In recent years, Delgado has advised scientists, helping them calibrate NLEAP
and the Nitrogen Index to assess the efficiency of nitrogen use in several states as well as in Argentina, Bolivia, Ecuador, Mexico, and Spain.
In Colorado's San Luis Valley, NLEAP is helping farmers more accurately estimate both how much nitrogen to apply to meet the needs of crops such as potatoes, small grains, lettuce, spinach, carrots, and rapeseed and how much remains in the soil.
NLEAP demonstrated that growers in that area can reduce nitrogen application rates by 20 to 45 pounds per acre and thus lower nitrate leaching by 3 to 41 pounds per acre.
We found NLEAP was doing a pretty good job estimating the amount of nitrates that were actually leaching underground," says James D.
Today, users of agricultural chemicals can call on the collective knowledge of experts and decision support systems like NLEAP.
The data used in NLEAP is specific for individual crops, soil types, local rainfall and weather conditions, and practices like irrigation.
NLEAP suggests options to the farmer on how to modify rates of fertilizer application, to reduce or redistribute irrigation water, or to grow a legume (such as alfalfa or soybeans) after corn.
Chapters and appendixes explaining NLEAP and its use and the computer diskettes containing NLEAP are included in the book.
A related geographical information system project intended to supplement the NLEAP activity is underway that is using geographical information system technology to expand site data.