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Most agricultural information is reported by government sources on a state or county basis. The purpose of this study was
to demonstrate use of geospatial data, the 2002 Agricultural Cropland Data Layer (CDL) for the mid-Atlantic region, to characterize
agricultural, environmental, and other scientific parameters for the Chincoteague Bay subbasin using geographic information
systems. This study demonstrated that agriculture can be characterized accurately on subbasin and subwatershed bases, thus
complimenting various assessment technologies. Approximately 28% of the dry land of the subbasin was cropland. Field corn
was the largest crop. Soybeans, either singly or double-cropped with wheat, were the second most predominant crop. Although
the subbasin is relatively small, cropping practices in the northern part were different from those in the southern portion.
Other crops, such as fresh vegetables and vegetables grown for processing, were less than 10% of the total cropland. A conservative
approximation of the total pesticide usage in the subbasin in 2002 was over 277,000 lbs of active ingredients. Herbicides
represented the most frequently used pesticides in the subbasin, both in number (17) and in total active ingredients (over
261,000 lbs). Ten insecticides predominated in the watershed, while only small quantities of three fungicides were used. Total
pesticide usage and intensity were estimated using the CDL. Nutrient inputs to cropland from animal manure, chemical fertilizer,
and atmospheric deposition were modeled at over 30 million pounds of nitrogen and over 7 million pounds of phosphorous. Crops
under conservation tillage had the largest input of both nutrients. 相似文献
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