With today's emphasis on higher crop yields, there is an increased need for calcium, magnesium and sulfur. These nutrients are vital to plant growth and development. They are three of the 17 essential plant nutrients.
Fertilizer urea Introduction
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.
Fertilizer urea
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 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 (urea)
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.

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.
Fluid urea
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 Banana and Plantain in the dry months, 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 vegetables. Urea is highly water soluble. 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 storage
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.

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 lb. on dry soils, 20 lb. when soil is moist.
• Apply urea on sod crops when atmosphere 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.

4R Nutrient Stewardship provides a framework to achieve cropping system goals, such as increased production, increased farmer profitability, enhanced environmental protection and improved sustainability.
To achieve those goals, the 4R concept incorporates the:
• Right fertilizer source at the
• Right rate, at the
• Right time and in the
• Right place
Properly managed fertilizers support cropping systems that provide economic, social and environmental benefits. On the other hand, poorly managed nutrient applications can decrease profitability and increase nutrient losses, potentially degrading water and air.
4R nutrient stewardship requires the implementation of best management practices (BMPs) that optimize the efficiency of fertilizer use. The goal of fertilizer BMPs is to match nutrient supply with crop requirements and to minimize nutrient losses from fields. Selection of BMPs varies by location, and those chosen for a given farm are dependent on local soil and climatic conditions, crop, management conditions and other site specific factors.
Other agronomic and conservation practices, such as no-till farming and the use of cover crops, play a valuable role in supporting 4R nutrient stewardship. As a result, fertilizer BMPs are most effective when applied with other agronomic and conservation practices.

Diammonium phosphate (DAP) is the world’s most widely used phosphorus fertilizer. It’s made from two common constituents in the fertilizer industry, and its relatively high nutrient content and excellent physical properties make it a popular choice in farming and other industries.

Production

Ammonium phosphate fertilizers first became available in the 1960s, and DAP rapidly became the most popular in this class of products. It’s formulated in a controlled reaction of phosphoric acid with ammonia, where the hot slurry is then cooled, granulated and sieved. DAP handles and stores well. The standard nutrient grade of DAP is relatively high, at 18-46-0, so fertilizer products with lower nutrient content may not be labeled DAP.

The inputs required to produce one ton of DAP fertilizer are approximately 1.5 to 2 tons of phosphate rock, 0.4 tons of sulfur (S) to dissolve the rock, and 0.2 tons of ammonia. Changes in the supply or price of any of these inputs will impact DAP prices and availability. The high nutrient content of DAP helps reduce handling, freight and application costs. DAP is produced in many locations in the world and is a widely traded fertilizer commodity.

Agricultural use
DAP fertilizer is an excellent source of P and nitrogen (N) for plant nutrition. It’s highly soluble and thus dissolves quickly in soil to release plant-available phosphate and ammonium. A notable property of DAP is the alkaline pH that develops around the dissolving granule.

As dissolving DAP granules release ammonium, the seedlings and plant roots nearest the volatile ammonia can be harmed. This potential damage more commonly occurs when the soil pH is greater than 7, a condition that often exists around the dissolving DAP granule. To prevent such damage, users should avoid placing high concentrations of DAP near germinating seeds.

The ammonium present in DAP is an excellent N source and will be gradually converted to nitrate by soil bacteria, resulting in a subsequent drop in pH. Therefore, the rise in soil pH surrounding DAP granules is a temporary effect. This initial rise in soil pH neighboring DAP can influence the micro-site reactions of phosphate and soil organic matter.

Management practices

Differences in the initial chemical reaction between various commercial P fertilizers in soil become minor over time (within weeks or months) and are minimal as far as plant nutrition is concerned. Most field comparisons between DAP and monoammonium phosphate (MAP) show only minor or no differences in plant growth and yield due to P source with proper management.

Non-agricultural uses

DAP also acts as a fire retardant. For example, a mixture of DAP and other ingredients can be spread in advance of a fire to prevent a forest from burning. It then becomes a nutrient source after the danger of fire has passed. DAP is used in various industrial processes, too, such as metal finishing. And, it’s commonly added to wine to sustain yeast fermentation and to milk to produce cheese cultures.

So, where exactly can one buy DAP?
E.g. in Ibadan, Oyo State?

We only have outlet in Asaba Delta state

hi am actually a new fish in the river and a soon to be a plantain farmer. but I have a question, pls can saw dust mixed together with the soil form as organic fertilizer for a period of year running?
I know poultry wasted, animal dunk are the best but due to low capital I intended to switch to saw dust..
can it actually work?

REFER AND WIN AT CROPLAND AGRO INDUSTRIAL PARK