Phosphorus. Who Knew?

Our mineral array from Free Choice Enterprises arrived Thursday morning. The company sent enough to last 10 cows a couple of months. Let me say that differently. They sent a bag of everything plus extra trace mineral arrays and extra extra phosphorus.

Good thing too. The cows attacked the phosphorus. Attacked. It.


As frost was arriving we were feeding comfrey to the cows. Apparently comfrey is a phosphorus accumulator. The cows loved it. Other phosphorus accumulators include dock and shagbark hickory. These are all plants that grow deep root systems over years and years…involving relationships with fungal environments. I don’t remember seeing the cows eating dock. Any tree leaves within reach are fair game though. I can’t discount the possibility that comfrey may simply taste good.

But why do the cows think we are short on phosphorus? There’s plenty of manure on the pasture all year. All manner of N-P-K has been spread on my farm for the last 60 years…or harvested and fed into my cattle…and dumped on the pasture. How could we possibly be short on phosphorus? It’s not like there’s a shortage of dock growing in my pastures.

I’ll tell you what I think. I probably won’t know if I’m right in my lifetime but I’ll tell you anyway.

I think it’s because the pastures have been grazed down to nothing forever. No residual left to cover the dirt summer or winter. Just pulses of spring and fall lush growth. That is an environment that favors bacterial growth…it inhibits fungal growth. Further, the cows tend to manure under shelter…to rest under shade then unload before walking away. Some percentage of the manure ends up on the pasture but a large percentage of it is concentrated under trees.

But over the next 50 years or so, if we can keep managing our grazing for high residual, we’ll see an increase in fungal activity and a more even distribution of manure. It will help when we establish diverse strips of trees on contour in our pastures. It also helps to have high diversity in our pastures.

But I have to wonder about the buffalo. What would a herd of buffalo do if they came across a phosphorus lick as they grazed the prairie? Would they stop to partake?

Do children like candy?

Maybe that’s what I’m seeing. Maybe it’s not so much a nutritional deficiency as just the cows stocking up on something hard to find while it’s on sale. We’ll see if the rate of consumption continues over the next 20 years…but I’m not jumping to conclusions if it does. What I’m really looking for is cows giving birth to healthy calves without difficulty. Cows without health problems. Phosphorus? Meh. I just have to trust that the cows know what is good for them…in this case. I don’t take the same position concerning lush alfalfa though.

All I really know is that I need to close the loop on my land as much as possible to keep our nutrients at home. Keeping our dirt covered and our roots deep should help with that. The cows and I will come to some accord concerning mineral consumption. So far I’m liking what I’m seeing.

2 thoughts on “Phosphorus. Who Knew?

  1. I’ve had a suspicion for some time that my Jerseys are low in phosphorous. I’ve seen them lick the wood in the barn at times. Not always but they go through phases. So I’ve suspected phosphorous. I didn’t know that comfrey accumulated phosphorous. Where did you find that info? And my Jersey that licks the most wood also eats dock where other don’t. I assumed it was due to dock’s anti fungal properties as this cow tends to get a fungal infection between her front quarters when she’s fresh.

    So what mineral resources have you found? I personally prefer books. I’ve read Pat Coleby’s. I’ve read through Jerry Brunetti’s Agri Dynamics catalog (he’s got those great forb/hedgerow charts that Nita has referred to….thanks Nita!) And Gerald Fry’s page on the signs of various mineral deficiencies. And there are some o.k. local resources too. I’d like to try the smorgasbord variety of mineral feeding you are doing but am loath to invest all that money. It is a bit heavy for what I’m doing here. I don’t use a tractor and need something I can move easily.

    What form of phosphorous are you using? And I do not think it is like candy. Anyway, sorry to ramble. I look forward to seeing your results on this.

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