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ProCrop |
Crambe Harvest
After flowering, crambe matures rapidly (one to two weeks). Timely harvest is important to avoid high shattering losses. During warm, dry weather the crop should be frequently monitored (daily or every other day) to determine correct harvest stage.
Crambe is physiologically mature when about 50 percent of the seeds have turned brown. At maturity, the appearance of the plant may range from stems and leaves remaining green to leaves turning yellow and dropping. Attention should be directed to the seeds and seed-bearing branches to determine the onset of harvest.
Crambe may be swathed or straight cut. Both harvest methods have been successful, but the choice depends on acreage, harvest equipment, weather conditions, uniformity of maturity, and weed density. Straight combining is recommended for a mature, clean and low moisture crop. If the majority of seed pods are brown, straight combining is recommended as swathing may cause excessive shattering. If approximately 100 crambe seeds per square foot are present on the ground from shattering, a 60 to 70 pound per acre yield loss occurs. Crambe seed moisture should be 14 percent or less for straight combining. Crambe seed containing greater than 14 percent moisture will cause harvest problems due to difficulty moving the green plant material through the combine. At seed moisture less than 12 percent, high shattering potential exists.
Swathing may be necessary if maturity is variable where some plants are beginning to shatter, while others are still slightly green. If a sufficient number of green weeds are present, swathing may be required. Crambe should be swathed when about 50 percent of the seeds have turned brown. If the majority of the seed turns brown before swathing, the swathing and combining operations may cause excessive shattering. When swathing, reel speed should be reduced to one-half to two-thirds of that for small grain. Seed shatter can be minimized by swathing during a time of day when humidity is high. Swathing should be done just below the lowest seed pods, leaving the stubble as high as possible. This will allow the windrow to settle into the stubble and reduce loss from wind. Crambe will dry quickly after a rain (compared to small grain) in a swath or if the crop is standing.
COMBINE SETTINGS FOR CRAMBE HARVEST
It is important that the combine be adjusted correctly when harvesting crambe. The first priority should be to harvest as much of the seed as possible with a minimum of seed damage. The seed should be harvested with the hulls intact.
Combine cylinder speed of 400 to 500 rpm is recommended. Concave clearance may range from 1/2 inch to near wide open, depending on combine type and crop characteristics. Excessive cylinder speed or narrow concave clearance can cause an increase in hulled or split seed. Rarely will hulls be found in the combine hopper because they are normally blown out the back of the combine. Splits can be detected by looking for bright yellow flecks on the ground behind the combine.
Conventional combine fan speed should be set at about 600 rpm. Never disconnect the fan to completely shut off the air. It may be necessary to place cardboard over a portion of the air intake to the fan if seed is being blown out the back of the combine at low fan settings. The sieve settings for small grains should be appropriate to begin harvest, followed by adjustments for crambe seed. When straight combining, set the reel to move only slightly faster than the ground speed of the combine. This is essential to reduce seed shattering.
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