ABSTRACT:
Simulation models of the nitrogen (N) cycle have been used for well over 20 years to help estimate nitrate (NO3-N) leaching, soil residual NO3-N, fertilizer N requirements, soil organic N status, and gaseous N emissions associated with agriculture. These models have been coupled with simulations of other related processes such as water and solute transport, crop growth, soil chemistry, temperature regimes, and management to make more complete models of cropping systems. At the core of these tools have been databases for soils, climate, model coefficients, and field/farm/watershed management scenarios. This paper reviews the basic types of N modeis, modeling techniques, and required databases. The accuracy of N models along with their strengths and limitations are discussed in a management context. Tips are provided on initializing N constituent pools, on using N models in Geographic Information Systems (GIS) applications, on developing confidence bands for N model output, and on using web-based N models. Finally, methods are described to analyze simulated NO3-N leached, nitrous oxide (N2O) emissions, and N use efficiencies.
Footnotes
Marvin J. Shaffer is a soil scientist at the U.S. Department of Agriculture-Agricultural Research Service-Northern Plains Area (USDA-ARS-NPA) Great Plains Systems Research Unit in Fort Collins, Colorado.
- Copyright 2002 by the Soil and Water Conservation Society
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