To maximize the benefits of faba beans in your rotation, choose fields that have low nitrogen (N) levels. Fallow fields, or fields with failed crops from the previous season, may have higher levels of available nitrogen. Available soil nitrogen levels over 55 kg N/ha or 50 lb N/ac may inhibit nitrogen fixation since faba beans will preferentially use the soil nitrogen rather than fixing nitrogen.
High moisture coupled with high soil nitrogen (commonly found on fallow fields) can produce excessive vegetative growth, may reduce pod set and seed production, and may delay maturity, especially for late-maturing varieties.
Faba beans are sensitive to some residual herbicides. Residual herbicides to consider with suggested recropping intervals are listed in Table 3.
Table 3. Suggested Recropping Restrictions for Faba Beans After Application of Residual Herbicide Year (or Season) After Application That Faba Beans Can be Grown (Refer to individual product labels for most up to date information)
5 + years - Tordon® 22K, Grazon™ (Spot treatments or broken pasture)
4 + years - Ally® Toss-N-Go (cropland), Escort® (broken pasture)
(persistence is extended when soil pH is 7.5 or greater)
Second season after application (ie. 18 months recropping)
Muster ® (Toss-N-Go / Gold II), Assert®, Everest®, Triton® C
Clopyralid (<123 gai/ac) (Lontrel™, Curtail™ M, Prestige™ XC, Eclipse™ III, Flaxmax®, Spectrum™)
Banvel® II/Oracle® (high rates >0.5L/ac)
PrePass™ (fall application)
2,4-D (high rates applied in fall)
Early seeding is very important as faba beans are a long season crop and early seeding generally results in higher yields. Seeding should take place once the average soil temperature, at depth of seeding, has reached 3-5°C. In Alberta, faba bean growers generally do not plant faba beans past May 7th, due to maturity concerns.
Germination occurs when soil temperatures reach 3-5°C. Upon seedling emergence, faba bean cotyledons and seed coat remain below the soil surface. Faba bean seedlings can withstand some late spring frost. If the frost is severe enough to kill the main shoot, regrowth from buds at one of the nodes at-or-below the soil surface can occur, but maturity will be delayed.
Seeding early also advances crop maturity, reducing the probability of flower abortion associated with high temperatures at flowering. Faba beans are less tolerant than field peas of heat stress at flowering.