Since the ancient times farmers have had to compensate nutrients in the soil when they grew crops.
In the past they spread animal manure and plant waste (green manure) on their fields. Subsequently, they began using MAN-MADE FERTILISERS.
The aims of fertilisers are:
1. enhancing plant growth
2. optimizing potential yields
FERTILISERS can be ORGANIC and INORGANIC. Both of them can be naturally-occurring compounds or man-made compounds through natural or chemical processes.
FERTILISERS are usually applied either through the soil or through foliar feeding.
Plants can absorb nutrients in a variety of ways, both through their roots and through portions of the plant that appear above the ground. In most cases, fertiliser is mixed into the soil from which the plant will extract what it needs with its roots system. There are also fertilisers that can be dissolved in water and applied to the above-ground portion of the plant.
Chemical fertilisers which contain only one nutrient are called STRAIGHTS
Chemical fertilisers which contain more than one substance are called COMPOUND or MIXED fertilisers.
Granular superphosphate , potassium chloride and anhydrous ammonia generally contain only one or two macronutrients.
Horticultural fertilisers often contain also micronutrients
Some inorganic fertilisers are called ISTANT RELEASE because they are water-soluble.
Other chemical fertilisers are called CONTROLLED RELEASE because they are relatively insoluble.
Fertilisers are applied depending on plant watering, growth rates, soil conditions, weather condition, soil temperature etc...
Many controlled-release fertilisers are applied every 3/6 months. Instant release fertilisers are applied at least every 1/2weeks.
ORGANIC FERTILISERS are made up of organic matter. They are environmental friendly. They are naturally-occurring organic fertilizers or naturally occurring minerals or manufaured organic fertilisers.
NATURALLY-OCCURRING FERTILISERS: manure, slurry, worm casting, peat, seaweed, guano, decomposing crop residue (green manure).
NATURALLY-OCCURRING MINERALS: Rock phosphate, sulphate of potash, limestone.
MANUFACTURED ORGANIC FERTILISERS: dried blood, bone meal, seaweed extract.
ADVANTAGES OF ORGANIC FERTILISERS
1) LOWER OPERATING COSTS -they are often produced on-site by farmers themselves.
2) NO LONG TERM PROBLEMS as burning plants, damages in the soil structure or texture and reduced soil impermeability.
DISADVANTAGES OF ORGANIC FERTILISERS
1) THEY ARE A DILUTE SOURCE OF NUTRIENTS
2) PROHIBITIVE TRANSPORTATION COSTS
3) HIGHER APPLICATION COSTS
4) THEIR COMPOSITION IS VARIABLE/ THE DENSITY OF NUTRIENTS IS MODEST.
Credits:
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