Studying nitrate-N leaching with a bromide tracer in an irrigated silt loam soil

Wright, J.L. and Westermann, D.T. and Lehrsch, G.A. (1998) Studying nitrate-N leaching with a bromide tracer in an irrigated silt loam soil. pp. 229-242. In: Schaack, J. and al, et (eds.) Proc. 1997 Water Management Conf. Best Management Practices for Irrigated Agriculture and the Environment. USA-ND-Fargo, 1997/07/16-19.

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Abstract

Most of the irrigated land in southern Idaho is Portneuf silt loam varying in depth from
3 to 30 ft over fractured basalt. Leaching of ag-chemicals through this soil is of
potential concern though major problems have not yet been generally encountered. We
evaluated downward movement of water and the bromide (Br) anion at a sprinkler
irrigated field site over a 3-year period to determine the potential for NO,-N leaching
losses. Potassium bromide as a conservative tracer was incorporated into the top 8 in.
of soil at the start of the study. Soil solution samples obtained from soil solution suction
tubes at six depths above bedrock were used to monitor the downward movement of Br.
Soil water drainage was determined by a soil water balance utilizing neutron meter data
and evapotranspiration computed from meteorological data and crop coefficients. Depth
of sampling varied among eight subplots from 12 to 16 ft. Preferential water flow was
evident in the initial downward movement of Br. However, drainage of water sufficient
to completely replace the initial soil water (44 in) was necessary to completely flush Br
from the profile. With recommended irrigation practices, about seven years would have
been required to leach Br and presumably, NO3-N as well, below 12 ft.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0976
Subjects:	Soil > Chemistry > Nitrogen Mass Import - autoclassified (may be erroneous)
Depositing User:	Users 6 not found.
Date Deposited:	20 Nov 2010 21:55
Last Modified:	17 Nov 2016 16:15
Item ID:	861
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/861