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Fig. 4. Amino sugar–N test (ASNT) values as a result of long-term crop rotation history. Soil samples were collected in the fall of 2002 after harvest and when corn was to be planted in the rotation in 2003. The bold, underlined crop letter indicates the crop in the rotation when the soil samples were collected. CCCC, continuous corn; CCOA, corn–corn–oat–alfalfa; CCS, corn–corn–soybean; COA, corn with alfalfa in the rotation; COAA, corn–oat–alfalfa–alfalfa; CS, corn with soybean in the rotation; CSCS, corn–soybean–corn–soybean.
