By: Woldeyesus Sinebo*, Demis Zewedu, and Tewedros Demise *Corresponding author: wsinebo@hotmail.com

1. Yield response of bread wheat under intensive on-farm management in southern Ethiopia
Woldeyesus Sinebo1*, Demis Zewedu2, and Tewedros Demise2
1
Southern Agricultural Research Institute and 2Areka Agricultural Research Center, PO. Box 06, Hawassa, Ethiopia; *Corresponding author: wsinebo@hotmail.com
Abstract
We undertook a series of on-farm and on-station experiments to evaluate the effects of nitrogen fertilizer application rates, seed rates, sowing methods, and sowing dates on bread
wheat in four zones of the SNNP. Averaged over 12 trials, increasing N application rate from 18 to 110kg/ha increased grain yield from 3.7 to 4.8 t/ha. Further increases in N
rate, on average, increased yield only slightly. In individual trials, additional yield attained due to the application of 110kg/ha N over the application of 18kg/ha N, ranged from
0.5t/ha to 1.9t/ha. Of the 12 trials, eight had yield gain of more than 1t/ha. The two trials conducted in farmers' fields around Waka in Dawro zone gave an average maxima of 6.9
and 7t/ha with the application of 248kg/ha N. Averaged over locations and sowing methods, yield increased from 3.5 to 4.2t/ha when seed rate was increased from 125 to
250kg/ha. There was a highly significant seed rate by sowing method interaction for grain yield. Yield increased more sharply with increase in seed rate under broadcasting than
under row sowing. Row sowing gave 200-300kg/ha more yield than broadcasting in two of the three locations. There was a quadratic relationship between sowing date and yield,
with a peak yield when sowing was done at about three weeks after the onset of rainfall. Early sowing resulted in lower yield presumably because of attack of seedlings by barley
shoot fly combined with bird damage after flowering. The results indicate high on-farm yield potential of current bread wheat varieties when management practices are optimized.
Keywords: nitrogen rate, seed rate, sowing date, sowing method
Introduction Materials and Methods
Bread wheat is an important cereal crop produced in most zones of the We undertook a series of on-farm and on-station experiments involving various nitrogen
SNNP region of Ethiopia. Although optimal crop management options fertilizer application rates, seed rates, sowing methods, and sowing dates in Hadiya,
are location and context specific, blanket recommendations developed Kembata-Tembaro, Wolaiyta, and Dawro zones. In one experiment, nitrogen fertilizer
for the central highlands of Ethiopia have been used for decades in the was applied at a rate of 18, 64, 110, 156, 202 or 248kg/ha with a blanket application of
46 P2O5 kg/ha across all the N treatments. The experiment was conducted in four
region. Moreover, in view of the changing climate and varietal
replications on nine farms and three sub-stations for a total of 12 trials. In another
dynamics, these existing recommendations developed long ago have
experiment, seed rates of 125, 150, 175, 200, 225, and 250kg/ha were tested in
not been updated. The objective of this paper is to report preliminary randomized complete blocks with four replications each under row sowing or
results from studies conducted to determine appropriate N fertilizer broadcasting in three locations. In a third experiment, six sowing dates, ranging from
rate, seed rates, sowing methods and sowing dates for bread wheat June 17 to August 16 were factorially combined with two varieties and tested in a
production in different zones of the SNNP. randomized complete block design with four replications at two locations.
Results
Table 1. Response of bread wheat to N (kg/ha) Table 2. Grain yield response of bread wheat to seed
Farm 18 64 110 156 202 248 Mean rate and sowing method in the SNNP
Angaf1 3609 4195 5094 5375 5438 5344 4842 Seed rate Angacha Hosaena Waka Mean
Angaf2 4883 5047 5500 5563 5688 5008 5281 (kg/ha)
Angast 2547 3063 3891 4039 4164 4781 3747
Hosf1 2031 2938 3438 3344 3469 3641 3143 125 3250 2875 4281 3469
Hosf2 4219 5266 5461 5641 5594 5523 5284
Hosf3 3977 4617 5336 5109 5484 5813 5056 150 3293 3305 4156 3585
Hosta 3328 3422 3938 3766 4063 3844 3727
Mishaf1 3156 3531 4188 4250 4875 4938 4156
175 3473 3516 4484 3824
Mishaf2 4297 4313 4969 5078 4641 4438 4622
wakaf1 4703 5938 5719 6313 6297 6969 5990
200 3293 3734 4523 3850
wakaf2 4219 5359 6078 6406 6219 6875 5859
wakast 3156 3359 3672 3609 4063 4391 3708
225 3914 3938 4617 4156 Picture 2. Row sown wheat at different seed rates
Mean 3677 4254 4773 4874 4999 5130
250 4051 4227 4375 4217
Table 4. Response of bread wheat to sowing dates
Mean 3546 3599 4406 Sowing Date Angacha Kokate Mean
Table 3. Seed rate × sowing method interaction on June 17 2027 2813 2420
bread wheat grown at three locations in the SNNP June 29 3348 2875 3111
Seed rate Broadcast Row
(kg/ha) July 9 4164 3125 3645
125 3250 3688
July 22 3727 2852 3289
150 3508 3662
175 3688 3961 August 3 4113 1621 2867
200 3815 3885 August 16 1773 984 1379
Picture 1. Nitrogen sufficient and deficient plots at 225 4260 4052 Mean 3192 2378
Angacha testing site 250 4430 4005
Conclusion
Bread wheat yield level of about 4.9t/ha envisaged in the Growth and Transformation Plan of the southern region can be achieved or even exceeded if, inter alia, the
current national recommendation for seed rate is increased from 150kg/ha to about 250kg/ha for broadcasted wheat, N fertilizer is increased to about 110kg/ha and
sowing is completed around the second week of July. Further works are ongoing to combine and test best practices from these findings and fine-tune the
recommendations.