This is the VOA Special English Agriculture Report.
use differs from country to country, and from too little to too much. Nitrogen
and phosphorus can produce big crops. But they can also pollute water and air.
recent policy discussion in the journal Science compared the nutrient balances
of different agriculture systems. Researchers compared the use of fertilizer in
three areas that grow maize as a major grain: China, Kenya and the United
By two thousand five, they say, farms in
northern China produced about the same amount of corn per hectare as farms in
the American Midwest. But the Chinese farmers used six times more nitrogen, and
produced almost twenty-three times more surplus nitrogen.
policies can have an influence. For example, as China sought food security, its
policies increased fertilizer use.
researchers note that farmers in the Midwest used too much fertilizer on their
crops through the nineteen seventies. But improved farming methods later
increased their yields and, at the same time, made better use of chemical
in western Kenya use just over one-tenth as much fertilizer as American farms. Corn
harvests remain small. The researchers say farming methods in Sub-Saharan
Africa need to improve or else poor quality soil will increase rural poverty. More
than two hundred fifty million people do not get enough nutrients from crops to
balances in agriculture differ with economic development. Farmers lack enough
inputs to maintain soil fertility is parts of many developing countries,
especially in Africa south of the Sahara. But countries that are developed or
growing quickly often have unnecessary surpluses.
Ammonia gas released by fertilized
cropland is a cause of air pollution. The land can also release nitrous oxide,
a heat-trapping gas.
runoffs from farms can create large dead zones, like those in the Gulf of
Mexico. Algae microorganisms in the water overpopulate because of the surplus
nitrogen. The algae take much of the oxygen from the water. Fish and other
Drinkwater at Cornell University in Ithaca, New York, was an author of the report.
Professor Drinkwater says farmers need to think about ways to solve some of the
causes of nutrient loss from agriculture. She says different countries need
different solutions based on location, environment, climate and population
that's the VOA Special English Agriculture Report, written by Marisel Salazar. I'm Steve Ember.