There are many articles written about soil and soil health and how it is necessary
for growing organic produce. Most of these articles concentrate on just one or two
of the things that are needed for good soil while ignoring others that are just as
important. Truly healthy organic soil takes time to build. For a farmer to get organic
certification it takes three years away from all chemicals and synthetic fertilizer
Good healthy soil can be broken down into four major contributors; they are 1) Soil
Structure, 2) Plant nutrients, 3) Organic material and 4) Soil Biology. These four
items in a proper balance will provide your plants most of what they need to produce
a nutritious end product.
The balance of these four items can vary considerably depending on the plants you
are growing and local conditions.
Much is said about soil pH and what you should be looking for as the ideal pH. First
look at what you are planning to grow, make sure they require similar conditions
before you put anything in the ground. You will need to adjust your soil to their
needs. Mixing acid loving plant with alkaline loving ones does not work well.
A pH of 6.4 is where the maximum availability of all plant nutrients but, many sources
recommends 6.5 pH as a minimum and 7.2 pH as a maximum.
Another major factor which can affect the four items mentioned above is the water
you use in gardening. Rain water is in most cases the best because it is mostly neutral
in pH though you need to be careful of the surface it is collected off of, in that
it can pick up harmful minerals. Chlorinated city water will kill soil biology. If
this is what you have, let it sit over night in an open container or use devices
that break the water into fine sprays, this will dissipate most of the chlorine.
Soil Structure: I break this down into three categories which are 1) sand, 2) silt
and 3) clay.
1) Sand is a naturally occurring material composed of small rock and mineral particles.
It does not hold water or nutrients well by itself. Sand needs a minimum of 2% organic
material in most cases to become productive. In highly arid areas it can be less.
2) Clay is a naturally occurring material composed primarily of fine-grained minerals,
which show elasticity through a variable range of water content, but becomes hard
and inpervitable when dry. The addition of organic materal will help keep clay from
becoming hard and unusable.
3) Silt is soil or rock derived granular material of a grain size between sand and
clay. It holds water and air but needs organic matter to make it fertile.
Organic Material: Without a continuous supply of fresh organic material soil will
loose its nutrient balance and will not provide quality produce. Organic material
can be broken down into three categories which are 1) fresh, 2) decomposing and 3)
stable. All three categories are needed to keep soil healthy.
The amount of organic material in the soil varies with temperature and moisture.
High temperatures and adequate moisture requires the highest supply of fresh organic
1) Fresh organic material added to soil needs to be made up of healthy, pathogen
free material that meets the needs of the plants you are growing. Too much material
with either to high a pH or to low can change your soils pH. Pine needles are great
but they have a very low pH and can adversely affect some crops. Do not use meat
scraps, milk products or animal waste of animals that eat meat.
The regular addition of organic matter is important to provide food for microorganisms,
insects, worms, and other organisms, and as habitat for some larger organisms. Soil
organisms can degrade potential pollutants, help control disease, and bind soil particles
into larger aggregates. Well-aggregated, crumbly soil allows good root penetration,
improves water infiltration, makes tillage easier, and reduces erosion.
Fresh organic matter can cause problems. It can draw needed nitrogen out of the soil
creating a temporary nitrogen deficiency for crops. Carbon-nitrogen ratio is important.
The other problem is when "Allelopathic" chemicals are formed where some residues
decay, and they can inhibit plant growth.
The biology is breaking down the easy to decompose portions such as sugars, starches
2) Decomposing organic matter or the second stage of decomposition is the soil biology
starts breaking down more complex items such as cellulose, lignin’s and others more
complex materials that may take several years to decompose. This group also breaks
down even more complex matter such as waxes and phenols that can take up to ten years
to decompose. Specific enzymes, not commonly produced by many microorganisms are
required to breakdown these compounds.
3) Stabilized organic matter is the organic matter that has been transformed into
new, very complex compounds. After years or decades of these transformations, what
remains are large, complex compounds that few microbes can degrade. Other compounds
become bound inside soil aggregates where microbes cannot reach. These hard-to-decompose,
or stabilized, substances make up a third to a half of soil organic matter. Scientists
often divide stabilized organic matter into three chemical groups: humic acids, fulvic
acids, and humins. The end result, after many thousands of years is what is called
humates. Humates are the result of decomposed prehistoric plant and animal matter.
Humates are mineral salts composed of humic or fulvic acids,
Plant Nutrients: I break plant nutrients into four groups being 1) Primary, 2) Secondary,
3) Macro and 4) Micro. All are needed in varying amounts and need to be in a form
which plants can absorb. All nutrients need to be transformed into a plant available
form. Iron is in many soils in abundance but is in a form that plants cannot use
so it needs to be provided in a chelated form. There can be many imbalances between
various nutrients that make one or the other unavailable to the plant so you have
to be very careful in keeping a useful balance.
1) Primary nutrients are nitrogen (N), phosphorus (P), and potassium (K). These major
nutrients use large amounts for plant growth and survival.
2) Secondary nutrients are calcium (Ca), magnesium (Mg), and sulfur (S). Calcium
and Magnesium are added when lime is applied. Sulfur is usually found in sufficient
amounts from the slow decomposition of soil organic matter, an important reason for
not throwing out grass clippings and leaves and other organic material.
3) Macronutrient is silicon (Si). Not considered as essential by many it is found
in many plants. The beneficial effects of adequate Si include decreased susceptibility
to fungal pathogens (and insects); amelioration of abiotic stresses, and increased
growth in some plants.
4) Micronutrients are those elements essential for plant growth which are needed
in only very small (micro) quantities. The micronutrients are boron (B), copper (Cu),
iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo), selenium (Se), sodium
(Na) and zinc (Zn).
Soil Biology: Soil biology breaks down into two parts which directly relate to plant
life are 1) bacteria and 2) fungi. To look at the total picture of soil biology the
soil food web you need to look at www.soilfoodweb.com and other sites that look at
the total ecological system. A truly healthy soil is impossible without soil biology.
We have mistreated the soil by using synthetic fertilizers, fungicides, herbicides
and pesticides that kill soil biology thus lowering the quality of our crops and
damaging the earth’s ecosystem. You can add nutrients to your soil but without soil
biology much of it will never be used by your plants.
1) Bacteria are able to perform an extremely wide range of chemical transformations;
including degradation of organic matter, disease suppression, disease, and nutrient
transformations inside roots (e.g. reducing bacteria in roots, bacteria cause nitrogen
Bacteria are the organisms in soil that are mainly responsible for transforming inorganic
particles from one chemical form to another. Their external digestion means that
some of the metabolites released by the use of extracellular enzymes may be used
by other organisms, such as plants. The bacteria gain nutrients and energy from these
processes and provide other organisms with suitable forms of chemicals they require
for their own processes. For example, in the conversions of nitrate to nitrite, sulphate
to sulphide and ammonium to nitrite that plants can use.
2) Fungi colonize the root zones of plants and surrounding soil is beneficial for
plant growth. As the fungi enlarge and weave through the root zones, they send threads,
far from the roots, to colonize the soil and produce water stable aggregates that
link up as macro-aggregates. This maximizes the percolation of moisture and air
into the root zones, improves soil structure and promotes subsurface plant growth.
Once colonization has occurred, the fungi suck up nutrients that, in effect, improve
the nutritional status of the plant and boost its ability to resist stresses from
drought and disease, as well as pests. Glomalin, a sticky protein and a byproduct
of a soil fungus seems to be the unsung hero of soil carbon storage. Discovered in
1996 it is quickly becoming a new force in soil health and carbon storage.
Summery: Soil health is complex and varies widely with the plant grown, temperature,
moisture availability, soil pH and others.
Soil tests should be done to show what needs to be done to balance your soil. Our
local government extension service office should be able to assist you with this.
Brining soil back to health after it has been subjected to chemical abuse can take
several years, but with proper techniques it can be done and is well worth the effort.
Healthy soil with a proper amount of organic material will compact so be careful
about where you walk. Many set up their garden so there are fixed pathways positioned
so that they are reach everything withour actually walking on productive areas.
Fertilizer and other additives:
Fish hydrolysate fertilizer contains all the vitamins, proteins, amino acids, enzymes,
growth hormones, and micro nutrients naturally found in whole fish. The nitrogen
and other nutrients are chelated, so they are readily available for the plant's consumption.
Hydrolysate Co of America, LLC (www.multibloom.com) produces a fresh water hydrolysate
from farm raised catfish that meets most organic growing requirements.
Natural Humates contain Humic and Fulvic acid, many trace elements and beneficial
soil biology and food for the biology. They can lock up harmful chemical compounds
in the soil and reduce them to less harmful substances. They can reduce your use
of fertilizer by holding in till needed and reduce water usage because they can hold
many times their weight water. Organic Products Company produces a dry product called
AgriPro Natural that I use in the potting mix. They also make a liquid product (Turf
and Garden Pro) that I use as a foliar spray and as a drench. Both are found on (www.turfprousa.com)
Kelp and other sea plants also contain relatively concentrated amounts of plant
auxins, growth regulators and stimulants, such as indole-3-acetic acid (IAA), gibberellic
acid and cytokinins. I use North Atlantic kelp by Maxicorp Seaweed
Other Organic Fertilizers besides fish hydrolysates come in a very wide range of
products from blood meal to alfalfa meal. They very greatly in the amount of N-P-K
they contain so you need to find which one fits your application and growing style.
Compost Teas have can be very useful but, be careful of what is used in the tea
brewing to avoid harmful pathogens plu they have a very limited shelf life.
Worm Tea has many benefits and works well as a soil additive.
Herb Teas are becoming very popular, especially for pest control with elements
such as chamomile, yarrow tops, oak bard and stinging nettles, to name a few.
Molasses can provide carbohydrates to feed soil biology, plus it is a good sticking
agent. It also is a good chelating agent and contains a number of essential elements.
When buying products for eco-friendly growing read labels carefully to make sure
you are getting verified for organic growing product.