Potassium (K)
The following section discusses potassium in animal husbandry and in soil and crops.
Potassium in animals
Potassium (K), together with chlorine (Cl) and sodium (Na), plays an essential role in the osmotic pressure of body cells and thus the fluid balance of the body. Together, these minerals determine the cation-anion difference (also called acid-base balance) of the ration and of the body.
Potassium plays a role in the production of enzymes (important in energy transfer in cells and carbohydrate metabolism). In addition, potassium is important for the transmission of muscle impulses, including the heart. The potassium level in the blood is kept very constant and any surplus or deficit is reflected in the urine.
| Category | g/kg dry matter | g/animal/day |
|---|---|---|
| Young cattle from 4 months | 4.3 | 17 |
| Young cattle from 9 months | 4.6 | 26 |
| Young cattle from 16 months | 4.9 | 56 |
| Dry 8-3 weeks to calving | 4.9 | 56 |
| Dry 3-0 weeks to calving | 5.0 | 55 |
| Lactating (20 kg) | 7.2 | 134 |
| Lactating (40 kg) | 8.1 | 190 |
Potassium deficiency
A potassium deficiency does not cause specific deficiency symptoms but leads to a reduction in feed and water intake and lower milk production. Other symptoms may include 'licking', muscle cramps and sensitivity to all kinds of stimuli. Normally, ration contains sufficient potassium.
Potassium excess
A potassium surplus inhibits the absorption of magnesium and calcium, making animals more susceptible to headaches and milk fever. The CVB (2005) indicates a toxicity limit of 30 g/kgds (for chronically high levels). Eurofins Agro recommends a maximum of 25 g/kg ds, preferably lower.
By performing Ration Check from Eurofins Agro, you can be sure of the potassium levels in your mixed ration and make immediate adjustments, if necessary.
Potassium in soil and crop
Potassium is essential for moisture management and plant metabolism and is the mineral absorbed in the second largest quantities, after nitrogen. A potassium deficiency therefore directly inhibits crop growth. Grass and alfalfa in particular contain relatively high levels of potassium and are sensitive to this. Maize contains much less potassium, as do CCM, pressed beet pulp and brewer grains.
| Fresh grass | Grass silage | Maize silage | Lucerne | |
| Average | 34 | 33 | 11 | 29 |
| Target range | 25-35 | 25-35 | 10-14 | 25-35 |
Additional fertilization with potassium
Potassium can leach out quite easily, especially on lighter soils. The amount of potassium in the soil that is available to the crop is decreasing in several region because less manure is applied each year (due to tightening fertilization rules), as well as the fact that the average potassium content in manure is decreasing. It is therefore important to use the Fertilization Manager from Eurofins Agro to assess whether your crop needs an extra dose of potassium. Additional fertilization with potassium (in the form of K2O; potash) generally has a positive impact on crop yield and quality by reducing the susceptibility of crops to drought, frost and fungi and improving shelf life.