Agronomic Investigations Using Continuous Function Experimental Designs—Nitrogen Fertilization of Sweet Corn
1973
Fox, R. L.
Simple experimental designs are needed for exploratory field studies and for generating data for well defined yield response curves and surfaces. A design was developed by which a variable was increased in many small increments along corn (Zea mays L.) rows. Individual plants were handled as plots. Sweet corn was grown in rows 12 m long, along which rates of N fertilization increased in 40 increments from 0 to 220 kg/ha. Replication was obtained by repeating the layout but rotating it through 180 degees. “Border effects” along the row could be ignored because the incremental change of applied N was very small and because the N rate increased in one direction and decreased in the other. Because there are many experimental points it was possible to show that low rates of N produced a “diluting effect” on leaf N, that N deficiency symptoms disappeared and second ear develop ment began at about 140 kg N/ha, that lower corn leaves are the most sensitive indicators of the N status of corn, and that yield response to applied N was linear to 200 kg/ha of N applied. If a second factor is varied at right angles to the first, a well defined response surface can be obtained.
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