . Potassium (K) application also improved agronomic K use efficiency on both soils. These findings refute the long‐held belief that Ethiopian soils are inherently rich in K. Future fertilizer recommendations for teff production on Nitisols and Cambisols should include K fertilization to improve productivity.