In the grand scheme of things, many people say climate change is the most critical issue facing mankind. But to me, the most important challenge is not just maintaining, but improving the productivity of the soil. Without healthy soil, we won’t be able to continue feeding the growing world population.
One thing we need to do is stop referring to plant residue as “trash.” It’s as valuable as the crops we sell because it sustains the soil. So it’s important to implement practices that keep residue on the surface in an aerobic environment so it can become humus.
Nature creates soil by taking the minerals in clay and sand and adding carbon to it from plant residue. And that starts at the surface and grows its way down.
Worms Build Nutrient Channels
Worms are a main carbon transfer — they feed on the surface and go below ground to hang out during the daytime in the transition area between the A and B horizons, where the temperature and moisture are to their liking. Then they come up at night to feed and take residue back into the ground where they excrete it out.
And if you don’t destroy the bio channels that the worms create, the plant roots follow down the channels and find this mother lode of nutrients and you get a mass of roots — and before you know it, your soils are getting deeper and deeper.
We also need to be very careful about the O horizon (the top 2 inches of the A horizon) and we do everything we can to avoid blending it deeper into the soil.
The O horizon in a regeneratively managed soil contains a lot of humus as well as fulvic acid and humic acid, the most important components to restoring natural structure and function to the soil. These acids are negatively charged and are needed to hold certain cations like calcium, magnesium or aluminum.
A healthy soil starts with microaggregates, which are particles of humus with all the negative charges around them. The negative charges can attach to a positive charge on the cation while another positive charge of the cation finds a weaker negative charge in clay aggregates, wrapping the humus particle and protecting it from mineralization. These microaggregates are the building blocks of natural soil structure and essential to water infiltration and retention, respiration, taking in air and expelling spent gasses.
Strip-till is an important part of our approach to protecting our soil resource. Our journey to using regenerative ag techniques like cover crops and strip-till started years ago when we still raised cows and pigs before prices crashed in the late 1990s.
Our manure pits were small, so when we would push production, the pits would fill up fast, which prompted us to try composting. We had cattle manure piles from winter along with hay that had gotten rained on or other carbon sources, and when it was composted properly it turn out to be wonderful stuff and we’d haul it to different places on the farm.
It was amazing to see how the ground where we had hauled the compost became much more productive and functional. But after the livestock prices dropped to the point that they wouldn’t pay the bills, we got rid of the animals and then realized we needed to find a way to continue feeding the soil naturally.
So we started studying regenerative agriculture and got into what we call “composting between the rows,” which involves making sure the crop residue doesn’t get buried but gets moved between the rows with a strip-tiller or residue wheels on a no-till planter.
Besides cutting tillage, the main reason for strip-tilling is precision nutrient placement. If you’re going to put nutrients like phosphorus (P) on the surface, it’s definitely going to wash away if the ground erodes. So we do spring strip-till to reduce the chances of soil erosion while placing purchased nutrients where they will be most accessible to the plant. We variable-rate our nutrients about 6-8 inches deep so they’re in a band right where the corn plants will need them. This year, we’re also experimenting with Pivot Bio Proven to see if we can get the corn to act like a legume and grow some of its own N needs on its roots.
Rainwater Stays Home
We know our methods are working because of the results we see when we have big rain events. In 2010, we got 13 inches over a 30-hour period, and the water ran off the roads and hard surfaces, but the fields infiltrated 85% of the rain. Plus, we’ve cut our non-land input costs to about $1 per bushel of corn yield.
By sequestering nutrients and managing covers and residue to create the optimal carbon-to-nitrogen ratio, we’re boosting humus and soil productivity for generations to come.