The Role of Microorganisms

Why feed microorganisms when you may also be feeding potential pathogens?   Microorganisms are essential in the recycling of organic matter in the soil.   In the process, they produce a vast array of chemical products that not only aid their survival, but unless they are pathogenic, also aid the plants growing in the soil.   The presence of microbes in the rhizosphere is so important that plants export up to 25 percent of their photosynthates to feed the organisms in the root zone.   One has to wonder whether turf cut at 1/8-inch or less has sufficient carbohydrate reserves to supply its own needs, much less export photosynthates to the rhizosphere.

Both roots and microbes produce polysaccharides.   Polysaccharides act in conjunction with humic substances and clay particles in the formation of stable soil particles.   In one study, the reformation of crushed solid aggregates was enhanced by 500 percent by the addition of 0.5 percent glucose to soil.

An extrapolation of several studies would suggest that maintaining an active microbial population and healthy plants would lead to a stable soil structure and a reduction of undecompsed organic matter.   For the golf course superintendent, this should result in accelerated thatch decomposition and elevated levels of humates in the soil.

In addition to polysaccharides, microorganisms produce extracellular enzymes and other compounds.   Many of these enzymes are involved in the breakdown of complex organic matter into forms that can be transported across cell membranes.   As this occurs in the soil, plant roots can actively compete for mineral and organic substances liberated by this process.   Futhermore, it has been shown that microbial-derived urease, the enzyme needed to convert urea to a usable N form, increased 700 percent with the addition of glucose to native soils.