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Tillage Destroys Soil's Physical Properties

By John Graham, Soil Health Specialist for NRCS in Kentucky

Landowners should be concerned about anything that depletes their soil health.  This is especially true in light of what tillage does to soil health.  Soil health is the soil’s ability to maintain and/or improve plants, animals, air, water, and human health.  An important part of soil health is the soil’s physical properties.  It is worth noting here that tillage destroys a soil’s physical properties and therefore the soil’s ability to function properly.  Tillage destroys and/or depletes the soil’s aggregate stability, structure, pore space, water holding capacity, infiltration, permeability, gaseous exchange and nutrient storage ability.  Soil pore space is of critical importance to any landuser growing crops or livestock.

Of the above listed physical properties soil pore space is of the most critical importance during the dryer weather conditions we seem to be experiencing more and more.  Soil pore space is how the water gets into the soil (infiltration), it is how the water moves through the soil (permeabililty), and it’s where the water is stored in the soil for plants to use in the dryer times of the year.  We need to remember that when we till the soil we destroy the soil aggregates creating a tighter soil where water infiltration is severely reduced and therefore soil water storage for the plants and microbes alike are depleted.  Instead of water going into the soil it runs off the soil surface taking with it valuable topsoil, surface applied chemicals and fertilizers.  This results in water quality and landscape degradation.  But tillage does something even more detrimental to the soil.  It not only destroys the soil physical properties but it also destroys the soil’s ability to heal itself.  Microbes that build soil structure live on live roots and eat dead and decaying organic matter either from surface plant residues or dead roots.  When we till the soil we drastically reduce the amount of live roots in the soil (the structure building soil microbes home) but we also cause the organic matter (plant residues) to be eaten by microbes in a hastened manner.  What does this mean?  It basically means when tillage is performed you take the microbes home and food source from them.  When this happens the microbes go dormant or die resulting in depleted physical soil health with no way to heal itself.

If landowners truly understood what tillage does to their soil you would see a lot less tillage and a lot more no-tilling of crops.  No-till with cover crops, maximizes live roots (the microbial home) and maintains substantial quantities of organic matter (microbial food).  The end result being maximized soil health building with minimal existing soil health destruction.