IFDC Evaluation of Portable Soil Testing Kits – Lessons Learned

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This document discusses the problem of poor soil fertility that leads to low food production in sub-Saharan Africa and South Asia. The lack of access to soil testing laboratories prevents smallholder farmers from accurately determining their soil's nutrient needs, resulting in fertilizer application based on blanket recommendations. To address this issue, portable soil testing kits are proposed as an alternative to laboratory analysis. IFDC conducted a literature study and evaluation of commercially available soil testing kits to identify accurate, affordable, portable, and user-friendly options. The objectives were to assess the kits' accuracy in determining soil pH, nitrogen (N), phosphorus (P), and potassium (K) concentration, their ability to predict plant nutrient availability, and their effectiveness in providing fertilizer recommendations to smallholder farmers. The evaluation was funded by USAID and involved multiple countries and diverse soils. Major findings indicated a good correlation with standard lab analysis for soil pH but inconsistent results for N, P, and K concentrations, particularly in acidic and alkaline soils. The publication highlights the positives and negatives of using portable soil testing kits, including their cost-effectiveness, reliability for pH determination, and usefulness in gauging nutrient adequacy or limitation. However, the accuracy for N, P, and K concentrations varies depending on the specific kit and field data calibration. The document concludes with lessons learned and recommendations, emphasizing the need for calibrations and further research to improve the effectiveness of these kits for making fertilizer recommendations.
Soil fertility, Smallholder farmers, pH, Nutrient management
Fugice, J., S. Agyin-Birikorang, and C. Dimkpa 2018. “IFDC Evaluation of Portable Soil Testing Kits – Lessons Learned,” IFDC, Muscle Shoals, Alabama.