Balancing Soil Using Organic Minerals
Soil Fertility
Fertile soil is a mixture of well-balanced minerals, high organic matter, humus, humic, fulvic and carbonic acids, good aeration and bountiful soil life. The biology or life in the soil is at its healthiest when the nutrients are plentiful and balanced, and there is sufficient oxygen and water. The top few inches of soil is the most vital, holding about 70% of the life and 70% of the organic matter. Below 6 inches the roots are feeding on mostly soluble nutrients since the micro-organisms are not able to thrive without sufficient oxygen. It is possible to create biological activity deeper with deep double dug or mechanical disturbance like spading. It is crucial to leave the soil as undisturbed as possible, although nontillage is very difficult in organic annual crops.
Increasing the quantity of earthworms and planting deep-rooted plants will let air into lower levels of the soil. Micro-organisms like bacteria, fungi, actinomycetes, algae, nematodes and protozoa, need oxygen to contribute directly to the release of nutrients to the plant. Some species of mycorrhizae tolerate very low oxygen levels, and infest roots much deeper than other species of beneficial microbes, providing nutrients and root protection. There are many symbiotic relationships going on between roots, organic matter, clay and micro-organisms to support the plant. Soil that is worked too wet annihilates air and water space, destroying the environment that microbes need. Soil that is worked too dry creates similar problems. Tending soil for optimum production means adding minerals and compost every year. Balanced, fertile soil makes for higher yields, better flavor, less disease and insect pressure and more nutritious food.
Compost
The best and cheapest organic fertilizer is compost. It contains organic matter, humus, calcium, phosphorus, potassium, nitrogen and many micro-nutrients, billions of microbes in each ounce and is a great food source for the biology in the soil. Compost made from plant residues and animal manures that have been fully decomposed can be applied every year at 1 to 8 tons per acre. In poor soils initial compost applications should be much higher, if the compost is fully digested and mature with proper C:N ratio. Vegetable crops often benefit from higher application rates, if the compost is aerobically digested and mature. Compost made from branches, leaves and plant residues without manures are best for orchards since this best supports fungal growth. Forests have soils that are inhabited predominantly by fungal growth. Orchard (non tilled) soil biology closely resembles forest soil biology. Compost containing woody residues mixed into the soil robs plants of soil nutrients. If the compost contains woody residues, it is not finished, or was made incorrectly. It should be used as mulch or added to the top of the soil. Too much compost in the soil is hard for the soil to break down quickly and will temporarily tie up nutrients. If the compost has a proper C:N ratio of approx. 10-12:1, it does not tie up nutrients. High carbon composts always tie up nitrogen and sulfur, and sometimes other nutrients when worked in to the soil.
Taking a Soil Sample
The aerobic zone is usually only 6-7” deep and should be all you need to sample for annual crops. Perennial crops may need to be sampled at greater depth to determine toxicity issues such as sodium, boron and carbonates. If the soil is double dug or mechanically deep tilled or spaded, soils sampling could go to 8” plus. Using a tube type soil probe or a shovel, take a minimum of five probes in different zones of the area being tested. Do not combine probes from areas that are not uniform to the sample desired, ie rocky, clayey, silty, flooded, or where noted difference in crop or weed growth occurs. Sample these areas separately but don’t combine them with the “normal” sample. Mix the soils together for each sample. It should be about 1½ cups. Don’t touch the soil with your hand. Don’t use a rusty shovel. Don’t place sample in plastic bag.
The highest rates of soil fertility are seen in the testing done in May and June, the lowest in the winter. To get consistent results test soil at the same time of the year from test to test. Scrape away the surface organic material or get an abnormally high reading.
Reading the Soil Test
There are many labs around the country that give soil results. The following recommendations are based on lab results from A&L Ag Labs in Modesto, California. Every lab uses different testing methods so the numbers may not be the same. It is best to use one lab consistently to track annual results.
(Note: To covert pounds per acre to pounds per 100 square feet divide by 440.)
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