Abstract:
A field experiment was conducted at Haramaya University, Rare site, to evaluate the effect of
blended NPSB fertilizer rates on the yield and yield components of common bean varieties, as
well as to calculate the cost-benefit ratio of NPSB rates during the main cropping seasons of
2022. Factorial combinations of three common bean varieties (Haramaya, Tinike, and Nasir)
and five level of blended NPSB fertilizer rates (0, 50, 100, 150, and 200 kg ha-1
) were laid out
in a randomized complete block design with three replications. Data on phonological, growth,
yield-related components, and yield were gathered and analyzed using Gene Stat Software
version 18. The main effects of variety significantly affected days to 50% flowering, days to
90% physiological maturity, number of total nodules, effective nodule number, number of
primary branches, final plant stand count, number of pods per plant, seeds per pod, hundred
seed weight, aboveground biomass and seed yield. Variety Haramaya produced the highest
number of primary branches (4.85), number of pods per plant (25.15), aboveground biomass
(6,479 kg ha-1
) and seed yield (3,110 kg ha-1
). The main effects of blended NPSB fertilizer
application rate significantly affected almost all parameters except seeds per pod. The
application of 150 kg NPSB ha-1
resulted in the highest aboveground biomass (6,764 kg ha-1
),
seed yield (3,160 kg ha-1
), number of pods per plant (22.96), and number of primary branches
(5.13). The interaction of variety and NPSB fertilizer application rate significantly effected
plant height and harvest index. The interaction effects of Tinike with 150 kg NPSB ha-1
produced the highest plant height (53.87 cm), while the Haramaya with 200 kg NPSB ha-1
produced the highest harvest index (53.92%). The interaction effects of variety Haramaya with
the application of 150 kg NPSB ha-1
yielded the highest net benefit of 130,638 birr ha-1 with a
marginal rate of return of 777.62% and also provided the highest agronomic efficiency (9.02
kg seed kg-1
of NPSB). Thus, the application of 150 kg of NPSB ha-1 with the Haramaya
variety offered the most economic benefit and could be used to produce common beans in the
study area. However, since only one season and one place were used for the experiment, more
seasons and locations should be used in the future to get a conclusive recommendation
