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Research article2017Peer reviewed

Modelling maize yield response to plant density and water and nitrogen supply in a semi-arid region

Magaia, E.; Famba, S.; Wesstrom, I.; Brito, R.; Joel, A.


tNitrogen (N) fertiliser use in Mozambique is very low, but blanket recommendations on higher fertiliserapplication rates may not be appropriate for small-scale rainfed farms in different edaphic and climateregions of the country. Data from field experiments with two water levels, three tillage methods (only onetillage method was used in the present study) and two fertiliser N application rates to maize (Zea maysL.) were used to calibrate and validate the Agricultural Production System Simulator (APSIM) model. Themodel was subsequently used to simulate multiple-season scenarios (25 years) and determine adequatefertiliser rates for rainfed and supplemental irrigation conditions on sandy loam soil in Southern Mozam-bique. For this, APSIM was configured to simulate long-term maize response to varying N application(0-120 kg ha-1) and planting density (1, 4.2 and 8.4 plants m-2) in a rainfed or supplemental irrigationsystem.The APSIM maize model proved capable of producing fairly accurate predictions of observed trends insoil moisture under rainfed and irrigation conditions in a semi-arid region. The model was also able topredict maize grain and biomass yield well.Multiple-season analysis of grain yield revealed that, compared with the medium (recommended) plantdensity (4.2 plants m-2), in rainfed conditions low plant density and high plant density (8.4 plants m-2)reduced overall grain yield by 1281 kg ha-1(40%) and 242 kg ha-1(8%), respectively. With high plantdensity, grain yield was below 1000 kg ha-1in 20% of simulated years, whereas with low planting densitythe lowest grain yield was around 500 kg ha-1(4% of simulated years). Irrigation stabilised grain yield inmost simulated years, except in some years with high planting density.Fertiliser and supplemental irrigation increased yield for all scenarios except those with low plantdensity. The optimal N fertiliser rate was identified as 33-102 kg ha-1in the rainfed system and38-86 kg ha-1in the supplemental irrigation system, compared with the national blanket recommen-dation of 120 kg N ha-1. The simulation results suggested that the national recommended rate is onlyappropriate for years and regions with adequate rainfall distribution (>300 mm per cropping season).


APSIM, Fertiliser rate, Multiple seasons, Crop modelling, Planting density, Semi-arid

Published in

Field Crops Research
2017, Volume: 205, pages: 170-181