We all appreciate legumes and their marvelous ability to fix atmospheric nitrogen and release it into the soil. But what happens after the legume plant releases this ammonium and nitrate?
I blithely figured that into the soil they went and the grass roots just picked them up. Hardly so! What I considered the “roots” of a plant actually represent only a tiny fraction of its actual absorptive mechanism. The real players are the soil “mycorrhizae,” beneficial fungi that colonize on plant roots and serve as a nutrient pipeline into the host plant. Not only do the mycorrhizae absorb water and mineral elements (phosphorus being a key one), they also break down other potential plant nutrients and funnel them to plant roots.
In a healthy soil structure, a single gram of soil contains over 150 feet of these fungal “hyphae.” On the average, one acre of soil that’s seven inches deep weighs two million pounds. Imagine the amount of mycorrhizal filaments in that one acre of healthy soil! They are there for us to use in our pastures.
Salt fertilizers can kill these good-guy fungi. Applying the fertilizer in small amounts multiple times throughout the growing season can lessen this mortality. However, seeking ways to promote an ever healthier and increasingly productive soil using biological processes appears to be the more futuristic and sustainable pathway. It may be profitable to use a mycorrhizal amendment to counteract the effect of salt fertilizer while we are transitioning to a more sustainable system.