Agricultural Chemicals - Fundamentals of Industrial Chemistry: Pharmaceuticals, Polymers, and Business - page 204

Six multinational companies: Syngenta, Bayer, Monsanto, DuPont, BASF,
and Dow are major players in the agrochemical industry [8]. Each has annual
crop protection chemical sales in excess of $3 billion and together they have
about 70% of the market [9]. China is emerging as first in world pesticide pro-
duction and second in usage with about 2,800 manufacturers and more than
400 million small-scale farmers [10]. There is great variety among pesticides.
For example, in Canada there are over 7,000 pesticide products and over 500
active ingredients are registered [11]. More than 80% of the pesticides used
in Canada are herbicides [12].
12.2 FERTILIZER
Fertilizers are compounds given to plants to promote growth [13]. Plants
require elemental nutrients in various amounts, which vary with species,
genotype, soil, and environmental factors [14]. For grain crops, as seed is
produced and removed from the field, nutrients are lost every season and
must be replaced. Fertilizers are used for this purpose. Nitrogen, phosphorus,
and potassium are primary nutrients. Primary nutrients are required in
large amounts and are quickly depleted from the soil. Retail fertilizers for
homeowners typically have a three-number designation such as 10-6-4.
These numbers designate the weight percent of nitrogen, phosphorus, and
potassium. The first number is the weight percent nitrogen in the fertilizer,
10% in this example. The second number is for phosphorus and represents the
amount on a phosphate basis. In this example, there is 6% P 2 O 5 . Recognize
that the phosphorus is not present as phosphorus pentoxide; this is a way
of reporting the number. The third number is for potassium on a potash
or potassium oxide basis. Fertilizer having the designation of 10-6-4 has
the amount of potassium equivalent to 4% K 2 O. In addition to these three
elements, many other elements are also needed for proper plant growth albeit
often in smaller quantities.
Nitrogen is usually the most limiting nutrient in crop protection, partly
because large amounts are required by plants and partly because it migrates
from the soil [15]. Common nitrogen fertilizers are ammonia and derivatives
of ammonia such as urea, ammonium nitrate, and ammonium phosphate.
To understand the role of fertilizers, it might be helpful to think about soy-
bean. Soybean is the world's most important source of protein and accounts
for nearly 70% of the protein meal consumption and nearly 30% of vegetable
oil consumption [16]. Nitrogen, phosphorus, and potassium (in that order)