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•Watershed and Flood Control
•Groundwater
_____- Keys to Clean Water
•Cost-Share
•Conservation Trees
•Regulations to Protect Soil and
Water
 We
All Hold the Key To Clean Water
Agricultural Best Management Practices:
Nitrogen Credits for Soil and Water
Farmers can sometimes use less fertilizer to raise a corn crop
if they take advantage of other nitrogen sources available to
the crop, such as residual nitrate in soil and irrigation water.
Here’s how to calculate the amount of nitrogen corn can obtain
from soil and irrigation water, based on University of Nebraska
recommendations:
Soil: An estimated one-third of cropped fields contain
enough residual nitrate to justify applying less fertilizer. Taking
soil samples is the only reliable way to find out. Soil samples
should be collected from a minimum depth of 3 feet (4 feet is
recommended). Each sample should represent no more than 40 acres
(20 acres or less if possible). Have the soil samples laboratory
tested. The fertilizer nitrogen requirement for a crop is reduced
by 8 lb/acre for each part per million of residual soil nitrate-nitrogen.
Water: Collect a sample during irrigation season, after
the well has been pumped for at least 24 hours. Containers are
available from county extension offices or testing laboratories.
The laboratory will report the nitrate concentration in parts
per million (ppm) or milligrams per liter (mg/l), which are the
same thing. Multiply this number by 2.72 to get the pounds of
nitrogen per acre applied with each foot of irrigation water.
For example, water that contains 10 ppm of nitrate would provide
27.2 pounds of nitrogen per acre for each foot of water applied.
Fertilizer can be reduced by this amount.
More details:
Contact the Cooperative Extension or USDA Natural Resources Conservation
Service
More information on-line:
[ Guidelines
for Soil Sampling (Extension NebGuide) ]
[ Testing
irrigation Water (Extension NebGuide) ]
[
University of Nebraska IANR Extension Publications ]
Other Agricultural Best Management Practices:
[ Fertilizer Rate and Expected Yield
]
[ Nitrogen Credits for Manure and Legume
Crops ]
Developed for the Dutch Flats Groundwater Quality Project.
The project is partially funded by a Section 319 Clean Water Grant
from the U.S. Environmental Protection Agency through the Nebraska
Department of Environmental Quality.
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