A very critical time of year is upon us. This is the time of year that we need to harvest prairie hay. And like everything else in agriculture, we run a pretty tight time frame. Timing of harvest of prairie hay is critical for two reasons. First of all, we want to harvest when the prairie hay is still at a fairly high quality level. Secondly, we need to give the plant adequate time to replenish root reserves before it quits growing in late summer.

When the native grasses first start growing in the spring, they have their highest protein content. As the summer goes along, this protein content drops about 2 protein points per month. It is important to remember this. Native hay starts the growing season at about 10% protein and by July 1st this can be down to 6%. Once any forage drops below 5% crude protein, it becomes a poor feed for livestock. The hay quality is so bad, that it takes more energy for the animal to digest than it gets back from the forage in food value.

The flip side of this coin is that forage quantity increases throughout the summer up through early August. Even in an abnormal year like this, however, there is not as much of an increase in total pounds of forage from early July through early August, as what many producers think. We would normally expect 75% to 85% of the total forage weight to be produced by mid July. Harvesting in early July offers us the best compromise between forage quality and forage quantity.

Some producers don’t seem to be very concerned about quality. They are looking for mulch or bedding quality hay. So they’ll cut clear into late August. This brings us up to the next concern. Once a native grass plant is harvested, it will usually start to regrow. Since you removed most of the leaf area, the plant has to use food reserves from the roots to accomplish this growth. Once the plant has enough leaf area redeveloped, it will start to build those root reserves back up.

It is very important to have good root reserves in the grass plants going into late summer. If a grass plant has low root reserves coming out of winter it will not be able to grow aggressively. This allows undesirable grasses and weeds a very good opportunity to invade the grass stand. Continued late mowing has the same negative impact that continued over grazing has. It leaves you with a pasture invaded with weeds, brush and undesirable grasses. It becomes a never ending, worsening, cycle until the management is changed and the hay meadow is given a chance to recover

The grasses need about 8 weeks of good growing weather, after harvest, to restore adequate levels of root reserves. The native grasses are going to stop growing by mid to late September, so hay harvest needs to be wrapping up by mid to late July. If you can not have harvest done by August 1st, you’re better off to not harvest at all. After frost you can graze or hay any native hay meadow without impacting the root reserves. If you do hay or graze after harvest, you want to leave enough fuel so you can burn the pasture or meadow next spring.

Finally, with the threat of drought ever looming on the horizon, we need to adjust our hay harvest management. We would normally try to mow at a 3 to 4 inch height. This leaves adequate residue and litter to protect and improve the grass stand. In drought conditions we need to increase that cutting height to about six inches. For more information, contact the Extension Office and ask for a copy of the bulletin, Native Hay Meadow Management.

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