Herbicide usage

Table II. Percentage of crop acreage treated with herbicides and total herbicide usage in the United States in 1971 and 1982...

National trends tend toward the decline of land in cultivation. Roughly 17 million hectares were removed from cultivation between 1982 and 1997. This has clearly led to net decreases in chemical inputs herbicide usage has decreased by almost 20 million kilograms (kg) of active ingredients, and total chemical use has likely decreased by more than 34 million kg. 

Similarly to usage patterns in the USA, 75% of the pesticides used in Ontario in 1998 were herbicides [26]. Furthermore, herbicides applied on field corn and soybeans accounted for 65% of the total pesticide used in 1998 in Ontario. Metolachlor, glyphosate, atrazine, dicamba, and bentazon were the major herbicides used in Ontario agriculture in 1998. These five herbicides accounted for 76% of the total herbicide usage in Ontario. Atrazine usage on... 

Until 1979> the primary herbicide used by foresters for brush control in the South was 2,4,5-T. This chemical could be applied inexpensively ( 15 -30/acre) at rates of 4 to 6 pounds per acre for site preparation. Most applications were conducted with aircraft. Surveys (1977) of herbicide usage on industrial forest lands in the South showed that of the 1,175,350 acres site prepared for planting, 118,100 acres (10 ) were treated with 2,4,5-T, 48,700 (4 ) were treated with other herbicides, and 909,000 acres (77 ) were treated mechanically (anonymous 1978). Obviously, the majority of the forest acreage was site prepared with machinery. Nevertheless herbicides filled an important... 

The benefits from herbicide usage are many (Table I). 

Herbicides reduce transportation and storage costs. A good example of the transportation and storage costs of weed seeds was given by a Canadian weed scientist ( 1). He reported that despite herbicide usage and grain-cleaning processes, 33 railroad carloads of weed seeds are transported across Canada from elevators to ports each day. 

Residues occur in the aquatic environment from emptying and washing herbicide application equipment or from discharge of industrial waste water. These occur infrequently and do not arise from normal herbicide usage. 

The use of green yard waste compost on farmland can lead to a positive environmental impact with lower water usage, lower fertilizer usage, lower herbicide usage, and sequestration. Life cycle impact assessments of environmental concerns from production and application of composted products provide a net positive environmental impact. The use of composting process and products provides a reduction in GHG, human toxicity potential, ecotoxicity potential, and eutrophication potential due to lower use of fertilizers, herbicides, water, and electricity (LCA for Windrow Compost 2006). 

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