Patent Publication Number: US-2005123644-A1

Title: Phosphate-containing fertilizer derived from steepwater

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation-in-part of PCT International Application No. PCT/US03/02354, filed 24 Jan. 2003 and entitled LOW PHOSPHOROUS ANIMAL FEED AND METHOD FOR MAKING SAME. This application also claims the benefit of U.S. Provisional Application No. 60/518,189, filed 7 Nov. 2003 and entitled PHOSPHATE CONTAINING FERTILIZER, and U.S. Provisional Application No. 60/351,725, filed  24  Jan. 2002. The entirety of each of these applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD  
      This invention generally relates to fertilizer compositions. Select embodiments provide fertilizers containing phosphorus derived from steepwater, e.g., corn steepwater, and methods of making such fertilizers from steepwater.  
     BACKGROUND  
      Wet milling of corn is a common technique in the commercial production of corn starch, corn syrup, and corn oil, among other corn products. In wet milling, the corn is steeper prior to breaking the corn. Steeping softens the kernels, making it easier to separate the corn into its components.  
      Corn contains phosphorous, primarily in the form of an organic phosphorous-containing compound, phytate. Steeping leeches phytate, along with a variety of other corn solubles, out of the corn. The soaked corn kernels can be removed, leaving a steepwater that includes phosphorous and other corn solubles. After reduction to remove excess water, steepwater can be used in a variety of further applications, including use as part of an animal feed or as a nutrient source for fermentation processes.  
      Phytate is poorly digested by monogastric animals. Although ruminants, e.g., cattle, can digest phytate, excess dietary phytate and other phosphates in a ruminant diet will pass through the animal&#39;s gastrointestinal tract to be excreted as manure. Excessive amounts of phosphorous from animal manure is undesirable from an environment standpoint. Furthermore, phytate can associate with multivalent cations. Some multivalent cations, e.g., calcium, are important nutritional elements in the animal&#39;s diets; phytate&#39;s association with these cations can interfere with their bioavailability to the animal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a process diagram schematically illustrating components of a facility that may be used to carry out aspects of the invention.  
       FIG. 2  is a bar graph schematically comparing samples made in accordance with various embodiments of the invention to a commercially available starter fertilizer. 
    
    
     DETAILED DESCRIPTION  
      A. Overview  
      Embodiments of the invention provide methods for making fertilizers that include phosphorus and may additionally include primary nutrients (e.g., nitrogen and potassium), secondary nutrients (e.g., sulfur, calcium, magnesium), and micro nutrients (e.g., metals). Some methods contemplate removing phytate from steepwater from wet corn milling by mixing the steepwater with an alkaline hydroxide, such as calcium hydroxide, magnesium hydroxide, ammonium hydroxide, or mixtures thereof. The hydroxide converts the phytate to an alkaline metal salt and/or ammonium salt (phytin), which precipitates to provide a phosphorous-rich precipitate and a reduced-phosphorous steepwater.  
      In one approach, the amount of alkaline metal and/or ammonium hydroxide added is effective to precipitate the phosphorous in the steepwater and to provide an alkaline metal- or ammonium-phytin complex or associate the divalent metal and/or ammonium ion with the phytin such that the phytin will precipitate with the calcium metal ions, magnesium metal ions, and/or ammonium ions. Calcium ions are believed to work better to precipitate phosphorus than other ions, even when the other ions are in an environment having a high pH. The alkaline metal or ammonium ions may also form complexes and precipitate a small amount of inorganic phosphate from the steepwater. Generally, the alkaline metal and/or ammonium hydroxide may be present in an amount sufficient to provide a pH of greater than about 5.5 and preferably greater than about 6.0.  
      The molar ratio of calcium to phosphorus may be selected to precipitate at least 75%, preferably 80% or more, of the phosphorus; a Ca/P ratio of at least about 1, preferably greater than about 1.0, is expected to suffice. The ion/phytin complex is separated from the steepwater to provide a low-phosphorous steepwater. This precipitated ion/phytin complex and other co-precipitates can be used directly as a fertilizer or fertilizer component. In one useful embodiment, the precipitate is further processed to free up the phosphorus for use as a fertilizer or component thereof.  
      The phosphorous-rich precipitate removed from the steepwater may also contain other primary nutrients, such as nitrogen (typically from protein) and potassium; secondary nutrients such as calcium and sulfur; and many micronutrients, e.g., iron, copper, magnesium, and oxalate. These other important fertilizer nutrients may co-precipitate with the ion/phytin complex.  
      B. Definitions  
      “Phytate” means myoinositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate). This compound associates with cations and forms complexes, which are sometimes called phytin. We shall also describe these metal or ammonium ion/phytate-associated molecules as phytin complexes.  
      “Corn gluten feed” is a by-product of the wet milling of corn for products such as corn starch and corn syrup. Corn gluten feed generally includes corn germ, corn bran, corn solubles, cracked corn, and fermentation end products.  
      Maize Components: Botanically, a maize kernel or corn kernel is known as a caryopsis, a dry, single-seeded, nutlike berry in which the fruit coat and the seed are fused to form a single grain. Mature kernels have four major parts: pericarp (hull or bran), germ (embryo), endosperm, and tip cap.  
      An average composition of whole maize, and its fractions, on a moisture-free (dry) basis is as follows.  
                                       TABLE A                       Fraction of   Kernel   Starch   Protein   Lipid   Sugar   Ash       Whole Maize   wt %   wt %   wt %   wt %   wt %   wt %                                                            Whole grain   100   71.5   10.3   4.8   2.0   1.4       Endosperm   82.3   86.4   9.4   0.8   0.6   0.3       Germ   11.5   8.2   18.8   34.5   10.8   10.1       Pericarp   5.3   7.3   3.7   1.0   0.3   0.8       Tip cap   0.8   5.3   9.1   3.8   1.6   1.6                  
 
      Germ: The scutellum and the embryonic axis are the two major parts of the germ. The scutellum makes up 90% of the germ, and stores nutrients mobilized during germination. During this transformation, the embryonic axis grows into a seedling. The germ is characterized by its high fatty oil content. It is also rich in crude proteins, sugars, and ash constituents. The scutellum contains oil-rich parenchyma cells, which have pitted cell walls. Of the sugars present in the germ, about 67% is glucose.  
      Endosperm: The endosperm contains the atarch, and is lower in protein content than the germ and the bran. It is also low in crude fat and ash constituents.  
      Pericarp: The maize kernel is covered by a water impermeable cuticle. The pericarp (hull or bran) is the mature ovary wall beneath the cuticle and comprises all the outer cell layers down to the seed coat. It is high in non-starch-polysaccharides, such as cellulose and pentosans. A pentosan is a complex carbohydrate present in many plant tissues, particularly brans, characterized by hydrolysis to give five-carbon atom monosaccharides (pentoses). It is any member of a group of pentose polysaccharides found in various foods and plant juices. Because of its high fiber content, the pericarp is tough.  
      Tip cap: The tip cap, where the kernel is joined to the cob, is a continuation of the pericarp, and is usually present during shelling. It contains a loose and spongy parenchyma.  
      C. Equipment  
       FIG. 1  schematically illustrates a steepwater processing system  10  in accordance with one embodiment of the invention. This system  10  includes a mixing tank  20  that receives a supply of steepwater via a steepwater supply line  22  and a supply of a suitable alkaline hydroxide via feed line  36 . A pH adjustment supply  24  may deliver any additional components needed to adjust the pH of the contents of the mixing tank  20 . If so desired, a process water supply  26  may also be coupled to the mixing tank. The contents of the mixing tank may be continuously mixed by a mixer  28 .  
      As discussed below, a variety of alkaline hydroxides may be combined with the steepwater in accordance with different embodiments of the invention. In the particular embodiment shown in  FIG. 1 , the alkaline hydroxide delivered via supply line  36  is lime, i.e., calcium hydroxide. A lime silo  30  may hold lime for delivery to a pair of mixing tanks  32   a  and  32   b . In the illustrated embodiment, lime from the silo  30  is delivered to the first mixing tank  32   a  and mixed with water by a mixer  34   a . A portion of the resultant lime slurry may be delivered to the second mixing tank  32   b , which is continuously mixed by a mixer  34   b . This ensures a ready supply of lime slurry to meet the process needs in the mixing tank  20 .  
      After suitable processing as detailed below, the steepwater and an entrained phosphate-rich precipitate may be delivered to at least one separator  60  by a delivery line  50 . In the illustrated embodiment, a flocculent supply  40  may deliver a flocculent to a pump  52  for delivery to the separator(s)  60 . A process water supply  54  may add any additional water necessary for the separator(s)  60 .  
      The specific system shown in  FIG. 1  employs a pair of decanter centrifuges  60   a  and  60   b . Suitable decanter centrifuges are commercially available, e.g., from Wesffalia. If so desired, the separated phosphate-rich precipitate may be delivered to a storage or processing facility. A reduced-phosphate steepwater may be delivered to a collection tank  70  via delivery line  64 . In one embodiment, the steepwater may be allowed to settle in the tank  70  to reduce any foam that may have formed in the centrifuges  60 . As explained in PCT International Publication No. WO 03/061403 (the entirety of which is incorporated herein by reference), the reduced-phosphorous steepwater in the tank  70  may be further processed for reuse, e.g., as a component of an animal feed.  
      D. Process  
      The first step in the wet milling of corn is steeping, in which corn is soaked in water under controlled processing conditions. Controlling temperature, time, sulfur dioxide (SO 2 ) concentration, and lactic acid content has been found to promote diffusion of water through the tip cap of the corn kernel into the germ and endosperm. Steeping softens the kernels, facilitating separation of the components of corn.  
      Bulk corn is cleaned on vibrating screens to remove coarse material and fine material. These screenings removed from the corn kernels are used for animal feed. If allowed to remain with the corn, fine material can cause processing problems such as restricted water flow through steeps and screens and increased steep liquor viscosity.  
      Steeping is well known in the art and need not be detailed here. Steeping parameters useful in connection with some embodiments of the invention are set forth in PCT International Publication No. WO 03/061403, the entirety of which is incorporated herein by reference. Generally, though, steeping involves putting corn into tanks and covering the corn with water. The corn and water blend may be heated to about 125° F. and held for about 22 to about 50 hours. Steeping may be done by continuously adding dry corn at the top of the steep while continuously withdrawing steeped corn from the bottom.  
      Water from the steeping accumulates corn solubles. The water may be treated with SO 2  to a concentration of about 0.12 to about 0.20 weight percent. The SO 2  increases the rate of water diffusion into the kernel and assists in breaking down the protein-starch matrix, which is necessary for high starch yield and quality.  
      Water moves from one steep tank to another and as the water is advanced from steep to steep, the SO 2  content decreases and bacterial action increases. This results in the growth of lactic acid bacteria. The lactic acid concentration is from about 16 to about 20% (dry basis) after the water has advanced through the steeping system and been withdrawn as light steepwater (steepwater without water evaporated therefrom). Meanwhile, the SO 2  content drops to about 0.01% or less.  
      During steeping some water is absorbed by the corn to increase its moisture content from about 16 weight percent to about 45 weight percent. Unabsorbed water is withdrawn from the steeping system. This light steepwater contains corn solubles soaked out of the corn, which include phosphorous and may also include one or more of protein, manganese, zinc, molybdenum, copper, and iron. The steepwater is mixed with a base, e.g., Ca(OH) 2  and/or Mg(OH) 2 , to precipitate the phytate in the steepwater as described below. Precipitation with calcium hydroxide is preferred; calcium ions work better to precipitate phosphorus than alternative ions even when the other ions are in a high pH environment.  
      One implementation of the invention employs a light steepwater that contains about 1-30 weight percent (wt %) solids, preferably about 4-13 wt % solids, and about 0.1 to about 3 wt % phytate, preferably about 0.4-1.3 wt % phytate, with a pH of about 3.5 to about 4.5. This light steepwater may be mixed with a sufficient amount of alkaline metal hydroxide (e.g., calcium hydroxide or magnesium hydroxide), and/or ammonium hydroxide to raise its pH to at least about 5.5 and to precipitate at least about 75% of total phosphorus in steepwater, typically as phytin and insoluble phosphates, e.g., calcium phosphate. In one embodiment, more than about 90 wt % of phytate and about 20 wt % to about 50 wt % of inorganic phosphate are precipitated out of steepwater as the calcium salt. The amount of hydroxide will vary depending on the pH of the starting steepwater and the desired degree of phosphorous removal. Generally, though, the hydroxide may be added to a concentration of at least about 0.07 wt %, e.g., about 0.07-3.0 wt %, and preferably about 0.3 to about 1.0 wt %.  
      The method may also precipitate out at least about 80 wt %, e.g., 90 wt % or more, of total oxalate in the steepwater as calcium oxalate. The resulting steepwater contains white calcium phytate/phosphate precipitate and calcium oxalate precipitate, which may be separated (e.g., by vacuum filtration or horizontal basket centrifugation) to produce a low-phosphorous steepwater and a phosphorous-rich precipitate that includes calcium phytate and calcium oxalate. In one embodiment that employed centrifugal separation, the precipitate included between 28 wt % and 32 wt % dissolved solids (DS).  
      One embodiment provides a precipitate that includes phosphorous and at least one other fertilizer nutrient, which may be a primary nutrient, a secondary nutrient, or a micronutrient. Suitable primary nutrients include nitrogen and potassium. Secondary nutrients include calcium magnesium, and sulfur and micronutrients commonly are metals such as manganese, zinc, molybdenum, copper, and iron. Depending on the treatment of the precipitate, the building blocks (i.e., carbon, hydrogen, and oxygen) may also be available. Analysis of the precipitate on a dry basis typically finds about 10-17 wt % total phosphorus, about 10-14 wt % calcium, about 9-24 wt % protein, about 2.45-3.55 wt % magnesium, and about 0.66-1.63 wt % sulfur.  
      Treatment of the precipitate can yield a fertilizer that has bio-available phosphorus as well as other essential elements. The organically bound phosphorus can be converted to a more bio-available inorganic phosphorus by chemical hydrolysis, enzymatic hydrolysis, or combustion.  
      For chemical hydrolysis, the precipitate may be dissolved in a mineral acid (e.g., sulfuric or hydrochloric acid) to a final pH of 2.0-3.5, desirably about 3, and heated to about 100° C. for several hours. Reaction time can vary depending on optimal conditions and desired level of hydrolysis, but 100% hydrolysis can occur after 24 hrs.  
      For enzymatic hydrolysis the precipitate is dissolved in mineral acid (e.g., sulfuric or hydrochloric acid) to a final pH of 2.0-3.5 and treated with about 0.1 wt % to 0.33 wt % of a phytase enzyme. Reaction is held at 37° C. for several hours. 100% hydrolysis can occur after 24 hrs, but hydrolysis time can vary depending on how much enzyme is used, what temperature is chosen, and what level of hydrolysis is desired.  
      In one embodiment, the precipitate is combusted to convert the organic bound phosphorus to inorganic phosphorus. In one example, the precipitate was dried to the following specifications: Moisture 3.79%, Carbon 18.0%, Hydrogen 3.36%, Nitrogen 2.56%, Sulfur 0.39%, Ash 52.4% and Oxygen 9.54% (by difference). Combusting the dry material released  3083  BTU/lb and yielded an ash with the following elemental analysis: SiO 2 &lt;0.01 wt %, Al 2 O 3 &lt;0.01 wt %, TiO 2 &lt;0.01 wt %, Fe 2 O 3 0.38 wt %, CaO 30.80 wt %, MgO 7.63 wt %, Na 2 O 0.02 wt %, K 2 O 6.76 wt %, P 2 O 5  55.06 wt %, SO 3  0.01 wt %.  
     E. EXAMPLES  
     Example I  
      Method of Making Low Phosphorus Reduced Steepwater: Various amounts of lime (calcium hydroxide) is added to light steepwater at about 50-600° C. with mixing to precipitate a phosphorous-rich precipitate. The mixture is filtered through a filter under vacuum to remove precipitate solids. The total phosphorus content can be measured by various analytical methods. One analytical method involves the use of phytase to hydrolyze phytate to free phosphates and measuring free phosphates with an ion chromatography.  
      The phytase hydrolysis reaction of the analytical method was done at about 379° C. for 4 hours in 0.2 M citrate buffer with a pH of 5. Under these analytical conditions, 96% of total phosphate is hydrolyzed from phytate. In this example, more than 80% of total phosphorus in steepwater precipitated out at a pH of at least about 5.5 and a calcium to phosphorus molar ratio (Ca/P) of about 0.75 or greater. Analysis of the calcium phytate precipitate collected at pH=6.4 found the precipitate contained about 11% protein, 56% ash, 13.9% calcium, 17.6% phosphorus, 3.6% magnesium, and 1.6% sulfur. The starting steepwater solids contain 3.6% phosphorus and the low phosphorus steepwater solids contain only 0.5% phosphorus. More than 85% of total phosphorus is removed from the steepwater.  
      Steepwater from another source was also processed as indicated above. Results of processing were as follows:  
               TABLE 1                          Phosphorous and Oxalate Removal with varying pH and Ca/P                                             % P   % oxalate           pH   Ca/P   Removed   Removed                                                 6.14   1.58   87.4   92.8           5.62   1.42   83.6   89.4           5.29   1.25   69.0   81.8           5.07   1.10   52.7   84.9           4.95   0.95   40.5   82.1           4.76   0.79   10.2   81.2           4.56   0.63   2.1   89.2           4.37   0.47   7.5   90.3           4.14   0.33   3.7   85.7           4.10   0.16   0   64.9           3.97   0.03   3.3   0                      
 
     EXAMPLE II  
      Materials and Methods:  
      A phosphorous-rich precipitate was formed generally as outlined above and quantities of the precipitate were collected over time to obtain a composite sample that reflected fluctuations in the wet mill operation. The composite sample was dried using a tray dryer and ground to a fine granular consistency. The composite sample was stored in a clean, dry 55-gallon drum to form a inventory of 200-500 lbs. Aliquots of the sample were used as starting material for pH adjustment, hydrolysis, and final pH adjustments as indicated below.  
      Sample 1: A sample of the phosphorous-rich precipitate was tray dried at 50° C. and ground to fine granular consistency. Table 1 lists the chemical analysis on a weight percent basis, fertilizer nutrients (pounds of nutrient/ton of dried precipitate), and the analytical method employed in each measurement.  
               TABLE 2                          Phosphorous-rich Precipitate (Sample 1)                             Sample 1   Analysis   Nutrients   Analysis       Parameters   wt %   lbs/ton   Method                                     Ammonium Nitrogen (N)   0.01   0.3   EPA 350.2       Organic Nitrogen (N)   2.81   56.2   EPA 350.2       Total Nitrogen (N)   2.82   56.4   EPA 351.3       Phosphorus (P 2 O 5 )   19.36   387.2   EPA 200.7       Potassium (K 2 O)   2.58   51.5   EPA 200.7       Sulfur (S)   0.37   7.4   EPA 200.7       Calcium (Ca)   9.37   187.3       Magnesium (Mg)   1.97   39.4   EPA 200.7       Sodium (Na)   0.02   0.3   EPA 200.7       Copper (Cu)    7 ppm   0.01   EPA 200.7       Iron (Fe)   641 ppm   1.28   EPA 200.7       Manganese (Mn)   240 ppm   0.48   EPA 200.7       Zinc (Zn)   555 ppm   1.11   EPA 200.7       Moisture   14.5       EPA 160.3       Total Solids   85.5   1710   Wheatstone       Total Salts       278.8   EPA 120.1       pH   6.4       EPA 150.1       Ash   37.2       Calc.       Phosphate Available (P 2 O 5 )   18.82       Calc.                  
 
      Sample 2: A sample of the phosphorous-rich precipitate was slurried in water to 33 D.S. and adjusted with sulfuric acid to pH 3.5 at room temperature. The slurry was then tray dried at 50 C and ground to fine granular consistency. Table 3 lists the chemical analysis on a weight percent basis, fertilizer nutrients (pounds of nutrient/ton of dried precipitate), and the analytical method employed in each measurement.  
               TABLE 3                          Acidified Phosphorous-rich Precipitate (Sample 2)                             Sample 2   Analysis   Nutrients   Analysis       Parameters   wt %   lbs/ton   Method                                     Ammonium Nitrogen (N)   0.04   0.8   EPA 350.2       Organic Nitrogen (N)   2.38   47.6   EPA 350.2       Total Nitrogen (N)   2.42   48.5   EPA 351.3       Phosphorus (P 2 O 5 )   18.34   366.8   EPA 200.7       Potassium (K 2 O)   1.89   37.8   EPA 200.7       Sulfur (S)   4.8   96   EPA 200.7       Calcium (Ca)   9.83   196.6   EPA 200.7       Magnesium (Mg)   1.77   35.4   EPA 200.7       Sodium (Na)   0.02   0.4   EPA 200.7       Copper (Cu)    6 ppm   0.01   EPA 200.7       Iron (Fe)   610 ppm   1.22   EPA 200.7       Manganese (Mn)   235 ppm   0.47   EPA 200.7       Zinc (Zn)   583 ppm   1.17   EPA 200.7       Moisture   11.2       EPA 160.3       Total Solids   88.8   1776   Wheatstone       Total Salts       371   EPA 120.1       pH   4       EPA 150.1       Ash   39.6       Calc.       Phosphate Available (P 2 O 5 )   18.21       Calc.                  
 
      Sample 3: A sample of the phosphorous-rich precipitate was slurried in water to 33 D.S. and adjusted with sulfuric acid to pH 3.5. The slurry was hydrolyzed by heating to 100 C until ion chromatographic analyses indicate &gt;85% PO 4  hydrolysis. The slurry was tray dried at 50 C and ground to fine granular consistency. The chemical analyses, lbs/ton of fertilizer nutrients, and analytical methods for the hydrolyzed calcium phytate precipitate are given in Table 4.  
               TABLE 4                          Hydrolyzed Phosphorous-rich Precipitate (Sample 3)                             Sample 3   Analysis   Nutrients   Analysis       Parameters   wt %   lbs/ton   Method                                     Ammonium Nitrogen (N)   0.07   1.5   EPA 350.2       Organic Nitrogen (N)   2.13   42.6   EPA 350.2       Total Nitrogen (N)   2.2   44   EPA 351.3       Phosphorus (P 2 O 5 )   13.78   275.7   EPA 200.7       Potassium (K 2 O)   1.62   32.4   EPA 200.7       Sulfur (S)   6.5   130   EPA 200.7       Calcium (Ca)   8.99   179.7   EPA 200.7       Magnesium (Mg)   1.3   26   EPA 200.7       Sodium (Na)   0.01   0.2   EPA 200.7       Copper (Cu)    7 ppm   0.01   EPA 200.7       Iron (Fe)   478 ppm   0.96   EPA 200.7       Manganese (Mn)   176 ppm   0.35   EPA 200.7       Zinc (Zn)   440 ppm   0.88   EPA 200.7       Moisture   17.9       EPA 160.3       Total Solids   82.1   1642   Wheatstone       Total Salts       239.8   EPA 120.1       pH   2.6       EPA 150.1       Ash   31.3       Calc.       Phosphate Available (P 2 O 5 )   13.56       Calc.                  
 
      Sample 4: A sample of the phosphorous-rich precipitate was slurried in water to 33 D.S. and adjusted with sulfuric acid to pH 3.5. The slurry was hydrolyzed by heating to 100° C. until ion chromatographic analyses indicated &gt;85% PO 4  hydrolysis. The material was cooled to ambient temperature and the pH was adjusted to 7.0 with aqua ammonia. The slurry was tray dried at 50° C. and ground to fine granular consistency. The chemical analyses, lbs/ton of fertilizer nutrients, and analytical methods for the resultant hydrolyzed, ammonia-adjusted precipitate are given in Table 5.  
               TABLE 5                          Hydrolyzed, Ammonia-adjusted Precipitate (Sample 4)                             Sample 4   Analysis   Nutrients   Analysis       Parameters   wt %   lbs/ton   Method                                     Ammonium Nitrogen (N)   5.78   115.5   EPA 350.2       Organic Nitrogen (N)   2.25   45   EPA 350.2       Total Nitrogen (N)   8.03   160.7   EPA 351.3       Phosphorus (P 2 O 5 )   15.44   308.8   EPA 200.7       Potassium (K 2 O)   1.78   35.7   EPA 200.7       Sulfur (S)   5.53   110.6   EPA 200.7       Calcium (Ca)   7.56   151.2   EPA 200.7       Magnesium (Mg)   1.46   29.2   EPA 200.7       Sodium (Na)   0.01   0.2   EPA 200.7       Copper (Cu)    6 ppm   0.01   EPA 200.7       Iron (Fe)   493 ppm   0.99   EPA 200.7       Manganese (Mn)   198 ppm   0.4   EPA 200.7       Zinc (Zn)   483 ppm   0.97   EPA 200.7       Moisture   15.2       EPA 160.3       Total Solids   84.8   1696   Wheatstone       Total Salts       331.8   EPA 120.1       pH   6.2       EPA 150.1       Ash   30.5       Calc.       Phosphate Available (P 2 O 5 )   15.35       Calc.                  
 
      Sample 5: A sample of the phosphorous-rich precipitate was slurried in water to 33 D.S. and adjusted with sulfuric acid to pH 3.5. The slurry was hydrolyzed by heating to 100° C. until ion chromatographic analyses indicated &gt;85% PO 4  hydrolysis. The material was cooled to ambient temperature and pH adjusted to 7.0 with calcium hydroxide. The slurry was tray dried at 50° C. and ground to fine granular consistency. The chemical analyses, lbs/ton of fertilizer nutrients, and analytical methods for the resultant hydrolyzed, calcium hydroxide-adjusted precipitate are given in Table 6.  
               TABLE 6                          Hydrolyzed, calcium hydroxide-adjusted Precipitate (Sample 5)                             Sample 5   Analysis   Nutrients   Analysis       Parameters   wt %   lbs/ton   Method                                     Ammonium Nitrogen (N)   0.01   0   EPA 350.2       Organic Nitrogen (N)   1.64   32.8   EPA 350.2       Total Nitrogen (N)   1.65   33.1   EPA 351.3       Phosphorus (P 2 O 5 )   12.04   240.8   EPA 200.7       Potassium (K 2 O)   1.42   28.4   EPA 200.7       Sulfur (S)   4.4   88.1   EPA 200.7       Calcium (Ca)   17.19   343.8   EPA 200.7       Magnesium (Mg)   1.19   23.8   EPA 200.7       Sodium (Na)   0.01   0.2   EPA 200.7       Copper (Cu)    5 ppm   0.01   EPA 200.7       Iron (Fe)   429 ppm   0.86   EPA 200.7       Manganese (Mn)   152 ppm   0.3   EPA 200.7       Zinc (Zn)   365 ppm   0.73   EPA 200.7       Moisture   11.9       EPA 160.3       Total Solids   88.1   1762   Wheatstone       Total Salts       396.2   EPA 120.1       pH   9.1       EPA 150.1       Ash   52.2       Calc.       Phosphate Available (P 2 O 5 )   11.82       Calc.                  
 
     EXAMPLE III  
      An acid, southern Iowa soil was air-dried and three kilograms of soil were added to each of a number of clean plastic greenhouse pots. The soil from each pot was transferred to a mixer to which appropriate amounts of limestone and a phosphate source were added to reach a particular pH and phosphorous content. Each pot contained either no additional phosphate source or one of seven different phosphate sources: di-ammonium phosphate (DAP), a commercially available 18-46-0 starter fertilizer, and Samples 1-5 from Example II above. After mixing, the treated soil was returned to its pot. four corn seeds were planted in each pot, and water was applied to achieve field capacity. After emergence, only two plants were kept in each pot. After nine weeks, the plants were harvested by cutting the stalks at one-half inch above the soil. Harvested plants were placed in paper bags, weighted and dried at 65° C. until constant weight was achieved. Dried plants and bags were weighed and the plant material was ground. Empty bags were weighed to enable determination of fresh and dried plant yields. Microwave digestion procedures were used to prepare plant samples for elemental analysis and total nitrogen was determined by dry combustion in a LECO CHN analyzer.  
      Corn germinated, grew and developed normally throughout the study with byproduct and fertilizer treated soils producing the greater growth than the check treatment. Tables 7 and, 8 present dry matter yield and compositional analysis and uptake of nutrients by the corn plants. A two-factor variance analysis showed that there were statistically significant differences (p-values less than 0.01) between the phosphorous sources in dry matter yield and in the corn contents of phosphorus, potassium, copper, iron, magnesium, and zinc. Treatment of the soil with limestone significantly altered corn magnesium and manganese contents; manganese uptake is greater in acid soils than near neutral soils.  
               TABLE 7                          Corn plant yield and tissue analysis.                                                                         Fresh wt.   Dry wt.   Total N   P   K   Al   Ca   Cu   Fe   Mg   Mn   Na   Zn                                         Source   Liming   grams   %   ppm   %   ppm                                                                                 No fertilizer   No lime   87   13.8   0.929   680   2.50   54   3,929   27   45   2,788   83   16   40       added   pH 6.5   106   17.4   0.956   887   2.26   67   5,158   20   76   3,201   30   18   41           pH 6.9   114   18.5   0.859   853   1.99   31   5,437   17   50   3,128   36   18   45       18-46-0 fertilizer   No lime   185   43.3   0.525   1,449   1.59   63   3,631   23   43   2,433   101   25   26       added   pH 6.5   173   33.3   0.694   1,656   1.45   25   3,399   12   24   2,776   28   14   24           pH 6.9   210   44.0   0.704   1,587   1.29   24   4,358   11   24   3,103   34   16   25       Sample 1   No lime   239   49.5   0.483   2,002   1.38   41   3,125   13   22   2,369   80   17   25       added   pH 6.5   236   53.5   0.670   2,156   1.45   32   3,857   11   41   2,796   24   17   25           pH 6.9   255   55.5   0.677   2,118   1.31   31   3,963   19   44   2,921   22   13   23       Sample 2   No lime   209   49.3   0.554   1,265   1.55   49   3,426   17   40   2,383   100   19   26       added   pH 6.5   248   53.2   0.654   1,350   1.45   31   3,780   12   21   2,684   26   14   23       Sample 3   No lime   300   79.9   0.851   1,837   1.13   149   5,942   9   71   3,516   71   14   28       added   pH 6.5   269   82.4   0.526   1,843   1.00   33   4,325   11   79   3,884   45   11   29           pH 6.9   295   79.3   0.999   1,910   1.11   27   4,834   6   78   3,964   23   14   49       Sample 4   No lime   190   35.5   0.506   1,571   1.66   48   3,734   15   25   2,459   96   12   32       added   pH 6.5   203   37.3   0.659   1,667   1.44   43   4,290   10   23   2,841   35   56   66           pH 6.9   217   39.3   0.737   1,772   1.35   9   3,971   6   18   2,904   26   9   30       Sample 5   No lime   254   51.8   0.492   1,146   1.23   31   3,230   9   20   2,251   69   12   44       added   pH 6.5   233   45.0   0.529   1,532   1.28   24   3,444   14   22   2,442   22   12   20           pH 6.9   220   52.3   0.548   1,540   1.19   13   3,907   6   19   2,590   27   13   24                 Italics indicate missed byproduct treatment             
 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                   
               
               
                 Corn nutrient and trace-element uptake. 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Dry wt. 
                 Total N 
                 P 
                 Ca 
                 Mg 
                 K 
                 Al 
                 Cu 
                 Fe 
                 Mn 
                 Na 
                 Zn 
               
            
           
           
               
               
               
               
               
            
               
                 Source 
                 Lime trt. 
                 grams 
                 milligrams 
                 micrograms 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 No fertilizer 
                 No lime 
                 11.4 
                 127 
                 9 
                 54 
                 38 
                 341 
                 732 
                 384 
                 630 
                 1,140 
                 225 
                 552 
               
               
                 added 
                 pH 6.5 
                 10.2 
                 153 
                 16 
                 79 
                 52 
                 346 
                 926 
                 321 
                 1,089 
                 462 
                 289 
                 647 
               
               
                   
                 pH 6.9 
                 18.6 
                 165 
                 16 
                 100 
                 58 
                 367 
                 577 
                 306 
                 917 
                 672 
                 329 
                 841 
               
               
                 18-46-0 starter 
                 No lime 
                 53.0 
                 226 
                 60 
                 155 
                 104 
                 668 
                 2,676 
                 957 
                 1,789 
                 4,286 
                 1,005 
                 1,098 
               
               
                 fertilizer added 
                 pH 6.5 
                 41.1 
                 227 
                 54 
                 111 
                 91 
                 469 
                 824 
                 372 
                 780 
                 905 
                 480 
                 779 
               
               
                   
                 pH 6.9 
                 57.1 
                 305 
                 66 
                 193 
                 136 
                 551 
                 1,123 
                 481 
                 1,022 
                 1,501 
                 654 
                 1,062 
               
               
                 Sample 1 added 
                 No lime 
                 44.1 
                 238 
                 99 
                 154 
                 117 
                 678 
                 2,022 
                 653 
                 1,117 
                 3,939 
                 865 
                 1,225 
               
               
                   
                 pH 6.5 
                 58.3 
                 351 
                 112 
                 208 
                 151 
                 763 
                 1,853 
                 602 
                 2,358 
                 1,264 
                 862 
                 1,411 
               
               
                   
                 pH 6.9 
                 53.6 
                 371 
                 116 
                 222 
                 162 
                 723 
                 1,622 
                 1,207 
                 2,552 
                 1,207 
                 726 
                 1,275 
               
               
                 Sample 2 added 
                 No lime 
                 58.0 
                 273 
                 62 
                 166 
                 116 
                 753 
                 2,396 
                 789 
                 1,952 
                 4,819 
                 921 
                 1,296 
               
               
                   
                 pH 6.5 
                 53.2 
                 348 
                 72 
                 201 
                 143 
                 774 
                 1,667 
                 631 
                 1,143 
                 1,381 
                 747 
                 1,221 
               
               
                   
                 
                   pH 6.9 
                 
                 
                   26.7 
                 
                 
                   238 
                 
                 
                   20 
                 
                 
                   106 
                 
                 
                   67 
                 
                 
                   389 
                 
                 
                   372 
                 
                 
                   233 
                 
                 
                   802 
                 
                 
                   611 
                 
                 
                   151 
                 
                 
                   669 
                 
               
               
                 Sample 3 added 
                 No lime 
                 101.9 
                 553 
                 127 
                 342 
                 267 
                 733 
                 7,566 
                 668 
                 6,011 
                 6,546 
                 831 
                 2,086 
               
               
                   
                 pH 6.5 
                 88.5 
                 506 
                 137 
                 330 
                 306 
                 763 
                 2,664 
                 904 
                 6,913 
                 4,310 
                 896 
                 2,286 
               
               
                   
                 pH 6.9 
                 87.5 
                 779 
                 149 
                 384 
                 313 
                 869 
                 2,166 
                 455 
                 6,245 
                 1,826 
                 1,122 
                 3,752 
               
               
                 Sample 4 added 
                 No lime 
                 32.8 
                 181 
                 56 
                 133 
                 87 
                 589 
                 1,700 
                 530 
                 907 
                 3,419 
                 423 
                 1,135 
               
               
                   
                 pH 6.5 
                 33.7 
                 247 
                 63 
                 161 
                 107 
                 542 
                 1,532 
                 381 
                 844 
                 1,323 
                 1,922 
                 2,348 
               
               
                   
                 pH 6.9 
                 31.2 
                 293 
                 69 
                 156 
                 114 
                 526 
                 357 
                 245 
                 707 
                 1,008 
                 371 
                 1,127 
               
               
                 Sample 5 added 
                 No lime 
                 58.0 
                 251 
                 61 
                 167 
                 116 
                 639 
                 1,545 
                 437 
                 978 
                 3,700 
                 627 
                 2,377 
               
               
                   
                 pH 6.5 
                 45.0 
                 238 
                 69 
                 155 
                 110 
                 575 
                 1,100 
                 621 
                 974 
                 984 
                 545 
                 888 
               
               
                   
                 pH 6.9 
                 37.5 
                 280 
                 80 
                 208 
                 138 
                 617 
                 768 
                 356 
                 1,093 
                 1,330 
                 674 
                 1,269 
               
               
                   
               
               
                   Italics indicate missed byproduct treatment    
               
            
           
         
       
     
      Although Sample 3 had been treated with ammonia, an analysis of ammonium content by KCl displacement yielded values less those measured for the other samples. This suggests that ammonium ions are held in the byproduct complex more strongly than ammonium ions held on the soil exchange complex.  
       FIG. 2  illustrates the phosphorous content of the phosphorous sources (stated as weight percent) and the percentage phosphorous uptake in the plants in each of the pots. As evident from  FIG. 2 , Samples 3 and 4 yielded excellent phosphorous uptake results. This, combined with the nitrogen content of Samples 3 and 4, suggests that they would make excellent starter fertilizers or components thereof.  
      Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in a sense of “including, but not limited to.” Words using the singular or plural number also include the plural or singular number, respectively. When the claims use the word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.  
      The above-detailed descriptions of embodiments of the invention are not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, whereas steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein can be combined to provide further embodiments.  
      In general, the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification, unless the above-detailed description explicitly defines such terms. While certain aspects of the invention are presented below in certain claim forms, the inventors contemplate the various aspects of the invention in any number of claim forms. Accordingly, the inventors reserve the right to add additional claims after filing the application to pursue such additional claim forms for other aspects of the invention.