Implicit fertilizer prices were estimated for nitrogen, phosphorus and potassium applied to the 1987 cotton crop that account for technical economies of size, pecuniary economies and for differences in prices of fertilizers used on irrigated versus dryland cotton. Nutrient prices for irrigated cotton suggest that more expensive forms were used on irrigated cotton, perhaps in conjunction with fertigation. Nutrient prices for dryland applications were lower than those for applications on irrigated cotton. Economies of size were found for the US and for the Delta region.