Do Soil Microbes Add Nutrients to My Soil?
Alan Blaylock, Ph.D.
Dr. Alan Blaylock brings extensive North American and international experience in nutrient management to the agronomy team. University studies and service as a university extension soils specialist prepared him for a long career in the fertilizer industry. Having managed both domestic and global research and education programs, Dr. Blaylock has a wealth of experience in applying science-based nutrient management principles and products to solving practical questions. Dr. Blaylock earned Bachelor of Science and Master of Science degrees in agronomy and horticulture from Brigham Young University and a Ph.D. in soil science from Iowa State University. He has been in agriculture his entire life — from his childhood on an irrigated farm in eastern Oregon to teaching soil science at Iowa State University to his current role as an agronomist at Nutrien. These diverse experiences helped Dr. Blaylock develop the skills to excel in translating complex scientific principles into practical solutions. Although early in his university studies he explored computer science as a profession, deep family roots in agriculture brought him back to the people and values of his heritage. His career satisfaction comes from helping others improve the performance of nutrients and cropping systems.
Much of the total nutrient reserve in the soil is “tied up” in soil organic matter (SOM). Every 1 percent SOM contains about 1,000 pounds of nitrogen, 100 pounds of phosphorus, and 100 pounds of sulfur along with other essential plant nutrients. The soil is a large reservoir for long-term nutrient supply, but most of this is not immediately available to plants.
Determining the “right rate” of these nutrients to add as fertilizer, a component of 4R Nutrient Management, requires an understanding of potential contributions from the soil organic fraction and microbial nutrient cycling. Soils contain abundant microorganisms that play various important roles. Active, healthy soil biology is a good general indicator of the overall health of the soil and is essential to nutrient cycling and crop residue decomposition.
But how do soil organisms actually contribute to plant nutrient need? Much recent attention has been focused on this and related topics. Recent articles from University of Minnesota and Soil Science Society of America explain how organisms influence nutrient availability. While there are a few special organisms in the soil than can add nitrogen by converting atmospheric nitrogen to plant available forms, the vast majority of soil organisms don’t actually add nutrients to the soil. They do, however, play an important role in making stored soil nutrients available by decomposing organic materials or weathering soil minerals and releasing nutrients in plant available forms, called mineralization.
While it is important to understand the amount and timing of mineralized nutrients, it is difficult to predict these biological processes. Though several tests are being developed and studied that could potentially help estimate these nutrient contributions, exact predictions are not yet available.