New Zealand Journal of Agricultural Research abstracts

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Depth distribution of simulated urine in a range of soils soon after deposition

R. M. MONAGHAN

AgResearch, Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
email: monaghanr@agresearch.cri.nz

P. CAREY

A. K. METHERELL
AgResearch
c/o Soil & Physical Sciences Group
P.O. Box 84
Lincoln University
Canterbury, New Zealand

P. L. SINGLETON

AgResearch, Ruakura Agricultural Centre
Private Bag 3123
Hamilton, New Zealand

J. DREWRY

AgResearch, Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand

B. ADDISON

AgResearch, Ruakura Agricultural Centre
Private Bag 3123
Hamilton, New Zealand

Abstract  The distribution of a solution simulating cow urine in soil was measured within 6 hours of deposition, by applying 2 litres of KBr-pyranine dye solution to the soil surface at a rate of 0.2 litres s^-1, followed by excavation and sub-sampling of the area affected by urine in 10-cm depth increments until no further pyranine dye could be detected under UV fluorescence. Preferential flow of simulated cow urine to below 20 cm soil depth occurred in 9 of the 10 soils examined. Up to 68% of applied solution moved below 20 cm, at an average of 17% over all soils examined. Two soils exhibited a high degree of preferential flow and excluding these from the data reduced the average loss to 11%. Although this preferential flow was significant, much of the urine nutrients moving via preferential flow would still be available for uptake by plant roots at depth, and therefore cannot be considered a loss to pasture. The movement of urine to below 20 or 30 cm soil depth was best predicted by saturated hydraulic conductivity calculated as the mean for the 0-30 cm soil layer. Saturated hydraulic conductivity measurements made for any one 5-cm depth increment, particularly the 0-5 cm soil depth, were poor predictors of urine flow to below 20 or 30 cm depth.

Keywords  preferential flow; cow urine; saturated hydraulic conductivity;potassium; pasture root distribution

New Zealand Journal of Agricultural Research, 1999, Vol. 42: 501-511

0028-8233/99/4204-0501 $7.00/0 (c) The Royal Society of New Zealand 1999

PDF file of entire paper: medium quality (928K); (scanned from paper original: notes about this process)

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