FERTILIZERS
These are commercially produced plant nutrients. Fertilizers increase the fertility of soil by supplying Nitrogen, Phosphorus, Potassium and other nutrients. These are used to ensure good vegetative growth giving rise to healthy Plants.
TYPES OF FERTILIZERS
Fertilizers are of following types:
1- NITROGENOUS FERTILIZERS- These are obtained from Ammonia and its derivatives. e.g., Ammonium sulphate, Calcium ammonium nitrate, basic calcium nitrate, calcium cynamide(nitrolim), urea, etc.
Ammonium sulphate [(NH4)2SO4] contains 25% ammonia which is transformed into the nitrate by denitrifying bacteria present in the alkaline soil. the nitrates are easily absorbed by crop plants.
In calcium ammonium nitrate [Ca(NO3)2NH4NO3], the amount of nitrogen is about 20% which is directly absorbed by plants. Because of its higher solubility, it has no adverse effect on the soil.
Urea (NH2CONH2) contains nearly 46% nitrogen and it does not affect the pH of soil. It is the extensively used nitrogenous fertilizer.
2- PHOSPHATIC FERTILIZERS- These are superphosphate of lime, triple superphosphate(obtained from bone ash) and Thomas slag or Phosphatic slag. Potassium chloride, potassium nitrate and potassium sulphate, etc are also included in this category. Superphosphate of lime is a mixture of calcium dihydrogen phosphate and gypsum. In this fertilizer, 16-20% P2O5 exists. Thomas slag contains 14-18% of P2O5. It is a by-product of steel industry because of its higher solubility, it is easily assimilated by plants.
3- NP FERTILIZERS- Dihydrogen ammoniated phosphate is an example of NP fertilizer because it supplies nitrogen and phosphorus to the soil.
4- NPK FERTILIZER- They supply nitrogen, phosphorus and potassium to the soil. They are also known as Mixed fertilizers. Urea is prepared by heating carbon dioxide with ammonia at 125-150 0C and 8.5 atmospheric pressure. This fertilizer is never bought in direct contact of seed. After using the fertilizer water is supplied 3-4 days later.
CO2 + NH3 ———–> NH2CONH2 (Urea)
EXPLOSIVES
These are the substances which on combustion produce extreme heat and energy with a strong cracking sound. They consists of pure compound like TNT or a mixture of fuel and an oxidiser. Explosives can be classified as primary explosives, secondary explosives and tertiary explosives. Some of the explosives are given below:
TRINITROGLYCERINE (TNG) C3H5N3O9
It is also called Noble’s oil and prepared by mixing conc. H2SO4 and conc. HNO3 in glycerine. So, it is an ester. It is a colourless oily liquid used in making dynamite, invented in 1846.
TRINITROTOLUENE (TNT) C7H5N3O6
It is prepared by the reaction of toluene with nitrating mixture (conc. H2SO4 and conc. HNO3). It is frequently used as explosive.
RESEARCH AND DEVELOPMENT EXPLOSIVE (RDX) C3H6N6O6
Chemically it is cyclo-trimethylene trinitramine. It is also known as Cyclonite in USA, Hexogen in Germany and T4 in Italy. It was invented by Henning in 1899. It is also called plastic exploser.
It is a very powerful explosive and can be used pure or in plastic explosives. When plastic substances like Polybutenic acrylic acid is added to RDX, it is called Plastic Bonded Explosive (PBE). The explosion energy in normal RDX is nearly 1510 Kcal. When some aluminium powder is added to RDX, explosive C-4 is obtained which is deadly destructor (cracker).
TRINITROPHENOL (TNP) C6H3N3O7
It is prepared by the reaction of phenol with conc. H2SO4 and conc. HNO3 . It is also called Picric acid.
DYNAMITE
It was invented by Swedish chemist and engineer Alfred Nobel in 1863. It consists of three parts nitroglycerin, one part diatomaceous earth (Kieseiguhr) and a small mixture of sodium carbonate. It is used in blast purposes inn mines.
POINTS TO REMEMBER
- Gun Powder is a mixture of nitrate, sulphur and charcoal.
- At present, in making dynamite in place of nitroglycerine, sodium nitrate or ammonium nitrate and wood pulp are used.
- Calcium nitrate, a nitrogenous fertilizer is also called Norwegian Saltpeter.
- Nitrolim is a mixture of Ca(CN)2 and carbon. It is used before introducing seeds into the soil.
- Reactive component of superphosphate of lime is calcium dihydrogen phosphate which is soluble in water.
- Basic calcium nitrate and ammonium sulphate increase the acidity of soil which is removed by adding lime to the soil.