More on this book
Kindle Notes & Highlights
by
Jon Stika
Read between
January 20 - May 19, 2022
A simple definition of soil health is “the capacity of a soil to function”
The five main functions of soil are: maintaining biodiversity and productivity, partitioning water and solute flow, filtering and buffering, nutrient cycling, and structural support.
It is the living organisms (both plant and animal) in the soil that perform many of the processes that keep the soil functioning.
her Vimeo presentation (https://vimeo.com/21310772) “The Biology of the Soil”, Dr. Kristine Nichols notes that soil organic matter (including living organisms) controls 90% of soil functions.
To view some profiles of farmers in the U.S. that understand and apply the principles of soil health on their farms, check out: http://1.usa.gov/1BbTNoh. Mike Zook is one of the farmers featured in the series. I had the privilege of interacting with Mike for years and watched as he improved both the health of his soil and his bottom line in Golden Valley County, North Dakota.
had these plant-nitrogen interactions explained to me by Dr. Kristine Nichols, Rodale Institute Chief Scientist, formerly a Research Soil Microbiologist with USDA’s Agricultural Research Service. I was amazed at the collaboration that occurs between plants and the Soil Food Web (SFW). This understanding shattered much of what I knew about modern agronomy. More about the SFW later.
A single-disk opener drill making a one-inch slice into the soil every 7-8 inches should be all that is necessary to accomplish seed placement for most crops.
The methods of planting without tillage have been perfected by a group of dedicated farmers known as the Northern Prairies Ag Innovation Alliance (formerly the Manitoba-North Dakota Zero Tillage Farmers Association).
In order to help the soil feed the plants, less disturbance, more diversity, and a carefully considered input of fertilizer can facilitate soil function by recognizing the soil as a factory full of working organisms.
Producers need to ask themselves; “What functions do I expect my soil to perform?”
In fact, 90% of the nutrients taken up by plant roots are cycled through a soil organism before becoming plant-available.
Less than a third of the nitrogen fertilizer applied to a field ends up in the plants grown there (Stevens, Hoeft & Mulvaney 2003). The rest is retained by some other form of life in the soil, volatizes into the atmosphere, runs off the field or leaches down below the root zone in the soil with the movement of water.
The bottom line is that the plant available water in the soil becomes plant available because soil microorganisms made the soil aggregates that allow the water to infiltrate and be stored in the soil.
What many folks don’t realize is that these two basic expectations of soil function (water and nutrient supply) are biologically driven.
There are three types of disturbance that can impact how the soil functions: physical, chemical and biological. Physical
The primary and most destructive disturbance we do to the soil is physical.
Research by the United States Department of Agriculture (USDA), Agricultural Research Service researchers Don Reicosky and Mike Lindstrom has shown that carbon leaves the soil in the form of carbon dioxide very rapidly when the soil is torn open by tillage (Reicosky et. al. 1993).
is this process that has been responsible for reducing the native concentrations of organic matter in soils to the low levels we see today.
Research conducted in the Red River Valley of North Dakota by David Hopkins and Brandon Montgomery of North Dakota State University showed this decline in soil organic matter quite clearly. They visited the exact locations of several soils examined as part of soil surveys during the 1960s by the USDA. One particular soil in Walsh County had 34 inches of soil above the C horizon (the original material left behind in the area by glacial Lake Agassiz). The soil was examined again in 2014 and was found to have only 15 inches of soil above the C horizon; a loss of 19 inches of soil in roughly 50
...more
Many of the agricultural soils in Walsh County currently contain about three percent organic matter. They originally contained nearly eight percent organic matter.
Agricultural soils do not have a runoff or erosion problem, they have an aggregate stability problem,
indicating poor soil health by the reduced capacity of the soil to perform the basic function of infiltrating, filtering, and storing water.
Soil erosion is not a problem. It is a symptom of unhealthy, ...
This highlight has been truncated due to consecutive passage length restrictions.
See the appendix for a lab where you can have soil analyzed for the particular presence and populations of soil organisms.
healthy soil should perform the basic roles of water cycling, nutrient cycling, and physical support.
buffering the flow of water into surface waters and groundwater. Soil aggregates are built by soil microorganisms and plants, not by tillage. Tillage can only degrade and disintegrate soil aggregates. Tillage induced aerobic erosion of soil organic matter results in the loss of the most fragile fraction of soil organic matter, the organic
Present agronomic soil testing and prescribing methods are well researched and accurate for dysfunctional soil.
supply crop nutrients are currently under development and are based on the number and diversity of organisms in the soil, their habitat, and the availability of food. More
Once we recognize soil organisms as the drivers of soil health, we understand that the most important element in soil nutrient cycling is not nitrog...
This highlight has been truncated due to consecutive passage length restrictions.
Soil aggregates can by assessed for water stability by simply drying them and then immersing them in water to see how long they hold together as they become wet. This is often referred to as the slake test or aggregate stability test. More about this test in Chapter
A soil that lacks biodiversity will have a greatly reduced capacity to function because members that perform certain tasks are lacking or unable to do their work under certain moisture or temperature conditions.
Tilling soil when it is warm and moist, adds oxygen to the soil atmosphere while simultaneously fracturing soil aggregates, and consequently making soil organic matter available for bacterial consumption. Thus, organic matter in the soil is quickly “burned” by bacterial respiration and lost to the atmosphere as carbon dioxide.
The majority of available plant nutrients are contained in, or made available by, the living fraction of soil organic matter.
Up to 10% of what we refer to as soil organic matter is living microorganisms.
Soil organic matter often makes up less than 5% of the soil by weight, but controls 90% of soil functions essential for plant growth. As soil organic matter increases from 1% by weight to 3% by weight, the water holding capacity of the soil doubles. 95% of the nitrogen and over 50% of the phosphorous in the soil is contained in soil organic matter.
Between 19% and 54% of the cation exchange capacity (ability of the soil to hold onto plant nutrients) of a soil is due to soil organic matter (Hoorman & Islam 2010).
The fundamental thinking that must change is from directly feeding the plants with fertilizer in a dysfunctional soil, to restoring a fully functioning soil that feeds the plants.
The easiest source of food for soil microbes is the sugar exuded through the roots of living plants. The next easiest food source is dead plant roots.
1st source of SFW fuel.
When existing soil organic matter is the only source of food available for soil microorganisms, soil organic matter will decline in both quantity and quality.
soil food webs, the exudates released by plant roots are not received very well by the intended soil organisms because many of them are not present. This causes the plant to expend additional energy on exudates in an attempt to feed a depleted SFW. Excessive soil disturbance simplifies the soil food web to include only a limited number of species; mostly bacteria. Thus, plants in a degraded soil often signal and supply food in vain for lack of the species of microorganisms that are supposed to be present in the
Deleted SFW makes for less efficient energy usage.
Dead plant roots comprise the next most available source of food for soil microorganisms.
2nd source of SFW fuel.
Other residues, left behind on the soil surface, are next in availability to soil organisms.
3rd source of SFW fuel .
In this way, the soil acts as a multi-stage external rumen, or stomach, as it decomposes complex carbohydrates down to where nearly all the energy has been extracted from them.
Soil is to plants what rumin is to ruminant.
The food of last resort for soil organisms is the soil organic matter itself. Regrettably, in soils that experience significant repeated tillage, this is often the source of food most readily available to opportunistic soil bacteria.
Last resort.fuel.
There are a number of biological products being developed in which particular organisms are being isolated from the rhizospheres of plants based on how those organisms have proven to affect plant performance.
Without creating good soil habitat, and restoring the entire soil food web, your soil will not become self-sustaining.
Legumes (plants that bear their seeds in pods, i.e. peas and beans) cooperate with Rhizobia bacteria that capture (fix) nitrogen from the air.
Brassicas; which are plants of the mustard family, such as broccoli, cabbage, cauliflower, and turnip, have robust soil-penetrating root systems that open pathways deep into the soil.
Once again, the principal inhabitants of the soil food web are: bacteria, actinobacteria, fungi, protozoa, nematodes, enchytraeids, arthropods and earthworms.
Actinobacteria aka Actinomycetes – Actinobacteria are bacteria that grow as thin microscopic filaments in the soil, similar to fungi.
