[deck]Careful handling of harvesting equipment and good judgement can save growers a few knocks and bruises this fall.[/deck]
Why are harvester settings and maintenance important?
Proper harvester settings are a must for maintaining high-quality, bruise-free potatoes. Bruising costs growers money by increasing storage losses due to shrinkage and disease, increasing labour costs for sorting and inspection, and decreasing contract value.
Good judgement applies to every stage of the process—for example, growers need to monitor temperature and soil conditions. Close attention to night and early morning temperatures to maintain a tuber pulp temperature of 45 to 60 degrees Fahrenheit is highly recommended.
Once the harvester is running, try to carry soil three-quarters of the length of the primary bed. Aggressive soil separation under wet conditions is not always re-adjusted as the soil conditions dry out, resulting in an inadequate amount of soil being carried up the primary bed. Additionally, growers should make sure shakers are off during dry conditions. This sounds simple, but a number of operations I visited thought they were off when they were not.
Bearings, gears, chains, rollers, beds and flights, and protective covering should all be replaced if they are worn. The top of the blade should be level with the top of the primary bed. Bulldozing potatoes onto the primary bed can cause excessive bruising, and jerky movements can also cause damage to potatoes when they move or roll around the beds. Beds should be kept as full as possible to minimize excessive tuber rollback.
Imagine the potatoes floating down a calm river: that is what they should look like moving through the harvester. If the harvester looks like class-five rapids and the potatoes are being thrown about, you have a serious problem that needs attention. Growers often can tell when the timing is off on their harvesters before it is measured, because the potatoes are not flowing across the beds or onto the harvester properly.
When in doubt, check the timing of the harvester and windrower. With the use of a tachometer, bed speeds can be measured. Generally, the speeds are compared by percentages; for example, if the primary bed is 1.2 miles per hour (100 per cent), then the secondary and deviner would be 1.2 mph (100 per cent), and the rear cross 1.4 mph (115 per cent). One speed for an entire season is not realistic, since adjustments need to be made as soil conditions change from wet to dry and vice versa. Changing ground speed and the speed of the PTO can achieve this modification. Replacing sprockets with different sizes will change bed speeds; this is where some problems can arise. If a grower discovers a sprocket that is badly worn in the field, and back at the shop he has one that has a couple more teeth, will it work? It will move the bed, but not at the right speed. Harvesters are designed with specific sprocket sizes for each bed. If a sprocket is replaced with a sprocket of a different size, the timing will not be correct.
The New Brunswick Department of Agriculture, Aquaculture and Fisheries has produced a fact sheet containing harvester bed speeds for New Brunswick. Speeds may vary depending on the volume of potatoes harvested and the soil conditions.
Prior to harvesting, take a long look at the harvesting equipment. Check for paint that has been removed and sharp edges from wear points. Take the extra time to add protective padding (see Figure 1 and Figure 2).
Missing paint may also be an indication that potatoes are not being properly placed on the beds. For example, paint removed from the outside wall of the side elevator would indicate that the rear cross is pitching the potatoes. Look for pinch areas where tubers may get stuck, and add guards to protect those areas. Check drop distances—newer harvesters have minimal drops, but older windrowers and harvesters can have drop areas in excess of six inches.
It is impossible to address every potential issue in a short article. Most importantly, growers should direct questions to their local extension specialists. They may not have all the answers, but they are there to help growers manage with what resources are available.