Nitrous Oxide Emission in Three Years as Affected by Tillage, Corn-Soybean-Alfalfa Rotations, and Nitrogen Fertilization
1998
MacKenzie, A. F. | Fan, M. X. | Cadrin, F.
Nitrous oxide (N₂O) produced from agricultural activities must be determined if management procedures to reduce emissions are to be established. From 1994 to 1996, N₂O emissions were determined using a closed chamber technique. Continuous corn (Zea mays L.) at four N rates of 0, 170, 285, and 400 kg of N ha⁻¹ was used on a Ste. Rosalie heavy clay (a very-fine-silty, mixed, nonacid, frigid Typic Humaquept) and a Chicot sandy loam (a fine-loamy, frigid, Typic Hapludalf). On two additional sites, a Ste. Rosalie clay and an Ormstown silty clay loam (a fine-silty, mixed, nonacid, frigid Humaquept) no-till (NT) and conventional tillage (CT); monocultural corn (CCC), monocultural soybean (Glycine max L.) (SSS); corn-soybean (SSC, CCS); and soybean-corn-alfalfa (Medicago sativa L.) phased rotations (SAC, CSA, and ACS) were used. Nitrogen rates of 0, 90, and 180 kg of N ha⁻¹ for corn and 0, 20, and 40 kg of N ha⁻¹ for SSS were used. Rates of N₂O emission were measured from April to November in 1994 and 1995, and from mid-March to mid-November in 1996. Maximum N₂O emissions reached from 120 to 450 ng of N m⁻² s⁻¹ at the Ormstown site to 50 to 240 ng of N m⁻² s⁻¹ at the Ste. Rosalie soil. Generally, N₂O emissions were higher in the NT systems, with corn, and increased linearly with increasing N rates, and amounted to 1.0 to 1.6% of fertilizer N applied. The N₂O emission rates were significantly related to soil denitrification rates, water-filled pore space, and soil NH₄ and NO₃ concentrations. A corn system using conventional tillage, legumes in rotation, and reduced N fertilizer would decrease N₂O emission from agricultural fields.
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