Evaluation of Blended and Non-blended Fertilizer Types and Rates on Potato (Solanum tuberosum L.) Yield and Yield Components at Assosa, Western Ethiopia

Abstract

Potato (Solanum tuberosum L.) plays a major role in national food security, poverty alleviation and income generation. However, the yield of the crop is constrained by a number of biotic and abiotic factors, among which soil fertility decline is one of the major factors limiting productivity. The study was designed to evaluate the effects of blended and non-blended fertilizers types and rates on yield and yield components of potato at Assosa, in 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 K2 O ha -1 )and two different formula of blended fertilizers with two N rates for each, formula 2 (100 % NPSB with adjusted N kg ha -1 and 200% NPSB with adjusted N ha -1 ) and formula 4( 100 % NPSZnB with adjusted N ha -1 and 200% NPSZnB with adjusted N ha -1 ). The treatments were laid out as a Randomized Complete Block Design with three replications. The experimental soil was strongly acidic in pH, clay loamy in texture, medium in organic carbon and CEC, low in total N and B, low in available P, sulfur and exchangeable K. Potato variety called Belete (CIP-393371.58) was used for the study. Analysis of variance revealed that the blended and non-blended fertilizers had highly significant influence on days to 50% flowering, leaf area index, underground dry biomass, plant height, mean tuber weight, marketable and total tuber yield, tuber dry matter content and large tuber size. It was observed that the maximum yields for marketable tuber yield (30.03 t ha -1 ) and total tuber yield (34.58 t ha -1 ) were obtained from the application of 110 kg N+90 kgP2O5 + 69kg K2 O ha -1 . The lowest marketable and total tuber yields were recorded with control. The highest N tuber concentrations were recorded at application of 100% NPSB+ 91.9 kg N ha -1 .The maximum P concentration in tuber were obtained at application of 110kgN+90kgP2O5 + 69kg K2O ha -1 and 165 kg N+ 135 kg P2O5 ha -1 . Highest nitrogen uptake of tuber was observed at application of 100% NPSB with adjusted N kg ha -1 whereas the lowest was recorded from control treatment. Maximum phosphorus uptake of tuber was obtained at application of NPK (110 kg N ,90 kg P2O5 , 69 kg K2 ha -1 ) whereas minimum phosphorus uptake was obtained at control treatment. The highest agronomic efficiencies of tuber yield were recorded from application of 100% NPSB with adjusted N kg ha -1 . Furthermore, 98.38 and 22.3% tuber apparent recovery efficiencies of N and P were obtained at 100% NPSB with adjusted N kg ha -1 . Tuber nutrients uptake was positively and significantly correlated to total dry tuber yields. The cost-benefit analysis indicated that application of 110 kg N, 90 kg P2O5 and 69 kg K2 O ha -1 resulted in highest net benefit and marginal rate of return. Therefore application of 110 kg N, 90 kg P2O5 and 69 kg K2 O ha -1 fertilizers can preferably be used as the most appropriate for potato production at Assosa area. However, since this experiment was conducted only for one season, further studies involving more levels of blended fertilizer including potassium over multi-locations should be conducted to give conclusive recommendation.