Agriculture Reference
In-Depth Information
Farmers in India purchase transgenic cotton seeds each year because the new var-
ieties cost less to produce a higher crop of cotton. However, there has been a reaction
among parts of farm society to actively preserve nontransgenic open pollinated seed.
The Protection of Plant Varieties and Farmers' Rights Act passed in 2001 gives indi-
vidual farmers legal protection for the distribution of registered varieties of crops
such as rice and maize. This means that a farmer who has developed an outstanding
variety can give it a unique name and sell it with the same legal protection as large
multinational companies.
10.12
FERTILIZERS: CHEMICAL OR ORGANIC
Fertilizers are an essential factor for increasing and maintaining yields of any crop.
Continually harvesting grain or forage from a field without replacing any of the nutri-
ents carried off is referred to as “mining the soil.” Ancient civilizations were able to
survive for many years because they developed their agriculture in floodplains along
rivers. The yearly floods brought in a new layer of fertile soil from eroded hills
upstream. Without this yearly addition of nutrients the crop yields decline and the
fields eventually must be abandoned.
The relationship between cereal grain yields and use of chemical fertilizers is
clearly shown in Figure 10.15. The regions of the world with lowest grain yields per
hectare (Oceania, former Soviet Union, sub-Saharan Africa) also have the lowest use
of chemical fertilizers. Western Europe and East Asia have higher grain yields and
higher rates of application of chemical fertilizers. Of course, application of fertilizer
is not the only factor that causes grain yields to increase. Variety, weed and insect
control, density of planting, and time of planting are only a few of the other factors
that contribute to higher grain yields.
Figure
10.15.
Relationship between grain yields and fertilizer use. (Chart courtesy of
A. Krauss, International Potash Institute, Horgen, Switzerland.)
