single nutrient fertilizer or a blend, with larger tolerance limits for multi-nutrient fertilizers. Tolerance limits for nutrient content deviations in West Africa are set by the 15-member Economic Community of West African States (ECOWAS).<sup>11</sup> Standards in East and Southern Africa are set by individual countries, though some work is being done to harmonize standards across the 21 countries that make up the Common Market for Eastern and Southern Africa (COMESA).<sup>12</sup> Low agronomic fertilizer quality (deficiencies in nitrogen or other nutrients compared to package specifications and compliance standards) can result from manufacturing problems, mismanagement along the supply chain, adulteration, or counterfeiting. Manufacturing problems are more common for blended fertilizers and relatively rare in single nutrient fertilizers such as urea. Adulterated fertilizer is fertilizer that has been deliberately mixed with non-fertilizer material including sand, rocks, dirt, or salt. Counterfeit fertilizer is when an entire bag of non-fertilizer material is sold as fertilizer.

A second dimension of fertilizer quality is its visually-observable properties: the degree to which the fertilizer is too wet, expired, sold in short bags (bags that are underweight relative to the labeled size), powdered, clumped into hard aggregates, discolored or dirty. While observable quality issues like clumping are not associated with nutrient shortages in the fertilizer, powdered, wet, and clumped fertilizer can lead to nutrient segregation in the bag. Clumping and powdering also potentially increase the costs and complexity of application for farmers. Michelson et al. (2020) find no relationship between the observed quality characteristics and the unobserved agronomic nitrogen content in Tanzania. The IFDC (2013) analysis of fertilizer quality in West Africa finds that high measured moisture content was strongly associated with fertilizer caking. IFDC also found that moisture content and nutrient segregation were strongly associated in NPK samples.

In locations with capital-constrained mineral fertilizer supply chains, degradation of observable quality is likely to be a fundamental and recurring challenge, due to limited resources to support investment, transportation, and storage. Storage and handling conditions including humidity and temperature control, preservation of the integrity of the bag and the type of bag used (laminated or merely woven material) and use of pallets for stacking bags in transport and storage can result in caking, powdering, and discoloration.

# **Pesticide Quality**

As with fertilizer, pesticides can be adulterated – diluted with another substance like water – or counterfeit – in which an entirely different product such as water is sold as herbicide or insecticide. Pesticides can also have quality problems due to errors in manufacturing. Counterfeits may present in

> 11 Tolerance limits for single nutrient fertilizers with up to 20% nutrient content have a tolerance limit of maximum 0.3 units and those with more than 20% nutrient content have a maximum tolerance of 0.5 units. Multi-nutrient fertilizers and blends have a tolerance limit of maximum 1.1 units for individual nutrients for primary nutrients and 2.5% for all primary nutrients combined. These are presented and discussed in Sanabria et al. (2013). Tolerance limits are also set for secondary nutrients (Ca, S, Mg) and for maximum deviations in fertilizer weight for 50-kg bags.

> 12 A range of standards exist across East African countries. The Kenya Standard 158 set in 2011 permits a maximum lower limit for solid compound fertilizers of 1.1%. The Ugandan government has no set tolerance limits for fertilizers. IFDC used Kenyan standards to evaluate Ugandan samples (Sanabria et al. 2018).

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