Abstract:
Variability in crop response and nutrient use efficiency to nutrient supply in maize is common
in the study area due to unbalanced fertilizer application due to the absence of site specific
and crop demand based fertilizer recommendation. Balanced fertilization based on soil test
and crop demand is imperative for efficient nutrient management and has a considerable role
for enhancing maize yield. Thus, a field experiment was conducted with an objective to
identify the most yield limiting nutrient (s) in Nitisols of Omo Nada District Southwestern
Ethiopia during 2019/20 cropping season through nutrient omission technique. The
experiment was laid out in RCBD with ten treatments replicated four times across four
farmers’ fields. The treatments were (Control, NP, PKS (-N), NKS (-P), NPS (-K), NPK (-S),
NPKS, NPKSZn (-B), NPKSB (-Zn) and NPKSZnB. Soil sample was taken at a depth of 0-20
cm before application of treatments. The results of soil were moderately acidic, sandy clay
loam texture, low in total N, available P and medium in K, S, Zn, B, OC, OM and CEC. Maize
yield and yield component datum were subjected to ANOVA using SAS 9.3 software. LSD test
was used to separate means at 5% level of significant (P < 0.05). Maize grain yield, Biomass
yield, Nutrient concentration, uptake and agronomic efficiency were highly affected by
nutrient omission. The highest grain yield of maize (8702.6kg ha-1) and biomass (20.13 t/ha)
were obtained from application of 120 N + 40 P + 40 K + 20 S + 5 Zn kg ha-1. The lowest
grain yield (2028.5 kg ha-1 and 2793.5 kg ha-1) and biomass yield (5.55 t ha-1 and 7.23 t ha-1)
were recorded from control and N-omitted plots, respectively. Yield reduction were ranked as
omission of N > P > K > S > Zn indicating N was the most yield limiting nutrient, followed by
P and K. Compared with NP, the NPKSZn treatment increased maize yield by 29.79 %. The
maximum nutrient uptake of N, P, K, S, Zn and B were obtained from plots treated with
NPKSZn. The highest agronomic efficiency of N, P, K, S and Zn were also recorded from
plots treated with NPKSZn. Moreover, this treatment generated the highest net benefit of
80,364 ETB ha-1with acceptable MRR (486.35%). Therefore, integrated use of major
macronutrients (NPKS) and Zn was recommended to increases maize production in the study
area.
Keywords: Maize, Nitrogen, Phosphorus, Potassium, Sulfur, Zinc, Boron, Limiting nutrients