Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
2000-12-08
2003-06-10
Sayala, Chhaya D. (Department: 1761)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S055000, C071S064030, C071S064020, C071S064070
Reexamination Certificate
active
06576035
ABSTRACT:
FIELD
The present application concerns compositions comprising calcium cyanamide and methods for their use including, without limitation, in industry and farming, decomposition (composting), odor and organism inhibition, nutrient stabilization, fertilizing and soil amending.
BACKGROUND
Commercial calcium cyanamide (CaNCN) is actually a mixture of several components formed during or remaining after production of the desired calcium cyanamide compound. Additional components found in commercial calcium cyanamide include calcium oxide (CaO), calcium carbide (CaC
2
), graphite carbon (C) and oxides of iron, aluminum, and silicon.
Typically for one reason or another, commercial calcium cyanamide is treated to alter the form of cyanamide or remove components remaining after manufacture. For example, because calcium cyanamide is a slow acting fertilizer that is sparingly soluble in water, it is often factory converted to water-soluble molecular cyanamide (H
2
NCN) which is faster acting and a higher analysis source of nitrogen. In this process, calcium cyanamide is forced to dissolve in water by precipitation of calcium ions (Ca
2+
) as calcium carbonate (CaCO
3
) and by acidification to convert initially formed cyanamide ions (NCN
2−
) into acid cyanamide ion (HNCN
−
) and then into molecular cyanamide, which predominates at a pH of 4.5-5.5. Insoluble calcium carbonate and graphite carbon which may be entrained in the calcium carbonate are then removed by filtration.
Calcium oxide and calcium carbide are also removed during this process. In the case of calcium carbide, the carbide ion reacts with water to form acetylene that is lost as a gas to the atmosphere. Thus, it is seen that many of the components originally in commercial calcium cyanamide are converted, removed, or lost.
A. Calcium
Calcium ions (Ca
2+
) are present in most organic matter and are necessary for many enzymatic reactions, including those that facilitate energy use by living organisms. Furthermore, calcium ions aid in soil reclamation by acting to flocculate soil and permit water percolation. Additionally, calcium tends to enhance the breakdown of organic matter through these and other actions.
While calcium ions are abundant in nature in the form of limestone (calcium carbonate, CaCO
3
), they are not readily available for uptake because of the relative insolubility of calcium carbonate. From this is seen the need to stabilize calcium ions in soluble form to enhance the speed of calcium uptake into organic matter, both living and dead, to aid plant growth and soil reclamation.
Completely ignored to this date is calcium cyanamide's potential as a source of stabilized Ca
2+
that can rapidly enter plants and flocculate soil. While promotional literature does mention calcium cyanamide as a possible soil amendment, unstabilized it is no more useful than inexpensive mined lime (CaCO
3
). However, if the soluble forms of calcium could be stabilized, it would provide added value to calcium cyanamide.
Stabilizing soluble calcium ions at the immediate first hydrolysis step during the production of molecular cyanamide from commercial calcium cyanamide has been overlooked. Typical descriptions of the hydrolysis of calcium cyanamide indicate conversion directly to molecular cyanamide and calcium carbonate. Furthermore, some prior art hydrolysis schemes ensure complete loss of soluble calcium through CO
2
enrichment during aerobic hydrolysis, to provide calcium free, acid stabilized molecular cyanamide or soluble acid cyanamide salts. Such processes leave lime (CaCO
3
) blackened by graphite carbon (C) in huge, now environmentally suspect piles, behind calcium cyanamide factories. Given the huge energy costs of initial calcium cyanamide production and subsequent analog production costs, it is unfortunate that a valuable nutrient such as calcium is left behind in piles of black lime for the sake of obtaining only nitrogen fertilizer from calcium cyanamide. The wastefulness of this practice is highlighted in that the major portion of commercial CaNCN is calcium. It is therefore desirable to stabilize and deliver the calcium component of calcium cyanamide for decomposition (composting) enhancement, odor and organism inhibition, plant nutrition, and soil flocculation.
B. Nitrogen
Nitrogen, in its molecular form (N
2
) comprises approximately 78% of the earth's atmosphere. Nitrogen is a component of all proteinaceous matter found in living organisms, but only a few organisms (such as nitrogen-fixing bacteria) are able to directly capture atmospheric nitrogen and add it to the biosphere.
Proteinaceous matter, contained in dead and decaying organic matter and additionally in the excreta of animals represents a vast potential source of nitrogen for growth of living organisms. However, in proteinaceous form, nitrogen is insoluble and unavailable to living organisms except through the action of decomposers, which release nitrogen in the forms NH
3,
NH
4
+
, NO
2
−
, and NO
3
−
. These forms can be utilized by plants and allow nitrogen to reenter the living biosphere.
In many instances the rate at which nitrogen becomes available from decomposing (composting) organic matter is insufficient to provide rates of plant growth that are desired by modem agriculture. Thus, there arises a need to supplement available nitrogen in soil and/or increase the rate at which nitrogen becomes available to plants from decomposing organic matter.
Modern agriculture has chosen to pursue a strategy of supplementing plant available nitrogen through the use of high analysis nitrogen fertilizers, such as inexpensive urea, ammonia, ammonium compounds, and nitrates. Concurrently, use of calcium cyanamide, the first commercially available high analysis fertilizer, has declined due to the high cost of its manufacture and to the handling, shipping, and phytotoxicity problems it poses.
While high analysis nitrogen fertilizers can provide abundant nitrogen for rapidly growing plants, their use has produced some undesirable consequences, such as leaching of nitrates into groundwater and losses of volatile ammonia to the atmosphere. These are also problems associated with composting and applying animal excreta directly to soils. Thus, it is desirable to provide compositions and methods that promote release of nitrogen from proteinaceous materials, yet slow its loss to the atmosphere and from soil. It is also desirable to provide compositions and methods that stabilize and extend the residence time of high nitrogen analysis fertilizers in the plant root zone.
C. Calcium and Nitrogen
Plants deficient in calcium but provided with an abundance of nitrogen are prone to parasitic organisms. Conversely, plants with high ratios of calcium to nitrogen resist parasitic organisms. It is also known that it is difficult to provide plants with calcium in direct proportion to the rate at which they can absorb soluble nitrogen forms, even if calcium and nitrogen are provided as water-soluble calcium nitrate (CaNO
3
). Slow acting calcium sprays and expensive chelated forms of calcium have been reported not to cure calcium deficiencies observed during intensive nitrogen demanding vegetable production in California (Crop Notes, UC Extension, Salinas, Calif., Jul. 2000). Therefore, it would be desirable to have compositions and methods that stabilize soluble calcium and promote calcium uptake by plants in proportion to nitrogen uptake, thereby conferring parasite resistance to the plants.
D. Calcium Cyanamide (CaNCN)
Calcium cyanamide which comprises 44% calcium and 24% nitrogen was first made in the late 1800s, as part of a search for a high analysis nitrogen source for industry and agriculture to replace low analysis (1-<12%) excreta deposits. It is produced in 1000 to >3,000° C. electric arc furnaces by burning black coal and white limestone in the presence of atmospheric nitrogen. Energy costs represent the bulk of the cost of production of calcium cyanamide.
Because calcium cyanamide is slow acting, one application at a
Hartmann Richard O.
Holt Timothy G.
Shirley, Jr. A. Ray
Hartmann Richard
Klarquist & Sparkman, LLP
Sayala Chhaya D.
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