Agricultural productivity implies greater output with less input, and it also
implies a more efficient use of scarce resources. As farms become more
efficient, they are able to produce more products at a lower cost, which tends to
stabilize food prices and make more food available to all people, which is vital
in developing countries. For example, between 1950 and 2000, the amount of
milk produced per cow rose an average of 250% and corn yields averaged an
increase of 300%. However, increases in productivity are often linked with
issues of sustainability, safety, pollution, and demands on resources.
Fertilizer
Fertilizers provide plants with the nutrients needed to grow healthy and strong.
There are two main categories of fertilizer: inorganic and organic.
INORGANIC
An inorganic fertilizer is a fertilizer mined from mineral deposits or
manufactured from synthetic compounds. It consists primarily of only three
(nitrogen, phosphorus, and potassium) of the 13 nutrients that plants need.
Soluble inorganic, chemical fertilizers contain mineral salts that plant roots can
absorb quickly; however, these salts do not provide a food source for soil
microorganisms or earthworms. Over time, soils treated with only inorganic
fertilizers lose organic matter and the all-important living organisms that help to
build a quality soil. As the soil structure declines and the water-holding capacity
diminishes, more and more of the chemical fertilizer applied will leach through
the soil as water percolates downward, requiring ever-increasing amounts of
chemicals to stimulate plant growth. Furthermore, these “leached” chemicals are
then sources of pollution for surface and subsurface water supplies.
ORGANIC
Any fertilizer that originates from an organic source, such as fish extracts,
seaweed, manure, compost, bone meal, and so on, is considered to be organic.
Advantages of using organic fertilizers include:
■ They improve the quality and structure of the soil, which improves water
retention and drainage.
■ They add organic matter and humus to the soil, which provides a constant
and balanced supply of nutrients and improves root growth.
■ They feed and sustain beneficial organisms that live in the soil, which
inorganic fertilizers often destroy by increasing acid levels in the soil.
■ They improve moisture retention in the soil, making leaching less likely.