In one study, the researchers ran the RZWQM simulation for several different planting scenarios at 41 sites across the Midwest from 1961 to 2005.
Overall, however, Malone notes, "The model underestimates the benefit of cover crops in reducing nitrate discharge, because the nitrate losses simulated by the RZWQM were about 30 percent less than field observations in Iowa."
Ahuja, "Evaluating nitrogen and water management in a double-cropping system using RZWQM
," Vadose Zone Journal, vol.
For cases in which a more detailed simulation and/or field study are needed, research models such as RZWQM
, LEACHM, or ecosys, and research plots or farms can be used to establish refined values for NLI.
RZWQM is a computer model that simulates plant growth and the movement of water, nutrients, and chemicals within and around the root zones of agricultural crops.
Initially, RZWQM was used in the Great Plains, Midwestern United States, and countries such as Canada, Germany, Portugal, and China.
Some of these models are NLEAP, LEACHM, CERES, EPIC, NTRM, RZWQM
, and GPFARM.
Some of these are EPIC, RZWQM
, CREAMS, SRM, WEPP, SHAW, NLEAP, and SPUR2.
Depending on the field type, management system or resource problem, the Root Zone Water Quality Model (RZWQM) (Ahuja et al.
RZWQM is an integrated physical, chemical, and biological process model developed to simulate the effects of agricultural management (e.g., tillage, irrigation, fertilization, manure application, crop rotation, pesticide application, and rile drainage) on crop production and water quality It was developed and tested in collaboration with the MSEA project.
"The Root Zone Water Quality Model (RZWQM) was developed over the past decade by a national team of scientists," says Lajpat R.
Actually, RZWQM is a series of compatible modules that can be attached or detached, as needed.