THE AMENDMENTS OF FERTILIZER AND THE BIOLOGICALLY ACTIVE SOILS

What are the soil mineral conditions that foster biologically active soils? Balance is the key when it comes to the amendments of fertilizer and the biologically active soils. Bringing soil nutrients in a state of balance so that none is in excess or deficient, it’s also called base-saturation theory which is used to guide lime and fertilizer application by measuring and evaluating the ratios of positively charged nutrients (bases) held in the soil. The positively charged bases include calcium, magnesium, potassium, sodium, ammonium nitrogen, and several traces of minerals. When optimum ratios of bases exist, the soil is believed to support high biological activity, becomes resistant to leaching, and has optimal physical properties, which is water intake and aggregation. The plants growing on such a soil are also balanced in mineral levels and are nutritious to humans and animals alike.

Through extensive research, one can determined the desirable percentages of base saturation in the soil. These percentages were optimal for the growth of most crops. These levels are: Calcium 60-70%, Magnesium 10-20%, Potassium 2-5%, Sodium 0.5-3% and others 5%.

Fertilizer and lime applications

Fertilizer and lime applications should be made at rates that will bring soil mineral percentages into an ideal range. Through this approach, the soil pH shifts automatically into a desirable range without creating the state of nutrient imbalances. The base saturation theory also takes into account the effect one nutrient may have on another and avoids undesirable interactions. For example, excess phosphorus is known to tie up zinc.

Sufficiency theory places little to no value on nutrient ratios, and lime recommendations are typically based on pH measurements alone. While in many circumstances base saturation and sufficiency methods present will produce identical soil recommendations and similar results, significant differences can occur on a number of soils. For example, suppose we tested a cornfield and found a soil pH of 5.5 and base saturation for magnesium at 20% and calcium at 40%. Base saturation theory would call for liming with a high-calcium lime to raise the % base saturation of calcium; the pH would rise accordingly. The present of sufficiency theory would not specify high calcium lime and the grower might choose instead, a high magnesium dolomite lime that would raise the pH but worsen the balance of nutrients in the soil. Another way to look at these two theories is that the base saturation theory does not concern itself with pH to any great extent but rather with the proportional amounts of bases. The pH will be correct when the levels of bases are correct.

Conventional Fertilizers

In commercial fertilizer, they can be a valuable resource to farmers in transition to a more sustainable system and can help meet nutrient needs during times of high crop nutrient demand, or when weather conditions result in slow nutrient release from organic resources. Commercial fertilizers have the advantage of supplying plants with immediately available forms of nutrients. They are often less expensive and less bulky to apply than processed natural fertilizers.

In conventional fertilizers, it’s not all that are alike, however. Many appear harmless to soil livestock but a few are problematic in nature. Anhydrous ammonia contains approximately 82% nitrogen and is applied subsurface as a gas. Anhydrous speeds the decomposition of organic matter which are present in the soil, leaving a soil more compact as a result. The addition of anhydrous contributes acidity to the soil, requiring 148 pounds of lime to neutralize 100 pounds of anhydrous ammonia or 1.8 pounds of lime for every pound of nitrogen contained in the anhydrous. Anhydrous ammonia initially kills many soil microorganisms in the application zone. Bacteria and actinomycetes recover within one to two weeks to levels higher than those prior to treatment. Soil fungi, however, may take seven weeks to recover. During the recovery time, the bacteria are stimulated to grow and decompose more organic matter due to the high soil nitrogen content. This is why their numbers increase after anhydrous applications. Farmers commonly report that the long-term use of synthetic fertilizers, especially anhydrous ammonia, leads to soil compaction and poor tilth. When bacteria increase in the soil and organic matter decreases, aggregation naturally declines because there is no more glue being produced to stick the soil particles together in a coagulated form.

Top soil

The top soil is the capital reserve of every farm. Ever since mankind started the operation of agriculture, erosion has been the single largest threat to the soil's productivity and consequently, the profitability of the farm. To sustain agriculture means to sustain the soil resource because that's where the farmer's livelihood comes from.

The major costs to the farm associated with soil erosion come from the replacement of lost nutrients and reduced water holding ability, accounting for 50 to 75% of productivity loss. Eroded soil typically contains about three times more nutrients than the soil left behind and is 1.5 to 5 times richer in organic matter. This organic-matter loss not only results in reduced water holding capacity and degraded soil aggregation but also the loss of plant nutrients, which must then be replaced with use of fertilizer. Five tons of top soil which is the so-called tolerance level can easily contain 100 pounds of nitrogen, 60 pounds of phosphate, 45 pounds of potash, 2 pounds of calcium, 10 pounds of magnesium, and 8 pounds of sulfur.

Sustainable Soil Management Principles

• Soil livestock cycle nutrients and provide many other benefits.
• Organic matter is the food for the soil livestock herd.
• The soil shall be covered to protect it from erosion.
• Tillage speeds the decomposition of organic matter.
• Excess nitrogen speeds the decomposition of organic matter.
• Moldboard plowing speeds the decomposition of organic matter, destroys earthworm habitat, and increases erosion.
• To build soil organic matter, the production or addition of organic matter must exceed the decomposition of organic matter.
• Soil fertility levels need to be within acceptable ranges before starting a soil building program.