Mineralization of Potassium?

[Douglas]

From OSU:
All applications of K should wait until the plants can utilize it better. If we were to look at soil levels of potassium during the year we would find that it is in greater concentration during the spring (due to mineralization of K during the winter. Plants have the ability to take up more potassium than they need. This is called luxury consumption. Luxury consumption can occur when there are high soil levels of potassium, like what we see in spring. High concentrations of potassium can affect magnesium uptake by plants. This not only affects the plant physiology but can also cause metabolic imbalances in animals that consume mainly forages. The metabolic imbalance in animals is usually referred to as grass tetany. Why apply potassium at a time when more is already available and plants can take up more than they need?

Can someone explain this part: "...potassium during the year we would find that it is in greater concentration during the spring (due to mineralization of K during the winter.

 

[G.S.]

Hi Douglas,
With the standard disclaimer, I'd ask if the writer might have been more clear by writing "...of K during dormancy"? Try reading this and see if it helps: http://beefmagazine.com/mag/beef_dont_short_salt
If you are still awake afterwards, let me know!
//G.S.

 

[Dave]

In general terms mineralization requires two things. Soil temperature and moisture. So this would depend on your area. here we have plenty of moisture but our winter soil temps are too low for much if any mineralization to occur.

I have seen first hand the affect of high soil K levels. The dairies in this area have been importing alfalfa from the irrigated east side of the state which is high in K. The manure is applied to the fields based on N which is over applying K. The K builds up in the soil to some pretty high levels (1,500 ppm or more). The plants luxury consume the K. And under consume magnesium and/or calcium. The result is an increase of cases of grass tetany or milk fever. A few years back one of the dairies I work with lost a couple cows. So they had me test the grass and the soil. I forget the number the soil tested at but the grass tested at 4.65% K on a dry wieght basis. The dairy nutritionist from WSU said if it got to 5% there wouldn't be a cow left alive on the farm.