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Kindle Notes & Highlights
by
Jon Stika
Read between
January 20 - May 19, 2022
The hyphae of mycorrhizal fungi can explore ten times the volume of soil that plant root hairs can, and 100 times that of plant roots themselves.
Basidiomycetes are another type of fungi found in the soil that feed on dead plant material rather than connecting to living roots. They live in the rhizosphere, close by, but not directly connected to plant roots.
Example: mushrooms.
The presence of earthworms is an easily observed positive indicator of soil health.
Regardless of the organism in question, habitat is simply a combination of food, water and shelter necessary for certain organisms to flourish.
Habitat for the organisms of the SFW includes undisturbed soil that is always covered with plants and/or plant residues and is inhabited by a wide diversity of plants whose roots are alive as much of the time as possible.
Keys to Restoring Soil Health ▪Less Soil Disturbance ▪More Plant Diversity ▪Living Roots as Much as Possible
Keep the Soil Covered at All Times
There is evidence that humans have been tilling the soil for over 7,000 years (Lowdermilk 1953). In that time, there has not been a single tillage operation performed that directly benefited the soil. Not one.
In a larger scale scenario weeds can be controlled with herbicides (conventional or organic), residue management, cover crops, crop rotational diversity, or grazing by livestock.
There is a crop rotation diversity index, developed by Dr. Dwayne Beck of Dakota Lakes Research Farm (near Pierre, SD) that can help in assessing your crop rotation plant diversity. The index and method of calculation are described in detail at Dakota Lakes Research Farms website http://www.dakotalakes.com/. A spreadsheet calculator of the index that I developed some years ago is available at the North Dakota State University Dickinson Research and Extension Center website https://www.ag.ndsu.edu/archive/dickinso/agronomy/jons%20worksheet.htm
The most easily obtainable source of food for soil microbes is the sugar exuded through the roots of living plants. This is the reason why maintaining living plant roots in the soil for as much time as possible is important.
Fallow Syndrome is a well-documented phenomenon where crops that would typically benefit from association with mycorrhizal fungi suffer yield loss after a season of fallow (Wetterauer & Killorn 2013). This is due to the lack of living roots that would support the fungi and thus the fungi decline and go dormant. This means that the crop that trails fallow in the rotation will not have an adequate population of mycorrhizal fungi to associate with and to supply it with water or phosphorous. The result is a poor performance by that deprived crop.
We can replace expensive inputs with actions that improve the soil and reduce the symptoms that we have created from degrading the soil.
It has been my personal observation that in most situations, more than 65% of the soil must remain covered to limit evaporation of water from the soil surface. Bare
but evaporating water leaves salts behind at the soil surface making the soil less hospitable to young seedlings. If the soil gets too hot, all but the most heat-loving organisms will go dormant, hindering many vital soil processes.
Soil cover consisting of plants or plant residues also protects soil aggregates from receiving a physical beating by raindrops.
may be applied manually using hay or straw, derived by laying a cover crop down with a roller or the hooves of livestock, or spreading crop residues with the same piece of equipment used during the harvesting operation, such as a straw and chaff spreader on a combine.
Producers need to weigh the value of crop residues that may be removed by grazing, baling or other methods against the value of those residues remaining on the soil surface.
planting equipment may be fitted with residue managers that gently sweep residue away from a narrow strip where the seed will be planted.
Higher rates of microbial respiration are a good thing if the respiration is coming from organisms building soil organic matter rather than organisms opportunistically devouring soil organic matter after a tillage event.
Increasing plant diversity will simultaneously increase the diversity of the organisms in the soil by providing them with a more diverse diet.
To assess the diversity of your current crop rotation and help you develop a more diverse rotation, I again encourage you to check out the crop rotation diversity index, developed by Dr. Dwayne Beck of Dakota Lakes Research Farm. The index and method of calculation are free and described in detail at Dakota Lakes Research Farms website http://www.dakotalakes.com/. A spreadsheet calculator of the index that I developed some years ago is also available free at the North Dakota State University Dickinson Research and Extension Center website
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Green Cover Seeds, owned and operated by Keith and Brian Berns of Bladen, NE has some excellent resources for developing multi-species cover crop mixtures https://greencoverseed.com/
Leaving a field bare or fallowed means the underground herd of microbes will not be fed and the soil functions dependent on those organisms will decline accordingly.
The productivity and profitability of your farm or ranch depends how well your livestock are fed above and below ground!
Keep the Soil Covered at All Times – We need a roof on the soil “house” to provide suitable habitat for the soil food web. Soil cover conserves moisture, deflects wind, intercepts raindrops, suppresses weed growth and provides habitat for members of the soil food web who spend at least some of their time above the soil. It is difficult to restore soil health and build soil aggregates in an unprotected soil. Ray Archuleta describes bare soil as “naked, hungry, thirsty and running a fever”. Don’t allow your soil to be any of those things.
To acquire the carbon and nitrogen a soil microorganism needs to stay alive (body maintenance + energy) it needs a diet with a C:N ratio near 24:1. 16 parts of carbon are used for energy and 8 parts for maintenance. It is this C:N ratio of 24:1 that rules the soil!
This is why composting operations strive to achieve a blend of materials with a C:N ratio of about 30:1, so the resident microbes can readily decompose the compost pile leaving a little food and structure left over to feed and shelter the microbes after the compost is applied to the soil (Lavelle & Spain 2005).
Cover crops included in a crop rotation can help manage nitrogen and crop residue cover on the soil. A low C:N ratio cover crop containing legumes (pea, lentil, cowpea, soybean, sunn hemp, or clovers) and/or brassicas (turnip, radish, canola, rape, or mustard) can follow a high C:N ratio crop, such as corn or wheat, to help the corn and wheat residues decompose, allowing nutrients to become available to the next crop.
Regardless of your approach, by monitoring soil health indicators you can determine if your progress toward improving soil health is on track. Keep an open mind and reexamine the principles of restoring soil health until you develop an approach that works for you on your farm.
a crop rotation to have a chance to restore soil health, it must have at least three different crop types in sequence on a given field. The four basic crop types include: cool season grass, cool season broadleaf, warm season grass and warm season broadleaf. The greater diversity of crop types you have in rotation or crop types in a cover crop the faster the soil will respond in a positive way.
By allowing livestock to consume half of the above-ground cover crop forage and trample much of the remainder onto the soil surface, the soil biology will be fed magnificently.
Another effective strategy is to feed the hay on the field it was harvested from so that the residues and nutrients are cycled immediately back where they came from.
This technique is often referred to as bale grazing (Manitoba Agriculture, Food and Rural Initiatives 2008).
The key to managing pastureland for plant and soil health is to manage how plants are grazed and allowed to recover. Repeated grazing of the plants without time for them to recover results in diminished root systems and soil collapse. This can lead to compaction of the soil and water runoff from the paddock. Lack of grazing results in plants that are not stimulated by being bitten by livestock. The soil food web is thus not sufficiently fed by root exudates and the effective surface area of plant leaves conducting photosynthesis is reduced. All plants must be grazed and then allowed to recover
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Rangeland is considered to be land where native plant communities are harvested by grazing livestock.
An approach that works in one region may not work in another region.
The United States Department of Agriculture Natural Resources Conservation Service’s (NRCS) soil health website has extensive information on how to assess soil health.
There are some relatively new soil testing methods that focus on the biology of the soil, to give you a more detailed picture of the organisms that live there, and their nutrient cycling capabilities. The Haney method of soil analysis combines a relatively passive water extraction of nutrients from the soil with a measure of the soil organisms and their food supply.
