Simulating the Impact of Management Practices on Nitrous Oxide Emissions
1998
Xu, C. | Shaffer, M. J. | Al-kaisi, M.
Effective evaluation of alternative management strategies to control global warming requires tools for simulating emissions of N₂O from soils across a range of soil properties, weather, and management inputs. We hypothesized that with modification to the nitrification and denitrification submodels of the Nitrate Leaching and Economic Analysis Package (NLEAP) model, we could simulate daily N₂O emissions as a function of soil moisture, temperature, N content, and other factors. Field parameterization was conducted on an Ulm clay loam soil (a fine, montmorillonitic, mesic Ustollic Haplargid) and validation experiments for N₂O gas emissions were performed on an on-farm swine effluent study site on a Valent sandy soil (a mixed, mesic Ustic Torripsamment). The unitless model parameters reflecting the maximum fraction of selected N transformations emitted as N₂O for nitrification (αN), wet-period denitrification (αw), and dry-period denitrifiation (αd) were calibrated as 0.065, 0.050, and 0.520 separately and then used in the validation study. The trends and magnitudes of simulated N₂O emissions were statistically consistent with the results obtained from the field experiments (r = 0.78). Experimental results showed that the decline of N₂O emission rates from 70 to 2 g N ha⁻¹ d⁻¹ during the growing season was related to soil N content decline from 33 to 4 mg kg⁻¹. Simulated effects of field management on annual N₂O emissions indicated that plowing decreased N₂O relative to notillage corn (Zea mays L.), irrigation increased N₂O 14% relative to dry-land corn, and doubling fertilization N rates from 100 to 200 kg ha⁻¹ increased N₂O emissions 60%.
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