Organic Gardening - Learning More About Soil Minerals
Continuing from our earlier articles about soil health and soil minerals in your organic gardening – today we will finish the topic on soil minerals, for now at least. Magnesium is the last of the macro minerals, which are needed in larger amounts in your soil. Magnesium needs to be balanced with calcium for the availability to be adequate for many of the other nutrients. Calcium to magnesium ratio should be 7:1. Many times magnesium levels are too high. Too much magnesium makes the soil too tight, like clay soils. This causes deep cracks when it dries out. Sandy and slate soils actually need more magnesium, which will tighten it.
Magnesium is involved with the chlorophyll formation. A deficiency will cause yellowing between the leaf vines in the lower leaves first. A light green color similar to a nitrogen deficiency is also a sign. Excess magnesium steals nitrogen from the soil. Keep your magnesium as low as possible and work to get the other macro minerals (nitrogen, phosphorus, potash, calcium, and sulfur), to their desired levels first. Do not use dolomite lime or agricultural lime because the calcium is not readily available in it. Hi Cal lime is 35% calcium and less than 5% magnesium which makes it an excellent choice.
Minor Soil Minerals: Most minor soil minerals, which are needed in smaller amounts, thus the name, are readily available through organic materials such as manure, compost, kelp meal, and fish fertilizer. Boron is one that leaches out and is deficient in many soils. Some of the most common signs of a deficiency is hollow stems in broccoli and cauliflower, and hollow spots in potatoes. Although boron is important, it takes a very small amount – only 4 lbs to an acre. Over doing it can be toxic. Horse and chicken manure are great sources of boron. Another option is applying it through foliar feeding with borax, 1/8 teaspoon to a gallon of water.
Carbon – Another Minor Soil Mineral: Carbon is the main moisture regulator in the soil. Without carbon, your soil is dead. Without carbon the soil washes away, and all the plants nutrients go with it. Carbon is converted to humus, which is energy and food for the plants, if broken down properly with microorganisms and oxygen. Carbon feeds the soil bacteria (microbial network), and in turn, bacteria action helps build carbon compounds.
A deficiency of carbon causes compacted (tight) soil, dry and dusty soil, soil pests, poor temperature, poor nutrient reserves, and poor bacterial growth. Hi-Cal Lime, plant and animal wastes, fish fertilizers, green manure (plowed down cover crop), molasses and sugars are excellent sources of carbon, which is food for the microbials and the earth worms to feed on.
Biology (Bacteria, Fungi, etc.) Soil biology is needed for proper plant residue digestion or breakdown, and for reduction of fungus and insects. Biology needs carbon, calcium, and phosphorus for food. Aerobic bacteria grows and thrives on oxygen which is needed to convert carbon to humus. It works in the uppermost layers of the soil.
Anaerobic bacteria lives without oxygen, on gasses, and needs nitrogen to break down carbon in the lower layers of soil. Without nitrogen and carbon it will form the wrong kind of gas. Working the soil too wet in spring is hard on soil bacteria, especially on low carbon soils. Herbicides, chemical fertilizers, pesticides, and liquid manures are bacteria killers.
Microorganism is the glue that attaches to carbon, creating a sponge-like soil that holds more water instead of being easily washed away. Other advantages of sponge-like soil: it does not cling to your shoes as much, and it will splatter less. On a last note: It will take up to 3 years to bring up the calcium levels and to balance out the rest of your soil minerals.
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