AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Spring 1999, No. 5
Proteins are complex combinations of amino acids, which are small, simple compounds composed mainly of carbon, hydrogen and nitrogen. Nitrogen is the key to protein. The more nitrogen a plant has, the more protein it can synthesize.
Protein does not contain any potassium, but potassium is as essential to protein as is nitrogen. Simply stated … potassium is required in every major step of protein synthesis. Some of these roles include:
• Enzyme activation. Enzyme activation is one of the most important functions of potassium in plants. Over 80 plant enzymes require potassium to activate them, and many of these are directly involved in nitrogen metabolism. Plants need high concentrations of potassium for full enzyme activation.
• Energy relations. Plants need potassium to make the high-energy phosphate molecules that are produced in photosynthesis and respiration. These compounds supply the energy required for nitrogen metabolism.
• Nitrogen movement. Potassium helps move nitrate-nitrogen into and within the plant. Potassium stimulates nitrate uptake by plant roots and then accompanies it to aerial plant parts where it can be converted into protein. Potassium is also involved in the transport of other needed materials to and away from the sites of protein synthesis.
Plants well supplied with potassium take up more nitrogen and utilize it better. Research has shown that wheat with ample potassium promotes the movement of nitrogenous compounds from vegetative plant parts to the grain…that means higher protein.
The ability of potassium to improve nitrogen uptake appears to occur regardless of the level of available nitrogen. One study with wheat found that high potassium combined with low nitrogen increased nitrogen uptake by 33 percent and increased percent protein from 13.3 to 15.3. When the wheat was supplied with high potassium and high nitrogen, nitrogen uptake increased 29 percent, and protein increased from 16.7 to 17.6 percent.
Grain protein is not the only quality factor positively influenced by potassium. Kernel weight, size and plumpness are also improved. And of course, yields increase when potassium is applied to deficient soils.
All plants require plenty of potassium. But high protein crops require so much more. Forage, oilseeds, and pulse crops all have one thing in common—they yield high protein, and they need to be well supplied with potassium to produce it.
The world’s population wants and needs more protein. To produce those proteins in the most efficient way…pay attention to potassium fertility. A pound of potassium makes a pound of nitrogen go further.