Dry bean harvesting must be considered in terms of an overall harvest system. Paying close attention to crop and equipment needs will usually result in earlier harvesting, higher quality and optimum yields. Dry bean harvest management must focus on maintaining seed quality for edible markets. Earth-tag (soil stains on seed), general seed stains, cracking of the seed coat, and splits, can result in lower grades. Harvest losses due to pod shatter or inability to access lower pods can result in yield loss. Maximizing quality and minimizing losses are important goals during harvest.
Field of Dry beans, Ready to be Harvested
Pre-Harvest Considerations
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.
Deciding when to harvest is focused heavily on reducing seed damage and losses. Quality is very important, and seed coat colour and viability must be high for seeds headed to the edible market.
Harvesting too early will result in immature seeds.
Harvesting too late – lower pod set and shattering of ripe pods can result in large losses if harvesting is not done in a timely fashion with equipment set to minimize losses, which can be as high as 40%.
The decision to start the harvest process will depend on crop maturity.
Pulling or undercutting should start when the bottom pods are dry and most of the pods are yellow.
Bean crops cut at the proper stage require approximately 7 to 10 days of good drying weather before they are ready for combining.
To minimize seed damage, dry beans should be combined when the seed moisture content is between 16% to 22%, as combining below 14% greatly increases the risk of cracking.
CROP MATURITY
Bean crops must be cut at the proper stage of maturity.
The ideal time to cut bean plants is when they are close to maturity, this is when 60% to 70% of the pods have turned a buckskin colour. At this stage, the beans have turned yellow but the pods are still flexible.
Even for determinate-type beans all pods will not be at the same stage when harvesting activities begin.
Depending whether beans are pulled (undercut), swathed, or straight combined, the stage of the pods on the bottom, middle, and top of the plant will vary.
Cutting earlier may result in unnecessary shrinkage and wrinkling of the seed coat.
Cutting later may result in excessive harvest losses due to pod shelling and the loss of whole pods.
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 right crop and the intended outcome.
Crop desiccation and dry down 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 for pre-harvest weed control and not for desiccation.
Pre-harvest glyphosate should only be applied when the dry bean seed moisture is less than 30% at 75% buckskin stage, in the least mature part of the field to prevent unacceptable residues.
Stems are green to brown in colour, pods are mature (yellow in colour), 80% to 90% leaf drop of original leaves.
Wait three full days (72 hours) after application before swathing to allow translocation for long-term weed control.
Growers are advised to consult with their grain buyer before using the glyphosate product on pulse crops. Some grain buyers may not accept pulse crops treated with pre-harvest glyphosate due to scrutiny in the global marketplace and low MRLs (maximum residue levels) for some pulse crops in certain major markets. (See – Keep it Clean below).
Glyphosate is not registered for crops destined for planting seed as irregular germination and seedling development can occur.
The crop and in-crop weeds must have enough green material remaining at application time for the herbicide to be effective.
Always read and follow the label.
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.
Desiccation
Chemical desiccation is used to burn off crop foliage and weeds, and can be very effective for dry bean.
Dry Beans in Field
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.
The crop is ready for desiccation at 80% pod colour change and 80% to 90% leaf drop, when the seeds are less than 30% moisture.
Timing of the application is critical because it has immediate drydown effects. Application too early will reduce seed size and yield of dry bean.
If some areas of the field are immature, it is better to go around those areas when desiccating if the goal is the highest quality seed production.
Apply the desiccant at the same time as the proper swathing stage, wait approximately five to seven days, then straight combine or swath and follow immediately with the combine.
BENEFITS OF DESICCATION
The benefits of chemical desiccation include:
The opportunity to have the crop harvested sooner, reduces 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, 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
Diseases and heavy weed infestations can reduce the effectiveness of the chemicals due to coverage reductions.
Harvest Systems
System options tend to revolve around two basic concepts:
Undercut the crop and then use a pick-up header to feed the material into the combine, or
Straight cut Black and Navy types.
Dry Bean Harvesting using Picket Combine
UNDERCUTTING
If beans are grown in row crop situations they may be first pulled (undercut).
Pulling should start when the bottom pods are dry and most of the pods are yellow.
Pulling beans involves cutting them off ¾ to 1 inch below the soil surface with either a fixed blade, rotary disc-type, or a rod-weeder type.
Undercutting equipment must be sized according to row spacing, as equipment designed for 22 inch rows will not work for 36 inch row spacings.
The blades on most cutters can be set at two different angles and may be shimmed to alter the angle at which they enter the ground – soil texture, compaction and soil moisture will all be determining factors for the preferred cutter settings.
Beans are then allowed to lay and dry for a period of time dependent on maturity and moisture. If beans are quite mature, pulling may be done only an hour or two prior to combining to allow soil on the roots to dry.
Some immature pods will dry down in the row after being cut off if left for several days, but the risk of moisture wetting and moulding beans increases the longer they are laying out.
Proper completion of the hilling operation during the growing season will definitely make it easier to cut the crop.
If a proper cutting edge is not maintained, a poor cutting job will cause heavy harvest losses – it’s essential to periodically check the performance of the bean cutter in case it requires re-adjustment.
The use of a rod to lift the roots out of the soil after undercutting is a common harvest practice – the rod ensures that no plants are left uncut or are held tightly by the soil.
A rod may be used either at the same time as cutting or immediately before combining, but a rod application should not be used at the same time as undercutting if the crop is overripe, as the crop will be at high risk of blowing – under these conditions, the rod should be used just ahead of the combine.
WINDROWING
Once the beans are undercut, 6 to 12 rows are then windrowed together to make a swath for combines to pick up.
Keep some green vegetation on the plant so that windrows will not be moved by strong winds while the curing process is taking place.
Although windrowing is not a preferred operation in harvesting a bean crop, windrowing may be necessary depending on the type of harvest equipment used.
Windrowing may be done by using a conventional windrower or a side delivery rake.
Some growers windrow at the same time as undercutting, and others just prior to combining.
If the crop is to be windrowed just prior to combining, it should be done when the crop is tough to reduce shattering.
Do not windrow any more than can be combined in one day because wind will move the bean swath.
Care should be taken to reduce shattering when windrowing. Early morning or evening can help reduce shattering losses to windrowing in some cases.
Indeterminate vine-type beans grown in 30 to 36 in rows are best suited for this process.
SWATHING
Beans grown in solid seeded systems are often swathed prior to combining.
Swathing occurs at a similar stage to pulling, when 50% to 70% of the pods are in a buckskin stage.
A few leaves left on the plant will help limit shatter losses, but green material can gum up on the knife and require cleaning.
Vine lifters and pickup reels can be beneficial to reduce losses by helping to get lower pods.
As with pulling, swaths are susceptible to both wind damage and rotting if swaths get quite wet from rain.
Dry Beans
COMBINING
Bean crops cut at the proper stage require approximately 7 to 10 days of good drying weather before they are ready for combining.
To minimize seed damage, dry beans should be combined when the seed moisture content is between 18% to 22%, as combining below 14% greatly increases the risk of cracking.
If moisture drops too low and cracking becomes an issue, waiting until moisture increases in the evening or early morning may be necessary.
If bean seed becomes too dry, the percentage of splits and cracks will increase during harvest and post-harvest handling.
Combines may either be specialized units designed specifically for harvesting dry bean or conventional units with either a cylinder or rotor threshing system.
Special bean combines such as the Bedwell or Lilliston have one or two cylinders. The bottom of the combine is a large screen and beans are moved around on conveyors to let dirt fall out. They are excellent for reducing damage to beans harvested in hot, dry conditions, especially when growing high-value coloured beans. However, they are a significant investment and if beans are a smaller acreage on a grower’s farm, conventional combines and rotary combines can be used.
In general, rotary combines are gentler on beans than conventional combines, especially if you can keep the rotor full to help cushion the beans. Cylinder speeds should be set as low as possible and adjusted during the day as beans dry. Concave spacing should also be increased during the day as beans dry down.
Conventional combines can be modified to be gentler on beans and allow more dirt to fall through earlier in the process to reduce earth-tag if a grower wants to have a combine for exclusive use on beans.
A number of harvest equipment combinations are:
Cut and rod in the same operation at 70% buckskin pod colour. Pick-up and combine. For normal row crop production of dry bean, this option results in the lowest harvest cost per acre while doing a good job of minimizing harvest losses.
Cut the crop at 70% buckskin pod colour. Rod just prior to combining. Pick-up and combine.
Cut at 70% buckskin pod colour. Rod just prior to windrowing. Windrow just prior to combining. Pick-up and combine.
Desiccate solid seeded upright/bush bean at 85% to 95% buckskin pod colour. Straight combine. This option is only viable for upright or bush types grown in a solid seeded field. A flexible header on the combine is necessary for this method of harvest, and lifter guards are also recommended for straight cut operations.
Dry beans may also be straight cut when 75% of the pods are dry and the remaining pods are in the buckskin stage.
It is recommended to use a harvest aid if enough weeds are present, or a desiccant to allow for quick plant dry down so the seed does not over dry while waiting on leaves and stems to dry down.
Some products may leave residues and checking with your buyer for market acceptance of desiccants used is a good idea. Some products are also moved through the plant and should not be used if crops are grown for seed purposes
Use of vine lifters or flex headers to maximize ability to capture low pods can be helpful.
Straight combining works best if the crop is even and free of green weedy material.
Vine type varieties (most often grown in southern Alberta) do not straight cut well, as pods often touch the ground, resulting in excessively high harvest losses.
COMBINE SETTINGS
Dry bean is very susceptible to splitting and cracking, so the rpm of the cylinder and the clean grain elevators should be reduced as much as possible – cylinder speeds between 170 and 350 rpm are satisfactory for most threshing conditions.
Clearances between the cylinder and concave, and between the wires in the concave, must allow the seed to pass through freely.
The use of perforated sheet metal (3/16 round) and slotted screens in the feeder housing or screening on the combine table will help eliminate dirt from the grain – and save wear and tear on the equipment.
The unloading auger should run at an idle speed to prevent damage to the seed – if you see evidence of seed damage or splitting, make immediate adjustments.
Two popular types of combine pick-ups are “Sund” and “Rake-Up”. Pick-up speed should not exceed the ground speed of the combine, to reduce shelling and pod loss.
Dry Bean Straw Management
Western Canadian research into the nutritive levels and value of dry bean straw is limited, but it is believed that dry 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 DRY BEAN STRAW ON THE FIELD
One of the benefits from growing a dry bean crop is the positive effect of dry bean residue in the soil. Dry 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 dry bean straw incorporation. In fact, most of the nitrogen returned to the soil after growing a dry bean crop comes from the straw.
Because of these benefits, it is recommended that dry bean straw remain on the field and not be baled off for feed purposes. Consider the following:
Dry 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 dry bean straw’s worth and not under-value 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.
There may be some variability in nutritive value between years and sites. This variability may be a reflection of soil fertility, moisture and environmental (growing) conditions.
Overall quality is usually better than cereal straw. Dry bean straw can be significantly higher in protein, but high fibre levels limit digestibility and expected feed intake.
Dry bean straw is primarily useful for beef cattle rations where high quality roughage is not as important as for other classes of livestock – when dry 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 dry bean straw a better match with grain than cereal straw).
Palatability studies (how well an animal will consume the feed) with dry bean straw have not been conducted – anecdotal evidence with beef cattle suggest a wide range in dry 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 dry bean straw should test it for protein, phosphorus, potassium and sulphur to determine the nutrient content.
A feed analysis of a representative sample of dry bean straw for protein, phosphorus, potassium and sulphur is needed to do the calculations on value of selling as feed versus improving your soil.
