Upon request, I receive the Argus North American Fertilizer e-newsletter. The one hitting my inbox most recently was the Dec. 4, 2023 issue. From that document I selected a few high spots, targeting three very high-volume conventional (non-organic) commodity ingredients. Quotes are for three different locations, depots boasting the most commercial transport for the commodities in question. Dollar figures (per short ton) are averages, calculated from a range of values cited in that newsletter for each of the three commodities selected.
The first was mono-ammonium phosphate at the Cincinnati depot, with FOB price of $678, compared to a year-earlier value of $773, for a drop of 12.3%. The second was urea-ammonium nitrate at the East Coast depot, FOB priced at $263, compared to a year-earlier value of $578, a drop of 54.5%. The third was muriate of potash at Vancouver, Canada, FOB priced at $258, compared to a year-earlier value of $543, a drop of 52.5%.
Of the three main fertilizer nutrients (nitrogen, phosphorus [P] and potash [K]), P is doing the poorest job of returning to lower pre-pandemic price levels.
Most readers are aware that I seriously advocate testing soils, forages, livestock performance, etc. Not knowing what nutrients are present or lacking in soils is a case where ignorance is seldom bliss. For instance, a farmer might call me to ask why a meadow is being overrun by horse nettle (wild tomato). I answer that question with my own question: What do your soil tests tell you? That question usually is followed by loud silence on the part of the non-testing caller.
It turns out wild tomato likes higher pH, low P and poor soil biology. Complete soil tests – including base saturation percentages – would have provided that crop person very useful information. Most of the time, giving the desirable plants the soil nutrient package they need helps chase away undesirable plants.
Testing forages is very important, particularly if the soils growing those forages were not tested. Intuition only goes so far in tying together feed programs. I take testing one step further, beyond soils and forages, occasionally testing total mixed ration (TMR) blends for dairy folks using this management tool.
TMR programs boast at least four advantages compared to separate ingredient feeding: they can ensure that every mouthful ingested is nutritionally balanced; they enable the cattleman to introduce dietary changes gradually, minimizing off-feed issues; TMRs generally increase total dry matter intake; and finally, TMR analyses provide report cards, grading the ration-balancing skills of the dairy person.
A TMR analysis report arrived in my inbox just before Thanksgiving for Chester, an organic grass-feeding dairyman in Herkimer Co., NY. I advise this organic farmer in both cropping and dairy nutrition. That printout, from the Dairy One Lab in Ithaca, provided about 30 values expressed on a dry matter basis, costing about $40.
On his TMR analysis report were a few values that raised my eyebrows. First, total dry matter (DM) percentage was about 38.9%; generally, when total diet DM drops below 50%, increasing DM intake (DMI) above current level becomes quite a challenge. In colder weather, soggier TMRs may freeze. Adding two to three pounds of chopped hay per head per day (PHPD) will help dry up the TMR, as well as not depress intake of other feeds. As total pounds of DMI increases, generally so does milk production. Chester’s herd consists of 35 – 40 mostly colored cows, with DMI/day about 35 – 38 lbs.
The second item concerning me was the TMR protein solubility of 47%. Normally, we try to keep that figure closer to 30% (definitely not over 35%). Wetter forages tend to have higher protein solubilities, with a greater proportion of their nitrogenous compounds showing up as non-protein nitrogen (NPN). Thus, more carbohydrates are needed to feed rumen microbes.
Upon receipt of the carbs, these tiny critters couple such energy sources with NPN, synthesizing the more complete – and complex – proteins needed for producing milk, meat, calves, etc. Adding a pound of molasses PHPD (okay for grass-fed organic, if the molasses is organic) provides these microscopic workers the carbs they need to perform this vital task.
My third point of concern (but not a worry) was net energy for lactation testing at 0.67 megacalories/#DMI – against a requirement of 0.60. The molasses that Chester is already feeding no doubt helped ensure that need was met. Note: if that dietary protein solubility hits and exceeds 40%, excess NPN in the rumen can result in too much blood ammonia, which actually requires energy to excrete through the kidneys – energy that otherwise could have supported milk production.
Point 4 was a calcium reading of 0.99% (against a requirement of 0.80%), plus a P reading of 0.48% (against a requirement of 0.40%). So these two nutrients looked pretty good.
Point 5 was a magnesium (Mg) score of 0.34% (okay against a requirement of 0.30%). But compared to a K reading of 2.53%, there’s a chance that the K can outbalance the Mg, predisposing these mostly colored dry cows to a hypo-magnesemic milk fever. I recommended that Chester feed 0.10 lbs. of Epsom salt (magnesium sulfate) PHPD to dry cows as soon as they start bagging up – and keep feeding it up till freshening.
Point 6 deals with salt, measured by a 0.126% TMR sodium reading. For 38 lbs. daily DMI in the TMR, this means the average cow is consuming about 2.5 ounces of sodium chloride per day. Not bad, but I still recommended Chester topdress a couple ounces of salt with selenium a couple times per week, just to be safe.
Confronted with all these numbers, let’s remember that grass-fed cow diets tend to run lower in P than regular grain-included rations. Per pound of DM, grains bring about twice as much P onto the farm as do forages.
And few folks know this: A little over 1 lb. of actual P accompanies every 1,000 lbs. of milk leaving the farm.
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