By Kirstee Schutte
Nebraska Extension Master Gardener
July 31 – Soil organic matter (SOM) is the portion of soil that is composed of living and dead things in various states of decomposition, such as plant roots and microbes. Organic (carbon-based) materials that we add to the soil, like compost or organic fertilizers, will also contribute to SOM as they are incorporated and decomposed by soil organisms. And although SOM only accounts for a small fraction of soil by volume (2-8 percent), it’s very important for soil and plant health. SOM is where the magic happens.
Aug. 1 – Soil is a mixture of mineral and organic material that makes up a complex ecosystem capable of supporting plant life. There is a web of life that exists beneath your feet. Plant roots interact with bacteria and fungi of which are food for larger microbes like nematodes and protozoa who are in turn eaten by arthropods. And the arthropods? They are eaten by snakes, birds, moles and other animals. All together they make up the soil food web. You can support the life in your soil by not applying synthetic fertilizers or pesticides, leaving leaves in the fall, and (so long as there is no disease or virus pathogens) leaving the roots of annuals to break down over winter months.
Aug. 2 – Soil is alive! Healthy soil supports healthy plants, but healthy plants also help support microorganisms. The energy that results from photosynthesis is used by plants to produce chemicals they excrete through their roots, called exudates. They are in the form of carbohydrates and proteins. Beneficial bacteria and fungi are attracted to the root zone by the exudates which they consume. The bacteria and fungi attract bigger microbes which consume them. The excreted waste is readily absorbed as nutrients by the plant. These nutrients are more readily available than synthetic fertilizers which negatively impact the soil food web.
Aug. 3 – Healthy soil is teaming with life! There are up to 50 earthworms in a square foot of healthy soil. A teaspoon of healthy soil can contain a billion invisible bacteria, several yards of equally invisible fungal hyphae, and several thousand protozoa and dozens of nematodes. Fungal hyphae travel through soil sticking to and binding particles together to form aggregates. The bacteria produce a slime to attach themselves to things so that they aren’t washed away. The slime can trap pathogens before it reaches the root and it too helps soil particles stick together.
Aug. 4 – Soil fertility is the ability of a soil to supply nutrients to a crop. Having the ability to have the right amount of nutrients available at the right time is critical to plant productivity, but you can have all those nutrients available but not the right conditions for the plant to uptake them. An often overlooked component of soil fertility is the cation exchange capacity which is a measure of the total negative charges within the soil that absorbs plant nutrient cations. It is a measure of the soil’s ability to retain applied nutrients, specifically positively charged nutrients called cations.