Abstract:
Black cumin (Nigella sativa L.) is an important annual flowering plant which mainly is grown by
producers for its seeds. An increasing demand of black cumin seed and oil in local, national and
international markets for medicinal, consumption and commercial purposes makes the best
alternative crop. In spite of its importance, much has not been done to improve its production
and productivity in Ethiopia. The average yield of black cumin in Dembia district is low due to
inappropriate agronomic practice, soil fertility, lack of improved varieties, absence of
recommended fertilizer rate and insect pest problems. A field experiment was conducted in East
Dembia district during 2019/20 cropping season. The study is designed to investigate the effects
of N and P fertilizer rates for achieving higher yields and economic return of black cumin.
Treatments were consisting of a factorial combination of four levels of N (0, 23, 46 and 69 kg ha
1
) and four levels of P
2
O
5
(0, 15, 30 and 45 kg ha
xvi
-1
) which were laid out in RCBD with three
replications. Data on growth, yield and yield components were collected and analyzed with SAS
computer software version 9.2. The result of the experiment reveled that N and P fertilization
significantly increased plant height, number of primary and secondary branches, capsule
numbers, capsule diameter, seed yield and harvest index. Similarly, very highly significant
interaction effects of N and P were observed on plant height, number of primary branches per
plant, number of secondary branches per plant, number of capsules per plant, capsule diameter,
harvest index and seed yield. The results also indicated that, the highest plant height (69.83 cm),
number of primary branches plant
-1
(11.53), secondary branches plant
-1
(22.78), capsule
numbers plant
-1
(34.70), capsule diameter (12.14mm), seed yield (1658.40 kg ha
) were recorded
from the combined application of 69 kg N and 45 kg P
2
O
5
ha
-1
; and the highest harvest index
(40.96%) was obtained from the combination of 46 kg N and 45 kg P
2
O
5
ha
-1
.While, the lowest
seed yield ha
-1
(820.62kg) and harvest index (27.48%) were recorded from the control. The
partial budget analysis revealed that 46 kg N ha
-1
combined with 45 kg P
2
O
fertilizer rate
showed high MRR (3242.08%) and highest NB (82056.66 ETB ha-1) followed by 23 kg N ha
5
combined with 45 kg P
2
O
5
ha
-1
-1
ha
fertilizer rate. So use of a combination of 46 N and 45 P
kg
ha
-1
for black cumin production is recommended in the study area and other similar
environments.
