Modeling nutrient and water productivity of sorghum in smallholder farming systems in a semi-arid region of Ghana

Dilys S. MacCarthy, Paul L.G. Vlek, A. Bationo, R. Tabo, M. Fosu

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

The CERES-sorghum module of the Decision Support System for Agro-Technological Transfer (DSSAT) model was calibrated for sorghum (Sorghum bicolor (L.) Moench) using data from sorghum grown with adequate water and nitrogen and evaluated with data from several N rates trials in Navrongo, Ghana with an overall modified internal efficiency of 0.63. The use of mineral N fertilizer was found to be profitable with economically optimal rates of 40 and 80kgNha-1 for more intensively managed homestead fields and less intensively managed bush fields respectively. Agronomic N use efficiency varied from 21 to 37kggrainkg-1N for the homestead fields and from 15 to 49kggrainkg-1N in the bush fields. Simulated grain yield for homestead fields at 40kgNha-1 application was equal to yield for bush fields at 80kgNha-1. Water use efficiency generally increased with increased mineral N rate and was greater for the homestead fields compared with the bush fields. Grain yield per unit of cumulative evapo-transpiration (simulated) was consistently higher compared with yield per unit of cumulative precipitation for the season, probably because of runoff and deep percolation. In the simulation experiment, grain yield variability was less with mineral N application and under higher soil fertility (organic matter) condition. Application of mineral N reduced variability in yield from a CV of 37 to 11% in the bush farm and from 17 to 7% in the homestead fields. The use of mineral fertilizer and encouraging practices that retain organic matter to the soil provide a more sustainable system for ensuring crop production and hence food security.

Original languageEnglish
Pages (from-to)251-258
Number of pages8
JournalField Crops Research
Volume118
Issue number3
DOIs
Publication statusPublished - Sep 2010
Externally publishedYes

Keywords

  • CERES-sorghum
  • Nutrient use efficiency
  • Rainfall variability
  • Soil fertility

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