If seeing is believing, anyone who has seen no-till vs. till soil demonstrations should understand what can happen to soil properties when a soil is tilled year after year. Unfortunately, one negative property is that the soil no longer has many natural channels or air pores in the soil to absorb rainwater.
Instead of working its way into the soil and becoming available for soil moisture recharge, rain just sits. That keeps soils saturated and you out of the field.
Tony Branham, district conservationist with the Natural Resources Conservation Service, recently took two samples of Genesee bottom land soil from the same area along the creek. One was in a field owned by a farmer who tills the flood plain every year. Genesee is naturally well-drained, even though it is in a flood plain or bottom land position.
The other field of the same soil type has been no-tilled for several years. Branham cut out a small chunk of both from the surface down, and then simulated a rainstorm using pans with holes in the bottom.
The difference was striking. The no-till soil let the water move in very quickly. It had pore spaces and worm channel holes. Some water went through the sample, taking a small amount of dirt with it, but not as much water came through as was poured in.
However, the till field soon had about three inches of water sitting on top. Branham had poured the exact same amount of water into the cloud simulator above each tray.
Why did the water sit there? Branham believes it's because the water has nowhere to go. The soil crusts over, and the breakdown in structure doesn't allow for infiltration.
It's the same reason why water ponds on your field unless the slope is steep enough for runoff.
There were no tricks – no sleight of hand. Every time this demonstration is done it turns out the same way. Reducing tillage obviously increases infiltration rate, an important component of soil health.