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<blockquote data-quote="cowtrek" data-source="post: 254585" data-attributes="member: 2847"><p>J-grass is good stuff. They don't call it "ice cream grass" for nothing. To the chagrin of row crop farmers everywhere (which I was one) the stuff was originally imported as a promising cattle forage. Only later was it found that the best way to kill it is continuous grazing. It spreads prolifically in non-grazing situations by seed and rhizome which is why it gets so bad in row crops and hay meadows that aren't grazed. Cattle will always eat johnsongrass first-- they love it like ice cream or candy, and they'll literally eat it to death. </p><p>Prussic acid is a risk with all the sorghums. It's a risk that is mostly overblown. The main time to worry is when you get a sudden flush of quick lush green growth right after a prolonged dry spell, and right after a burning frost. I'd pull the cattle off the jonsongrass for about a week or so right after either of those events. That is when it builds up prussic acid and about a week or two will allow it to go away. If you want to make absolutely sure you won't have any prussic acid problems, cut the J-grass for dry hay. The prussic acid quickly gasses out during the drydown process. If it were me and I needed hay and was scared to graze it, I'd just bale it and call it good. The regrowth should be fine. It's usually the quick growth spurt caused by a rain after drought stress that causes a problem, I don't think the drought stressed grass should have prussic acid but you can have it tested to be sure if you want to graze rather than bale it. </p><p></p><p>The other problem, usually overblown, is nitrate poisoning. Nitrate accumulation is usually a result of heavy fertilizer use in a drought situation when there is simply not enough water to sustain new growth. When water is the limiting factor to growth with high soil nitrogen levels, the plant draws moisture and dissolved nitrogen in through the roots for metabolism and growth, but the plant doesn't have enough water for more growth, so it stores the nitrogen in the stem tissues waiting for rain so that it can use that nitrogen rapidly for growing when the water is no longer the limiting factor. It's sorta like us gaining ten pounds or so over the holidays, we eat more than we need so our bodies store it til we need it. If we don't eat so much or increase our activities (like plant growth does) then it's not a problem. In dry conditions you want to use less fertilizer since water is the limiting factor to plant growth. Using a lot of N just increases costs and wastes fertilizer and causes nitrate problems. When water is in abundance, then N availability is the limiting factor and fertilizer will help. But NO amount of N will increase yields above the amount of growth that can be sustained with the limited supply of water. So, in a drought, apply little or no N until you get a rain (depending on severity) and when it does rain you can put out some fertilizer when it will actually do some good. </p><p></p><p>Hope this helps. OL JR <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p></blockquote><p></p>
[QUOTE="cowtrek, post: 254585, member: 2847"] J-grass is good stuff. They don't call it "ice cream grass" for nothing. To the chagrin of row crop farmers everywhere (which I was one) the stuff was originally imported as a promising cattle forage. Only later was it found that the best way to kill it is continuous grazing. It spreads prolifically in non-grazing situations by seed and rhizome which is why it gets so bad in row crops and hay meadows that aren't grazed. Cattle will always eat johnsongrass first-- they love it like ice cream or candy, and they'll literally eat it to death. Prussic acid is a risk with all the sorghums. It's a risk that is mostly overblown. The main time to worry is when you get a sudden flush of quick lush green growth right after a prolonged dry spell, and right after a burning frost. I'd pull the cattle off the jonsongrass for about a week or so right after either of those events. That is when it builds up prussic acid and about a week or two will allow it to go away. If you want to make absolutely sure you won't have any prussic acid problems, cut the J-grass for dry hay. The prussic acid quickly gasses out during the drydown process. If it were me and I needed hay and was scared to graze it, I'd just bale it and call it good. The regrowth should be fine. It's usually the quick growth spurt caused by a rain after drought stress that causes a problem, I don't think the drought stressed grass should have prussic acid but you can have it tested to be sure if you want to graze rather than bale it. The other problem, usually overblown, is nitrate poisoning. Nitrate accumulation is usually a result of heavy fertilizer use in a drought situation when there is simply not enough water to sustain new growth. When water is the limiting factor to growth with high soil nitrogen levels, the plant draws moisture and dissolved nitrogen in through the roots for metabolism and growth, but the plant doesn't have enough water for more growth, so it stores the nitrogen in the stem tissues waiting for rain so that it can use that nitrogen rapidly for growing when the water is no longer the limiting factor. It's sorta like us gaining ten pounds or so over the holidays, we eat more than we need so our bodies store it til we need it. If we don't eat so much or increase our activities (like plant growth does) then it's not a problem. In dry conditions you want to use less fertilizer since water is the limiting factor to plant growth. Using a lot of N just increases costs and wastes fertilizer and causes nitrate problems. When water is in abundance, then N availability is the limiting factor and fertilizer will help. But NO amount of N will increase yields above the amount of growth that can be sustained with the limited supply of water. So, in a drought, apply little or no N until you get a rain (depending on severity) and when it does rain you can put out some fertilizer when it will actually do some good. Hope this helps. OL JR :) [/QUOTE]
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