Unlocking Tied Up Fertilizer
Low grain markets and high fertilizer prices have more and more growers looking for ways be more efficient with their fertilizer dollars and unlock tied up fertility in the soil profile. We’ve all heard about the three pools of nutrients found within the soil profile: The Total Pool, The Extractable Pool and the Plant Available Pool. Simplified, The Total Pool of Nutrients representing all the nutrients within the soil regardless of their availability to the plant. This would include nutrients bound by minerals, organic matter and soil particles. This pool is not immediately available. The Extractable Pool refers to nutrients that can be extracted from the soil in the short term, but are currently not plant available, while the Available Pool describes what is readily available and can be immediately absorbed by plant roots. Within this article we are going to focus on the nutrients that are tied-up and how, with a few changes, we can unlock our fertility investment already found in our soil profile.
I recently attended a BW Fusion meeting where Sean Nettleton, BW Fusion Agronomist shared the following statement: “The soil is designed to feed the plant and the plant is designed to feed the soil.” What Sean was describing was the symbiotic relationship between the soil and the corn plant. The corn plant absorbs carbon dioxide and sunlight to create energy and sugars and the roots then excrete root exudates to feed the microbes in the soil. These root exudates consist of sugars, amino acids, organic acids, vitamins, hormones and enzymes. Root exudates provide soil microbes an energy source to grow and reproduce. These soil microbes, consistt of bacteria, fungi and other beneficial microbes that play a crucial role in nutrient cycling in the soil. Soil microbes release tied-up nutrients in several different ways. Microbes break down organic matter releasing tied up nutrients that were previously unavailable to plants. Microbes also help mineralize organic forms of nutrients into inorganic forms that plants can absorb. An example of this would be organic nitrogen which is converted to ammonium and nitrate which are both readily available to plants. Finally, microbes also help solubilize nutrients in the soil. Certain microbes produce organic acids and enzymes that dissolve nutrients tied up in the soil. An example could be phosphate-solubilizing bacteria that releases organic acids that dissolve phosphate compounds making phosphorus more readily available. Intuitively, increasing our populations of soil microbes will increase our ability to cycle nutrients within our soil more efficiently. Several years back I had a wholesale salesman pay me a visit. At the time, biological products were just starting to gain traction and he wanted me to take on a dealership for his company. As part of his sales pitch, he told me something that has stuck with me over the years. He said this, “You can argue whether or not my products work on your farm, but what you can’t argue is whether biology works in the soil”. He was absolutely right! Our soils are alive and the biology within our soils are working. The real question is how do we keep them working and maximize nutrient cycling? How do we utilize biology to accelerate the release of tied up fertility in our soils?
I will preface my comments by saying there are a lot of biological based products on the market and not all are created equal. Here are a few products we have successfully utilized with our customers. For starters, We believe the best starting point is to begin with a residue management product like Meltdown. Meltdown is a biological stubble digestor we apply to corn stalks in the fall. We start with this product, because it is a visual product. You can actually see the results over time and we all know corn stover is loaded with nutrients. One ton of corn stover is equivalent to 17# Nitrogen, 4# P205, 34# K20, 3# S). The key to breaking down residue is time, temperature and moisture. Therefore, the quicker we can get this product applied the better. Soil microbial activity decreases substantially below 49 degrees. Meltdown applied at 32oz per acre in the fall works well with fall burndown herbicides. Another biological product we utilize to unlock fertility in our soils is BioCast Max. BioCast Max is a microbial biostimulant that unlocks nutrient availability, enhances soil biology and improves fertilizer efficiency. It contains phosphate-solubilizing microbes, potassium-solubilizing microbes, nitrogen-fixing microbes and residue-degrading microbes. It can be used at pre-plant, side-dress or Y-dropped. Trial data has shown BioCast Max cuts Nitrogen needs by ~15lbs/acre, Phosphorus by ~35lbs/acre and Potassium by ~15lbs/acre. The final BW Fusion product that was new in 2025 is BioBoost. BioBoost is a planter box treatment designed to enhance early season vigor, improve germination, promotes even emergence and delivers critical microbial and nutrient support. This novel planter box treatment is an encapsulated blend of microbial strains, essential amino acids, microalgae food source and micronutrients: zinc, cobalt, molybdenum, iron and manganese. This is a great product to introduce biology into your operations without major changes to the way you farm. BioBoost replaces your current talc/graphite box treatment.
Another line of products that we started utilizing are from Phycoterra. Phycoterra has a lineup of microalgae products that serve as a food source for the microbes in our soils. 75% of native microbes lie dormant in our soils, therefore, feeding our microbes is crucial to waking them up and getting them working. Unlike other sugar based products, microalgae is rich in carbohydrates, proteins and lipids. A diverse food source for the diverse world of soil microbes. Phycoterra is available as a soil amendment, foliar and seed treatment.
The final product that we just were introduced to by Russell Hendrick, 2022 World Record Dryland Corn Record Holder (459.1bu), this year is from Miller Chemical. The product is called C.A.L.F.A. C.A.L.F.A. is a carboxylic acid. Carboxylic acid, similar to organic acids produced from some microbes, help break down and release phosphorus and micronutrients that are tied up in the soil. We are excited to take a look at this product in 2026.
We believe the trend towards becoming more efficient with our fertilizer dollars is not going away any time soon. While we are certainly not advocating getting away from the use of synthetic fertilizer, we believe we can aggressively seek ways to maximize nutrient cycling with the addition of microbial consortiums, microbial food sources, and organic acid type products. If you’d like additional information on any of the products referenced, check out the tech sheets and labels found on our site. Thanks for reading this blog.
-Brian
Disclaimer:
This blog may contain pesticide recommendations that are subject to change at any
time. These recommendations are provided only as a guide. It is always the pesticide
applicators responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to ever-changing labels and product registrations, some of the recommendations given on this site may no longer be legal by the time you read them.