Abstract:
Appropriate fertilization practices based on actual limiting nutrient and crop requirement for a
given crop is economic and judicious use of fertilizers for sustainable crop production. Balanced
nutrition must be achieved to optimize maize productivity. A field experiment was conducted
with an objective to identify which of macronutrients N, P and K are limiting maize grain and
yield components in the study area during 2017/18 cropping season. The experiments were laid
out in a completely randomized block design with six treatments replicated across six farmers’
fields in Kersa district, Jimma zone, south western Ethiopia. The trial consisted of six treatments,
which include; control, PK (-N), NK (-P), NP (-K), NPK and NPK+ CaMgSZnB. Among the six
treatments, -N, -P, and -K were set to estimate the inherent N, P and K supplying capacity of soil
respectively. The yield and soil fertility gap between a full NPK fertilizer plot and a fertilizer
omission plot was used as a good diagnostic tool to assess the extent of macronutrient
limitations. Average maize yields were the highest in the NPK treatment, followed by those in the
NPK+CaMgSZnB plots among all treatments. Maize yield, a significantly increasing trend over
time was found in the NPK-treated plots and a decreasing trend in the PK and NK-treated plots.
In the absence of N or P, maize yields were significantly lower than those in the NPK treatment.
A balanced use of NPK has a remarkable influence on maize growth and yield. Among different
treatments NPK combinations, provided the highest grain yield of 9185 kg ha-1
andthe lowest
(1861.3 kg ha-1
) was obtained from control plots. Nitrogen, Phosphorus and Potassium are
macronutrients that play a major role in plant growth and crop yields. Yield responses to
fertilization were ranked NPK > NPK+CaMgSZnB >NP>PK>NK, illustrating that N deficiency
was the most limiting condition in maize production, followed by P and K deficiencies. As
compared with the NP treatment, the NPK treatment was significantly increased maize yields by
15.4%. However, maize yields under the NPK treatments were statistically better than those in
the NPK+CaMgSZnB treatment. Based on the results, it was concluded that the inherent N, P
and K supplying capacity of soil is very low. Therefore, use of appropriate balanced fertilizers
should be used for efficient nutrient uptake which ultimately increases maize productivity.
