Today, we wanted to explain zone building a little more, and tell you what we've learned in different areas.

The net results when zone building is done right, include a reduction in soil compaction, a warmer and drier seed bed, deeper plant roots, better nutrient utilization, more drought resistant crops, and consistently higher yields.

Here's what zone building is all about…pulling a toolbar though a field with several shanks on the toolbar that are basically straight and fairly narrow. What you're trying to accomplish is to cut a slot in the ground that goes below your deepest compaction zone. Then, you'll get the most bang for the buck if you can plant right over the top of that slot in the spring.

Let's talk about the compaction issue first. On most farms, there are usually 2 compaction layers in the soil. One that is man-made at 6 to 10 inches deep. The other is a natural compaction layer found commonly at 14 to 20 inches. While the top compaction layer has been caused by tillage or traffic in a field, the lower layer is usually a result of natural soil factors. If you can cut through both layers of compaction when zone building and then plant over the top of the zone next spring, your crop's roots should have smooth sailing all the way down to the water and nutrients held deep in the soil.

The reason why this is important is that even in severe drought years, it is common to find some moisture below the first compaction layer in a soil, and to find a great deal of moisture below the bottom compaction layer. When your roots go deeper, you are not as dependent on timely rains to keep your crop doing well.

Another thing you'll find when zone building, is that your seedbed will be warmer and drier next spring. Because you've made the seedbed black in the fall, it will warm up quicker in the spring. Then, because you've cut a slot deep into the ground, you will improve your drainage in the zones, and moisture will move down in the soil easier.

One of the things we have learned this past fall is that the soil conditions and your speed make a huge difference in the zone you leave yourself for next spring. For example, on our farm we started out zone building with a 4-shank machine pulled by a 270 horse tractor going 4.5 to 5 miles per hour. What we found is that we kicked the soil out quite a ways from the center of the zone. When we slowed down to 3.5 miles per hour, we did a much better job, and we were able to pull a 6-shank machine with that 270 horse tractor.

Another thing we've learned this past fall is that the drier the ground, the more difficult the zone builder pulls through the field. In fact, we have one farmer we know in north central South Dakota who is pulling a 4-shank machine with a 400 horse tractor because his ground is bone dry and heavily compacted. However, on our farm, where we've had plenty of moisture since August 1st, we are able to pull through almost any field without much difficulty, despite the fact that we have severe compaction in certain areas.

As far as the condition we leave the field in after we've zone built, when the ground settles back in after 2 to 3 weeks, all that is left is a slight depression everywhere our shanks ran. Some people have set up coulters and a rolling basket behind their zone builder, so they can actually mound up the soil, creating a ridge. However, on our farm we've felt that we would pull more plant residue back over the zone, so we are doing nothing other than running these straight shanks through the field at about 18 to 20 inches deep.

When zone building, it is our suggestion to follow the example of Ray Rawson, who zone builds his soil the first 2 years he has a particular piece of ground, and then through traffic management in the field, only zone builds a few end rows from time to time after that point. Rawson's zone builder has straight shanks set at 30". In year one, he zone builds in between last year's rows and then plants right over the top of those zones in the spring. In year two, he zone builds in between the slots he had put in the year before and then plants over THOSE zones the following spring, so when he's done, he has zones every 15" across the field, and he rotates back and forth from one zone set to the next each year.

One of Rawson's big principles is to farm vertically, rather than horizontally. By cutting deep slots in the ground and planting over the top of them, plant roots can go deeper into the soil. When roots can get deep into the ground, they can extract more water and more nutrients out of the soil. That in effect makes your plants more drought tolerant, because they have a much larger reservoir to pull from.

Another thing you should consider is that your soils will be richer in oxygen and have more extensive earthworm activity once these slots are cut in each field. Oxygen will be able to get deeper into the soil, and because of that, you will find deeper plant growth, more biological activity, and more earthworms.

Why are the earthworms important, you ask. Well, earthworms can move and breakdown a considerable amount of plant residue each day. The earthworms commonly pull residue from ground level down several inches deep in the soil. They also feed on some of this residue and leave manure behind that is high in nutrients and very beneficial to your crops.

Add all these things up, from a reduction in soil compaction, a warmer and drier seed bed, deeper plant roots, better nutrient utilization, more drought resistant crops, and greater biological and earthworm activity, you WILL get higher yields when you zone build properly and plant over the zones the following spring.

Again, what we've learned this fall is that you will need more horsepower per shank the drier the soil, and that going slow leaves the best zone for the following spring.

For more information on zone building, talk to one of our agronomists today at 605-529-5413 or email them at info@agphd.com.