Field peas (Pisum sativum L. var. arvense) are cool-season annual legumes distinct from the shelling peas commonly grown in gardens. They are primarily utilized in agriculture as a cover crop, high-protein forage for livestock, or green manure. The plant’s ability to fix atmospheric nitrogen into the soil provides a significant benefit for subsequent crops in a rotation. Successfully establishing this crop requires attention to environmental conditions, seed preparation, and precise planting techniques.
Determining Planting Site and Timing
Field peas thrive in cool conditions and should be planted early in the spring, as soon as the soil is workable, or in late summer for a fall crop. Planting is best initiated when the soil temperature consistently reaches at least 40°F, with optimal germination occurring between 40°F and 65°F. Sowing later risks the flowering stage coinciding with hot, dry weather, which can significantly reduce yield.
The planting site must provide full sun exposure throughout the day for maximum growth. Field peas tolerate a range of soil types, but they must be well-drained. A soil pH ranging from slightly acidic to neutral (around 6.0 to 7.5) is preferred.
Prior to planting, the seedbed should be finely tilled to remove large clumps, preparing a smooth surface for uniform seeding. Excessive tillage in the spring should be avoided because it can quickly dry out the seedbed. Proper soil preparation ensures good seed-to-soil contact, which is necessary for successful emergence.
Preparing the Seeds
Before planting, select the correct seed variety, distinguishing between semi-leafless types (preferred for commercial grain production) and leafy, vining types (better for forage or cover cropping). Field pea seeds must be treated with a specific microbial inoculant containing the bacteria Rhizobium leguminosarum. These bacteria form a symbiotic relationship with the pea roots, converting atmospheric nitrogen into a usable form.
Applying the inoculant ensures the plant can meet most of its nitrogen needs without relying on synthetic fertilizers. Inoculants come in various formulations, including liquid, peat-based powder, and granular forms, which are typically mixed with the seeds immediately before sowing. Keep inoculated seeds cool and out of direct sunlight, as the Rhizobium bacteria are sensitive to heat and ultraviolet light.
Sowing Techniques and Depth
Sowing depth significantly influences successful emergence and should be precisely controlled. Field peas have a relatively large seed size, providing the energy needed to emerge from deeper soil placement. The recommended planting depth is typically between one and two inches, ensuring the seed is placed into firm, moist soil for consistent germination.
The method of sowing depends on the objective of the planting. For large-scale production or forage harvesting, using a grain drill or air seeder to plant seeds in rows spaced six to twelve inches apart is the most common practice. This method allows for a uniform density, often targeting seven to eight plants per square foot, or approximately 300,000 to 350,000 plants per acre.
Broadcasting the seed is an alternative for cover cropping, but this method often results in less uniform emergence and may require a higher seeding rate. After the seeds are placed, the soil must be lightly firmed to press the soil around the seed. This eliminates air pockets and secures seed-to-soil contact, which is vital for moisture uptake and germination.
Early Growth Management
Following planting, consistent soil moisture is necessary to trigger and sustain germination. The soil should be kept uniformly moist until the seedlings emerge, which typically occurs within seven to fourteen days. Once the plants are established, the watering schedule can shift to deeper, less frequent soakings, especially during the flowering and pod-fill stages.
Weed management is a priority during the early growth phase because field peas are poor competitors with weeds. A pre-seed or pre-emergent herbicide application is often employed to provide control before the pea plants emerge. Delaying weed control until four weeks after emergence can result in a significant yield reduction.
For vining varieties, providing physical support helps prevent the plants from sprawling, which reduces the risk of disease and makes harvesting easier. This support can be achieved by trellising or, more commonly in field settings, by companion planting with a cereal grain like oats or barley. The cereal crop grows upright, providing a structure that the pea tendrils can climb, leading to better air circulation and light interception.