Machinery used for swathing semi-leafless field peas
Growers have swathed field pea with self-propelled swathers (for example, John Deere fitted with Honeybee swathing front, Case and John Deere fitted with MacDon swathing front, Case fitted with Case swathing front) and also used headers with offset or side release drapers (for example, New Holland fitted with Honeybee swathing front). All of which had either steel or plastic finger-tine reels.
If a batt reel is used, attaching rubber flaps is recommended to prevent bulldozing the crop at the cutter bar. Snowball (1986) used a tow-behind PTO swather and noted far wheel drag to be a problem which may be overcome by motorizing the far wheel, or joining the far end of the swather to the front of the tractor using rope, metal cable or chain with a spring section.
Crop lifters
Swathers are normally fitted with lifters at 30cm spacings. Lifters may have to be spaced closer (15cm) for short, thin crops. In thick, well-grown crops, growers have successfully swathed field pea without lifters which reduces the amount of soil brought onto the belts. However, on gravel soils, lifters may be necessary to allow small buckshot gravel to fall out of the crop as it is picked up.
Shorter lifters may be required if the crop is very short or the lifters may have to be removed to allow the cutter bar below the lowest pod. It is best to swath or direct head a lodged pea crop at right angles to the direction to which the crop is laying.
Adjustments to suit crop stage and bulk
Where possible, adjust the swather table to enable the cutter bar to be close to the ground and the crop to come off the draper evenly. Adjustment of the pick-up reel, backward or forward, may alleviate piling problems.
If swathing is delayed and the crop dries out, it is more likely to pile up on the knife and belts. It may therefore be necessary to alter the reel so the fingers are flatter and set to push the crop slightly downwards rather than lifting. A raised cross-auger fitted above the belt on the draper front may also assist in reducing piling in dry crops.
Be aware that when the crop is green the plant material often wraps around the raised cross-auger and it may be better to remove it.
It is important to match swath bulk and width to the capacity of the swather, rollers and subsequent harvester. In very well grown high yielding crops (greater than 2t/ha) the swath width may need to be narrowed so that the roller and harvester can deal with the large amount of material in the windrow. Similarly for offset discharge drapers, a full width cut may be too large and hinder the flow of material across the belt to the side exit.
In years when crops have grown well but, a dry spring limited yield, the flow of material out of the exit hole of drapers have created problems. In most other years a greater proportion of seed to tops will ensure a better flow of material. Some people have fitted a canvas shroud just behind the exit of a self-propelled swather, which improves the flow of material. The rollers used behind the exit hole of offset drapers may assist the flow of material.
Rolling of swaths
To minimise movement of the swath by the wind, field pea swathed at 50% maturity (that is, 50% of pods brown) must be rolled as soon as possible, ideally immediately after the swather. Wind tends to get under the start and end of runs, causing the swath to move. Keeping runs as long as possible will minimise wind damage.
Canola rollers work well on wind-rows of crops yielding up to 2t/ha. In very well grown crops with an anticipated yield above 2t/ha it may be necessary to make the roller wider by adding centre extensions. The shape of canola rollers may not be suitable for lighter field pea wind-rows with an expected yield less than 1.2t/ha because the edge diameter may be too large, and a flatter roller, like a tyre roller, may work better. Shedding has not been a problem when Kaspa swaths have been rolled with a rubber tyre roller.
On side-release swathers, some growers have fitted a fluted roller directly behind the exit hole enabling a one-pass swathing operation.
Harvest
Field pea can be safely harvested at 16% moisture and the grain will naturally dry out in an open stack or shed floor without any need for specialist aeration equipment prior to delivery. This allows a longer period over which wind-rows can be picked up because it can be done in cool and damp weather when most other crops cannot be harvested. It also enables the windrows at night to be picked up at night.
Varieties with the sugar-pod trait, however, may be harder to thresh and chop than other varieties in cool weather. In these cases conventional pick-up fronts can be used to harvest the swaths.
Seed crops
For grain to be retained as seed it is important to have good seed germination. Snowball (1986) showed the germination percentage of field pea was not adversely affected when the crop was swathed as high as 60% seed moisture content. Therefore seed can be kept from swathed crops provided growers swath no earlier than the suggested time (that is, 50% crop maturity and an average seed moisture content of 40-45%).
Seed crops should not be croptopped (desiccated) with glyphosate becauseit can reduce the germination and vigour of seed. Seed should be at 13% seed moisture content prior to storing in sealed silos.
All seed should be tested by a certified laboratory prior to planting. Consider buying new seed if the germination test is less than 80% because the seed may lack vigour or if the level of blackspot infection on seed exceeds 15%.
Acknowledgments
Funding provided by Grains Research and Development Corporation and the Department of Agriculture and Food, Western Australia. Illustration and editing by Pam Burgess. Photographs by Mark Seymour.
References
Snowball, R 1986, 'Harvesting methods in south coastal, high rainfall crops', Department of Agriculture Western Australia Division of Plant Research Technical Report, No.4, pp.112-120.