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Nitrate-Nitrogen Leached Below the Root Zone During and Following Alfalfa

Robbins, C.W. and Carter, D.L. (1980) Nitrate-Nitrogen Leached Below the Root Zone During and Following Alfalfa. Journal of Environment Quality. 9(3):447-450. July 1980.

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Abstract

The nitrate-nitrogen (NO?-N) contribution to subsurface drainage
water by irrigated alfalfa (Medicago sativa L.) in crop rotations was
evaluated by measuring the soil water flux and NO?-N concentration
below the root zone of alfalfa and crops following alfalfa with and
without additional nitrogen fertilization. Under alfalfa grown on
Portneuf silt loam (Durixerollic Calciorthid) with a permeable hardpan,
44 kg NO?-N ha-1 year-1 moved below the root zone at concentrations
between 3 and 15 ppm. During the growing season following
alfalfa, 85-96 kg NO?-N ha-1 year-1 moved below the root zone under
nonfertilized bean (Phaseolus vulgaris) crops at concentrations
between 1 and 83 ppm. The second growing season after alfalfa, 17-29
kg NO?-N ha-1 year-1 at 3-15 ppm NO?-N moved below the root zone
of nonfertilized bean and wheat (Triticum aestivum L.) crops. A
field planted to corn (Zea mays L.) and fertilized with 200 and 170 kg
N ha-1 the first and second year after alfalfa lost 153 and 108 kg NO?-N
ha-1, respectively, from leaching. Leachate N concentrations varied
from 1 to 64 ppm. Unfertilized corn lost 60 and 17 kg NO?-N/ha the
first and second year after alfalfa, respectively, at leachate concentrations
of 1-31 ppm. The NO?-N concentration in the soil solution
below only slightly permeable hardpan areas was between 13 and 67
ppm, but only 10-23 kg ha-1 year-1 moved below the root zone because
of the lower water flux through the hardpan. Comparing these results
with previous data for the same area suggests that considerable denitrification
and/or dilution takes place at the water table interface
since 5.2 ppm NO?-N was the highest concentration measured in the
subsurface drainage water with an average of 3.2 ppm NO?-N. The
NO?-N contributed by alfalfa in the crop rotation was estimated to
equal just half of that accounted for in the subsurface drainage in a
previous study on the same irrigated tract

Item Type: Article
NWISRL Publication Number: 0446
Subjects: Irrigated crops > Alfalfa
Mass Import - autoclassified (may be erroneous)
Depositing User: Dan Stieneke
Date Deposited: 20 Nov 2010 21:52
Last Modified: 31 Jan 2017 19:45
Item ID: 362
URI: https://eprints.nwisrl.ars.usda.gov/id/eprint/362