Abstract
A field experiment was conducted during the 2013/2014 season to evaluate the performance of CERES-maize model in simulating the effect of date of planting, nitrogen fertilizer and root-zone soil water profile on growth and yield of maize (Zea mays L.) at the Field Research Station of the School of Agricultural Sciences, University of Zambia, Zambia (15°23.6859'S, 28°20.226'E; 1,261 m.a.s.l). The experimental design was a split plot with three replicates, three planting dates (November 24, December 8, and December 22) assigned to main plots and two nitrogen fertilizer rates (112 and 168 kg N ha-1) assigned to sub-plot. Phenological stages and aboveground biomass were used for model evaluation and these were observed at vegetative and reproductive stages. Soil water profiles were monitored using the Diviner 2000 Probe. Planting date significantly affected grain and biomass yield at P < 0.05. The coefficients of variation for grain and biomass yield were below 12% and considered efficient. The Generalized Likelihood Uncertainty Estimation (GLUE) programme was used to estimate the genetic coefficients for the CERES-maize model. The model’s prediction of plant emergence (±1 days), time to anthesis (>= -3 <= ±1 days) and maturity (>= -4 <= 6 days) was good. Simulation of biomass (RMSE = 1135 kg/ha, d = 0.96, EF = 0.86) was reasonably accurate while leaf area index (d = 0.54, EF = -0.65) was simulated with less accuracy due to poor d-stat and forecasting efficiency. The model’s simulation of grain yield was fair (NRMSE = 21.4%) while soil root water availability demonstrated that substantial potential yield may have been lost due to water stress. The results showed that the model can be used to accurately determine optimum planting date, biomass yield and nitrogen fertilizer rates with reasonable accuracy.
Highlights
Maize (Zea mays L.) is the third most important cereal crop in the world after wheat and rice
The results showed that the model can be used to accurately determine optimum planting date, biomass yield and nitrogen fertilizer rates with reasonable accuracy
Simulation of soil root water availability demonstrated that substantial potential yield may have been lost due to water stress under rain-fed conditions especially for the third date of planting (Figure 4)
Summary
Maize (Zea mays L.) is the third most important cereal crop in the world after wheat and rice. It is grown across a wide range of climates but mainly in the warmer temperate regions and humid subtropics. Maize is the most popular crop due to its high yielding per unit area and low cost of production and it is the major cereal staple crop in Zambia. In western countries maize production is highly mechanized whilst in many developing countries such as Zambia, smallholder and medium-scale farmers still use traditional and low-input technologies and yield under such conditions are generally low. Africa being a minor producer of maize by world standards, accounts only for 7% of global production. Sub-optimum temperatures and low solar radiation levels are the most common adverse environmental condition that can seriously affect crop growth and reduce aboveground biomass and grain yield during the growing season
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