Guest Blog: Potash Keeps Crops Drought and Disease Resistant
By: Zachary Adams
Account Manager, Intrepid Potash
With harvest in full swing across the Corn Belt, growers are beginning to turn their attention toward fall fertilization and replacing nutrients that will be removed in the record 2014 crop. Addressing potassium (K) removal is important for continuing to produce record crops and maximizing the value of improved seed varieties and fertilizer inputs. The USDA’s latest yield projections from the Oct. 10 forecast of 174.2 bu/ac and 47.1 bu/ac of corn and soybeans respectively equates to 73 lbs/ac and 94 lbs/ac of muriate of potash needing to be applied per acre to replace the removed K. From a national level, there will need to be a total of 6.9 million st of muriate of potash to replace K removal from the record corn and soybean crops.
The Law of the Minimum from Justice von Liebig states that when just one of the 17 essential nutrients is deficient it will negatively affect yield potential even when all others are in abundant supply. Potassium is one of three macronutrients, along with nitrogen and phosphorus, which plants require in the highest levels. The majority of K is stored in the residue or straw of the crop so removal rates can be even higher in forage crops such as alfalfa, bermudagrass hay, or corn silage. Potassium is an immobile nutrient in the soil meaning that it doesn’t move freely through the soil profile. As plant roots remove K from soil solution, the process of diffusion takes place where exchangeable K on the cation exchange complex moves back into the soil solution to replace what was taken up by the plant’s roots.
Potassium is referred to as the regulator nutrient since it is involved in the activation of 60+ enzymes processes affecting such things as drought resistance, disease resistance, and efficiency of nitrogen uptake. Adequate K fertilization strengthens the cell wall of plants making it more difficult for disease organisms to infect the plant. Stronger cell walls also decrease the incidence of lodging in corn by making a stronger more stable stalk for the plant. Perhaps one of the most well-known benefits is the influence that K has on a plant’s stomata cells. The stomata openings become smaller with adequate K present allowing less water to escape and keeping water pressure in the cell at higher levels which helps the plant with drought and disease resistance. Because K is immobile, dry conditions which limit root growth will induce a K deficiency.
Potassium application is a key to maximizing return on fertilizer inputs and improved seed varieties. A study from University of Illinois in 2008 showed K uptake to be 19 percent higher in corn rootworm resistant varieties versus nonresistant hybrids with a yield benefit of 14 percent. Additionally, a Kansas study from 2005 showed that when potassium fertilizer was added it improved N fertilizer recovery almost 40%. These examples and others show that by utilizing soil tests, removal data, and yield projections, potassium application remains a profitable agronomic and business practice.