Identifying Major Determinant Nutrients for Potato (Solanum tuberosum L.) Growth and Tuber Yield in North Western Amhara, Ethiopia

In Ethiopia, fertilizer consumption has shown a linear increment. One-year-on-farm research was conducted in the Amhara region to identify major determinant nutrient types for potato (Solanum tuberosum L.) growth and tuber yields in Amhara region. The experiment was conducted in 2021 under rain fed conditions on eight farm fields in the Amhara region classified under three major potato-growing domains (Quarit-Yilmana Densa, Dembecha, and Baja-Sekela). A total of ten treatments (NPSZnBK, NPSZnK-B, NPSBK-Zn, NPZnBK-S, NPSZnB-K, NSZnBK-P, PSZnBK-N, NPS, NP, and control) were evaluated in the experiment. The treatments were laid out in a randomized complete block design (RCBD) and replicated three times. The improved potato variety “Gudenie (CIP-386423–13)” was used as a test crop. Urea, TSP (triple super phosphate), KCl (muriate of potash), MgSO₄ (magnesium sulfate), EDTA, and Borax were used for the sources of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), zinc (Zn), and boron (B) nutrients, respectively. Except for urea, all fertilizer sources were applied once at planting, while urea was applied in three equal splits at different crop stages (planting, flowering, and tuber initiation). Before planting, one composite soil sample from each experimental site was taken at 0–20 cm depth, and analysed for some important soil parameters. Both potato yield components and biological yield (tuber yield) were taken. Marketable and total tuber yields of potato showed highly significant differences among treatment means at each experimental site as well as from combined analysis in the study domains. The main driving force for the occurrence of significant differences between treatment means in the ANOVA was due to omitting N and P nutrients. Tuber yield of potato showed quick and automatic responses to omitting N followed by omitting P. However, both marketable and total tuber yields did not show any significant differences, either due to adding or omitting S, Zn, B, and K nutrients. This showed that currently N and P nutrients are major potato yield-limiting nutrients in Amhara region, Ethiopia.