Energy & Fertilizer Use in Diverse Rotations


Started out with a pretty clear idea that
because we’re including red clover and alfalfa in the rotation sequence and because we’re
returning manure back to the system that the quantities of synthetic fertilizers we’d have
to add based on soil test results would be less than in the two year system where we’re
managing exclusively with mineral fertilizers. And that’s been true over the last twelve
or more years we’ve been able to reduce our synthetic nitrogen applications by 90 percent. The clover alfalfa that we plant with the
small grain is one of the key things that we use for the fertility for corn. I’m not sure how much you get per acre from
just the first year but I would think it’d be 50-60 pounds of nitrogen per acre and then
of course if you can leave the alfalfa or the clover for a following year then you can
get up into the 150 pound area. And there’s a couple of Iowa State publications
that show no benefit to fertilizing corn after that hay year so it definitely is part of
our fertility program. So energy use goes down considerably where
you grow oats and alfalfa and clover in rotation with corn and soybean because the large energy
consumers in our conventional Iowa ag system are fertilizers, mineral fertilizers. The gas to dry corn grain and if you’re
doing some form of conventional tillage like chisel plowing the fuel consumed in tractor
operations. So where you move toward perennial crops where
you’re not tilling the ground and where you’re losing much less nitrogen fertilizer and where
you’re growing corn less frequently and having to dry it fewer years, you save a lot of energy. In our case we save 50-60 percent of the fossil
energy embodied in natural gas, tractor fuel, and fertilizer when you move toward diverse
rotations.

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