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When is My Grass Going to Grow?!

By   /  May 19, 2014  /  2 Comments

Is your spring late or early? Does it seem like some forages aren’t springing up like you wish they would? Victor Shelton shares some background on “Growing Degree Days” and their impact on photosynthesis and plant growth.

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I’ve heard several comments that we are having a late spring.  I suppose that depends on your definition or basis for the comment.  I believe some people are still trying to use 2012 as a comparison.  In 2012, we certainly did have an abnormally early spring, so comparing any other year to it, even an average year, will seem later than “normal.”  I think our “normal” is out of whack.

There's an App for that!  Here's a link to figuring out what's happening in your neck of the woods. Just click to learn more.

There’s an App for that! Here’s a link to figuring out what’s happening in your neck of the woods. Just click to learn more.

Probably the most common way of assessing where we are in plant growth compared to other years is comparing Growing Degree Days (GDD).  Growing Degree Days are calculated by taking the average between the daily maximum temperature and daily minimum temperature and subtracting the base comparable temperature for each day.  Days are then added together to compare periods.  There is a fair amount of research tied to GDD’s and so it is quite often used to predict planting dates, maturity dates and everything in between on row crops.  In 2012, April was really not that much different than the average, but March was a different story; it even surpassed April in GDD’s.

Plant growth is highly influenced by the ambient temperatures but also very dependent on adequate moisture and photosynthesis.  Heat units without adequate moisture or sunshine are just not the same.  Moisture is easy enough to understand, but getting enough sunlight for photosynthesis is important for energy.  Photosynthesis probably has less impact on yield as compared to its impact on energy for the plant and for what consumes it.  Those soluble carbohydrates in the forages are highest after good sunny days.  This variability can even be tracked in a normal day with values peaking in the afternoon and lowest being in the early morning.  Numerous days with little or no sunshine can therefore impact forage quality, mainly energy.  On the other hand, it is a nice reminder that when you are cutting forages for hay or balage, those forages will have the highest energy when cut on a sunny afternoon.

Where am I going with all of this?  I guess to say we are just a little behind the average this year in forage growth.  Comparative clippings I’ve taken over the past few years puts us realistically only about 300-400 pounds of dry matter per acre behind the norm for the southern part of Indiana.  Bring on the sun!

Cattle grazing in Indiana

Cattle grazing in Indiana

Forages are on the verge of really taking off and we will see huge spurts of growth in the next few weeks.  Once forages really start growing fast, make sure to keep livestock moving in the rotation.  Doing some “top” grazing during this fast growth spurt will help retard seed head production some, and will help keep forages in plant stage two which is more balanced for animal production.  If growth control becomes unstoppable, then that is when you might consider either clipping the pastures to maintain the stand in a more vegetative condition or maybe cut it for hay.  Cutting for hay is certainly an option, but I would think twice about it when possible because you must consider the removal of nutrients that you will need to replace and if it was grazed, most would be returned without direct withdrawal from your wallet.  Some hay is always going to be needed, but we should always be looking for ways to feed less, ideally from grazing instead.

Top grazing is generally a very short grazing period for the particular field, allowing the grazing livestock to be more selective and take off just enough to slow seed head production some.  Even if this field is cut later for hay, grazing can improve forage quality.  Most grass hay is best cut in early boot stage, prior to seed head production.  Technically, boot stage is when the seed head is still enclosed within the sheath of the flag leaf.  Weather will highly influence when we are able to cut hay, so management to delay seed head production or utilizing late maturing varieties of forages can help improve quality when delayed.

Last thought today is to consider using a high magnesium mineral supplement.  With some cooler than normal conditions, and lots of very green wet grass, grass tetany is a concern.  Locations where more than adequate nitrogen and potassium have been added would be at higher risk.  Consult your local veterinarian or Extension educator for more information.

This is a good time of year, with a little extra moisture in the ground, to drive fence posts in the ground for new divisional fences and also to reseed pastures.  If you are planning on putting in any waterlines, earlier is usually better and should be ideally done before doing any reseeding in that same field.  Thank goodness the days are longer now so we can get more accomplished during this busy time of year.

Enjoy the spring weather and keep on grazing!

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About the author

For more than 25 years, Victor Shelton, Indiana agronomist and grazing specialist with the Natural Resources Conservation Service, has provided advice about grazing’s best practices. He travels across the state conducting pasture walks, working one on one with farmers and participating in grazing talks. He also writes a newsletter called "Grazing Bites" as a way to talk about current and seasonal grazing issues and what farmers need to be prepared for.

2 Comments

  1. Victor Shelton says:

    Thanks. Forages have leaped forward the last two weeks since I wrote that article, but still not normal yet. Seeing quite a bit lacking normal growth yet pushing reproductive stages already…this is typically brought on by stress. Yes, the cows know best when it comes to nutrients.

  2. bill elkins says:

    Good post. We’re in same boat (I mean our grass is) here in SE PA,. AND OUR CATTLE ARE VERY NOTABLY GOING BANANAS WITH THE HIGH MAG selection in FREE CHOICE MINERAL cafeteria sold by Mark Bader .

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