Effects of chemical fertilizer types and rates on tuber yield and quality of potato (Solanum tuberosum L.) at Assosa, Western Ethiopia

Potato tuber yield and quality is constrained by a number of biotic and abiotic factors, among which low soil fertility is the prime one. Thus, the objective of the study was to evaluate the effects of chemical fertilizer types and rates on tuber yield and quality of potato at Assosa, Western Ethiopia. The treatments consisted of control, three rates of NP combinations (55 kg N and 45 kg P2O5, 110 kg N and 90 kg P2O5, 165 kg N and 135 kg P2O5 kg ha-1), one NPK combination (110 kg N, 90 kg P2O5  and 69 kg K2O ha-1), formula 2 (100 % NPSB + 91.9 N kg ha-1 and 200% NPSB + 128.8 N kg ha-1) and formula 4 (100 % NPSZnB + 93.1 N kg ha-1 and 200% NPSZnB + 131.2 N kg ha-1). It was observed that higher marketable tuber yield (30.03 t ha-1) and total tuber yield (34.58 t ha-1) were obtained with the application of NPK (110 kg N + 90 kg P2O5 + 69 kg K2O ha-1) implying that K is an important limiting nutrient besides N and P in the study area. Therefore, NPK fertilizer application is recommended for high yield and quality tuber production in Assosa area, western Ethiopia.   Key words: Chemical fertilizer, potato, tuber, yield.