【分析解答题】

(46) U.S. farmers are planting more acres of crops using soil building and pollution fighting faming systems than traditional methods that rely on the plow or intensive tillage, according to a report due to be released early next month.

The report, titled "NationalCrop Residue Management Survey," shows a 6 million acre gain for environmentally friendly farming systems this year.
(47) It also shows traditional farming methods, which result in greater soil erosion and run off from fields, declined by 4 million acres.
(48) The survey, conducted on a county-by-county basis by USDA、Natural ResourcesConservation Service, indicates that farmers in Iowa, Illinois, SouthDakota, Kansas, and Indiana contributed the most to the increase in acres grown with environmentally friendly farming systems known as conservation tillage systems.
These states accounted for 5 million of the 6 million acre increase in conservation tillage this year.
All conservation tillage systems, such as no-till, mulch-till, ridge-till, strip-till, and zone-till, rely on less tillage or less soil disturbance to plant and manage crops.
Farmers who use these systems leave plant materials stems, stalks, and leaves—on the surface of fields after harvest.
The plant materials, also called crop residues, serve as a blanket to protect the soil from erosion.
The crop residues slowly decompose to add organic matter to the soil much like mulching or composting add organic matter to a garden.
The survey results for 1997 indicate that conservation tillage systems now account for 109.8 million acres or fully 37 percent of the 294.6 million annually planted cropland acres in the United States.
In the meantime, traditional systems that rely on the plow or intensive tillage fell to 107.6 million acres this year.
The remaining acres are in an intermediate farming system known as reduced till.
(49) The head of the nonprofit center that compiles and publishes the annual survey is calling on consumers and farmers alike to focus increased attention on conservation tillage systems.
"(50) Independent research and practical application across the country show that these systems not only replenish and build organic matter in the soil for improved fu ture food productivity but they will also protect water quality and enhance wild life and the environment for future generations," says John Hebblethwaite, executive director of theConservation Technology InformationCenter. "There is also growing evidence that these systems can even help us combat the potential for global warming," he adds.
Conservation tillage has long been credited for protecting water quality by reducing runoff from farm fields, according to Hebblethwaite.
He notes the latest research also indicates that soil enriched by crop residues offers natural protection for groundwater.
Conservation tillage systems save the farmer money by reducing trips through the field for planting and cultivation.