Page 21 - Introduction to Agriculture by: Aqleem Abbas

Introduction to Agriculture Notes prepared by: Aqleem Abbas

Many fertilizers used since ancient times contain one or more of the three elements important to
the soil. For example, manure and guano contain nitrogen. Bones contain small quantities of
nitrogen and larger quantities of phosphorus. Wood ash contains appreciable quantities of
potassium (depending considerably on the type of wood). Clover, alfalfa, and other legumes are
grown as rotating crops and then plowed under, enriching the soil with nitrogen.

The term complete fertilizer often refers to any mixture containing all three important elements;
such fertilizers are described by a set of three numbers. For example, 5-8-7 designates a fertilizer
(usually in powder or granular form) containing 5 percent nitrogen, 8 percent phosphorus
(calculated as phosphorus pentoxide), and 7 percent potassium (calculated as potassium oxide).

While fertilizers are essential to modern agriculture, their overuse can have harmful effects on
plants and crops and on soil quality. In addition, the leaching of nutrients into bodies of water
can lead to water pollution problems such as eutrophication, by causing excessive growth of
vegetation.Fertilize calculation is done to provide optimum amount of nutrients to crops to
enhance crop production and quality, to increase farmer income to sustain soil fertility, to avoid
environment pollution.

Nitrogenous fertilizers N P K
Urea 46%
Ammonium sulphate . NH4SO4 21%
Ammonium nitrate. NH4NO3 35%
Phosphate fertilizers
Single super phosphate 18%
Triple supper phosphate 46%
Potash fertilizer
Sulphata potash K2SO4 50%
Murata potash KCL 60%
Compound fertilizers
DAP 18 % 46%
Nitrophosphate 23% 23%

Amount of fertilizer =

Amount of nutrient required(recommended by researcher) × 100

%age of nutrient in grade (in table