Even though ammonium nitrate is a highly beneficial fertilizer for the plants, it is still considered an unstable material with explosive hazard characteristics. Stabilized Ammonium Nitrate (SAN)
Stabilized Ammonium Nitrate (SAN) is a granular high-nitrogen fertilizer with 33% nitrogen (N) and 1% MgO. Along with phosphorus, it contains nitrogen in two forms to provide plants with a steady supply of nutrition during their whole growing period. The fertilizer contains readily-available, water-soluble forms of nitrates and phosphates. Simultaneously 50 percent of nitrogen exists in ammonium form. The compound’s chemical formula is NH4NO3. NO3 and NH4 are those forms of nitrogen that can be easily absorbed by the plant, provided some external factors convert the nitrogen into readily absorbable form.
The stabilization process
Ammonium nitrate by itself is relatively unstable. It is stabilized in crystallized mixture with addition of proportionate amount of boric acid or a salt like diammonium phosphate or ammonium sulfate, or both. This substantially reduces the physical sensitivity of the ammonium nitrate to II-IV and/ or III-IV crystal type transitions. It is also highly effective in reducing dust formation. Apart from improved physical stability, it also makes the compound harder and more resistant to caking and lower moisture sensitivity.
The fertilizer is made available in the market in the form of prills, granules and pellets. To prepare these, any dust or fines are separated from the product and reprocessed in the plant. To prill ammonium nitrate, its solution at 280 F. or above is sprayed in a prilling tower countercurrent to cooling air which solidifies the droplets into prills which are ultimately cooled to ambient temperature. The prills are dried with hot air.
The main properties of the stabilized compound due to which, it finds wide application as fertilizer and preferred over ammonium nitrate fertilizer are low risk granulated product, fire hazardous oxidizer, foreign mechanical impurities, high quality and efficient performance.
Varied uses of stabilized ammonium nitrate
The compound has various uses –
- The first and the foremost use of the compound are as a fertilizer. With high nitrogen content, it is a wonderful fertilizer for all types of crops and can be used as either spring, pre-planting or for top dressing application. A more stable compound than ammonium nitrate, it is additionally suitable both for straight application and blending.
- The compound is used to prepare nitrous oxide chemically.
- It find wide application in various industries like oil industry, gas industry, Civil engineering units, power metallurgy units, geology exploration units and wood fire extinguishing units.
Benefits of using stabilized ammonium nitrate fertilizer
The stabilized ammonium nitrate fertilizer is nothing but an improved and more efficient version of ammonium nitrate fertilizer. It offers several advantages like –
- It has extremely high content of nitrogen which is water soluble and thus easily available to plants. Nitrogen is a very fundamental and critical nutrient required by plants to grow. A major component of chlorophyll, it is essential for the plant to manufacture food. It is the nitrogen which can make any leafy vegetable appears greener as well as increases the plant’s ability to produce fruit. Thus a high nitrogen supplier fertilizer implies higher production and better profitability for the farmers.
- The fertilizer has two nitrogen sources. The readily available nitrogen is made available through the hydrolysis process. This nitrogen is dissolved in water and absorbed by the plant through its roots readily. The other nitrogen is made available in due course to the plant in due course only after nitration. However, due to stabilization, both the transformation gets suspended and thus the loss of nitrogen due to volatility, denitrification and leaching is arrested to a great extent. This results in the fertilizer becoming more effective for a longer period of time since the process of release of nitrogen is reduced by keeping the nitrogen in its ammonium form for a longer period of time.
- Once the efficiency of the nitrogen is increased, it results in lower cost per use due to high performance of the fertilizer. It also proves more economical as fewer applications are subsequently required.
- Another benefit of stabilized fertilizer is its versatility. It is not only highly effective as a component of dry granular fertilizer blends but also as a soluble nitrogen source for liquid application.
- The fertile is suitable for all types of crops and can be used throughout the year, be it spring, pre-planting or for top dressing application.
- Because of the fertilizer’s ability to provide balanced plant nutrition, it is excellent for basic, pre-sowing fertilization and feeding. The fertilizer is almost essential for later feeding of autumn crops under conditions of elevated temperatures and parching soil surface.
- Because the fertilizer has been stabilized, the risks of the dry weather conditions are reduced.
- The storage and handling of the fertilizer is lot easier owning to its stabilization.
- The fertilizer leaves no residue in the soils and thus do not damage the texture and characteristics of the soil.
Precautions while using and storing the fertilizer
Despite the stabilization, the intrinsic properties of ammonium nitrate are still present. Hence the following precautions must be adhered to –
- The material is still highly explosive. It forms a major ingredient of various important military explosives and has been involved in several fires and accidental explosions. Thus its handling, application and storing must be done with utmost precaution and all prescribed rules and precautionary measures followed to the core. Simple adherence to some basic rules makes the fertilizer quite safe.
- The fertilizer’s tendency to cake is greatly reduced but not eliminated. The major factor influencing it is the fertilizer’s hygroscopicity i.e. the property of absorbing moisture and high solubility. Hence during its storage and transportation, dry conditions must be maintained to prevent any untoward incidents. It is mandatory to use water resistant bags for their transportation and storing. Bags made of five or six plies of heavy kraft paper are asphalt laminated to make them water repellent. The bags should not be exposed to snow, rain etc or placed on damp floors.
- The bags of fertilizers which have been opened for use must be tightly reclosed each time it is opened for use. All torn bags must be promptly re-bagged. If any fertilizer has been spilt on the floor, it should be taken care of immediately and cleaned completely. Else, it may absorb moisture and become dangerous.
- The fertilizer may cake when subjected to intense pressure. Hence it’s best to pile just 6-8 bags of the fertilizer and maximum of 12 bags to prevent caking of the lower bags. Additionally heavy objects should not be placed on top of bags.
- It should always be stored in well ventilated rooms.
- The fertilizer should not be sprinkled on top of soil but well incorporated in the soil for maximum and the most effective results.
Nitrogen efficiency, value and versatility are the hallmark qualities of stabilized ammonium nitrate fertilizer which is highly appreciated and adorned by those connected to agriculture. The stabilized fertilizer gives any farmer the versatility he needs for optimal results with minimal applications. Compared to other fertilizers like sodium nitrate, it has less expectations of injury and fewer and simpler precautions are required.