Farmers in Zambia may not be getting the most out of fertilizer due to soil conditions. A study looked at 1,453 fields and found that soil characteristics like pH levels and organic matter affect how well maize responds to fertilizer. Depending on the soil, maize yield from fertilizer can range from zero to 5.7 kg per kg of fertilizer. Most Zambian farmers may not be making a profit from using fertilizer at current prices. The study's model and data are unique in considering multiple soil factors and their impact on fertilizer effectiveness.