RESPONSE OF FABA BEAN (Vicia faba L.) VARIETIES TO PHOSPHORUS FERTILIZER RATES IN LIMU BILBILO DISTRICT OF ARSI ZONE, SOUTH EASTERN ETHIOPIA

Abstract

Faba bean production is a common practice in Limu Bilbilo areas. However, its productivity is affected and limited by poor soil fertility and lack of alternative technologies such as application of optimum phosphorus fertilizer for different faba bean varieties. Limited studies on the role of P on faba bean varietal yield and yield components are reported in Ethiopia, especially in the case of Limu Bilbilo conditions. Studies on the effect of phosphorus (P) fertilization are generally missing in the area. Farmers have been using fertilizer rates based on blanket recommendations. Apart from this, there is scanty information on the optimum P rates for faba bean to enhance its production and productivity. In view of this, a field experiment was conducted on farmer’s field during the 2017 main cropping season at Limu Bilbilo with the objectives to determine the response of faba bean varieties to different rates of P fertilizer and its effect on yield and yield components of faba bean varieties in Limu Bilbilo district. The treatments include three faba bean varieties (Tumsa, Gebelcho and Dosha) and five phosphorus levels (0, 10, 20, 30 and 40 kg P ha-1) from triple super phosphate (TSP). The experiment was laid out in a randomized complete block design with factorial arrangement of 3 x 5 =15 treatment combinations with three replications. Selected physical and chemical properties of soil, nodulation parameters, growth parameters, yield and yield components were recorded and analyzed. The available P content of the soil was generally found to be very low to low and application of P significantly (P<0.05) affected available P concentration and total N of the soil. The highest concentration of available P (9.94 mg kg-1) was recorded at phosphorus level of 40 kg ha-1. Significantly (P< 0.05) higher total number of nodule, effective nodules and plant height were recorded from Tumsa variety. Stand count at emergence, total productive tillers per plant, number of nodules per plant, thousand kernel weights, harvest index and biomass yield were significantly affected by main effect of varieties. Higher total number of nodules per plant (63) and total productive tillers per plant (1.53) were obtained from application of 30 kg P ha-1. Higher plant height (153 cm), biomass yield (14,158 kg ha-1) and grain yield (6,323 kg ha-1) were obtained from application of 40 kg P ha -1. Applications of different rates of P had a highly significantly (P<0.001) influenced faba bean agronomic phosphorus use efficiency. Higher agronomic phosphorus use efficiency (569 kg grain kg-1P) was recorded from plots applied with 10 kg P ha-1. Most of the parameters studied were positively correlated to biomass and grain yield of faba bean. The higher economic return of ETB 59,689 ha-1 (502%MRR) was obtained from application of 30 kg P ha-1. Therefore, it can be concluded that application of 30 kg ha-1 of P with Tumsa, Gebelcho and Dosha faba bean variety was proved to be productive and superior both in seed yield as well as economic advantage and might be recommended for Limu Bilbilo area. Further study should be conducted in the future both over locations and years in order to give full recommendation for practical application.