Students need to critically analyze what they read

Abstract

The need for students to critically analyze what they read is clearly apparent. In reviewing literature in preparation to teach a course in organic agriculture, it became evident that one needs to carefully check references and statistics cited in the articles. Consequently I developed a handout for the students to stress this need. The handout starts with an excerpt from an article and traces a series of references to show that statistics had been misinterpreted and resulted in an erroneous conclusion by the most recent author. The erroneous statement claimed that more and more chemical fertilizer was required each year to sustain the same yield. The supporting reference said essentially the same thing but cited a third source. This earliest source cited statistics to show that more N was used per unit of corn yield in 1968 than in 1949. The author of the primary information did not state that more N was required to produce a given yield per unit area in 1968 than in 1949. The handout I developed illustrates how the biological principles of a decreasing rate of yield response to applied N results in low efficiency of N at high application rates. The use of higher rates of N in 1968 resulted in lower overall N efficiency, and thus more N was required to produce a unit yield of corn. The long-term fertility trials at Rothamsted illustrate that more fertilizer is not needed each year to sustain yields.