Source of Selenium


Source of Selenium?
  • The natural source of Se is through the food.

  • The food Se level is dependant on the soil Se status.

  • Highly leached soils in high rainfall areas & those derived from Se poor parent material are likely to be Se poor.

  • In SA, soils along the Eastern seaboard are prime candidates as well as intensively farmed soils under irrigation.

  • Soil Se levels <300 ppb would be severely deficient.

Factors affecting Selenium uptake
  • The uptake of Se by grasses is generally good & is more efficient than legumes.

  • Most fodder crops (roots, grains, forage) take up similar levels of Se to grasses (ryegrass,  Eragrostis). Uptake in maize silage is similar to ryegrass.

  • Selenium will leach under heavy precipitation (heavy rain, irrigation).

  • Some forms of lime interfere with the uptake of selenium.

  • High crop yields will dilute the Se content (e.g. spring flush).

  • Recycled Se is bound-up in the soil by the OM & by the soil colloids & is rendered unavailable to the plant.