What lies beneath: a look into fall fertility

With crops being harvested and yield reports coming in after a tough season in many parts of our trade territory, growers are starting to look toward 2023. Right now, there is more uncertainty in agricultural inputs than ever before. Will fertilizer costs begin to level off? Will herbicide supply become more consistent and prices begin to balance? Can producers afford to grow corn with the challenges continuing to stack up? Will diesel remain above $4.50 a gallon?

These are all factors beyond your control. Instead of seeking answers to these questions, ask what prac­tices will allow you to survive the uncertainty. I believe looking below the ground at soil fertility is the quickest and easiest way to slow the bleeding and maximize one of your main farm inputs.

Fall is the perfect time to evaluate fertility and put plant food invest­ments to work. Applying phospho­rus and potassium in the fall gives these nutrients ample time to break down into the soil structure. They will stay persistent throughout the winter and be available in the spring for planting. Then, we can apply ni­trogen for cereal, grass or corn crops.

With the massive jump in fertilizer costs over the past couple of years, many growers decided to ease up on their inputs or try something different, such as cutting rates by half, running a maintenance recommendation or not applying P and K at all. If you were growing a cereal, grass or corn crop, nitrogen was still used to the same degree but maybe with different practices or sources of fertilizer. Looking at the current prices of fertilizer inputs and ongoing conflicts in key production areas, this trend does not seem to be reversing anytime soon.

There is nothing wrong with trying to flex your input dollars when the time arises. However, if your farm didn’t experience extreme drought like some parts of our trade territory, you could be looking at a crop that surpasses your yield goal this year. High yields will be a problem for future fertility if inputs continue on their upward trend and soil levels start to deplete by using the same practices year after year. Generally, a 150-bushel corn crop requires close to 68 pounds of phos­phorus and 38 pounds of potassium to achieve that yield goal.

A big concern is if crop plans change from field corn to silage. Silage corn removes a tremendous amount of potassium from the soil, close to 10 pounds per ton. The 38 pounds of potassium initially applied for grain removal would be exhausted after 4 tons of silage yield. Even drought-stressed corn will yield more than 4 tons of silage.

The most efficient way to manage soil nutrient levels and fertilizer dollars is to employ an intensive grid soil-sampling program such as Nutri-Track. Many soil nutrients can be tied up with pH values in the low 5s and upper 7s, making your fertilizer unavailable to the plant. Achieving optimum pH is the foundation of any fertility program and can be an affordable option to help existing soil nutrients be more available to the plant.

Fertility cannot be changed overnight, but managing it will be a step in the right direction. Studies show that 80% of our trade territory requires variable-rate lime appli­cations that average just over 1 ton per acre. Compared to Granddad’s favorite rate, “2 tons to the acre,” we are already being more efficient with our fertility dollars. As you correct pH, soil nutrients are used to their maximum degree, and a bank of reserve phosphorus is opened.

In some instances, you may be overapplying nutrients compared to the crop rotation. When looking at cropping plans, you should fertilize for how those plants use certain nutrients. The soil tests we send to Midwest Labs measure fertility on 2.5-acre grids, on a furrow-slice depth of 6 inches. These tests ana­lyze soil pH, organic matter, cation exchange capacity, phosphorus, po­tassium, calcium, magnesium, sulfur and zinc. The results give us that underground view of our nutrient levels so we can address any issues.

Another option to help the checkbook this fall is to incorporate the previous year’s yield data. We can flip that data into a variable-rate fertilizer application. Good, cali­brated yield data from our precision specialists helps ensure your replace­ment-maintenance recommendation is as accurate as can be.

As volatile as the agricultural industry is today, managing your acres differently is a progressive foot forward. When fertilizer dollars are stretched thin, make sure you are in­corporating the right practices. Look where you can adjust and manage certain nutrient inputs. Fall is a great time to sample and to get a repre­sentative analysis on row-crop and pasture acres. Your local MFA to can put you in touch with a precision specialist who will help.