Location: Sugarbeet and Potato Research
Project Number: 3060-21650-001-054-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2022
End Date: Dec 31, 2023
(1) Identify the optimal seeding depth for fall planted peas; (2) Identify optimal seeding rate and explore the use of nitrogen starter fertilizer to maximize winter pea yield and protein content; and (3) Improve nitrogen fixation of winter peas by evaluating Rhizobium inoculum sources and formulation in acidic soils.
This project will involve a series of greenhouse and field studies to assess several agronomic aspects of winter pea production in annually cropped regions of the Inland Pacific Northwest. Trials will be strategically located in the primary pulse growing regions of the Palouse and Camas Prairie in northern Idaho. The field trials will be initiated in the fall of 2022 and continue for three growing seasons (2023 to 2025). For Objective 1, field studies will be initiated at three locations in northern Idaho. Several green cotyledon food quality peas will be seeded at depths of 2.5 cm, 5 cm, 7.5 cm and 10 cm. Fall and spring plant stand will be assessed as well as vine length, canopy height and shattering of pods at crop maturity. After plots are harvested, total yield and seed size will be measured. Seed protein also will be measured. For Objective 2, field studies will be conducted as described in Objective 1. Several green cotyledon food quality peas will be seeded at five seeding rates of 86, 97, 108, 118 and 129 seeds per square meter and two rates of nitrogen (0 and 30 kg/ha) will be evaluated in a split plot design with four replicates. Fall emergence and spring emergence will be recorded and nodule formation will be assessed in the spring. During the growing season, NDVI (Normalized Difference Vegetation Index) measurements will be collected to assess nitrogen levels within each plot. Standard agronomic measurement will be recorded including yield, size of winter peas, and seed protein. A greenhouse study will be conducted to complement the field work with the addition of nitrogen fertilizer. Soils will be collected from a field previously cropped to spring barley. Six rates of nitrogen from 0 to 50 kg/ha (10 kg/ha intervals) will be applied to soils and seeded to winter pea. The study will consist of four replications of ten plants each. Pots will be destructively harvested to determine the number of nodules for root system and total root and shoot biomass will be collected. For Objective 3, a greenhouse study will be initiated to assess the impact of Rhizobium formulations at three pH levels. Soil will be collected from a field that has a starting pH of approximately 4.2. The pH will be modified to 5 and 6 using an ultramicronized formulation of calcium carbonate and half of each soil will be steamed to eliminate native Rhizobium. After incubation of the soils, winter pea seed will be seeded along with different commercially available liquid, granular and powder formulations of Rhizobium leguminosarum. These trials will consist of 10 plants in each of four replicates for each treatment. Plants will be harvested and assessed for number and size of nodules as well as root and shoot biomass. The greenhouse study will be conducted twice. In the second and third year of the study, a field trial will be in a soil that has a pH of approximately 4.2 compared to an adjacent strip that was limed in 2016 to a pH of nearly 6. Several formulations of Rhizobium inoculant will be evaluated. Measurements will include plant stand, number of nodules per plant, vine length, canopy height, seed yield and protein.