The Effects of Late Season Usage on Cool Season Grasses
09/08/2017

You don’t have to travel very far from east to west or north to south across northeast Kansas to find huge differences in soil moisture levels. It’s easy to see the effects of moisture levels not only on our field crops, but on forage crops as well.

As we head in to mid-September, cool season grasses are responding to cooler temperatures with increased growth in preparation for winter dormancy. Photosynthesis via green plant leaves produces energy that is transported to roots to maintain the plant through the winter and initiate green up when conditions are right next spring. Our management now, therefore, has a lot to do with how plants will grow and produce next year!

For those in areas with adequate moisture, you might be looking out at a hay field that appears to have recovered well from summer harvest and think it might be a good time for some grazing! For those with little to no moisture this past summer, even a little regrowth might be better than what a drought stressed pasture is producing right now, making grazing pretty attractive as well. While I won’t say that it can’t be done successfully, doing so will take some careful management on the part of the grazier so that longer term damage doesn’t occur.

Without adequate energy reserves in the root system going in to winter dormancy, plants can lose winter hardiness and can have the green up process slowed come spring time. So while it may appear that there is plenty of green growth out there right now, it doesn’t take much removal to put the plant in to a deficit again. Grazing (or taking a second cutting of hay) this fall has to be done with extreme caution. At all times, the stand should have at least four to six inches of green growth – with even more preferred! Harvesting below a four-inch level means that the plant not only has to respond to the harvest of photosynthetic area, but depletes root reserves to do so. If adequate time and rest isn’t given to replenish those root reserves, the stand can be compromised.

If in doubt, stay out! Fall grazing without adequate recovery time before our first killing frost can do long term damage to the cool season grass stand. There are certainly species differences to consider as well (fescue tends to be more tolerant to heavier grazing than does brome grass or native species during this time of the year), but all grasses need recovery time so that stand reductions are avoided. Before turning cows out, do a thorough walk through of the area to be grazed, using a ruler or other measuring device to determine the average grass height. If it’s not tall enough, try to find an alternative! If regrowth has been good, grazing might be okay, but should be done with extreme caution to avoid removal of forage growth needed to help next year’s stand.

 


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