Why Does Overapplication of Phosphorus Fertilizers Occur: Insights from North Carolina Farmers

To minimize environmental damage, conserve global diminishing fertilizer reserves, all while maximizing food production, it is essential that farmers apply phosphate fertilizers at the optimal rate. The purpose of this study is to assess grower attitudes and behavior, with respect to proper application of phosphorus, and to investigate how certain exogenous factors might influence such applications. Data were analyzed from a survey conducted in North Carolina, USA, with 122 farmer participants. The findings reveal that annual phosphorus applications consistently exceed recommendations, which indicates overapplication, leading to economic inefficiency and environmental concerns. Overapplication is neither due to knowledge gaps in nutrient concentrations in the soil nor the lack of interest in soil sampling, as 99% of farmers submit soil tests as frequently or more frequently than every two years. Only 36% of growers indicated that they would not apply phosphorus if their soil report indicated that levels were sufficient, and that none was required. Additionally, overapplication is not strongly influenced by price effects, as only nine percent of growers abandoned applications in 2021, following a dramatic spike doubling fertilizer prices. The adoption of reduced phosphate fertilization will depend on strong local trusted technical assistance and continued extension education.