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Published May 01, 2009, 01:05 PM

The key to high quality forages

Forage harvest is just around the corner and a successful harvest of high quality forage begins with the proper use and set-up of the mower-conditioner.

By: Jim Stordahl, DL-Online

Forage harvest is just around the corner and a successful harvest of high quality forage begins with the proper use and set-up of the mower-conditioner. A key factor in achieving a high quality harvest is productivity — getting the crop cut and off the field as fast as possible to avoid weather damage. One way to achieve the needed productivity is to cut quickly. This is why the disk cutterbar mower-conditioner is rapidly gaining favor in cutting forage. Another way to achieve productivity is to help the crop dry to the desired moisture content as fast as possible. This can be achieved by proper level of conditioning and by forming a wide, uniform swath.

Farmers know the formula for high field productivity — cut wide and cut fast. Of course there are limits to speed and width. Mower-conditioner width is limited by transport concerns and slows drying from the large mass of crop in the windrow or swath. The speed of cutting is limited by available power and field roughness and something engineers call “critical travel speed”. Critical travel speed is defined as the maximum ground speed at which the cutting systems can operate without pushing the crop forward and leaving a ragged, uneven cut.  

The most important factor we can control that affects the drying rate is the width of the swath and the swath density. For a given cut width, laying the crop in swath (about 70 percent of cut width) will reduce the drying time by about 25 to 40 percent compared to laying in a windrow (about 45 percent of cut width). This can be a reduction in drying rate of up to 6 hours under typical weather during second cutting (probably longer during first crop). This is the easiest adjustment that can be made on the machine, typically just the flip of a lever, and the one that can pay the most dividends.

Although it is very important to maximize the effect of incoming solar radiation by laying the crop wide, it is quite detrimental to lay the crop so wide that the tractor tires cannot be spread wide enough to prevent the swath from being driven over. If a typical tractor tire drives over the edge of an 8 foot wide swath, then fully 20 percent of the swath will dry at a much slower rate than the remaining 80 percent. And it’s the time when that slow drying 20 percent of the swath reaches baling moisture that will dictate when baling can begin.

The most significant environmental factors that affect the drying rate of forages in order of importance are: sunshine, temperature, soil moisture, relative humidity and wind velocity. We cannot control these factors, but we can try to maximize the positive effects of some of these factors. Laying the crop in a wide swath gives the most benefit from sunny conditions. Making a uniform, fluffy swath by having uniform feeding through the mower-conditioner will help promote good airflow through the crop. Finally, having the harvesting capability to cut as much crop as possible during good drying conditions will help maximize the quantity of high quality forage produced.

  Finally, for maximum performance from your mower conditioner, be sure the roller clearance is set correctly. If the clearance is too close, excess leaf loss and roll wear will occur. If the clearance is too loose, then the crop will not be conditioned as effectively resulting in slower drying rates.

I have a handout that shows how to check your rollers using a very simple procedure, if you would like a copy, please feel free to contact me at the Polk County office in McIntosh, or at the Clearwater County office on Wednesdays. Our toll free number is 800-450-2465. If email is your thing, contact me at stordahl@umn.edu Source: Kevin Shinners, UW Extension

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