EFFECT OF COMBINED APPLICATION OF FARMYARD MANURE AND INORGANIC FERTILIZER (NP) SOURCE ON YIELD AND QUALITY OF POTATO (Solanum tuberosum L.) IN HADIYA ZONE, DUNA DISTRICT, SOUTHERN ETHIOPIA.

Abstract

Potato (Solanum tuberosum.L) is one of the most important tuber crops produced in southern Ethiopia. However, production and productivity of the crop is far below the world average due to inappropriate agronomic management practices including nutrient management. An experiment was conducted to study the effect of combined application of farmyard manure (FYM) and inorganic fertilizer (NP) on yield and quality of potato. Treatments consisted of five levels of NP (0, 25, 50, 75 and 100% of recommended NP) and four levels of FYM (0, 5, 10 and 15 t ha -1 ). The treatments were assigned in completely Randomized Block Design (RCBD) with a 5x4 factorial arrangement with three replications. Data were collected on growth, yield and quality parameters and analyzed using SAS 9.0 software. Results revealed that most of the growth, yield and quality parameters such as, plant height, days to flowering, main stem number, days to physiological maturity, total tuber number, marketable tuber number, total tuber yield, marketable tuber yield and specific gravity were influenced by the main effect of inorganic NP and farmyard manure. The result also indicated that interaction effect of inorganic NP and farmyard manure significantly affected unmarketable tuber yield, aboveground fresh yield, aboveground dry yield, large sized tuber (%), Medium sized tuber (%) and Dry matter content. The highest aboveground fresh yield, highest aboveground dry yield, highest large sized tuber and medium sized tuber were obtained from application of 100% inorganic NP with 15t ha -1 farmyard manure. While the lowest values of parameters were recorded from the control treatment. Further, the highest marketable yield, total tuber yield and highest tuber dry biomass were obtained from each of 15 t ha -1 FYM and 100% NP fertilizer. From economics point of view, the maximum marginal rates of return (2446.90%) with its net benefit value of 190,128 ETB ha -1 was recorded from the application of 10t ha -1 farmyard manure. With regard to inorganic fertilizer 50% of recommended NP showed the highest marginal rate of return (1176.14%) with a net benefit of 167645ETB.Therefore, farmers in the study area can apply 10t ha -1 farmyard manure or 50% of recommended inorganic NP fertilizer.