Dry Blend Bulk Fertilizer
Ask the Agronomist
"Time for Some Fertilizer Math..." http://www.uwex.edu/ces/crops/FertMath.htm
0-0-60 POTASH Potash fertilizer is used by growers all over the world. It keeps plants healthy by allowing nutrients and sugars to move throughout the plant, helping to keep it stress and disease free. Potash fertilizer is therefore an essential ingredient in producing good crops.
Using a potassium fertilizer such as potash helps to increase the use of other nutrients in the plant and promotes root growth. It also helps to cope with drought situations and increases the plant's ability to survive in frosty conditions. In agriculture, potash fertilizers help grains to increase the protein oil and vitamin C in their harvest, and gives food a better color and flavor.
1. Is an ideal combination of N and P2O5 for use as a starter fertilizer on small grains, row crops, tree crops and forages.
2. Chemically compounded N and P2O5. The ammonium phosphate combination in each pellet enhances the uptake of
phosphorus by the plant. The highly water soluble phosphate goes to work quickly allowing efficient utilization by
plants. The ammonic form of nitrogen reduces nitrogen losses by leaching.
3. Works well in acid or alkaline, calcareous or non-calcareous soils.
4. For specific crop recommendations, see your local distributor.
1. Is well adapted to a wide range of application methods–preplant broadcast, banded at planting time, drilled with
small grains at seeding time, sidedressed, or broadcast on pasture or alfalfa stubble.
2. An excellent product for use as a base in dry blends because of its N:P ratio and its uniform pellet size.
3. Has uniform pellet size: free flowing, blends well, spreads evenly, dust free, resists crusting and bridging in storage
ENHANCED MAP with AVAIL
EFFECT OF AVAIL ON CORN PRODUCTION IN MINNESOTA
Gyles Randall and Jeff Vetsch1/
Monoammonium phosphate (MAP) a fertilizer that has been coated with a "shield" that surrounds the fertilizer granules are commonly referred to by the fertilizer name AVAIL. The purpose of this coating, which expands when applied to the soil, is to block the elements (Fe, Al, Ca, and Mg) in the soil that fix P. The goal is to provide enhanced nutrient availability making more of the fertilizer P available to the plants root systems all season long and the opportunity for higher yields and increased profit (Source—www.specialityfertilizer.com). The objective of this study was to evaluate the performance of AVAIL (coated DAP and MAP fertilizers) compared to conventional DAP and MAP on corn production in southern Minnesota.
Experiments were conducted on fine-textured glacial till soils at the Southern Research and Outreach Center, Waseca, MN in 2002, 2003, and 2004. All experimental procedures are presented in Table 1. In 2002 and 2004, the experiments were located on calcareous Canisteo soils that had low levels of Olsen extractable P. The site in 2003 was located on a Webster soil, which is very closely associated with the Canisteo soils, but does not have a calcareous surface soil. Exchangeable K was high to very high each year; thus, fertilizer K was not applied. Recommended rates of N as urea were applied each year. In 2004, an additional 30 lb N/A as UAN was applied sidedress because of excessive late May and early June rainfall. The conventional and coated forms of DAP and MAP and the urea were broadcast applied in late April. The experimental site was field cultivated once on the same day to incorporate the treatments. Corn was planted at high populations within a couple of days. Excellent weed control, high populations, and adequate rainfall provided high-yield conditions where yield responses to fertilizer P were expected. The P treatments, including rates, sources, and method of application, varied each year. However, the granular AVAIL fertilizer (DAP in 2002 and 2003 and MAP in 2004) was provided by Specialty Fertilizer Products each year. In 2002, we mixed the appropriate amount of AVAIL product with the 7-21-7 before applying in a 2 x 2 starter band.
Results and Discussion
Corn grain yields were increased over the zero-P control by about 17 bu/A with broadcast-applied DAP and about 37 bu/A with the AVAIL (coated DAP) in 2002 (Table 2). The 20 bu/A advantage for broadcast AVAIL compared to conventional DAP was considerably different compared to applying AVAIL with the 2" x 2" starter. When applied with 8 gal/A of 7-21-7, the treatments containing 2 or 4% AVAIL (coated DAP) reduced yields about 15 bu/A compared to 7-21-7 without AVAIL. Thus, Broadcast-applied AVAIL produced corn yields about 30 bu/A greater than the 2" x 2" starter-applied AVAIL. At this time, we have no explanation for the poor performance of the starter treatments. Plant stands were not affected, and no visible indicators of phytotoxicity were observed.
1/ Soil Scientist and Professor and Assistant Scientist, respectively, Southern Research and Outreach Center, Univ. of Minnesota. Waseca, MN 56093.
21-0-0-24S AMMONIUM SULFATE is used to correct or prevent a sulfur deficiency. In the soil, this material's ammonium ions are converted to nitrate by soil bacteria.
Curtis J. Overdahl, George W. Rehm and Harvey L. Meredith
In the past decade urea has surpassed and nearly replaced ammonium nitrate as a fertilizer. This has brought about new questions on urea and its use.
Urea, a white crystalline solid containing 46% nitrogen, is widely used in the agricultural industry as an animal feed additive and fertilizer Here we discuss it only as a nitrogen fertilizer.
Physical Forms of Urea
Commercially, fertilizer urea can be purchased as prills or as a granulated material. In the past, it was usually produced by dropping liquid urea from a "prilling tower" while drying the product. The prills formed a smaller and softer substance than other materials commonly used in fertilizer blends. Today, though, considerable urea is manufactured as granules. Granules are larger, harder, and more resistant to moisture. As a result, granulated urea has become a more suitable material for fertilizer blends.
Advantages of Fertilizer Urea
- Urea can be applied to soil as a solid or solution or to certain crops as a foliar spray.
- Urea usage involves little or no fire or explosion hazard.
- Urea's high analysis, 46% N, helps reduce handling, storage and transportation costs over other dry N forms.
- Urea manufacture releases few pollutants to the environment.
- Urea, when properly applied, results in crop yield increases equal to other forms of nitrogen.
Incorporate Urea for Best Use
Nitrogen from urea can be lost to the atmosphere if fertilizer urea remains on the soil surface for extended periods of time during warm weather. The key to the most efficient use of urea is to incorporate it into the soil during a tillage operation. It may also be blended into the soil with irrigation water. A rainfall of as little as 0.25 inches is sufficient to blend urea into the soil to a depth at which ammonia losses will not occur.
Urea Losses to the Air
Urea breakdown begins as soon as it is applied to the soil. If the soil is totally dry, no reaction happens. But with the enzyme urease, plus any small amount of soil moisture, urea normally hydrolizes and converts to ammonium and carbon dioxide. This can occur in 2 to 4 days and happens quicker on high pH soils. Unless it rains, urea must be incorporated during this time to avoid ammonia loss. Losses might be quite low in the spring if the soil temperature is cold. The chemical reaction is as follows:
CO(NH2)2 + H2O + urease 2NH3 +CO2
The problem is the NH3, because it's a gas, but if incorporated the NH3, acts the same as incorporated anhydrous ammonia. Also, half of 28% liquid N is urea and the same thing happens with this half as with regular urea.
Urea Losses Related to Soil Temperature and pH
The volatility of urea depends to a great extent on soil temperature and soil pH. Tables 1 and 2 show that after a few days warm temperatures or high pH would cause losses.
|Table 1. Percent of surface-added urea volatilized as ammonia at different temperatures and days on the surface. |
| ||Temperature (F) |
|Days ||45 degrees ||60 degrees ||75 degrees ||90 degrees |
| ||(% of added N volatilized) |
|0 ||0 ||0 ||0 ||0 |
|2 ||0 ||0 ||1 ||2 |
|4 ||2 ||2 ||4 ||5 |
|6 ||5 ||6 ||7 ||10 |
|8 ||5 ||7 ||12 ||19 |
|10 ||6 ||10 ||14 ||20 |
|Data abstracted from curves in SSSP 24, pages 87-90, 1960. Urea was added on a silt loam soil at 100 lbs N. |
|Table 2. Percent of surface-added urea volatilized as ammonia at various soil pH levels and days on the surface. |
| ||Soil pH |
|Days ||5.0 ||5.5 ||6.0 ||6.5 ||7.0 ||7.5 |
| ||(% of added N volatilized) |
|0 ||0 ||0 ||0 ||0 ||0 ||0 |
|2 ||0 ||0 ||0 ||0 ||1 ||5 |
|4 ||1 ||2 ||5 ||10 ||18 ||20 |
|6 ||4 ||5 ||7 ||11 ||23 ||30 |
|8 ||8 ||9 ||12 ||18 ||30 ||33 |
|10 ||8 ||10 ||13 ||22 ||40 ||44 |
|Data from SSSP 24, pages 87-90, 1960. Urea added on silt loam soil at 100 lb. N. |
Fall Application Comparisons
Urea can be readily nitrified—that is, converted to nitrate (NO3)— even when applied late in the fall, and can be quite susceptible to denitrification or leaching the following spring. Anhydrous ammonia (AA) applied in the fall does not nitrify as quickly, due to the stunting of microorganisms in the AA application band.
A two-year study conducted at Waseca compared late-October applications of both AA and urea for continuous corn (Table 3). These data show a 6 bu/A advantage for AA over urea when applied in the fall without a nitrification inhibitor. But when N-Serve was added, a 16 bu/A advantage was shown with AA. This indicates that the inhibitor has a better degree of contact with the AA mix than is possible with urea.
|Table 3. Corn yield as influenced by N source, time of application, and nitrification inhibitor at Waseca. |
| || ||1981 - 82 Avg. || || |
|N Source * ||Fall ||Spring |
| ||- - - Yield (bu/A) - - - |
|AA (82% N) ||162 ||168 |
|AA + N-serve ||170 ||172 |
|Urea (45% N) ||156 ||164 |
|Urea + N-serve ||154 ||162 |
|*150 lb N/A ||Malzer & Randall |
Studies with continuous use of urea have been conducted at Lamberton since 1960. Corn yields over a 24-year period averaged 5 to 6 bushels per acre higher with spring application of urea compared to the fall plowed-down application (Table 4).
|Table 4. Corn yield as influenced by fall and spring applications of urea at Lamberton. |
| ||Time/method of Urea Application* ||24-year |
| ||bu/A |
|Fall, plowed-down ||97 |
|Spring, top-dressed ||102 |
|Spring, side-dressed ||103 |
| || |
|* 80 lb N/A || |
Urea applied in the fall has generally not been as effective as AA. This is especially true in south-central Minnesota and Iowa. When fall soil-moisture conditions are dry, there is little difference between AA and urea. But when soil-moisture content is high, fall applications of urea haven't performed as well as AA. Applications of urea-ammonium nitrate (UAN) in the fall are not recommended due to rapid nitrification and a high potential for loss.
Soil Application and Placement of Urea
If properly applied, urea and fertilizers containing urea are excellent sources of nitrogen for crop production.
After application to the soil, urea undergoes chemical changes and ammonium (NH4 +) ions form. Soil moisture determines how rapidly this conversion takes place.
When a urea particle dissolves, the area around it becomes a zone of high pH and ammonia concentration. This zone can be quite toxic for a few hours. Seed and seedling roots within this zone can be killed by the free ammonia that has formed. Fortunately, this toxic zone becomes neutralized in most soils as the ammonia converts to ammonium. Usually it's just a few days before plants can effectively use the nitrogen.
Although urea imparts an alkaline reaction when first applied to the soil, the net effect is to produce an acid reaction.
Urea or materials containing urea should, in general, be broadcast and immediately incorporated into the soil. Urea-based fertilizer applied in a band should be separated from the seed by at least two inches of soil. Under no circumstances should urea or urea-based fertilizer be seed-placed with corn.
With small grains, 10 lb. of nitrogen as urea can generally be applied with the grain drill at seeding time even under dry conditions. Under good moisture conditions, 20 lb. of nitrogen as urea can be applied with the grain drill. Research results at North Dakota State University indicate that under dry conditions, urea at the rate of more than 20 lb. nitrogen per acre, applied with a grain drill in a 6-inch spacing, can reduce wheat stands more than 50% (Table 5) Research at the University of Wisconsin indicates that seed-placed urea with corn, even at low rates of nitrogen, is very toxic to the seed and greatly reduces yields (Table 6). When urea was side-placed as a 2" x 2" starter, however, little if any damage was noted (Table 7).
In Minnesota, good crop production usually requires an application of more than 20 lb. of nitrogen per acre. Farmers can avoid damage from urea by broadcasting most of the urea nitrogen fertilizer ahead of seeding. Data in Table 8 indicate that urea broadcast prior to seeding is equal to or more effective than similar ammonium nitrate treatments.
|Table 5. Seed-placed ammonium nitrate (AN) and urea comparisons on seedling damage to spring wheat under limited moisture conditions. North Dakota, 1975. |
|TREATMENTS ||Seedlings per 40 ft. of Row |
|Absaraka ||Williston ||Casselton |
|0 ||- ||600 ||270 ||760 |
|20 ||AN ||570 ||220 ||600 |
|30 ||AN ||590 ||240 ||690 |
|40 ||AN ||590 ||260 ||660 |
|20 ||Urea ||400 ||200 ||550 |
|30 ||Urea ||280 ||110 ||430 |
|40 ||Urea ||220 ||70 ||220 |
|Source: Dahnke, North Dakota State University, 1975. |
|Table 6. Effect of urea and ammonium nitrate placed with seed on corn grain yield. Wisconsin, 1973. |
| ||Yield, bu/A |
|lb. N/A* ||Urea ||Ammonium Nitrate |
|0 ||137 ||137 |
|5 ||60 ||142 |
|10 ||36 ||143 |
|20 ||33 ||92 |
|* Sufficient N broadcast prior to planting. Source: Liegel & Walsh Plainfield Sand, Hancock, Wisconsin |
|Table 7. Effect of urea and ammonium nitrate side-placed on corn grain yield. Wisconsin, 1973. |
| ||Yield, bu/A |
|lb. N/A* ||Urea ||Ammonium Nitrate |
|0 ||142 ||142 |
|25 ||145 ||145 |
|50 ||146 ||146 |
|100 ||150 ||141 |
|*Sufficient N broadcast prior to planting. Source: Liegel & Walsh Plainfield Sand, Hancock, Wisconsin. |
|Table 8. Effect of source and placement of urea and ammonium nitrate (AN) on corn yields. Lamberton, Minnesota Experiment Station, 1960-84. |
|lb. N/A ||Treatment ||Source ||Av. Yield |
|0 ||— || ||62 |
|40 ||Plow-down—fall ||AN ||79 |
|40 ||Plow-down—fall ||Urea ||86 |
|40 ||Surface—fall ||AN ||82 |
|40 ||Surface—fall ||Urea ||85 |
|80 ||Plow-down—fall ||AN ||98 |
|80 ||Plow-down—fall ||Urea ||97 |
|160 ||Plow-down—fall ||AN ||104 |
|160 ||Plow-down—fall ||Urea ||105 |
|40 ||Topbress—spring ||AN ||89 |
|40 ||Topdress—spring ||Urea ||88 |
|80 ||Topdress—spring ||AN ||100 |
|80 ||Topdress—spring ||Urea ||102 |
|Source: MacGregor, Malzer and Nelson, University of Minnesota |
Spreading of Urea
Urea can be bulk-spread, either alone or blended with most other fertilizers. It is recommended that the spreading width not exceed 50 feet when combined with other fertilizer materials.
Urea often has a lower density than other fertilizers with which it is blended. This lack of "weight" produces a shorter "distance-of-throw" when the fertilizer is applied with spinner-type equipment. In extreme cases this will result in uneven crop growth and "wavy" or "streaky" fields.
Blending Urea with Other Fertilizers
Urea and fertilizers containing urea can be blended quite readily with monoammonium phosphate (11-52-0) or diammonium phosphate (18-46-0).
Urea should not be blended with superphosphates unless applied shortly after mixing. Urea will react with superphosphates, releasing water molecules and resulting in a damp material which is difficult to store and apply.
Uniformity of particle size is important with dry solid urea, whether applied directly or in blended formulations. Some imported urea appears to be below U.S. quality standards on granule uniformity. Dissolving urea and marketing the liquid solution is an attempt to overcome this lack of uniformity and still take advantage of the favorable urea price.
The liquid mix of urea and ammonium nitrate (UAN 28% N) has been on the market for a long time. The characteristics of this solution, however, are not the same as when urea alone is dissolved in water. A solution of 50% urea by weight results in 23-0-0 and has a salting-out temperature of 60 degrees F. In order to store and handle liquid urea during cooler temperatures, the nitrogen concentration must be lowered to reduce salting problems. There are several possible formulations that can be used for this, such as adding small amounts of ammonium nitrate, ammonium sulfate, or anhydrous ammonia.
Research, particularly on liquid urea, is very limited. Generally, where dry urea functions successfully, the fluid urea should perform equally well and may have the advantage of better uniformity over some dry urea sources.
Biuret in Urea
Biuret in urea can cause agronomic problems if placed near the seed. or even if added preplant in bands where seeds will later be planted.
Most U.S. manufacturers of urea keep biuret content low by keeping high temperatures to a minimum. Biuret content is typically around 0.3%, although urea of foreign origin appears to be higher.
High heat is normal during the manufacture of urea. If heat exceeds 200 degrees F there is a slight conversion of urea to biuret, but this takes place only during the manufacturing process. No such conversion happens in storage or in the soil.
Biuret converts to ammonia, but conversion is much slower than for urea. Since biuret remains in the soil for several weeks, the potential for seed damage continues beyond the brief period of conversion of urea to ammonia. The major damage of biuret is to germinating seeds. There is little damage through plant absorption, although some citrus crops have been affected.
Application of Urea to Growing Crops
Urea can be applied to sod crops, winter wheat. or other small grains. This application, however, should be made during cool seasons. During warm periods (60 degrees F or above), urea in contact with vegetative material will tend to give off ammonia.
If urea must be applied on grass pastures in the summer, apply when there is a high probability of rainfall.
Foliar Application of Urea
Urea can also be applied as a foliar spray on some crops, such as potatoes, wheat, vegetables, and soybeans. Urea is highly watersoluble. At normal atmospheric temperatures, approximately 1 lb. Of urea can be dissolved in 1 lb. of water.
Research data indicate that urea should contain no more than 0.25% biuret for use in foliar sprays. For many crops the quantity of nitrogen applied at one time should not exceed 20 lb. of nitrogen per acre.
Urea is neither combustible nor explosive. It can be stored safely with no loss of quality under normal circumstances. Small or fast-moving augers should not be used to move granular urea. Urea particles are generally soft and abrasion can break the granules. Belt conveyers should be used whenever possible.
Urea should not be stored with ammonium nitrate. These materials, when in contact, rapidly absorb water when the relative humidity is above 18%. Table 9 indicates the relative humidity at which urea and ammonium nitrate absorb moisture from the air.
|Table 9. Critical relative humidities (CRH) of urea, ammonium nitrate, and a mixture of the two. |
| ||Material ||CRH% || |
|Urea ||75.2 |
|Ammonium Nitrate (A.N.) ||59.4 |
|Urea + ammonium nitrate ||18.1 |
Slow Release Of Urea
Urea fertilizer can be coated with certain materials, such as sulfur, to reduce the rate at which the nitrogen becomes available to plants. Under certain conditions these slow-release materials result in more efficient use by growing plants. Urea in a slow-release form is popular for use on golf courses, parks, and other special lawn situations.
Urea Do's and Don'ts
- Store separately from ammonium nitrate.
- Do not use small, fast-moving augers to move the urea.
- Do not exceed a spreading width of 50 feet when urea is applied.
- Do not place in direct contact with corn seed.
- Keep rates of nitrogen applied together with small grain in drill to 10 1b. on dry soils, 20 lb. when soil is moist.
- Apply urea on sod crops when atmospheric temperature is below 60 degrees F.
- When urea is broadcast on soils of high pH (above 7.5), the material should be incorporated into the soil as soon as possible.
|Curtis J. Overdahl |
Extension Soils Specialist
|George W. Rehm |
Extension Soils Specialist
|Harvey L. Meredith |
Department of Soil Science
COLLEGE OF AGRICULTURE, FOOD, AND ENVIRONMENTAL SCIENCES
PROTECTED UREA with NUTRISPHERE
| |Remarkable Science for Remarkable Results
Where some nitrogen-fertilizer “enhancers” operate for hours or days by killing the spectrum of soil bacteria, NutriSphere-N® manages nitrogen fertilizer — protecting it —at the molecular level. It’s good science and good environmental stewardship.
NutriSphere-N works for you in three exclusive and important ways.
Pelletized lime can be used to stabilize soil pH, even in no-till.
One advantage to pelletized lime is that it can be blended with dry fertilizers.
The product costs more than ag lime, but neutralizes soil more quickly.
As farmers look to minimize trips across the field, one option may be to apply pelletized calcium — often called pelletized lime or pell lime — in conjunction with other dry fertilizers, effectively solving pH and fertility problems with one trip. High-quality pelletized calcium can be broadcast with a well-calibrated spreader, according to Cliff Snyder, southeast director of the Potash and Phosphate Institute. “That may not be the case with conventional ag lime, which may be too wet to be used with a spreader,” Snyder says. And, pelletized calcium often can be blended with dry potash and phosphate products, giving producers the benefi t of fertilizer and pH stabilization in one pass.
Pelletized calcium has another benefi t, Snyder suggests: It is a higher quality of fi nely ground calcium and can work to stabilize soil pH on contact. It does not, however, have long-term pH stabilizing ability. Thus, producers may have to apply pelletized lime very year or two — a practice which makes economic sense if producers rent land. “I’ve seen cases where folks have an acidity problem in the root zone, but they don’t want to apply a full rate of lime because they don’t know if they will be renting the ground long-term,” he says.
Without working the product into the soil, it takes several years for pelletized calcium to move through the soil to the root zone. Pell lime vs. ag lime “Pelletized lime is more of a pH stabilizer, not a modifi er,” says Roy Stephen, president and chief executive officer of Arise Research and Discovery, a Martinsville, Ill., fi rm that has conducted research on the product for several years. “We use the pelletized calcium as a nutrient feed, or fertilizer. That’s due to the distribution and fi neness of the grind. Once it breaks down, calcium is available to the soil immediately,” Stephen explains. “Ag limestone has various particle sizes. Some of it breaks down quickly and some doesn’t.”
One negative about pelletized calcium is that it must be applied annually, depending upon the crop rotation. “We put pelletized calcium on prior to planting soybeans,” Stephen adds. “Going into corn, we either bypass an application or put on just enough so that soil acidity does not progress.” Pelletized calcium and fi nely ground ag lime applied before planting helped increase soybean yields in a Purdue University/Farm Progress Bean Booster test plot.
Soybeans in the trials responded to the lime application the same year it was applied, says Tom Bechman, a Farm Progress editor. Lime and potash, Bechman notes, were broadcast on the surface. Pelletized lime was the only pH neutralizer applied during the first few years of the Bean Booster soybean plots; the cooperator added regular ag lime thereafter. Both products produced a 7-bushel-per-acre yield boost this year, Bechman says.
“Pelletized calcium can improve structure in no-till,” says Bechman. “But is it worth the extra cost?” At the test plots, pelletized calcium was applied at 300 pounds per acre and ag lime at 1 ton per acre. What matters is cost per acre, says Jeff Phillips, who coordinated the test plots. Be sure to price shop, using cost per equivalent amount of neutralizing power as your guide.
For more information about pelletized calcium, consult your experts at Riverdale Ag Service.
Alfalfa Starter (5-8-37-5S)
Alfalfa Top-Dress (6-8-36-5S-.3B)
0-0-55-5S-.25B (elemental Sulfur source)
0-0-40-5S-.3B (sulfate Sulfur source)
20-6-7-3S-PELL PASTURE SPECIAL
0-0-60 Potash (bagged)
46-0-0 Urea (bagged)
19-0-15-5S (bagged lawn fertilizer)
32% UAN Solution
Protected 32% UAN with NutriSphere