Soil health has been a hot topic in agricultural circles in recent years. The concept of improving long-range crop yields through healthier soil — promoted by increasingly popular practices such as cover crops — frequently makes the agendas of farmer meetings and conferences.
Maybe that’s why this recent news release headline grabbed our attention: “Can ‘Unhealthy’ Soils Consistently Produce Exceptional Yields?”
This question may seem to fly in the face of current conversations about the productivity benefits of a healthier soil, but Dan Frieberg, president of Premier Crop Systems in Des Moines, author of the Feb. 26 article, goes on: “There is a strong relationship in parts of fields between consistently high yields and soil health. I believe you can have healthy soils that aren’t exceptionally high-yielding (maybe limited by other management choices). But I don’t believe you can get consistently high yields on unhealthy soils.”
In the early 1970s, Frieberg worked for a farm that took soil conservation very seriously. Serving on state soil conservation boards, building terraces and implementing no-till at a time when planters and weed control options were crude by modern standards, they were pioneers in soil stewardship.
“Because of their mentorship, I’ve always taken soil conservation seriously,” he said.
In the 1980s, he found himself defending the use of commercial fertilizers, often described by their critics as “chemical fertilizers.” As anyone who has studied the Periodic Table of Elements in a basic chemistry class knows, nutrients are chemicals. Phosphorus and potassium are minerals mined from the earth, and nitrogen is made from the air. Nitrogen fertilizer is a chemical, and combining hydrogen from natural gas with nitrogen from the air to produce it was a significant scientific achievement, according to Frieberg.
“What I understood then, as I do now, is that we need integrated approaches to crop management to be both economically and environmentally sustainable,” he said. “How we manage weeds, insects, nutrients — including organic nutrients, tillage, residue and crop rotations — have serious consequences both for the environment and growers’ balance sheets.
“One of the thoughts that’s been rumbling around in my head relates to soil health. In some circles, soil health tends to end up in a discussion about farming practices — almost a checklist of do’s and don’ts. Other approaches try to quantify soil health with a test,” he said. “I tend to like the test concept because it starts to allow us to make comparisons from field to field, within fields, benchmark over time and eventually be able to quantify changes.”
Frieberg said farmers’ best bet is to manage variability within fields and between fields to maximize their return on investment, using files from calibrated yield monitors to measure success both agronomically and economically. Multiple-year yield maps work well to reveal differences in soil health within fields.
“I find that there are parts of fields that are amazing in their ability to consistently kick out exceptional yields. I understand that there are examples of ‘throw the kitchen sink’ at production and have everything work perfect in a given year,” he said. “I’m not talking about a one-hit wonder. I’m talking about areas of fields that are exceptional-yielding on (a) consistent basis. Are those areas of the field ‘healthier’ than other areas? Is it possible for them to be unhealthy and be so consistently high-yielding?”
Repeatedly high-yielding areas seem to have a few things in common, he said. They offer ideal drainage, deeper A horizons, more organic matter and a soil pH that’s just right. Nutrient cycling also seems to be superior in these parts of the field.
No one knows the land like the one who farms it year after year, and growers can easily appreciate how healthier soil may support productivity. But like most things in nature, it’s much more complex than that. There are many dimensions to sustainable soil management; soil testing, crop rotation and tillage choices all influence soil properties, and it can be difficult to see how these practices work in tandem to better the soil. An informed, coordinated approach just makes sense.