Chemistry: fertilizers – Processes and products – Inorganic material
Utility Patent
1999-02-01
2001-01-02
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Inorganic material
C071S033000, C071S034000, C071S064100
Utility Patent
active
06168643
ABSTRACT:
BACKGROUND
This invention relates to phosphorus fertilizers and their method of preparation. In particular, this invention relates to a fertilizer having a combination of phosphorous acid or its salts thereof, and either (a) polyphosphoric acid and its salts thereof; or (b) phosphoric acid and its salts thereof. This combination phosphorus fertilizer, when combined within a specific ratio range, reduces the risk of formation of phosphorus or calcium phosphate precipitates. It further increases the phosphorus uptake to plants and thereafter can be oxidized into a form more readily useable by a plant system.
Fertilizers have long been used to supply needed nutrition to plants. The principle components of plant fertilizers have centered on three elements: nitrogen, phosphorus and potassium.
Phosphorus is not found in nature in its elemental form. The principal source of phosphorus for the fertilizer industry, however, is obtained from the ores of phosphorus containing minerals. The usual practice in the fertilizer industry is to convert phosphorus ores into a phosphorus product containing the phosphoric radical (PO
4
−3
) which can be absorbed, although rather inefficiently, into plants and thereafter used as nutrition. It is well known in the prior art that phosphorus is biologically active and nutritionally useful to plants only in the phosphoric form (PO
4
−3
). A common source of the phosphoric radical (PO
4
−3
) for fertilizers is phosphoric acid.
Many of the phosphorus fertilizers currently used have a number of undesired qualities. First, if prepared in concentrated solutions, they tend to form undesired precipitates in a short period of time. Further, these concentrated solutions must be maintained within a narrow pH range to prevent precipitation, which results in fertilizers with limited application. Precipitates are undesirable since they can not be absorbed by plants.
Still another problem with phosphorus containing fertilizers, particularly phosphoric fertilizers, is that they are not readily absorbed by foliage and must be applied to the soil and thereafter absorbed by the plant root system. Since only a small portion of the phosphoric fertilizer applied to the soil is actually absorbed by a root system, frequent reapplication usually occurs. This is undesirable because it can lead to leaching of phosphate into the groundwater which may cause eutrophication of lakes, ponds and streams.
Prior art formulas of phosphorus fertilizers have identified these problems. U.S. Pat. No. 5,514,200, issued to Lovatt, describes a formula utilizing the more readily absorbed phosphorous form (PO
3
−3
) in a composition buffered with an organic acid. However, as is discussed below, the present invention represents an improved and more effective composition for providing phosphorus to plants.
SUMMARY
The present invention is directed to a concentrated phosphorus fertilizer solution which consists essentially of phosphorous acid or its salts dissolved in water and stabilized with an inorganic complexing agent such as polyphosphoric acid to prevent phosphorus or calcium phosphate precipitation. Reduction of the formation of phosphorus or calcium phosphate precipitates, allows the concentrated phosphorus fertilizer to be stored for long periods of time. When subsequently diluted, the fertilizer can be applied to plants and/or soil, being easily absorbed through the foliage or the root system of a plant. The absorbed phosphorus is then used by plants to perform or accelerate biological functions which are defined here to include plant growth, improved quality, improved disease resistence, and improved vigor.
Although the present invention can function properly and remain dissolved in solution in the range of pH between 0.5 and 10.0, it is preferably maintained in a pH range between 5.0 and 7.5 for ideal absorption into plants either by foliar or soil applications.
Testing, the results of which are provided below, indicate that phosphorous acid or its salts, in combination with either (a) polyphosphoric acid or its salts, or (b) phosphoric acid or its salts, when used as a plant fertilizer, has a synergistic effect which improves plant growth than if phosphorous, polyphosphoric or phosphoric fertilizers were used individually on plant systems.
The desired weight ratio of phosphorus derived from phosphorous acid or its salts to phosphorus derived from either (a) polyphosphoric acid or its salts, or (b) phosphoric acid or its salts, is between 1:10 to 10:1. However, the range can be from 1:20 to 20:1. Alternatively, (a) and (b) described above may be combined so that the weight ratio to phosphorous acid or its salts is between 1:20 to 20:1.
Other features and advantages will become apparent to those skilled in the art upon review of the following detailed description and claims.
DESCRIPTION
A phosphorus fertilizer is prepared by mixing phosphorous acid or its salts with either: phosphoric acid or its salts; or, polyphosphoric acid or its salts. The phosphorus derived from phosphoric acid or its salts or polyphosphoric acid or its salts is designated as PO
4
−3
and phosphorus derived from phosphorous acid or its salts is designated as PO
3
−3
. The ratio of PO
4
−3
to PO
3
−3
in the prepared phosphorus fertilizer ranges from 1:20 to 20:1. Mixing of PO
4
−3
with PO
3
−3
produces a synergistic effect of PO
4
−3
and PO
3
−3
on plant growth and uptake of phosphorus by plants.
Mixing of PO
4
−3
and PO
3
−3
also enables the preparation of high phosphorus liquid fertilizers with better stability and little, if any precipitation. However, although liquid preparations are more desirable, dry preparations are also possible.
To prepare the fertilizer of the present invention, phosphorous acid or its salts, PO
3
−3
are dissolved in water. The solution is then stabilized by adding PO
4
−3
, added in intervals, until the PO
4
−3
constitutes within the range 1:20 to 20:1 by weight relative to the amount of PO
3
−3
present.
The novel composition can be delivered to plants by foliar or soil applications such as through an irrigation system. The phosphorus fertilizers so prepared are taken up by plants in the phosphorous form and are gradually converted by enzymes in the plants to phosphoric form to perform or accelerate biological functions in the plant.
Phosphorous acid is a genus which includes the following species: phosphorous acid, hypophosphorous acid, polyphosphorous acid, polyhypophosphorous acid.
Salts of phosphorous acid contemplated by this invention include but are not limited to ammonium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, potassium phosphite, sodium phosphite, and zinc phosphite.
Phosphoric acid exists in the meta (HPO
3
), pyro (H
4
P
2
O
7
) and ortho (H
3
PO
4
) form.
Salts of phosphoric acid contemplated by this invention include but are not limited to ammonium phosphate, calcium phosphate, ferrous phosphate, aluminum phosphate, ferric phosphate, magnesium phosphate, manganese phosphate, sodium phosphate, and zinc phosphate.
Polyphosphoric acid is a genus which includes the following species: polyphosphoric acid, dipolyphosphoric acid, tripolyphosphoric acid, tetra polyphosphoric acid, penta polyphosphoric acid, hexapolyphosphoric acid or combinations thereof.
Salts of polyphosphoric acid include but are not limited to potassium polyphosphate, ammonium polyphosphate, sodium polyphosphate, zinc polyphosphate, magnesium polyphosphate and iron polyphosphate.
The desired pH range is between 5.0 and 7.5. However, the pH can be from 0.5 to 10.0.
In order to more clearly define the invention, the following examples of methods of preparation are set forth. These examples are illustrative only and are not limiting as to the scope of the invention.
Examples I and VII are typical fertilizer found in the prior art. Examples II and VIII embody the present invention with regards to phosphorous acid and an inorganic complexing agent. Examples III and I
Arant Gene W.
Chabot Ralph D.
Langel Wayne
Safergro Laboratories, Inc.
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