Johnson Grass

[St3]

So many mixed opinions out there. Need some clarification. To my knowledge we haven't had any issues with toxicity. Cattle eat it and love it…. but what kind of hay does it make? Some folks say it has zero nutritional value, others say it's high energy.

Thoughts ?

 

[kenny thomas]

Johnsongrass (Sorghum halepense) is a warm-season perennial bunchgrass that can be used as forage for cattle and hay. It has high-quality forage with an average protein level of 12% and total digestible nutrients (TDN) of around 55%. Johnsongrass can also have a crude protein of 10 to 14 percent and total digestive nutrient values of 50 to 60 percent.

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Johnsongrass can compete favorably with other warm-season species such as bermudagrass. However, it doesn't tolerate grazing pressure well and pastures that are continuously grazed often won't have any johnsongrass. This is because cattle tend to preferably overgraze the species, and its growing point is 4 to 8 inches above the soil surface. Johnsongrass can also be challenging to dry when used to produce hay.

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Johnsongrass can also accumulate nitrate and prussic acid, which are poisonous to livestock at high levels. This can happen when plants resume growth after undergoing stress, such as a rainfall followed by a severe drought period. To avoid nitrate and prussic acid poisoning, you can test forage for these concentrations after long drought periods or frost.

 

[chaded]

It makes very good hay but like anything else, it needs to be cut at the right time. Early boot stage. I have noticed the people that don't like it around here are the ones that cut it when it is so ripe it's basically straw.

 

[Hpacres440p]

After having one cow with prussic acid toxicity last year (after 6 bites)-it scares me in pastures when it starts getting hot.

 

[bird dog]

In most cases, a field of Johnson grass in early to mid summer that has the proper moisture in the soil will have all stages of the plant. Some will be seeded out, some will be just coming up. It can make good hay and a lot of it. My cows do just fine on it as hay or grazing.
Under continuous grazing as Kenny mentioned, the cows will clean it out before it reseeds. Under rotational grazing you can manage it to where it reseeds pretty well. If your stand gets thin, a good discing will revitalize it some. My fields are on a 45 or so day of rotation. That seems to be about right for the plant to rest and reseed. It can be toxic at times as mentioned. It can also be a excellent grass on poor soil that will come back every year without any inputs.

 

[Brute 23]

Makes great hay for very low inputs. It's very hardy. I'm on a list to get seed this year, hopefully.

 

[Logan52]

I have it in red clover/orchard grass hayfields. It is just starting to grow in the first cutting and does not add much to the hay.
Usually, by the time I get around to the second cutting the johnson grass is overmature and difficult to cure, very straw like even if you can cure it without mold.
If the stand of johnson grass was thick enough to manage the cuttings when it was just starting to head, it would be good hay. Since the stand is scattered, it is more like a weed I would be better without.

 

[Mark Reynolds]

Well, Johnson grass itself is like the opinions about it. Pretty much all over the place. For starters, learn about the TWO (2) separate toxins that Joynson grass can accumulate. First, prussic acid, and then, nitrates. The prussic acid "burns off" once conditions change. The nitrates are there to stay if drought causes them to become a factor. It makes great pasture. It can be 'grazed out'. It's highly digestible/palatable when vegetative. It becomes unpalatable when mature. As for hay, it's good (as long as not stressed with one or both toxins). If it gets too mature, quality drops like a stone as well as the plant becomes too coarse to cure/dry properly. A field of 'uniform' Johnson grass can be very good for either hay or grazing. If it is patchy or clumpy, it's almost unmanageable and preference dictates it's better if the Johngrass wasn't even there to begin with. Prussic acid and nitrates both accumulate with drought stress, nitrates at a much slower rate. Removal of drought stress eliminates the prussic acid after as little as 7 days, but up to 14 days. The nitrates, once there, are there and can't removed. Frost damaged/killed Johngrass will be contaminated for 7 days or so by prussic acid, but it burns off in a week or 2. Nitrates are uneffected by frosts/winter kill. The nitrates will always be there, if they have formed. Where Johngrass is 'clumpy' It is often too dense to be able to dry or cure.

 

[1982vett]

Good explanation Mark, but what does drought stress look like. 100 degree temps will "stress" actively growing grass.

I've always believed it (prussic acid) was post drought that was the problem. Once it started rapidly growing again after drought much the same as haygrazer and sorghum isn't to be grazed till 18-24 inches tall. My "fix" is to put the cows on before water (dry conditions) and heat become a problem and keep them on it all summer.

I agree that nitrate would build as it became stressed and slowed growth.

 

[Mark Reynolds]

That is a good question @1982vett, I honestly don't know. I would gather there is some 'threshold' to look for in terms of number of days above "X" temperature or a certain level of dryness, and these two factors probably work in some sort of complex combination. Johnson grass is actually classified as a prohibited noxious weed in Ohio.

The Ohio Department of Agriculture (ODA) is in charge of designating "prohibited noxious weeds." The list may change from time to time, but currently, noxious weeds include: Shatter cane (Sorghum bicolor) Russian thistle (Salsola Kali var. tenuifolia). Johnsongrass (Sorghum halepense).

As I said earlier, opinions are all over the place on it.
The thing to do with Johnson grass if you are concerned about nitrates (and there can be good reason if climate conditions (heat & Drought) have been questionable) is get the Johnson grass tested. Remember, the nitrates will not dissipate. In all honesty, I believe that prussic acid is much more of a problem in frost damaged Johnsongrass than it is with drought conditions. I am guessing that prussic acid is 'perceived' as a drought problem in Johnson grass because prussic acid levels become fatal in black cherry in wilting conditions to those leaves. The research information I know of with prussic acid problems in Johnsongrass has all been in relation to frost damage. Frost damage and drought damage mechanisms are different.

 

[Twisted]

It is almost never seen in a pasture because the cows will eat it before anything else. Ever tried pulling a clump out of the ground? It has a root structure kind of like a corn stalk except it is a rhizome, so it sends out shoots underground and reproduces through these. It takes very little seed to get a crop started. I was raised on a farm where Johnsongrass was the largest percentage of our hay crop and I baled it for years. Once it matures to the point that the stalk starts getting red spots on it, it is overmature and the top of the plant is about all that has any value as feed, but the cows will eat it anyway if they have nothing else. Also, if you let it fully mature before baling it, thick stands plug up a hay rake and the baler, I have baled lots without raking it, then run a rake over the field to clean up the remainder. In good conditions, it will grow over 6 foot tall.
A lot of ranchers crimp it to alleviate some of the moisture in thick stands to help with the drying.

 

[Twisted]

I should add, The threat of prussic acid leaves the plant when it dries. So there are no prussic acid issues with dry hay.

 

[bird dog]

Vett is right, its after the first rain on stressed grass where you have problems. If it was a problem just because of dry weather, you would have a lot more dead cows along the back roads every time one got out.

I lightly disc my Johnson grass stubble after the last grazing to avoid the frost issues. It also plants some seed for the next crop.

 

[Allenw]

Well, Johnson grass itself is like the opinions about it. Pretty much all over the place. For starters, learn about the TWO (2) separate toxins that Joynson grass can accumulate. First, prussic acid, and then, nitrates. The prussic acid "burns off" once conditions change. The nitrates are there to stay if drought causes them to become a factor. It makes great pasture. It can be 'grazed out'. It's highly digestible/palatable when vegetative. It becomes unpalatable when mature. As for hay, it's good (as long as not stressed with one or both toxins). If it gets too mature, quality drops like a stone as well as the plant becomes too coarse to cure/dry properly. A field of 'uniform' Johnson grass can be very good for either hay or grazing. If it is patchy or clumpy, it's almost unmanageable and preference dictates it's better if the Johngrass wasn't even there to begin with. Prussic acid and nitrates both accumulate with drought stress, nitrates at a much slower rate. Removal of drought stress eliminates the prussic acid after as little as 7 days, but up to 14 days. The nitrates, once there, are there and can't removed. Frost damaged/killed Johngrass will be contaminated for 7 days or so by prussic acid, but it burns off in a week or 2. Nitrates are uneffected by frosts/winter kill. The nitrates will always be there, if they have formed. Where Johngrass is 'clumpy' It is often too dense to be able to dry or cure.

Nitrate amount will lower with adequate moisture and time just like any other sorghum. You are correct that they won't change once the plant is harvested or winter killed.

 

[cowman82]

i've planeted dwarf sudan in JG fields, it matches its growth rate pretty good.

 

[Brute 23]

Do yall have nitrate issues naturally?

My understanding is it came from a lot of fertilizer which is not really necessary with JG.

 

[kenny thomas]

Do yall have nitrate issues naturally?

My understanding is it came from a lot of fertilizer which is not really necessary with JG.

I have never had an issue with nitrates but guess i could. I only fertilize in the spring and our Johnson Grass doesn't do much until July and August. Its always around 90 days after fertilizer is applied so most nitrogen has been used up by then.

 

[Allenw]

Do yall have nitrate issues naturally?

My understanding is it came from a lot of fertilizer which is not really necessary with JG.

It's always been my understanding that nitrates shouldn't be a problem in johnsongrass unless a lot of nitrogen is present.

 

[Mark Reynolds]

'Problem levels' of nitrates are likely caused by a combination of factors. Each factor in of itself 'could' se the sole cause, but it's probably a combination of factors. Things I'm seeing as potential contributors are nitrogen in the soil (fertilizer is a much bigger deal than 'organics' like clover, but...), day length (actually, short days are the contributor and light deprivation, not long days), and stress (water and temperature).

Also, the 'problem level' of nitrates is variable based on the livestock. Needless to say, the higher the level gets in the forage (cut hay I'm guessing) the riskier it gets.