Thursday, May 7, 2009
ISSUES WITH PHOSPHATE FERTILIZERS
Phosphate is an essential macro nutrient and is a critical component of adenosine triphosphate, (ATP) the energy molecule which drives most biological processes. It is also found in DNA and RNA. Phosphate enhances the fundamental processes of photosynthesis, nitrogen fixation, root growth, flowering and fruiting. Phosphate deficient plants will usually be stunted, thin stemmed; but the foliage will often be dark and even purple in some plants. Phosphorous is very mobile in the plant, therefore older leaves show deficiencies first.
Most soils are low in phosphate. To make matters worst, less than 0.01% of the total soil phosphorous is available to plants. Phosphorous binds easily to calcium, iron and aluminum. As a result, it does not readily leach, but for the same reason, it is not readily available for plant uptake. Even when phosphorous is added in the form of an inorganic fertilizer, it will rapidly become insoluble.
The dilemma is that calcium is also essential to plants. It is often added to soils in the form of lime rock, dolomite or gypsum, not only to replenish soils low in calcium but to also raise pH in soils made acidic by nitrates. Calcium carbonate will dissolve and calcium ions will latch on the phosphate ions, becoming a nearly insoluble compound.
In the last decades, growers have progressively added more phosphate to their fertilizer mix to counter this problem. However, even the little leaching that occurs creates enormous environmental problems. Some vegetable growers are taking a different approach. They apply a small amount of phosphate at time of planting in the furrow (starter fertilizer); then at four to six true leaves, they foliar spray (usually a mixture of potassium phosphate) on a weekly basis thereafter, (based on tissue samples). I use 3-18-18 high grade liquid fertilizer which is designed for this very reason. It is composed of food grade materials, meaning the same high quality products used in the food industry.
Most soils are low in phosphate. To make matters worst, less than 0.01% of the total soil phosphorous is available to plants. Phosphorous binds easily to calcium, iron and aluminum. As a result, it does not readily leach, but for the same reason, it is not readily available for plant uptake. Even when phosphorous is added in the form of an inorganic fertilizer, it will rapidly become insoluble.
The dilemma is that calcium is also essential to plants. It is often added to soils in the form of lime rock, dolomite or gypsum, not only to replenish soils low in calcium but to also raise pH in soils made acidic by nitrates. Calcium carbonate will dissolve and calcium ions will latch on the phosphate ions, becoming a nearly insoluble compound.
In the last decades, growers have progressively added more phosphate to their fertilizer mix to counter this problem. However, even the little leaching that occurs creates enormous environmental problems. Some vegetable growers are taking a different approach. They apply a small amount of phosphate at time of planting in the furrow (starter fertilizer); then at four to six true leaves, they foliar spray (usually a mixture of potassium phosphate) on a weekly basis thereafter, (based on tissue samples). I use 3-18-18 high grade liquid fertilizer which is designed for this very reason. It is composed of food grade materials, meaning the same high quality products used in the food industry.
Labels: 3-18-18, fertilizer, gardening, Lawn Care, leaching, liquid fertilizer, macro nutrients, phosphate
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