Harvesting buckwheat

How to harvest

There are two methods of harvesting buckwheat. Windrowing is the traditional method, and is well suited to the way that buckwheat matures. Direct combining allows the harvest to be completed in one operation, and is effective when the plants are killed by frost just at maturity. In areas where most of the leaves are off the plant at maturity, direct combining is common. In warmer sites, there may be too much green matter at harvest time, and windrowing is preferred.

Windrowing or swathing

When three fourths of the seeds are brown and hard the crop should be cut and windrowed prior to combining. Cut as high as possible so that the windrow is held up in the air to cure. That will speed drying and make rain less of a problem.

After swathing or windrowing, allow buckwheat to cure a few days in the windrow (usually 7 to 10 days). During this time, some dry matter will translocate into the nearly-mature seeds and they will ripen in the windrow. This maturation increases the yield. Windrowing also helps reduce shattering because weather is not dictating the harvest time. It can be windrowed when the grain is ripe and combined when the weather permits.

Windrowing buckwheat is the normal practice in the western US, Canada and Maine. It removes most of the risk of shattering during direct combining, often increasing the harvested yield. Windrowing also reduces the risk of crop loss to windy and rainy weather.

Machine settings
When windrowing, cut the stem as high as possible to keep the windrow off the ground for easier combining and for fewer stones. To avoid excess grain shattering during the combining operation, adjust the reel speed to correspond to the forward speed of the combine or windrower, and reduce the combines pick-up speed to a minimum.

Pictures of combining windrowed buckwheat

Direct combining

Direct cutting green buckwheat (before a killing frost) is possible because the lower leaves fall off. The greatest challenge is to avoid excessive straw-wrapping. Many combines can be adjusted to do a good job. Feel whether the kernels come off the plant easily enough to combine, but not so easily that they shatter. They may be 100% black by this time.

If buckwheat is been killed by frost, it should be harvested as soon as possible (within a week). Although this action may create a few problems with straw wrapping in the combine, early harvest after a killing frost will reduce shattering losses.

Whether direct combining after a frost or windrowing, cutting buckwheat when there is a dew on the ground in the morning or after dusk seems to help reduce shattering losses because the plant is tougher.
 
Rotary combines
Case rotary combines with standard rotors will not work for direct cutting. They grind up the stems and leaves until the machine is completely clogged. The special bean rotor is available that works well with buckwheat also. 
New Holland twin-rotor combines that work for soybeans will also work for buckwheat. Open the concaves all the way, slow the rotors to 550 rpm, raise the fan to 600. These settings worked well on a field that had green leaves and stalks, 100% black kernels that did not fall off when hit with the hand, and a yield of 1600 lb/ac at 20% moisture.

Machine settings

When direct combining, cut the crop as high as possible and keep the ground speed down so that the machine is not overloaded. Use as much air as possible without blowing out clean grain. Regulate the chaffer openings so that the grain drops to the lower sieve before it has passed over 2/3 the length of the chaffer; but without admitting too much coarse material. Close the lower adjustment sieve as far as possible without carrying clean grain into the return elevator.

The quality of the grain suffers from rough handling, so the combine should be adjusted accordingly. Go slow. Reduce the cylinder speed to only 1/3 of that used for wheat or oats (typically 400 to 500 rpm). Proper adjustment of the concave openings, both front and rear, is very important. Open the concaves as high as possible to remove the maximum amount of grain without excessively breaking the straw. The straw should ride straight through. This clearance is approximately 3/8 inch in the front and 3/4 inch in the rear. This adjustment will need to be adjusted during the day as the seed is more easily removed.

Before doing much harvesting, make a trip around the field and then check the grain to see if these adjustments are correct. If the seed is cracked and broken, reduce the cylinder speed until the damage no longer occurs. Your operators manual probably has useful information for harvesting a green crop.
 

Other links

Dockage in buckwheat
Storing buckwheat
Drying buckwheat