Nitrogen requirements associated with improved conservation tillage for corn production

Abstract

Excessive soil erosion and use of N fertilizer are costly to the Atlantic Coastal Plain corn (Z. mays L., ''Funks G 4507'') producer and both may serve to create environmental hazards. An in-row chisel (36 cm deep) tillage method was compared with the standard 5 cm fluted coulter method for planting corn in premature wheat (Triticum aestivum L.) residues grown on an Organeburg sandy loam (Typic Paleudult). Five orthogonal N levels ranging up to 440 kg of N/ha were used to determine an economic N optimum for each tillage method. The in-row chisel tillage method provides a possible yield advantage in the Atlantic Coastal Plain because of observed restricting soil layers within the normal corn rooting zone. The estimated profit-maximizing quantities of N fertilizer were 262 and 295 kg of N/ha (234 and 263 lb of N/acre) for the fluted coulter and in-row tillage procedures, respectively. Corn grain yields associated with these inputs were 9.6 .times. 103 and 12.6 .times. 103 kg/ha (153 and 200 bu/acre), respectively. The yield increase associated with in-row chiseling through a 2.5 metric ton mulched surface is attributed to potentially improved rooting and more efficient water storage and use.