Early signs of success

Agronomic challenges that plague your fields can be time consuming, frustrating, and costly. It’s estimated that some problems, like compaction, can cost you up to 60% of your yield. The frustration compounds when it’s difficult to tell whether your solutions are actually working. We know that with the right approach, you can begin to heal the individual problems you’re having in your fields, and begin to holistically improve your soil health. Here are three common agronomic problems we see growers deal with across regions and soil types, and the solutions to fix them. But most importantly, we’ll tell you how you can determine whether you’re seeing early signs of success from instituting your changes.

The University of Minnesota says moderate compaction typically leads to a 10-20% yield loss, and that those losses could jump to 60% or more-when there’s severe compaction.  And the problem can be wide in scope, impacting up to 30% of farmland in North Dakota and Minnesota resulting in nearly $1.8b in costs. Contrary to the beliefs of many farmers, compaction doesn’t solve itself or eliminate damage through freeze-thaw cycles. That’s because the freeze-thaw action usually only affects the top 2-5 inches of soil, meaning any compaction below that is not addressed through these cycles. Reducing tillage and introducing cover crops will address compaction by making your soils more stable. 

Need help deciding which cover crop is best for you? 

If you’ve already incorporated covers and reduced tillage and you want to see whether it’s working, there are some simple tests that will answer your question. Here is the step by step version of one popular test:

• First you need a penetrometer, soil probe, or a steel rod. The most accurate will be a penetrometer which measures compaction in pounds per square inch, or psi.
• Push the penetrometer into the field- it’s best to do this test in the spring about 24 hours after a soaking rain. The penetrometer will show you how much pressure it takes to get through the soil. The easier it is to push in, the better your soil structure.
• Return to the field year after year to measure. If your practice changes are working, it’ll get easier to push in the penetrometer, probe, or steel rod. 

Infiltration is the Goldilocks of soil health. If moisture infiltrates your soil too deep, you could be dealing with nutrient leaching out of the root zone. Too slow, and you’re looking at ponding, runoff and erosion. By increasing your soil’s organic matter through cover crops and no till practices you can get closer to more ideal rates. Further, these practices will improve soil structure and macropores; vital to establishing healthy water storage and movement capacity. There are some simple tests to see if incorporating these practices is doing anything for your fields. But again, this will be tested over time, so the most important thing to do is get a good understanding of your baseline performance- how your field is performing today. The USDA has a simple way to measure your baseline, which can be repeated in following years to measure your progress. 

Here’s what you’ll need

• 3 or 6 inch-diameter aluminum ring
• Rubber mallet or weight 
• Block of wood or plastic insertion cap 
• Plastic wrap 
• Plastic bottle marked at 107 mL (3-inch ring) or 444 mL (6-inch ring) for 1 inch of water, or graduated cylinder 
• Distilled water or rainwater
• Stopwatch or timer

Steps

1. Clear all residue from the soil surface. Drive the ring into the soil to a depth of 3 inches using a rubber mallet or weight and a plastic insertion cap or block of wood. Take care to drive the ring downward evenly and vertically. Gently tamp down the soil inside the ring to eliminate gaps.
2. Cover the inside of the ring with plastic wrap, and drape it over the rim
3. Pour 444 mL of distilled water or rainwater into the plastic-lined ring
4. Gently pull the plastic wrap away. Record the time it takes for the water to infiltrate the soil. Stop the timer when the soil “glistens.”
5. Repeat steps 2, 3, and 4 to determine the steady-state infiltration rate. Several measurements may be needed.
6. Record the results
7. Remove the ring with the soil intact. This intact soil core can be used indoors for respiration and bulk density tests. 

Another simple test uses a number 10 coffee can. Cut out both ends and place it in the soil. Pour about two inches of water into the can and see how long it takes water to seep into the soil. 

When you repeat these tests each year, you should notice better infiltration rates. Either tests are a good way to determine whether your cover crops, reduced tillage, or both are working to improve infiltration.

If you’re wondering just how damaging erosion can be to your profitability, consider what scientists found in the Piedmont region of the United States- a region of aggressive agriculture production and as a result, one with very thin soil. Scientists ultimately found that growers lost 2.9 bushels of corn per acre per inch of lost topsoil, and .7 bushels of soybeans per acre per inch. 

That particular region had a rough go- an estimated 7 inches of topsoil eroded. If you do the math, that means 20.3 bushels of corn and 4.9 bushels of soybeans per acre were lost just due to erosion. Let’s say corn was $5 per bushel and soybeans were $13 per bushel. That means a grower is losing $102 of corn per acre per year and $64 of soybeans per acre per year. To stop erosion, agronomists recommend utilizing cover crops and reducing tillage- both an effort to keep that topsoil from being disturbed.

An article from Agfuse has a simple way to measure whether your efforts at slowing or stopping erosion are working. Eyeballing it, actually can work pretty well. But for a more in-depth test, place stakes with measurement marks at the edges of your field. Over time, check the measurements on the stakes to see if your soil levels are staying steady, or going down. It’s especially helpful if you want to measure the difference on bare soils vs. soils with cover crops so you can see a difference. However, because these stakes will heave with frost, the RUSLE2 modeling program is a better option. RUSLE2 was developed by the NRCS. It is a computer model that predicts erosion using rainfall and runoff information. For more information on how to utilize RUSLE2, visit Agriculture Research Services with the USDA.

Some of these tests may seem simple, and that’s the point. When growers make changes, they want milestones so they can measure their progress. Building soil health can be a generations-long endeavor, but knowing you’re on the right track now and having some quick wins can make all the difference between staying the course and seeing a positive outcome, or giving up before you realize the true potential of your soil.