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Testing DAYCENT Model Simulations of Corn Yields and Nitrous Oxide Emissions in Irrigated Tillage Systems in Colorado
Author(s) -
Del Grosso S. J.,
Halvorson A. D.,
Parton W. J.
Publication year - 2008
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2007.0292
Subject(s) - tillage , soil carbon , environmental science , fertilizer , nitrous oxide , soil organic matter , soil texture , agronomy , conventional tillage , soil water , soil science , chemistry , organic chemistry , biology
Abstract Agricultural soils are responsible for the majority of nitrous oxide (N 2 O) emissions in the USA. Irrigated cropping, particularly in the western USA, is an important source of N 2 O emissions. However, the impacts of tillage intensity and N fertilizer amount and type have not been extensively studied for irrigated systems. The DAYCENT biogeochemical model was tested using N 2 O, crop yield, soil N and C, and other data collected from irrigated cropping systems in northeastern Colorado during 2002 to 2006. DAYCENT uses daily weather, soil texture, and land management information to simulate C and N fluxes between the atmosphere, soil, and vegetation. The model properly represented the impacts of tillage intensity and N fertilizer amount on crop yields, soil organic C (SOC), and soil water content. DAYCENT N 2 O emissions matched the measured data in that simulated emissions increased as N fertilization rates increased and emissions from no‐till (NT) tended to be lower on average than conventional‐till (CT). However, the model overestimated N 2 O emissions. Lowering the amount of N 2 O emitted per unit of N nitrified from 2 to 1% helped improve model fit but the treatments receiving no N fertilizer were still overestimated by more than a factor of 2. Both the model and measurements showed that soil NO 3 − levels increase with N fertilizer addition and with tillage intensity, but DAYCENT underestimated NO 3 − levels, particularly for the treatments receiving no N fertilizer. We suggest that DAYCENT could be improved by reducing the background nitrification rate and by accounting for the impact of changes in microbial community structure on denitrification rates.