Abstract:
In the Ethiopian highlands, low soil fertility which is resulting from soil acidity has been a
major problem and maintaining sufficient available P and N for crop growth is a major
challenge. Therefore, use of legumes with efficient P uptake and N fixation capacity under
such conditions can increase yield of legumes and soil fertility that contribute for sustainable
crop production. This study was carried out on farmer field in the highland of southwestern
Ethiopia to evaluate faba bean varietal difference in growth, yield, P-uptake and N2 fixation
with and without P application in acid soils. Eight faba bean varieties consisting of improved
varieties (Dagaga, Gebelcho, Gora, Dosha and Tumsa) and farmers’ varieties (Arabe,
Kambata and Orome) were grown with two levels of P application (0 and 23 kg P ha-1) with
factorial arrangement in a Randomized Complete Block Design with three replications.
Collected data were subjected to ANOVA using SAS statistical package version 9.3. The result
showed that variety and P application significantly affected growth, yield components, P and
N accumulation, biological nitrogen fixation (BNF) and %Ndfa of faba beans. Significant
interaction of variety by P was observed for root dry weight and yield. Variety Gebelcho had
the highest total P accumulation (20.7 kg P ha-1), total N accumulation (130.5 kg N ha-1) and
N2
fixed (94.0 kg N ha-1), while variety Orome had the lowest value of 10.0 kg P ha-1, 65.4 kg
N ha-1 and 29 kg ha-1 for the respective parameters. Variety Tumsa had the highest %Ndfa
(68.1%) and Orome had the lowest value (36.2%). P application significantly influenced N
fixation as 48.9 kg N ha-1 was fixed by the plants without P application and plants with P
application fixed 86.4 kg N ha-1and, thus, p application increased nitrogen fixed by 77%.
Variety Gebelcho with P application had the highest grain yield (5.6 t ha-1), haulm weight
(4.88 t ha-1) and total above ground biomass yield (10.49 t ha-1), while variety Orome had the
lowest grain yield (2.1 t ha-1) and total above ground biomass yield (4t ha-1) with no P
application, and haulm weight with P application (1.89 t ha-1). Variety Gebelcho showed the
highest P uptake, N2 fixing and yield capacity. Among the farmer’s varieties, Kambata
showed statistically similar capacity to that of Gebelcho except having lower yield with P
application. Application of P with improved varieties like Gebelcho could be ideal for acid
soils with low P and N in the Ethiopia highlands cropping systems. However, under condition
in which farmers cannot afford for agricultural input package the variety Kambata could give
farmers an option to increase soil fertility, contributing to sustainable agricultural
intensification to enhance resilience of resource poor farmers.
