Fertilizer direct application

Table 21.2 lists all important direct application materials and their percentage of direct application fertilizers. Direct application use is increasing mainly because of anhydrous ammonia gas becoming popular. It can be pumped in 3-6 in. beneath the soil during plowing and is absorbed by the soil rapidly. Nitrogen solutions can also be applied in this manner (mixture of free ammonia, ammonium nitrate, urea, and water). 

Direct Application Rock. Finely ground phosphate rock has had limited use as a direct-appHcation fertilizer for many years. There have been widely varying results. Direct appHcation of phosphate rock worldwide amounts to about 8% of total fertilizer phosphate used, primarily in the former Soviet Union, France, Brazil, Sri Lanka, Malaysia, and Indonesia. The agronomic effectiveness of an apatitic rock depends not only on the fineness of the grind but also strongly on the innate reactivity of the rock and the acidity of the sod performance is better on more acid sods. Probably more than half of the potentially productive tropical sods are acidic, some with pH as low as 3.5—4.5. Certain phosphate rocks may thus become increasingly important as fertilizer in those areas. The International Fertilizer Development Center at Muscle Shoals, Alabama is active in researching this field (30). 

Table 11. Direct Application of Single-Nutrient Fertilizers vs Application in Mixtures...

CaNCN is used as a direct application fertilizer, weed killer, and cotton defoliant it is also used for producing cyanamide, dicyandiamide and melamine plastics. Production formerly exceeded 1.3 million tonnes pa, but this has fallen considerably in the last few years, particularly in the USA where the use of CaNCN as a nitrogenous fertilizer has been replaced by other materials. In 1990 most of the world s supply was made in Japan, Gennany and Canada. 

Ammonia is one of the most important inorganic chemicals, exceeded only by sulfuric acid and lime. This colorless gas has an irritating odor, and is very soluble in water, forming a weakly basic solution. Ammonia could be easily liquefied under pressure (liquid ammonia), and it is an important refrigerant. Anhydrous ammonia is a fertilizer by direct application to the soil. Ammonia is obtained by the reaction of hydrogen and atmospheric nitrogen, the synthesis gas for ammonia. The 1994 U.S. ammonia production was approximately 40 billion pounds (sixth highest volume chemical). 

Uses. Since 1947, 70 to 85% of the annual USA production of nitric acid has gone into the production of NH4 nitrate fertilizer, initially in the form of solid prills currently, increasing amounts have been supplied mixed with excess ammonia and/or urea as aqueous nitrogen solution for direct application to the soil. Some 15% is used in explsj (nitrates nitro compds), and about 10% is consumed by the chemical industry. As the red fuming acid or as nitrogen tetroxide, nitric acid is used extensively as the oxidizer in proplnts for rocketry. It is estimated that current USA capacity for nitric acid is in excess of 10 million tons (Refs 30, 34, 36 37)... 

Interest in phosphate rocks (PRs) as direct application fertilizer stems from the facts that... 

In spite of this, PRs are not widely used as direct application fertilizers. The reasons are ... 

Fertilizers may contain all three primary nutrients, in which case they are called mixed fertilizers, or they may contain only one active ingredient, called direct application fertilizers. Recently the ratio of direct application to mixed fertilizers is 60 40 in the U.S. Nitrogen and potash are consumed mainly from direct application fertilizers. Phosphate is applied mostly from mixed fertilizers. 

In addition to borax, which can be applied directly as a fertilizer, special borate products are manufactured for fertilizer use. These include granulated beads for blending with other common fertilizer products and soluble borates for application as liquid foliar sprays. Boron fertilizers are typically applied at a rate equivalent to about one to two pounds elemental boron per acre, depending on the specific crop and soil conditions. As with most fertilizers, excessive application can have adverse results. Borate fertilizers are phyotoxic at high levels and are sometimes used as non-selective herbicides. 

Excretion from treated animals is yet another source of APIs in the environment. The application of manure as fertilizer is the main source of such veterinary pharmaceuticals into the environment. These APIs can be washed into the surface water by rainfall either after the application of manure or after the direct application of pharmaceuticals on to animals (e.g. anti-parasites). 

AMMONIA. [CAS 7664-41-7]. Known since ancient Irmes. ammonia, NH3 has been commercially important for well over 100 years and has become tlie second largest chemical in terms of tonnage and the first chemical in value of production. The first practical plant of any magnitude was built ill 1913. Woildwide pioduction of NH as of the. early 1980s is estimated at 100 million metric tons per year or more, with the United States accounting for about 14% of the total production, A little over three-fourths of ammonia production iii tlie United States is used for fertilizer, of which nearly one-third is for direct application, An estimated 5.5% of ammonia production is based in the manufacture of fibers and plashes in termediates. 

Solid urea containing 0.8—2.0 wt% biuret is primarily used for direct application to the soil as a nitrogen-release fertilizer. Weak aqueous solutions of low biuret urea (0.3 wt% biuret max) are used as plant food applied to foliage spray. 

In 2002 it was estimated that anhydrous ammonia is produced in about 80 countries, and about 85% of all ammonia production is used to make nitrogen fertilizers. About 6% of the ammonia production is applied directly to the fields36. In the United States the distribution of ammonia use differs slightly from the worldwide uses. In the USA only 80% of the ammonia is used to make fertilizers, but 20% is used as a direct application fertilizer. Chemical intermediates (such as acrylonitrile and caprolactam) account for 19% of the ammonia use while the remaining 1% is used in pulp and paper, metals and refrigeration applications37. 

Another important aspect of the ammonia business is seasonality. The major end use for anhydrous ammonia (excluding production of downstream nitrogen products) is as a direct application fertilizer. The application season, particularly in Canada and the northern United States, is limited and significant storage capability is needed. As a result, it is normal to expect a plant to produce a downstream nitrogen product (such as urea) that is 1) easier to store and handle and 2) does not have such a limited application season. Industrial markets are normally nonseasonal57. 

Commercial grades of AN include solutions that contain about 83% AN and solid products. Both grades are used for direct fertilizer applications, or they are blended with other materials to form mixed solid and liquid fertilizers. High density, prilled AN is usually used for direct applications while other solid AN is mixed with phosphate and potash for multi-nutrient fertilizers. Solid AN has lost market share to urea because it has a lower nitrogen content (33-35% for AN vs. 45-46% for urea), plus it costs more per ton. In addition to direct application, AN solutions are mixed with urea to make nitrogen solution fertilizers240. 

Calcium cyanamide (CaNCN) is used as a direct-application fertilizer, weed killer, and cotton defoliant. It is also used to make cyanamide, dicyandiamide, and melamine plastics ... 

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