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Faba Bean Harvesting

Faba beans are perhaps the most trouble-free pulse crop to harvest. If planted early in the season and desiccated at the appropriate time they can be the last crop harvested. Largely unaffected by early snows, faba beans will remain standing through most adverse fall weather while retaining quality. 

Photo Credit: Aerial shot from Greg Stamp

Pre-Harvest Considerations

MATURITY
  • Depending on type and variety, seeding date and seasonal moisture (drought to excess moisture), faba bean crops require a growing season of approximately 110 to 130 days.
  • Colour change of the whole plant of 90% or greater is considered physiologically mature and ready for harvest.
  • As faba bean matures, the lower leaves darken and drop, and bottom pods turn black and dry progressively up the stem.
  • Time of maturity, crop height at maturity, and pod ripening can vary greatly from year to year.
  • Late seeded fields will usually have increased days to maturity, decreased yield and slower pod ripening.
  • Faba bean is sensitive and responsive to moisture, and thus swathing or baling is not recommended for faba beans.
  • Closer to harvest, focus on lower pods where the majority of production comes from, instead of waiting too long for top pods to ripen.
  • A faba bean crop can shatter as more pods are allowed to mature to the black stage or left standing until complete drydown; this is especially true if the crop is affected by drought or wind.

SEED MOISTURE CONTENT
  • The crop is ready for harvesting at 18% to 20% seed moisture content if you have a clean sample and can aerate the seed.
  • Seed should be aerated down to 16% moisture for safe storage.
  • Dry for faba beans is <16% seed moisture content.
  • Tough for faba beans is between 16.1% and 18% seed moisture content.
  • Damp is >18% seed moisture content.

FIELD MONITORING
  • Pre-harvest field monitoring will help determine which harvest system to consider, if more than one is available, and will greatly assist in determining when to begin harvest operations.
  • Monitoring fields means checking plants in numerous locations for uniformity of stages of maturity.
  • Most fields will not be 100% uniform in topography – there could be greener conditions in lower, wetter areas and further advanced plants on higher areas.
  • A decision to begin harvest will hinge on a majority of the field meeting certain criteria. Do not sacrifice the quantity and quality of your crop waiting for smaller greener areas to reach the proper stage to start harvest.
  • Harvesting too early will result in immature seeds.
  • Harvesting too late when the pods are dry and brittle may result in shatter losses and will increase the risk of poorer quality seed due to adverse weather.
  • The decision to start the harvest process will depend on three factors: 
    • crop maturity (stage of uniformity – how variable is the crop’s maturity?);
    • seed moisture content; and
    • presence of weed growth.
  • Other considerations may include weather patterns, and marketing considerations.

PRESENCE OF WEED CONTROL
  • Waiting for green weed growth to drydown will jeopardize quality and yields.
  • Swathed green weeds are unlikely to dry sufficiently in a few days, so combining will be delayed.
  • Green weed material in a straight-cut operation will cause extra wetness in the threshing areas of the combine, resulting in moisture on the seed coat and dirt adhering to this moisture (earth tag).  Grades will be lowered because of earth tag (see Grading Section).

PRE-HARVEST AIDS (GLYPHOSATE) 
  • Various chemical harvest management tools are available to aid in the preparation for combining. It’s important to select the right product for the right crop and the intended outcome.
  • Crop desiccation and drydown and pre-harvest perennial weed products are not the same. Make sure to select the right product, follow label directions, and timing of application. Harvest aid products vary in speed of activity, efficacy, and pre-harvest intervals.
  • Apply glyphosate, a systemic herbicide, for pre-harvest weed control but not for desiccation. See Desiccation information further below.
  • Glyphosate can be sprayed when the seed has less than 30% moisture content. At this stage, faba bean stems are green to brown, pods are yellow to brown, and 80% to 90% of the leaves have dropped.
  • Timing your pre-harvest herbicide (glyphosate) can be a challenge. Applying glyphosate too early can reduce yield and seed size, and late-season application may result in levels of glyphosate in the seed that exceed maximum allowable levels.
  • Glyphosate is registered for pre-harvest applications on faba beans and may be used to control perennial weeds such as quackgrass, Canada thistle, sow thistle, common milkweed, toadflax, and dandelion.
  • This treatment will also stop late season chickpea regrowth, and some drydown. However, drydown is inconsistent and is unlikely to occur under cool, wet conditions.
  • The crop and in-crop weeds must have enough green material remaining at application time for the herbicide to be effective.
  • Glyphosate is not registered for crops destined for planting seed because irregular germination and seedling development can occur.
  • Applying glyphosate too early can reduce yield and seed size, and late-season application may result in levels of glyphosate in the seed that exceed maximum allowable levels
  • Growers must take appropriate risk mitigation steps to ensure product residues remain below maximum residue limits (MRLs) set by regulatory agencies.
  • Prior to applying glyphosate check with potential buyers.  Some companies are NOT accepting peas where glyphosate was used pre-harvest as weed control.

KEEP IT CLEAN
  • Certain crop protection products can restrict the marketing options for your pulse crop. Before you make your crop management plans, talk to your grain buyer and read the Keep it Clean Pulse Maximum Residue Limits Advisory for a list of products of concern for this year, and the steps you can take to mitigate risk.
  • More than 85% of Canada’s pulse production is exported to feed the world. Market access is important to the Canadian pulse industry, and growers play a key role in keeping the doors open.
  • Source: For the latest “Keep it Clean” updates, visit Keep it Clean main website.

Desiccation

Watch this Desiccation Video for Faba Bean.

WHEN TO USE CHEMICAL DESICCATION
  • The goal of desiccants or harvest aids is to make sure the crop is dry and goes through the combine efficiently.
  • Diquat is a registered desiccant for faba beans. Diquat should be applied when most plants are ripe and dry. At this stage, pods are fully filled and the bottom pods will be tan or black in colour. Always read and follow label directions prior to application.
  • Timing of your desiccant (Diquat) application in faba beans can be a challenge. Spraying too early can decrease yield and seed size while spraying too late, especially after a frost, can greatly delay the drydown of the crop.
  • The bottom pods will begin yellowing first, eventually to a brownish colour. Comparing the colour change of the hilum (the scar or crease on the seed) in the top pods and bottom pods on the main stem is key to proper timing. The seeds in the top pods of the plant should be full size and the hilum should be similar in colour change to those seeds at the bottom pods.
  • The hilum colour change in tannin variety faba beans, typically for food markets, is from a greenish colour to black. When top pod seeds and bottom pod seeds hilum colour is similar and changed to a black in colour, it indicates the top seeds have fully matured.
  • Low tannin varieties such as Snowbird are more difficult to notice the change in hilum colour. When the hilum on the bottom pod seeds and top of the plant pod seeds on the main stem have both changed from green to light tan in colour, this indicates the seeds have fully matured.
  • Ensuring the seeds at the top of the plant have matured fully will prevent reduced seed size and ensure you achieve your full yield potential. In most cases, it is better to err on the later side than to spray too early.
  • Remember, Diquat has a much faster dry down period while glyphosate aids in perennial weed control.

BENEFITS OF DESICCATION
  • The benefits of chemical desiccation include:
    • To be able to harvest the crop sooner, reduces the risk of exposure to wet weather, and eliminates the risk of swath movement from wind.
    • Standing desiccated crops will also dry more rapidly after a rain, compared to a crop in swath.
    • Reduces the time from maturity to threshing readiness and reduces shatter loss. However, a desiccant will not assist in maturing immature seed.
    • A desiccant is a contact herbicide, so green material is killed quickly and drydown begins within a very short time compared to natural drydown. Thus, drydown is faster and more even and can be achieved late in the season when days are shorter and generally cooler.
    • The use of a desiccant will usually eliminate the need for swathing, thus avoiding potential problems with wind blown swaths, rain-soaked swaths and pick-up losses.
    • Standing desiccated crops will also dry more rapidly after a rain, compared to a crop in swath.
  • Germination of seed is not affected unless applied in advance of the recommended stage.

HOW TO APPLY
  • Spray only as many acres at one time as can be combined in two or three days after drydown.
  • If the entire crop will take more than two or three days to combine, stagger the desiccant application so that not all the crop is ready at the same time.
  • Use proper rates, high water volume and spray at the correct crop stage.

OTHER CONSIDERATIONS
  • Powdery mildew and heavy weed infestations can reduce the effectiveness of the chemicals due to coverage reductions.

Harvest Systems

Faba bean has excellent standability and straight combining is the harvest method of choice for Alberta. Opinions vary as to the best pre-harvest management. Alberta experience has been the best with desiccation and straight cutting, whereas Saskatchewan has found success with swathing. Below is a description of both practices.

SWATHING
  • Faba beans may shatter if left standing until full maturity or left standing until complete drydown – this is especially true if the crop is affected by drought.
  • The crop should be swathed when about 25% of the plants in the field have the lowest 1 to 3 pods turning dark. By this time the uppermost pods should be fully developed and the middle pods will be turning light green. At this stage the moisture content of the most mature seeds may be over 40% and the seeds in the upper part of the plant may have moisture content over 60%.
  • A light narrow swath should be used as the crop may take up to 3 weeks to dry once cut.
  • Seeds in the most mature pods will have a moisture content of over 40%, while seeds found in the upper portion of the plant may exceed 60% moisture content (moisture content of the whole plant will be 70% or greater at this stage).
  • Seed yield can be reduced by up to 50% from harvesting too early or because of late seeded crops that don’t mature before frost.
  • Seed loss (lb./ac.) = Number of seeds/ft.2 x 1000 seed weight (g) ÷ 10.
  • Swathing should be done during periods of higher humidity to prevent shatter losses.
  • Lower areas of the field (which remain green) should be ignored when the proper swathing or straight cutting time approaches for most of the field. Delayed cutting to allow these areas to advance in maturity may jeopardize quality and quantity of the remainder of the crop.
  • Make every effort to harvest your faba bean crop in the fall. Overwintered faba beans left in the swath will develop toxic moulds and be unsuitable for sale, even as livestock feed.

COMBINING
  • Most producers will start combining at 18% -20% moisture to reduce shattering and cracking, and typically use aeration to dry them down to 16%.
  • Combining in the early morning can reduce seed damage if the seed moisture content is lower than 18% – 20%. 
  • Combine settings for faba beans are similar to peas.
  • Bean concaves are recommended and some producers have had success removing concave wires. The concaves should be open wide although if roping is occurring with rotor combines, they may need to be tightened up. Cover plates for the first two concaves may also be considered with rotor combines.
  • Check behind often and ensure that you are comfortable with what is being thrown over. Remember to only adjust one setting at a time and check behind again prior to adjusting another.
  • Starting points for conventional and rotor combine settings:
    • Rotor combine: Rotor 400-500, Concaves 12-18, Fan 900-1100, Presieves 5-7, upper sieves 18-24, lower sieves 28-22.
  • Conventional walker combines:
    • Cylinder 400-600, Concaves 15-35mm, Fan 900-1100 and adjust your sieves according to faba bean seed size.
  • Check your return elevator and adjust according to amount of product coming back over the cylinder.
  • To reduce seed coat cracking, minimize drop distances when moving faba bean seed.
  • Faba bean can be straight combined, although seed shattering can be severe if the whole plant is not dry enough to pass through the combine properly.
  • Seed moisture content of straight cut samples is usually 22% to 26%, and a two-stage drying process may be necessary.
  • Do not plan to straight cut faba beans without desiccation. Straight cutting faba beans that have not been chemically dried down will most likely result in significant shattering losses.
  • Drought stressed crops have most often been straight cut. Even under these conditions, straight cutting is not recommended, as a crop swathed at the correct stage can dry down evenly without shattering.

Faba Bean Straw Management

Western Canadian research into the nutritive levels and value of faba bean straw is limited, but it is believed that faba bean straw has considerable nutrient value when used as an alternative feed source and as a nutrient when returned to the soil.

BENEFITS OF LEAVING FABA BEAN STRAW ON THE FIELD
  • One of the benefits from growing a faba bean crop is the positive effect of faba bean residue in the soil. Faba bean straw contains nutrients, which once broken down by the soil micro-flora, can be made available to the following year’s crops.
  • Improved soil structure, tilth and recycled nitrogen for succeeding crops are all benefits of faba bean straw incorporation. In fact, most of the nitrogen returned to the soil after growing a faba bean crop comes from the straw.
  • Because of these benefits, it is recommended that faba bean straw remain on the field and not be baled off for feed purposes. Consider the following:
    • Dry faba bean straw breaks up and pulverizes quite readily when combined.
    • Straw that is slightly green or tough will remain almost whole going through the combine.
    •  A good straw chopper and chaff spreader will cut and spread the straw and chaff sufficiently so that tillage or direct seeding is not a problem.
    • Tough straw will wrap around the chopper drum if the straw chopper knives are dull and worn.
  • The decision to work straw back into the soil or bale and feed it is entirely up to each individual operation. It’s important to recognize faba bean straw’s worth and not undervalue it.

VALUE AS A FEED SOURCE
  • When assessing the benefits of baling versus incorporating these nutrients into the soil, the cost of baling straw and hauling it must be taken into consideration.
  • Baling faba bean straw may prove challenging. The nature of the stems results in straw that breaks up into fine and short pieces making picking up a swath quite difficult.
  • Faba bean straw is primarily useful for beef cattle rations where high quality roughage is not as important as for other classes of livestock – when faba bean straw is fed with higher quality roughage and/or grain, it can produce a very cost-effective ration (the higher protein levels generally make faba bean straw a better match with grain than cereal straw).
  • Palatability studies (how well an animal will consume the feed) with faba bean straw have not been conducted – anecdotal evidence with beef cattle suggest a wide range in faba bean straw palatability (cattle devouring the feedstuff versus complete rejection).
  • Processing the straw (such as grinding or chopping it with machines like mix mills or hay busters) and mixing the straw with other feeds may help with palatability.
  • Farmers thinking of removing faba bean straw for the purpose of feed should test it for protein, phosphorus, potassium and sulphur to determine the nutrient content.

RESOURCES

LINKS

Special thanks to Saskatchewan Pulse Growers and Manitoba Pulse and Soybean Growers.