This is the VOA SpecialEnglish AGRICULTURE REPORT.
American scientists are developing ways to limit pollution fromagricultural fertilizers in rivers and other waterways. Thescientists say they found one method that provides a natural line ofdefense. Their method involves small pieces of wood called woodchips.
The scientists buried a largeamount of wood chips near crops treated with nitrate fertilizer.They found that the areas filled with wood chips reduced the nitratein the water by as much as seventy percent.
Dan Jaynes of the United States Agricultural Research Service isleading the study. He works at the Soil and Water Quality office inAmes, Iowa.
In the United States, devices called drainage tiles can speed theremoval of extra water from cropland. Farmers build drainage tilesnear their fields. The devices help direct unneeded water to nearbywaterways. Mister Jaynes notes that farmers use drainage tiles onthirty percent of all cropland in the central United States.
However, when water is removed from fertilized crops, nitrate maynot reach deep into the soil. As a result, the fertilizer cannothelp plant roots. Often the nitrate fertilizer is washed into riversand other waterways. It feeds the growth of underwater plants. Asthe plants die and break down, they use up all the oxygen in thewater. This causes a condition known as hypoxia. Plants and animallife cannot live in the water if it does not contain enough oxygen.High levels of nitrate have also caused problems for communitiesthat use rivers for drinking water.
The American scientists carried out their experiment on land withcorn and soybean crops. They dug large holes around the fields.These trenches are two meters deep and about two-thirds of a meterwide. They extend in the same direction as the drainage tiles.
The scientists filled the trenches with wood chips up to aboutone-third of a meter below the surface. Then they covered the chipswith soil.
The wood chips create a natural barrier that helps change nitrateinto nitrogen gas, which is common in the atmosphere. Mister Jaynessays the method works equally well for small and large farms. Hesaid farmers do not need to supervise the system.
The scientists now will study how long the wood chips areeffective before they break down.
This VOA Special English AGRICULTURE REPORT was written by GeorgeGrow.