Concave clearance: When crop moisture is at 10% or less, conventional machines should be set open to give a cylinder to concave spacing of about 1" at the front of the cylinder and about 0.75" at the rear. A smaller concave clearance should be used only if some seed is left in the heads after passing through the cylinder. If seed moisture exceeds 15 to 20%, a higher cylinder speed and a closer concave setting may be necessary, even though foreign material in the seed may increase. Seed breakage and dehulling may be a problem with close concave settings. Make initial adjustments as recommended in the operator's manual. Final adjustments should be made based on crop conditions.
Rule of thumb for acceptable harvest loss: 10 seeds per square foot (don't forget heads that have seed left in them) represents a loss of 100 pounds per acre.. Adjust seed counts taken directly behind the combine discharge for the concentrating effect from the width of cut down to the separator width. Do this by dividing the number of seeds found by 4. In other words, in the discharge area, 40 seeds per square foot represent a loss of 100 pounds per acre.
Watch for moisture rebound: When taking a moisture reading on sunflower seeds that are being dried in a bin, keep in mind that the hull dries faster than the kernel. Thus, a moisture reading taken on sunflower being dried may be artificially low; for example, a moisture meter may give a reading of 10%, then climb back up to 12% the next day. To get a more accurate reading, place some seed in a covered jar overnight and take a moisture reading the next day, after the hull and kernel moisture have equalized.
Are your bins ready? Bins with perforated floors work better for drying sunflower than those with ducts. Aeration is essential, especially in larger bins. Aeration may be accomplished with floor-mounted ducts or portable aerators. Aeration fans should deliver 1/10 to 1 cfm per cwt of sunflower. If aeration is not available, sunflower should be rotated between bins to avoid hot spots developing in the stored grain.