His manure was highly variable, and his prior fertility program used only limited soil testing in low density across his acres to estimate the needs of his soil.

In VRAFY, we have an equation that takes into account the added nutrition of his manure application, as well as his yield data, to make variable rate fertility application maps. We developed this because we wanted to take the high-density data provided by a yield map and help farmers choose the right removal targets.

To illustrate how this works, consider that most soil tests are done in very large grids or across a large amount of acres, if they are pulled at all. A grid size of five acres is most common, and this isn’t very fine-tuned. On the other hand, your yield monitor constantly provides you with data you can use to figure out your crop removal rates.

With a 30-foot corn head harvesting at 3.5 miles per hour and generating yield information every second, you effectively have a data point on about every 160 square feet. That means in a five-acre area (217,800 square feet), you would get about 1400 yield data points. Compare that to just one soil sampling point on those same five acres, and you can see how a high-density dataset based on collected yield is powerful if you want to capture soil variability.

When the farmer compared his previously collected soil test data and compared it to the yield maps taken from his combine, he was able to drill down his variable applications of supplemental P and K, instead of flat rating the whole field like he did in the past. By combining this data and building an application program that accounted for crediting his manure, he could apply custom fertilizer blends.

VRAFY was wildly successful for him right from the start. When he tried this out on his first 120 acres, the changes he made with his yield data saved him $4000 in fertility costs compared to his previous standard applications. As soon as he saw the report, he signed up all the rest of his acres and had similar savings on a per-acre basis across his whole farm.

This spring, we had an Iowa farmer sign up for VRAFY. He was looking for a good, efficient way to manage fertility across his acres, so we set up grid sampling plans for some fields and imported recent soil tests from previous years so we could have data on every field we could use to create prescriptions in just a few seconds.

As soil results came back, we began discussing a fertility plan we could move forward with. The farmer informed us that he had been applying lime for the past couple of seasons, and he was planning on applying more this year in order to balance soil pH across his acres. As we started creating lime prescriptions, the results called for less lime than originally expected and was concentrated more in specific locations in his fields. The customer was a little surprised to hear this, as he was under the impression that he needed to lime even more this year.

With the help of VRAFY analysis, we were able to better allocate thousands of dollars spent on fertilizer, placing it exactly where it was needed most based on the soil tests.

In other fields, we were able to figure out exactly how much product the farmer needed to buy for each nutrient, saving him from spending even more money on fertilizer he didn’t actually need.

With VRAFY, you can create your own prescriptions in seconds and fine-tune your application plan down to the exact dollar/pound, helping you save money and better manage your farm.

LAURALEE EATON

I worked with a farmer from western Minnesota who had highly variable soil. His stated yield goal was 220 bushels, and he had been applying fertility at a flat rate to every acre over the whole field for years with that goal in mind. However, many areas of his field experienced lower-than-average yields and had not reached sufficient removal rates to overcome the flat rate he had been applying.

This year, he added his fields to VRAFY and ran Mehlich 3 soil tests in 2.5-grids. What we discovered was this grower had extremely variable phosphorus levels across the whole field due to the flat rate he had previously applied, but crop removal in much of the field didn’t keep up with the application rate.

By using the formulas in VRAFY, we were able to target yield in areas and apply crop removal rates of various nutrients while opting to mine out the excess phosphorus.

Through this variable rate fertility strategy, we were able to save the grower not only on his overall fertility costs, but by also applying the proper amounts of nutrition in the areas of his field where it was needed most to maintain and improve field balance, he could use his fertility budget more efficiently, improving the return on his fertilizer investment by thousands of dollars across his farm.