Using plant analysis to guide research and extension programs in the Gambia

Abstract

To support the development of viable plant nutrition research in The Gambia, a basic soil fertility laboratory was established in the Department of Agricultural Research, Ministry of Agriculture, by the Gambia Agricultural Research and Diversification (GARD) Project. To assess the fertility status of soils throughout the country, 1, 152 soil samples were collected from maize (Zea mays), millet (Pennisetum glaucwri), and groundnut (Arachis hypogaea) fields. The supply of available nutrients was assessed in 567 fields using plant analysis on the same three indicator crops. Soil fertility levels as measured by soil tests were found to be much higher in fields where maize was grown than in fields planted to groundnut or millet. Tissue analyses indicated that zinc (Zn) and nitrogen (N) were most limiting to maize production. Millet was very efficient in utilizing nutrients available at relatively low levels. Nitrogen was frequently limiting in groundnut, suggesting that proper nodulation is not occurring. Plant analysis data can be used to help guide future soil test calibration work and agronomic and horticultural research. Secondary and micro‐nutrient levels shown to be limiting production in this study should be taken into consideration before running traditional nitrogen‐phosphorus‐potassium (N‐P‐K) studies.

The maps generated for this report help pinpoint districts where research and extension efforts should be focused for the three crops studied.

Notes

Department of Soil Science, University of Wisconsin, Madison, WI, 53706.