Identifying limiting nutrient(s) for better bread wheat and tef productivity in acidic soils of north-west Amhara, Ethiopia

Food crop productivity is still low because of the decline of soil fertility in Ethiopia, particularly in north-western Amhara. Fine-tuning the source and rate of nutrients is required to solve soil fertility problems along landscape positions. Therefore, this study was initiated to investigate the need to apply selected nutrients to tef and wheat in acidic soils. This nutrient omission study was conducted in 74 farmers’ fields of Gozamen and Machakel districts. The omitted nutrients were sulfur (S), zinc (Zn), and boron (B). Potassium (K) was added, consisting of N, P, K, S, Zn, and B (All+K). Nitrogen plus phosphorus (NP) and no fertilizer treatments were used as positive and negative controls, respectively. Furthermore, 50% and 150% of the All+K treatments were also included. The finding revealed that the application of different nutrient types at variable rates had a significant role in the grain and biomass yield of both test crops in the acidic soils. No tef yield and the lowest yield of bread wheat were obtained from the no fertilizer application treatment. The application of All+K had no significant yield advantage compared to NP fertilizer alone. This implies that N and P are the most yield-limiting nutrients to produce tef and bread wheat, whereas KSZnB nutrients are not yield limiting. Therefore, refining the rates of N and P in acidic soils is needed for the economical use of fertilizers. Finally, applying blended fertilizers without empirical evidence is not recommended for smallholder farmers in the study area.