APEX Model Upgrades, Data Inputs, and Parameter Settings for Use in CEAP Cropland Modeling.

摘要

The Agricultural Policy/Environmental eXtender (APEX) model addresses the impacts of management on environmental and production issues for whole farms and small watershed. It is constructed to evaluate the wide array of management strategies applied to crop, pasture, and grazing lands and estimates long-term sustainability of land management in respect to erosion (wind, sheet, and channel), economics, water supply, water quality, soil quality, plant competition, weather and pests for crop land as well as grazing and pasture land. Management capabilities simulated include: irrigation; surface and subsurface drainage; furrow diking; buffer strips; terraces; waterways; windbreaks; fertilization and manure management, lagoons and water retention reservoirs, crop selection and rotation; fertilizer, nutrient and pesticide fate and application; grazing management; tillage timing and intensity; and harvest timing and methods. Furthermore, APEX can address strategic implications of global climate/CO2 changes; confined animal feeding facilities, production systems for bioenergy; and other spin off applications. The model operates on a daily time step (some processes are simulated with hourly or less time steps) assimilating the changes in daily weather and with specific timing and application of management practices in context of our current knowledge of physical, biological and environmental processes. Simulations can examine one year or hundreds of years if necessary and results can be summarized and examined daily, monthly, yearly or with multi-year analyses. APEXs unique feature is the ability to subdivide farms or fields by soil type, landscape position, surface hydrology or management configuration represent crop diversity and landscape characteristics within a field or farm. Each subarea may be linked with each other according to the water routing direction in the farm or watershed, starting from the most distant subarea towards the watershed outlet.