____ in the early 20th century, there were ____ advances in theproduction of cereals with ____ agronomic practices, ____ use of fertilizerand irrigation, and, most importantly, greatly improved genetics of the seed. The____ of hybrid corn together with genetic selection has increased yields of corn.The advent of agricultural biotechnology with genetically modified seed is ____losses because of weeds and other pests, such as the European corn borer.In the United States, the ____ yield for corn increased tremendously in the20th century. The 1860–1920s’ yield was 26.0 bushels per acre (1.2 metric tons perhectare ____). In 1940, 39.1 bushels per acre (1.8 t/ha) were produced. A total of161 bushels per acre (7.4 t/ha) was ____ in 1990. In 2000, 187 bushels per acre(8.6 t/ha) were yielded. A total of 202 bushels per acre (9.3 t/ha) was produced in2004.

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