Tillage and Nitrogen Source Impacts on Relationships between Nitrous Oxide Emission and Nitrogen Recovery Efficiency in Corn
2019
Omonode, Rex A. | Vyn, Tony J.
Quantitative understanding of relationships between N₂O emission and plant N uptake are needed to select environmentally optimal management systems for corn (Zea mays L.) production. Studies were conducted from 2014 to 2016 in Indiana to assess long‐term tillage and N source effects on N₂O emission, and in 2015 and 2016 on relationships between N₂O losses and N recovery efficiency (NRE) and N use efficiency (NUE), in a continuous corn system. Tillage treatments (mostly in place since 1975) consisted of no till (NT), strip till (ST), chisel plow (CP), and moldboard plow (MP), whereas the N source comparison involved sidedress urea ammonium nitrate applied at 220 kg N ha⁻¹ with and without nitrapyrin. Grain yield averaged 6.5% greater for MP than for CP and NT in the 3‐yr period. Nitrapyrin never increased grain yield or NRE but reduced cumulative seasonal N₂O emission in 1 yr. Tillage affected N₂O emission in 2 of 3 yr, when emissions decreased in the order MP > CP > ST > NT. Significant negative linear relationships existed between N₂O emission and NRE under NT and ST, and between N₂O and NUE under ST, but not for CP and MP. Overall, N₂O losses under ST and NT decreased by 17 and 13 g N ha⁻¹, respectively, per unit increase of NRE, and by 63 g N ha⁻¹ per unit increase of NUE under ST. Our results confirmed that selected management systems such as NT or ST that improved NRE and/or NUE can potentially reduce N₂O emissions during continuous corn production. CORE IDEAS: Seasonal N₂O losses were lower for no till (NT) and strip till (ST) vs. chisel and moldboard plow. Mean N recovery efficiency (NRE) in continuous corn with 220 kg N ha⁻¹ exceeded 70%. Negative linear relationships existed between NRE or NUE and N₂O under NT and ST. Rate of cumulative N₂O emission decline per unit gain in NRE was highest under NT.
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