I received a question via my ILSoyAdvisor column about whether a grower should apply a cocktail of amino acids to soybeans to make sure there are no shortages. Many growers are interested in increasing soybean yield today, and with all the products available can we mimic what we do for human health to improve soybean health?
Seems logical, but then soybeans aren’t mammals like we are.
Amino acids are components of protein and all living organisms require proteins. In plants, proteins are either enzymes that drive critical metabolic functions or storage proteins that are important components in end products.
Mammals get amino acids in their diet while plants produce their own. There are 20+ amino acids, some considered essential and others non-essential. And since protein meal contains 46 to 48% crude protein, amino acids are essential since feed companies buy meal for its amino acids.
Can we effectively feed soybeans amino acids to supplement what the plant manufactures and perhaps increase crude protein levels or improve amino acid composition in the meal at the same time?
Seth Naeve, extension soybean specialist at the University of Minnesota, says “No. Amino acids will be metabolized in the soil before any uptake occurs. And besides, plants take up minerals and nutrients as salts, not large compounds like amino acids. However, having lots of organic compounds (e.g., manure) is good, but the plants are only seeing the salt forms of nitrate, ammonium, sulfate, phosphate, potash, etc.”
If you see products that promote themselves as a good source of amino acids for plants, just note that when they are applied to the soil they are broken down by microbes, their component parts are then mineralized as nutrients, and they essentially become a fertilizer.
While plants take up minerals as salts, either via the roots or across leaf surfaces, it is plausible that if amino acids are applied foliar they could pass through the stomates and enter the plant that way, but don’t rely on this for a substantial source of amino acids. And even if amino acids get into the plant leaf, will they enter the pool of amino acids from which proteins are built and increase protein production?
Amino acids are important in plants, but remember they make their own. If you have a good fertility program, the plant will produce what it needs. Applying an amino acid as a supplement will probably not directly benefit the product or protein levels in the seed. Remember this the next time you see an advertisement recommending you apply amino acids to your crop.
Soybean agronomist Daniel Davidson, Ph.D., posts blogs on topics related to soybean agronomy. Feel free to contact him at firstname.lastname@example.org or ring him at 402-649-5919.