Al-Qadisiyah Journal For Agriculture Sciences (QJAS) ISSN : 2618-1479 Vol.12, Issue. 1 ,(2022), pp. 98-110 https://jouagr.qu.edu.iq/ Page 98 | University of Al-Qadisiyah , College of Agriculture DOI: 10.33794/qjas.2022.133490.1037 This is an open access article under the CC BY 4.0 licence (https://creativecommons.org/licenses/by/4.0/) Response of Common Bean (Phaseolus vulgaris L.) to NP Fertilizer Rates and Plant Population Density at Jimma Zone, Southwest Ethiopia Muhidin Biya 1 , Eshetu Yadete 2 and Sisay Gurmu 3 1-3 Jimma Agricultural Research Center, P. O. Box 192, Jimma, Ethiopia. 1 Corresponding author E-mail: muhibiya@gmail.com Received : 8/4/2022 Acceptance : 30/5/2022 Available online: 1/6/2022 Abstract. Field experiments were carried out for 2018-2020 main cropping seasons at kersa and Omonada Jimma on farmers’ fields. The treatments consisted of factorial combinations of 23/23, 23/46, 46/46 and 69/69 NP kg ha-1 levels with inter and intra (333333, 250000, 200000 and 166667 plant density ha-1) respectively laid down in a randomized complete block design (RCBD) with three replications using (Nassir) common bean variety. Across season and location data analysis of ANNOVA showed that all parameters were significantly affected by different densities and NP fertilizer rates including above ground biomass, harvest index and grain yield except harvest index was not affected by NP fertilizer rates. The highest plant height (72.51cm) was recorded from the highest (69/69 kg ha-1) NP fertilizer rate. The highest above ground biomass and grain yield of 6.40 and 2.45 t ha-1 were obtained from the highest (333333) plant density ha-1. Also, it showed still there was an increase in plant density increases with 26.29 and 6.52% grain yield advantage over the lowest density and control recommendation respectively. Also from economic and sensitivity analysis results treatments (333333) ha-1 plant population density, (23/23) and (46/46) kg/ha NP fertilizer rates gave the highest yield response and net benefit with MMR 1035, 111 and 224% respectively. In conclusion, intra and inter row spacing 3*10cm or equivalent (333333) ha-1 plant population density with applications of one of the two (23-23) or (46/46) kg/ha NP fertilizer rates based on their resource was recommended to farmers of study areas and similar agro ecology. Keywords. Plant, Density, NP, fertilizer, Rate. 1. Introduction The common bean (P. vulgar is L.) is a pulse that serves as an important protein supplement in the cereal-based Ethiopian diet and forms a significant export commodity group to fetch hard currency for the country. Also, it was highly preferred by farmers for fast-maturing than all crops for consumption, fresh local market cash income and also its compatibility for intercropping with maize. When the common bean's economic importance is considered, it is used as a source of foreign currency, food crop, means of employment and source of cash, and plays a great role in diversifying the farming system [1]. Common bean in Ethiopia is produced in almost all the regional states with varying intensity and is widely grown in low land and mid-altitude areas. The crop also does well in some areas as low as 500 m and as high as 1900 m a.s.l. that receive a well-distributed average rainfall of 500 to 1500 mm throughout the growing season [2]. It is an important pulse crop occupying about 366,877 ha (19.69% of the land area allocated to pulses) and producing about 463,008 tons of grain (16.83% of the total pulses production) [3]. The average yield (1.26 t ha–1) of common bean is low which is partly because phosphorus is deficient in about 70% of soils of Ethiopia [4]. Phosphorus is considered the first and nitrogen is the second limiting plant nutrient for bean yield in the tropical zone of cultivation. It’s the basis for the formation of useful energy, which is essential for sugar formation and translocation reported that a common bean crop dependent on nitrogen fixation needs more inorganic phosphorus than the same crop provided with mineral nitrogen. Beans are