Lentils can be a profitable cropping choice due to well-established market connections. With consideration given to seeding, rolling and management of weeds, harvest can be a simple operation given the right equipment. Because lentil plants are short and stand well, combining with a straight cut, flex header can simplify the harvest process. The days to maturity of lentils result in early harvest with less risk of inclement weather, ensuring the harvested grain is of high quality.
Lentils are considered mature when the bottom third of the pods turn yellow to brown and rattle when shaken. This is the stage recommended for swathing, desiccation, or pre-harvest herbicide application.
Under Alberta conditions, long-season lentil varieties seldom mature naturally. Some varieties will mature, but unevenly, resulting in shatter losses as some pods become over-dry while others are still green.
SEED MOISTURE CONTENT
Combining green lentils at 16% to 18% seed moisture content is ideal, assuming drying to 14% can be accomplished.
While green lentil is considered dry and safe to store at <14%, red lentils are considered dry at 13% seed moisture.
Green lentils are tough at 14.1% – 16% seed moisture, and considered damp at >16.0%.
Red lentils are tough at 13.1% – 16.0% seed moisture, and damp at >16.0%.
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 which will result in downgrading.
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
presence of weed growth.
Other considerations may include weather patterns, and marketing considerations (for human consumption, livestock feed or seed).
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 AIDES (GLYPHOSATE)
Apply glyphosate for pre-harvest weed control and not for desiccation.
Some buyers will not purchase lentils if a pre-harvest glyphosate application occurred. Check prior to application to ensure you are able to sell your crop.
Pre-harvest glyphosate should be applied on lentils when the crop is at less than 30% seed moisture with a pre-harvest interval of 7 days. Assessing seed maturation in an indeterminate crop like lentil is challenging.
Timing is critical for maximizing yield, minimizing quality concerns, and ensuring grain is marketable.
What to look for to determine if your lentils are at 30% moisture:
Eighty percent of the plant is yellow to brown in colour – this applies to the entire field, including the greenest part.
Tops of the plants may still have slight green colour, but seeds are fully formed and not juicy.
Seeds from bottom third of plant are tan-brown, hard, and pods rattle when shaken.
Seeds from middle third are full size and firm, with 100% colour change (light green to tan-brown).
Seeds from upper third of the plant have 50 – 75% colour change with no immature seeds (shiny green).
To assess crop stage, walk along a transect through a representative field section and randomly sample pods from the entire canopy (bottom to the top of the plants). A minimum of 50 pods should be sampled. Seeds should be shelled from the pods and the representative seed sample assessed.
Applying pre-harvest weed control or desiccation product at the incorrect stage can result in elevated residue levels, poor seed quality, and can adversely impact the marketability of your lentils.
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.
Source: Keep it Clean.
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.
Chemical desiccation to dry down crop foliage and weeds will reduce the time from maturity to threshing readiness, reduce shatter loses, and result in improved quality if the seed is harvested before being exposed to wet weather.
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.
Desiccant will not assist in maturing immature seed.
The crop is ready for desiccation or swathing when the bottom third of the pods are yellow to brown, and seeds inside the pods rattle when shaken; upper pods will still be green but should be filled.
There are numerous products registered for use as desiccants in lentils. Always speak with your input supplier and refer to the “Keeping it Clean” resource. Some products may be limited by market access concerns. Consult product labels prior to use for final detailed instructions.
Timing of the application is critical because it has immediate drydown effects. Application too early will reduce seed size and yield and delay can result in excessive shatter losses and may result in residue levels founds in the seed.
To drydown the crop quickly and evenly, a producer can either chemically desiccate or swath (crop staging is the same for either method). Lentil plants can be ready slightly earlier to thresh in 4 to 7 days, if hot, dry, sunny weather follows (although the time period is more commonly 7 to 10 days).
Application in the evening and into the night, using high water volumes, and using the high end of the recommended rate will result in quicker and more consistent drydown.
Days to threshing following application will increase under wet, cool conditions.
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.
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.
Powdery mildew and heavy weed infestations can reduce the effectiveness of the chemicals due to coverage reductions.
Harvest Systems – Swathing
Lentils are a short plant with good standability. Swathing is generally not a recommended practice as swaths are vulnerable to blowing and have an increased risk of reduction in quality of the harvested crop. With proper field prep and rolling, straight combining is preferred and the most efficient harvest method.
Should circumstances lead to the need to swath consider the following.
WHEN TO SWATH
Lentils can be cut and swathed into windrows approximately one week before harvesting to dry down the weeds.
Swathing will hasten drydown and prevent shattering.
Under good drying conditions, the quality of the swathed seed is usually better than if chemically desiccated, especially for green varieties.
To reduce shatter, cut under conditions of high humidity.
ROLLING & SWATH ROLLING
Spring rolling lentil fields is recommended for proper swathing, since bottom pods are only a few inches off the ground
Swath rolling may be necessary to protect the swath from wind damage if the swather lays a dense narrow swath.
Swaths can be susceptible to wind movement (especially if cut later than the recommended stage), however, rolling swaths may result in greater seed shattering in the swath.
Lay a wide, shallow swath that will cure and dry quickly – adjust the discharge opening of the swather to as wide as possible to lay a wide swath (avoid piling the swath in bunches).
CUT, SPEED AND ANGLE
Lentil must be cut close to the ground to get the bottom pods with an angle of 20° to 30° suggested for the cutter bar. Keep the cutter bar clean to improve cutting action.
If the crop is lodged, cut across or at an angle to increase the effectiveness of the pick-up reel and vine lifters.
Swathers with a floating or flexible cutter bar and/or adjustable gauge wheels will increase swathing speed and minimize damage to the cutter bar, especially on uneven land – a narrow swather can be more successful on uneven land.
Swathers or straight-cut combines should have a pick-up reel and vine lifters since lentil plants tend to lay at or on the ground at harvest.
Pick-up reels should be adjusted ahead of the cutter bar and run at ground speed. Vine lifters will provide maximum lifting action but should not be cultivating the soil.
Dirt in the swath can result in earth tag and can result in downgrading.
If the swath is subjected to heavy and/or prolonged rain, quality loss can be high due to sprouting, wrinkling and disease build-up compared to a standing crop.
Wet swaths can flatten out, making them harder to pick up (the use of swath turners or side-delivery rakes is not recommended due to excessive shatter losses).
Harvest Systems – Combining
WHEN TO COMBINE
A 16% seed moisture content is considered ideal for harvesting lentil.
It is preferable to thresh at about 18% moisture and use aeration to dry the sample to 14% for green varieties and 13% for red varieties for safe storage.
Acceptable seed moisture for threshing can range from 16% to 20%, provided adequate drying or aeration facilities are available.
While green lentil is considered dry and safe to store at 14% seed moisture and red lentil at 13%, it should only be threshed at 14% by producers who do not have drying or aeration equipment available (threshing at 14% moisture will result in higher shatter losses and quality losses from seed damage).
Lentils can be straight combined when seeds and pods are fully mature, or after desiccation
The moisture content of lentil seed can change quickly in warm and windy conditions. Excessively dry seed will chip and peel during threshing.
To obtain high-quality seed, the crop should be carefully and frequently monitored before combining.
The red lentil splitting industry prefers product with moisture content below 13% to improve the efficiency in their splitting plant. Check with your red lentil buyer for any seed moisture content requirements.
Rotor or cylinder speed is usually a compromise between a slow speed to prevent seed damage and a faster speed to prevent cylinder plugging – the ideal is usually between 250 and 500 RPM.
Set concaves to allow good threshing and separation, with minimal seed damage – since the crop threshes easily, concave settings will usually be wider.
Chaffers should be set at 3/4” and cleaning sieves at 3/8” and then adjusted accordingly; tailings should be kept to a minimum.
Grain and return elevator chains should be adjusted correctly to avoid splitting or cracking seed: fan speed should be increased only to the point where an acceptable clean sample is produced; excessive fan speed will blow lentil seed out the back of a combine.
Threshing equipment equipped with flex header, automatic height control, pick-up reel or air reels and vine lifters are an asset. These modifications keep soil from being mixed in with the seeds.
Pick-up reels should be adjusted ahead of the cutter bar and run at ground speed.
Vine lifters will provide maximum lifting action but should not be cultivating the soil.
Lentil Straw Management
Western Canadian research into the nutritive levels and value of lentil straw is limited, but it is believed that lentil straw has considerable nutrient value when used as an alternative feed source and as a nutrient when returned to the soil.
BENEFITS OF LEAVING LENTIL STRAW ON THE FIELD
One of the benefits from growing a lentil crop is the positive effect of lentil residue in the soil. lentil 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 lentil straw incorporation. In fact, most of the nitrogen returned to the soil after growing a lentil crop comes from the straw.
Because of these benefits, it is recommended that lentil straw remain on the field and not be baled off for feed purposes. Consider the following:
Dry lentil 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 lentil 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.
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.
Farmers thinking of removing lentil straw should test it for protein, phosphorus, potassium and sulphur to determine the nutrient content. A feed analysis of a representative sample of lentil straw for protein, phosphorus, potassium and sulphur is needed to do the calculations on value of selling as feed versus improving your soil.