Abstract
Denitrification rates under various tillage systems were determined in the corn (Zea mays L.) cycle of a corn‐oats (Avena sativa L.) rotation. Denitrification was measured directly with an in‐situ soil cover method which supplied the soil with acetylene (C2H2) and evacuated the nitrous oxide (N2O) produced. Denitrification rates were measured in both a field or non‐wheel track (NWT) area and in a compacted wheel track (WT) area for the no‐till (NT), chisel plow (CH), moldboard plow (MP) tillage systems after nitrogen (N) was applied by broadcast/incorporation with 112 kg N/ha as ammonium nitrate. Nitrogen was also applied to the NT treatment by injection with modified anhydrous ammonia knives prior to planting. Most of the cumulative N loss occurred over a 22 day period following heavy rainfall in June. Denitrification was greatest on days after rainfall events for the NT systems. Cumulative N loss was estimated at 25, 16, and 11 kg N/ha from May 29‐September 8 for NT, CH, and MP treatments, respectively, for the broadcast/incorporated N application. Mean denitrification rates from WT areas were about 1.6 times greater than the NWT areas.
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