How long should my pasture rest before I graze it again?
After a pasture cell has been grazed it should rest that the plants in it can regrow, restore nutrients, and stay viable. How long the pasture rest should be, depends on the time of year. Pasture rest in humid climate like in New England, the Northeast, and Midwestern states is very different than pasture rests in arid climates out west. My article will speak exclusively to humid climates like at my farm in western New York.
Let’s assume for the sake of this article that we have a well-established pasture or hay field with cool season grasses and legumes as well as a variety of desirable weeds. The growing season starts with spring. The early weeks of growing season include exclusively vegetative growth. This rapid growth will only last until about mid-May and seed stems and seed heads will emerge. During these early weeks of pasture growth, the pasture rest should be relatively short, as short as three weeks. Longer rest periods will lead to pasture growing ahead of you and quality and palatability being lost. Spring is also the most forgiving time for pasture. At that time, it is less vulnerable to shorter rest periods and even to shorter grazing.
When the seed stems and seed heads emerge and throughout the summer the pasture rest should be increased. More time is needed to restore depleted resources. I suggest a rest period of five to six weeks. The closer we get to the fall, the more critical is a longer rest period.
Stockpiling starts, depending on the region, sometime in August and as late as early September. Seven to nine weeks or about 50 to 65 days of stockpiling are desirable. Somewhat longer grass has the added benefit to be more accessible when sheep dig through the snow in the winter to get to the forage.
Longer pasture rests than I described can under extreme or unusual circumstances be desirable such as restoring soil health on depleted farms or when establishing a new seeding. However, longer pasture rests under normal circumstances offer no added benefits but carry several risks.
The biggest risk of longer pasture rests is the loss of quality in the forage (less energy and less protein) as well as lower digestibility. When studies compared pasture rests of 50, 65, and 80 days, a steady drop in nutrients and digestibility was proven. The yield at 50 days was lower compared to 65 days but not much yield was gained beyond it. Forage with fewer nutrients and lower digestibility reduces animal performance in two ways. It leads to less nutrient absorption and less intake. I have learned that lesson the hard way when I used to stockpile pasture well beyond 50 days, only to find out that a lot of pasture was not eaten, and no added benefit was gained. Since then, I have a shorter than 60-day pasture rest for stockpiled pasture, still get the full benefit of the pasture, don’t waste much, and yet go into the winter with the desirable residue of about four inches.
There are other reasons why a longer pasture rest can be detrimental to your pasture. White clover, a desirable pasture legume with extraordinary longevity under ideal conditions, needs light to thrive. Long pasture rest may lead to grass that is so tall for too long of a time that it deprives the clover of light and thus outcompetes it.
The thickness of a stand is negatively influenced also when pasture rests become too long. However, a thick stand is desirable because a lower but thicker stand yields more desirable forage than a taller but thinner stand.
There are financial considerations as well. If you purchased the farm and you have to pay a mortgage – and many of us either do or have – you want a return for your investment. After all, many of us need to make a living. If you now extend pasture rest beyond a point that it benefits yield and quality of your forage, beyond a point that soil health is being improved, and beyond a point that benefits the longevity of your pasture species, then you will rotate your flock less often through your pastures, grow less quality forage and feed fewer sheep. That translates into a loss of income.
I am aware that there are people who practice pasture rests of over 60 days and even 90 to 120 days. Customers, who pick up breeding stock from my farm or hire me for consulting services bring it up at times because they heard or read about it somewhere. These ideas go hand in hand with so-called “tall-grass grazing”. These ideas are unsuited in states like mine or states with similar climates and pastures with cool season grasses and legumes. They were developed for arid climates. Practicing longer rest periods than I described will lead to a loss of production, will have no added benefits, and in the end hurt the bottom line.