Biological Soil Management

What’s the best way to manage turf? A question that has been pondered since we started maintaining sports turf for the pleasure of our guests. Much of the conversation has been focused exclusively on what is best for the plant with little emphasis on the soil. The soil conversation has too often been limited to pH and soil chemistry, but recently golf course superintendents and sports turf managers are asking questions about soil biology. There are few fertilizer manufacturers today who have not introduced carbon amendments to their products, materials like humic acids, kelp meal or sugars. The reason for this change is that we are all discovering the importance of promoting beneficial micro-organisms in our soils.

One of the fastest growing and most exciting agronomic concepts today is Biological Soil Management. This is a “Soil First” approach to turf management and one that addresses soil chemistry through soil testing. This helps to open the soil physically, allowing more air and water to move through the soil profile creating an environment where soil microbes can proliferate. Along with soil balancing we apply diverse forms of available carbon amendments to provide food energy for soil microbial populations. This allows soil microbiology to do what they do best — digest ligneous roots systems into humus. This process has been successful in helping manage water availability, improving nutrient flow, flocculating tight compacted soils, building better and deeper root systems, and reducing overall plant stress.

The approach follows the theories of the three-legged stool where soil chemistry affects soil physics, which affects soil biology. However, it’s the soil biology that gets the least attention while providing the greatest benefits to the plant. There is an old adage that states “microbes eat at the table first” that describes how all fertilizer molecules must go through microbial degradation in order to become available to the plant. Nitrogen molecules go through nitrification, which breaks them down from a molecule to NH4 to NO2 and then to NO3, the nitrate form of nitrogen, that is easily taken up by the plant so it can be utilized intra-cellularly. This process is done by soil microbes that need energy in the form of available carbon to function and to get the plant nitrogen in the form that it needs. When we continuously feed the soil a straight diet of synthetic nitrogen, we “burn out”, or use up, the available carbon (humus) in the soil and the nitrification process is weak. We then need to apply more and more fertilizer to get the same results.

Biological Soil Management does not exclude the need for synthetic nitrogen from time to time. It is simply focused on balancing the carbon to nitrogen ratio (C:N), which is the most critical agronomic function. This new trend of suppling carbon to the soil is about feeding soil microbes, not about feeding the plant as many have erroneously suggested. One of the greatest results of a Biological Soil Management program is reduced inputs, less thatch (which is directly related to the overuse of synthetic nitrogen and an imbalance of the soil’s C:N ratio) and ultimately a healthier plant.

Biological Soil Management is a simple concept of balancing the soil chemically and feeding the soil with available carbon sources that allow microbes to grow in population and activity. For over 35 years, EarthWorks has been a pioneer and staunch advocate of Biological Soil Management in the turf industry. Naysayers argue that “organics” won’t work until the soil warms up in the late spring and then all that fertilizer kicks out all at once causing plant stress and disease! But superintendents wouldn’t use anything that would do that! In fact, many of them have shared their success stories on the EarthWorks Podcast.