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Spring flush

Woody Lane, Ph.D. for Progressive Forage Published on 30 January 2018
Green grass

“Green grass at last! These first beautiful days of spring; deep blue skies, white puffy clouds, a delicious warmth in the sunshine. And look at that grass! Emerald green, 3 inches high, like those legendary green hills of Ireland.

My pastures are really growing in this spring sunshine. It’s time to get my cows out of the barn. Finally, after all these grim winter months, I’ll open the gate and let the girls out onto those pastures. The cattle will have a great time, and I’ll also save some hay and finally get a chance to clean the barn.”

Does this sound familiar? Every year there comes a day, a bright, clean, warm day in March or April or early May, depending on your area, when you just know that it’s time to move animals onto that wonderful young grass. You’re exhausted from feeding hay around the barn all winter.

Besides, the hay or silage is running low, and the bedding is pretty thick. So you think: It’s time to turn the page and move into summer mode, to trail the cattle away from the barn and move them out onto those green fields.

We’ve all been there. It’s so tempting. But here’s the rub: When we turn cattle onto that first flush of green pasture in the early spring, we are doing more than giving the animals great feed and giving ourselves relief from feeding hay. We are virtually guaranteeing we will have lower forage yields from that field, reduced persistence of our best forages, increased risks of weed intrusion and higher expenses for the entire year.

Huh? Let’s talk.

I’m not, of course, disputing the fact that grazing grass is cheaper than feeding stored hay or silage. That’s almost always true – when we focus on the short-term effects. But when we look at our pastures, we need to look at the bigger picture. Grazing too early usually causes damage to our forages, and we should consider the seasonal and long-term ramifications of this.

What are the characteristics of these early spring pastures? Well, the earliest growth is almost exclusively grass, not legumes. This is primarily because cool-season grasses begin growing when soil temperatures reach 40ºF, while the cool-season legumes (clovers, alfalfa, birdsfoot trefoil) don’t start growing until soil temperatures reach 50ºF.

Which means that our early spring pastures are composed mostly of young grass plants. No surprise there, but let’s think about this for a moment. Let’s say that those young plants are only 2 to 4 inches high. Since they don’t have much leaf area yet, those young plants may be still drawing nutrients from their reserves.

Yes, I know that leaf photosynthesis is clearly active in this beautiful sunshine, but its rate is still much lower than it will be in two weeks because the young plants haven’t produced enough solar panels yet. In a technical sense, the forage in these young fields is in the Phase 1 part of the growth curve, with a total mass of probably less than 600 pounds of forage dry matter per acre.

This young grass is very palatable and nutritious – 20 percent crude protein or higher, with an extremely high digestibility. It’s also relatively low in dry matter at 15 percent or less (hence the occasional moniker “washy grass”). Basically, our field is composed of very lush, very palatable grasses that are high in energy and protein and low in dry matter. The cows love it, especially coming off that barn hay. Just ask them.

But now for the big issues. Putting livestock onto early pastures when the grass is only 2 to 4 inches high can really stress the plants. Those young grasses are just beginning to manufacture carbohydrates from photosynthesis. Their nutrient reserves are being depleted and have not yet been replenished. When animals graze those plants and defoliate them, what nutrients are available for regrowth? Not much, which forces these small plants to regrow slowly as they recreate more leaves.

Here’s another thing: Young grasses, especially annual species, will not have developed an extensive root system yet, which means grazing animals can easily pull these plants out of the ground. Either way, grazing spring plants too early puts them under quite a bit of stress.

Let’s also consider some plant genetics. The grasses that come up first in the early spring are some of our most desirable plants. These are the species and varieties that respond quickly and aggressively to warm conditions. When we stress these plants and reduce their ability to thrive and reproduce, we are in effect putting selection pressure against our earliest forages.

We are systematically putting these plants at a competitive disadvantage compared to species that will come up later. Therefore, our grazing management, instead of encouraging our earliest plants to thrive and provide high yields early in the season, is causing great stress on these grasses and creating conditions that favor other plant species that will emerge later and/or are less palatable.

Here’s another risk that occurs during an early grazing period, especially if the stocking density is too high: The young plants can be overgrazed. Animals can easily damage the growing points which are close to the ground.

If left intact, healthy growing points would ultimately develop into tillers (secondary shoots), but if these growing points are damaged, the plants will produce fewer tillers, especially later in the season. Bunch grasses like orchardgrass and tall fescue rely on tillers to thicken the pasture and provide more leaf area. But grazing too early damages the growing points so that these species won’t produce many tillers later in the season. The result: lower yields, weaker plants and more open spaces between the plants.

Speaking of open space, we know that nature abhors a vacuum, particularly in a pasture. If our early grasses cannot thrive and grow well, openings will develop between the plants. Something else will grow in these openings – like weeds.

And also forages like the low-growing, low-yielding grasses and legumes that come up later and have growing points low to the ground – such as some of the bentgrasses, foxtails, medics and even the bluegrasses. This results in two important consequences: (1) increased costs for weed control and (2) establishment of forages that are less desirable and lower-yielding.

Okay, we get the idea. But still, that early green grass looks awfully attractive. If we must stay off those beautiful fields, what are some alternative strategies?

Well, the first and most obvious strategy is to wait. Stay in the barn; don’t open the gate. Be patient for another two or three weeks, especially if the weather is warm. Continue to feed hay or silage, just like you’ve been doing for the past few months. Let that grass grow!

Give your plants a chance to establish better roots, create more leaf solar panels and begin to replenish their nutrient reserves. I know it’s hard, and that pasture is soooo tempting. But the dollar-and-cents analysis of grazing too early is a sobering exercise. If you still have some stored feed, it’s worth your trouble to feed it for another couple of weeks. If you’re out of feed, maybe you can get some from a neighbor.

Another strategy is to find some alternative feeds for those couple of weeks. Are there any byproducts nearby? Old hay? Dried distillers grains? Last year’s onions? Again, this is just a stopgap. Did you plant turnips last summer that are still in the field because you didn’t quite use them all in the fall? If you haven’t looked for alternative feeds, this could be a good chance to explore.

Here’s a strategy that takes some planning: During the previous summer, identify one or two fields as your early-forage fields. Select them wisely, like fields with south-facing slopes that warm up first in the spring, especially fields with good drainage so the soil warms quickly. These are fields that always seem to turn green earlier than the others. Then plant them specifically with forages that specialize in early growth.

Your goal is to have forages that will explode out of the ground as soon as the snow melts and the soil temperature starts to rise. Every region of the country has forages that will do this: small grains like winter rye, wheat, oats or triticale. Or annual ryegrass or some of the Italian ryegrasses or crested wheatgrass.

Or plants that were stockpiled over the winter, like tall fescue or the forage brassicas or last fall’s turnips. In any case, you need to plan this strategy in advance and plant the annuals during the previous summer or fall. The reward is that you have forages to graze early in the following spring while keeping animals off the rest of your fields for a few extra weeks.

Here’s an outside-the-box strategy: Overgraze one field in early spring on purpose. Why? Because you’re managing that field as a sacrifice area. Yes, this can be a real strategy. In this strategy, you want to graze that early forage and stress those plants because you don’t care about regrowth, because you plan to renovate that field later in the season or use the field for a different crop. While it sounds a bit weird, a sacrifice area is a perfectly valid strategy. It can be a powerful management tool if used well.

Finally, let’s think of our neighbors. Seriously. Maybe someone down the road has a field or two that needs “cleaning up.” It has grass; you have cattle. Maybe you can reach a deal: You can help them out with weeds, brush control and fire danger. You’ll get early feed, your pastures get a rest during the early spring and your neighbors get a clean field. Not bad.

Early spring is indeed a wonderful time. Those gorgeous spring days brighten your life and make you want to jump up and click your heels. So do it! Enjoy yourself in the sunshine. But keep the cows off those fields for another couple of weeks. Your pastures will thank you for it.  end mark

ILLUSTRATION: Illustration by Getty Images.

Woody Lane is a certified forage and grassland professional with AFGC and teaches forage/grazing and nutrition courses in Oregon, with an affiliate appointment with the crop and soil science department at Oregon State. His book, From The Feed Trough: Essays and Insights on Livestock Nutrition in a Complex World, is available through Woody Lane.

Woody Lane, Ph.D.
  • Woody Lane, Ph.D.

  • Lane Livestock Services
  • Roseburg, Oregon
  • Email Woody Lane, Ph.D.

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