Research Objective
Phosphorus application produced a significant yield response at four of the six sites, with responsive sites showing yield increases of 11–31%. Overall, yields did not differ significantly between fertilized treatments when at least 20 kg P2O5/ha was applied. While some sites showed a linear yield response with the highest yields at higher phosphorus rates, in most conditions rates above 40 kg P2O5/ha were not justified. Soil test phosphorus levels were low at all sites in the study.
This study found no yield response to applying either sulfur or nitrogen. Since peas fix their own nitrogen, applying additional nitrogen beyond that found in phosphorus or sulfur fertilizers is not recommended, as it may negatively affect yield or protein.
There was no significant difference between protein levels of yellow peas in response to phosphorus, sulfur or nitrogen application. Protein levels varied by environment, and fertilizer treatments interacted by site, but no clear trends emerged.
This study was continued in 2020.