Dryland pea seeding rates can be reduced without yield or economic penalty

Montana is the leading producer of field peas (Pisum sativum L.) in the United States. A density of 8 to 10 plants ft⁻² is recommended when growing field peas in that state, but this recommendation is based on work done elsewhere. Field experiments were conducted in central Montana from 2021 through 2023 and at three additional locations in the final year to determine the yield and the economically optimum plant population (EOPP) when growing field peas for grain. The semi-leafless, yellow-cotyledon variety Montech 4152 was planted at five rates (5, 7, 9, 11, and 13 pure live seed [PLS] ft⁻²) in all 3 years with two additional rates (3 and 15 PLS ft⁻²) added in the final year. A minimum plant density of 6 to 8 plants ft⁻², or planting field pea at 7 to 9 PLS ft⁻², produced a grain yield comparable to or greater than amounts produced at other seeding rates. The minimum EOPP across the six experiments ranged from 3 (2.8) to 7 (6.4) plants ft⁻², corresponding to a seeding rate of 3 to 7 PLS ft⁻². However, more weeds were observed when field pea was planted at 3 PLS ft⁻² than at higher rates in one of the experiments. A field pea density of 6 to 8 plants ft⁻² is sufficient to optimize grain yield and economic returns in Montana and similar dryland environments.