SOIL BIOLOGY
The Most Important Livestock on the Farm

When farmers and gardeners gear up for another growing season and review soil test results and recommendations along side what they witnessed in the field, they are often disappointed and confused by the outcome. Purchasing soil amendments and crop protection products based on lab reports alone does not give the grower the whole picture by any means. The common soil test is a single chemistry snapshot in a fast changing system of variable and exchangeable reserves which are potentially there to be utilized by the crop. It represents a narrow view of the soil’s savings account, not all of which can be drawn on, and in many soil systems, only a small percentage becomes available depending on the capacity of the soil to function. The role of micronutrients and trace elements is also underestimated.  As science catches up with nature it has become evident that well over 60 elements are key players in soil and crop nutrition. At the heart of soil nutrition is soil biology, (the cooks in the kitchen).

The recipes that are applied to the soil are for the most part biologically dependant, especially if they are mineral amendments that are relatively insoluble.
The microbial community that resides within soil is often referred to as the rhizosphere or ‘soil foodweb’. It is a complex system of organisms working as direct trading partners or as second or third level participants in nutrient cycling.  With mycorrhizal associations, almost all plants, except rather primitive ones, produce carbohydrate exudates (sugars from photosynthesis), which are exchanged with their fungal house- guests for extra water, soil enzymes and microbial digested minerals that the plants can’t reach or decompose for themselves. These beneficial fungi, with their far foraging web of hyphae serve to extend the feeding range of crops significantly farther than by themselves and increase the nutritional spectrum that can be assimilated.  The web-like structures of these soil fungi leave in their wake of activity a soil aggregating substance known as glomalin, which may be responsible for the bulk of what we know as true soil organic matter or humus.  (Raw organic matter must be converted by bacteria and fungi) before it becomes supportive of crops and soil structure as humus. The greater the percentage of humus a soil has to work with, the greater the water, air, biology, and exchangeable elements it can deliver. It is also much like a deep cycle storage battery of the Earth’s electromagnetic field, which significantly influences all soil and plant life.  Humus is a result of biological carbon sequestration, (condensing atmospheric CO2 into the soil system through photosynthesis).

Along with the beneficial fungi, we have dense colonies of diverse bacteria that directly feed on the plant exudates and soft dead matter, which are in turn consumed by larger protozoa, nematodes, micro-arthropods and earthworms. These release ‘micro-manure’, a tremendous source of ammonium (AN), and eventually nitrate nitrogen (NN), which are the primary electrolytes that allow the flow of energy to develop between elements of different electromagnetic charge and is responsible for all cell division in plants.

Almost all crops that we value grow best in the aerobic zone, and almost all of the microbes responsible for good soil quality and crop nutrition are oxygen dependant aerobes, with a smaller group being facultative (living with or without oxygen).

Modern agricultural practices are rather dependant on traffic and frequent tillage, which means compaction and collapse of soil structure and the disruption of microbial colonies, especially the delicate and critical fungal portions. Without good atmospheric flow in the soil (gas exchange), the oxygen breathing aerobes (our cooks and cooperators) are suffocated, leaving vacancies for pathogens, (many are anaerobes-no oxygen), to fill the gaps. Crops in these conditions are living on limited nutrition and facing trouble without adequate immune systems. Anaerobic or low functioning soils cannot build adequate humus to support crops that are mycorrhizal dependant. Plant roots and their microbial trading partners drown in non-exchanging gasses or trapped stagnant water and no matter how good the chemistry tests in the lab, it is not necessarily what the plant experiences.

In order to maximize the effect of soil amendments and make your dollars count, the needs of aerobic soil life must be addressed. Reducing tillage and compaction, especially in wet soil conditions, is critical yet easy to over look. Clay and silt loams are more sensitive to this damage than sandy or coarse soils yet have greater nutrient holding capacity. Cease or reduce using products that harm the soil foodweb, especially chemical fungicides and herbicides, organic growers can get into trouble with this too! Work with more diverse soil and plant inoculants, composts and compost teas to shield the plants from pathogens with competitive microbial partners.
Get into the practice of composting rock powder soil amendments before they go on the ground. Grow and mineralize cover crops aggressively to build humus and aerobically structured soil efficiently. 

Provide a mix of fast and slow microbial foods for generating high populations of diverse soil aerobes. This would mean simple and complex microbial foods such as fish and seaweed products, alfalfa meal, blood meal, feather meal, or any other sources of volatile bypass products that bacteria can utilize as a complex energy source along with molasses, humates or humic acids, which are sometimes used as carbohydrate binders to pelletize,(prill), some rock powders.

Any volatile source of fertilizer that has NN or AN in it is a more effective microbial food and plant nutrient when a carbon source is added to stabilize it. This begins the formation of peptides and amino acids that ultimately become proteins. Carbon sources that act as barrier reefs for almost all beneficial microbes can be found in humates or good quality finished composts. In fact all inert or mineral amendments are more effectively activated and delivered if combined with a microbial workforce and it’s easy food supply.

A clear example of what this would look like: Layer a manure spreader with all the dry amendments between composts or manures. Top off with extra traces, inoculants and liquid microbial foods as a full spectrum package. If this is a cover crop recipe, then add the seed so that it is also coated with microbes and their food supply.  Disk or rake in slightly at the onset of rain.  Save some for side dress as crops develop, (this is called ‘split applying).’ Common sense says protect the biology from UV and drying conditions,  spread your recipe on overcast cool days or in the evening.
In Review; making conditions for beneficial soil life comfortable, well fed, watered, and aerated, will make those soil numbers more effective and keep your amendment dollars close to home.                

Copyright Mark Fulford 2007