Sunday, July 19, 2009
HOW TO SHOP FOR FERTILIZERS
If you look at a bag of fertilizer, you will see labels with headings such as: 10-10-10; 16-8-8; 6-0-6. What this means is the percent concentration of nitrogen (N), phosphorous (P) and potassium (K) in that order. A bag of 10-10-10 has 10% nitrogen, 10% phosphorous and 10% potassium; the rest is filler such as lime rock, sand or sludge. Every nutrient adds to cost. For example a 50 lbs bag of 16-0-8 should cost less than a 16-8-8 because it does not have any phosphorous. To complicate matters, every manufacturer uses a slightly different composition from others and has a different coverage rate. Nitrogen is the most expensive component, so one way to compare apples with apples is to take similar compositions and compute the cost of nitrogen per pound. Example: You are looking at two 50 lbs bags of fertilizer. One is a 16-4-8 for $26.97 the other is a 20-5-11 for $29.99. In the first case multiply 0.16 (16%) nitrogen by 50 lbs = 8lbs of nitrogen. Divide $26.97 by 8 = $3.37 per pound of nitrogen. In the second case: $29.99/ (0.20x50) = $2.99 per pound of nitrogen. This means you are getting more bang for the buck with the second bag. Now divide your cost for nitrogen by the advertised coverage rate and you get your cost per square foot.
Liquid fertilizers are absorbed by the plants through leaves 10 times more efficiently than through roots. As a result, much less liquid fertilizer is needed to compensate for a deficiency. When comparing prices of fertilizers between liquid and dry, once again consider the coverage per pound of nitrogen, phosphate or potassium (based on which ever has the greatest concentration).
Slow release fertilizers are more desirable than dry or liquid fast release fertilizers. However, their costs are significantly higher. The choice depends on your time. Fast release fertilizers are most effective when applied in small quantities frequently.
Also consider the ingredients. For example, plants can absorb nitrogen in ammonium or nitrate form. However, the use of only one form can be detrimental to plant growth. So an ammonium nitrate combination is more desirable. Better yet, a calcium nitrate, potassium nitrate, ammonium phosphate and ammonium sulfate combination provide the essential macronutrients. Stay away from any muriate of potash, (potassium chloride), due to the potential salt damage from the chloride.
Finally, if buying dry fertilizers, strive for organic inert material. If you buy a 10-10-10, 70% of the bag is inert material such as sand, gypsum, lime rock or organic waste. Unless you are growing vegetables, which may come in contact with the soil, strive for organic inert fillers.
Remember that cheap fertilizers can cause more harm than good. In the end, you get what you pay for.
Liquid fertilizers are absorbed by the plants through leaves 10 times more efficiently than through roots. As a result, much less liquid fertilizer is needed to compensate for a deficiency. When comparing prices of fertilizers between liquid and dry, once again consider the coverage per pound of nitrogen, phosphate or potassium (based on which ever has the greatest concentration).
Slow release fertilizers are more desirable than dry or liquid fast release fertilizers. However, their costs are significantly higher. The choice depends on your time. Fast release fertilizers are most effective when applied in small quantities frequently.
Also consider the ingredients. For example, plants can absorb nitrogen in ammonium or nitrate form. However, the use of only one form can be detrimental to plant growth. So an ammonium nitrate combination is more desirable. Better yet, a calcium nitrate, potassium nitrate, ammonium phosphate and ammonium sulfate combination provide the essential macronutrients. Stay away from any muriate of potash, (potassium chloride), due to the potential salt damage from the chloride.
Finally, if buying dry fertilizers, strive for organic inert material. If you buy a 10-10-10, 70% of the bag is inert material such as sand, gypsum, lime rock or organic waste. Unless you are growing vegetables, which may come in contact with the soil, strive for organic inert fillers.
Remember that cheap fertilizers can cause more harm than good. In the end, you get what you pay for.
Labels: 10-10-10, fertilizer, liquid fertilizer, npk, slow release fertilizer
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
Subscribe to Posts [Atom]
