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Abstract Corn ( Zea mays L.) was planted in a Maury silt loam soil under conventional tillage and in a chemically‐killed bluegrass ( Poa pratensis L.) sod in 1970 and 1971 in order to determine the behavior of nitrate and the yield of corn under both cultural systems. Nitrate under both cultural treatments was sampled before and after June rainfall periods in both years. A large fraction of the nitrate was lost from the top 90 cm of soil under the killed‐sod plots, whereas, no nitrate was lost from the conventionally‐tilled plots. The loss of nitrate under the killed sod was attributed to two factors: 1) lower evaporation from the mulched soil; and 2) deep penetration of water and nitrate through larger pores in the wetter, mulched soil. Corn yields where nitrogen was applied tended to be higher on the killed‐sod plots in a dry year (1970) and about the same in a wet year (1971). However, the no nitrogen treatment on the mulched plots had a much lower yield than did the conventionally‐tilled no nitrogen treatment in the wet year of 1971. The results suggest that higher nitrogen rates may be required when corn is grown in a killed sod mulch as compared to conventionally‐tilled corn.
Thomas et al. (Sat,) studied this question.