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

MacCarthy, D S and Vlek, P L G and Bationo, A and Tabo, R and Fosu, M (2010) Modeling nutrient and water productivity of sorghum in smallholder farming systems in a semi-arid region of Ghana. Field Crops Research, 118 (3). pp. 251-258. ISSN 0378-4290

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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 waterand 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 80 kg N ha−1 for more intensively managed homestead fields and less intensively managed bush fields respectively. Agronomic N use efficiency varied from 21 to 37 kg grain kg−1 N for the homestead fields and from 15 to 49 kg grain kg−1 N in the bush fields. Simulated grain yield for homestead fields at 40 kg N ha−1 application was equal to yield for bush fields at 80 kg N ha−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

Item Type: Article
Uncontrolled Keywords: Nutrient use efficiency; Rainfall variability; Soil fertility; CERES-sorghum
Subjects: Mandate crops > Sorghum
Depositing User: Ms K Syamalamba
Date Deposited: 13 Jun 2012 10:18
Last Modified: 20 Sep 2013 09:15
Official URL:
Acknowledgement: UNSPECIFIED
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