Field Study_ Building the Microbial Bridge for Soil Health
Fred Newcombe

This week we are talking about soil health.

PJC Organic stays up to date on industry research to provide customers with organic product and program recommendations. We evaluate field studies and look for ways to implement and improve our current programs. Here, we give you our take on the scientific research behind productive turf grass and soil management.

This week we are taking a look at EcoFarming Daily’s article: Building the Microbial Bridge for Soil Health by Gary Zimmer and Leilani Zimmer Durand. This article breaks down how the microbial bridge creates soil health. The Zimmers dive into WHAT the microbial bridge is, how it works, and ways to build it. The article is rich in analogies and practical information. 

Sean’s Take:

In this article, the Zimmers discuss that building the microbial bridge means focusing on feeding soil biology and creating an environment in which they proliferate. By balancing soil, plants and microbes the plants will get nutrients they need without constant soluble chemical inputs.

A hugely important but rarely discussed aspect of soil health is the Carbon:Nitrogen ratio and the biology that influences. Turf stands thrive in a Carbon:Nitrogen ratio range of 25:1 or 30:1, where fungi generally present around 40:1 and greater. An oak stand in a forest is fungi dependent and is around 800:1 C:N for comparison.

The proper C:N ratio is integral to efficient nutrient cycling. Meaning, bacteria convert carbon molecules into plant available minerals at lower C:N ratios and simply cannot do so at higher C:N ratios. That’s where fungus comes in. Fungus can convert carbon chains into plant available nutrients at significantly higher C:N ratios – over a much longer period of time.

A grass clipping that is returned to the top layer of the soil surface after mowing is being broken down by bacterial colonies, not fungal colonies. A fast energy conversion process of a simple carbon structure that is converting into bioavailable minerals in weeks. A decomposing tree in the woods is being broken down by fungal colonies, not bacterial colonies. A slow energy conversion process of a complex carbon source into minerals that will take years to complete its full cycle.

While balancing bacterial and fungal colonies in the soil is important for any plant habitat – that ratio is very broad depending on the plant you are trying to grow. Ultimately, you are going to have a far better impact on the turf grass by allowing bacteria to proliferate. 

Fred’s Take:

This article brought to mind the dichotomy between many chemical approaches to growing grass versus our organic approach focusing on soil health. Over 20 years ago, people just wanted to ‘grow grass on steroids’.  Back then—as is still the case with many synthetic chemical turf care practitioners—healthy soil biology isn’t even an afterthought. Simply juice the plant with water soluble fertilizers.

Many turf managers force feed the plant micro and macro nutrients according to their time schedule, regardless of whether or not the plant even needs it. Therefore, they simply cut out the middleman—soil biology—from the equation. To them, it doesn’t matter if force feeding the plant creates plants with weakened cell walls, therefore causing turf to be more prone to disease and pest attraction. Moreover, they’ll simply treat those negative side effects synthetically as well. 

For some, caring for the soil biology and encouraging soil life diversity so that the good guys keep the bad guys in check, equates to no longer being in the driver’s seat. Although the truth is, you were never in the driver’s seat. With Thanksgiving quickly approaching, let’s take a different approach. Let’s set the table, put together a feast, and see the community we can attract.