Yesterday I attended a Soil Health/
Cover Crop Workshop in Elsberry, MO. If you haven’t been to the Elsberry Plant
Materials Center it is very interesting. They have many plots of different
cover crops seeded at different planting dates. They also had a rainfall
simulator demonstrated by Doug Peterson. If you haven’t seen a rainfall
simulator demonstrated YouTube has some pretty interesting videos done by the
NRCS that would be good to watch.
The first thing Doug did was perform a slake
test. He placed a soil aggregate from a no-till field into a jar of water and
also placed a soil aggregate from a conventionally tilled field in another jar
of water. Immediately the conventionally tilled soil aggregate started falling
apart compared to the no-till field where very little soil fell apart. This
shows that tillage is destroying the soil glomalin which holds the soil
together.
He then started the rain fall
simulator. The first soil tray was a conventionally tilled soil. The second
tray was a conventional till soil with cover crops. The third tray was a no
till soil which has no cover crops (only because the grower didn’t have time to
get them on this year). The fourth tray was a pasture soil with short grass on
it. The fifth tray was a pasture soil with well managed grazing and a better
grass cover. For each tray there are two jars underneath the front one was to
catch the run off, and the back jar was to catch water that had infiltrated
through the soil. As you can see from the pictures the first tray had a lot of
muddy runoff and almost no infiltrated water. The second tray had a little more
runoff (it received a little more “rain”) and quite a bit more water that
infiltrated the soil. The third tray had no significant runoff and a lot of
infiltration. The fourth tray had quite a bit of runoff and some infiltrated.
The fifth tray had no runoff and all of the water infiltrated. I think this
demonstration speaks a lot for no-till.
What was really interesting to me
was how important managing your pasture ground is. I was surprised at how much
runoff there was in the short pasture ground. I would have thought the grass
roots would have held the soil and allowed for more water to infiltrate. The
well managed pasture had almost no runoff. This shows how keeping the soil
covered can be a benefit. In another picture you can see that Doug dumped the
first tray out upside down. The top of the tilled soil was completely saturated
and the soil that was on the bottom of the tray was completely dry. That shows
that the tilled soil didn’t have any pore space and the water wasn’t able to
penetrate anything but the surface. That is how the soil forms that top hard
concrete crust when you get a rain.
 | |||||
| Slake Test |
 |
| Rainfall Simulator |
No comments:
Post a Comment