- B. O'Neill, R.G. Kachanoski, and D.E. Elrick, Department of Land Resource
Science, University of Guelph, Guelph, Ont.
Evaluation Summary (Tech. Transfer Report Summaries)
View / Download Final Report [836 KB pdf]
Associated SWEEP/LSP Research
Completed: September, 1990
run-off, infiltration rate, minimum tillage, moldboard plough, no-till,
porosity, Guelph Pressure Infiltrometer, erosion, bulk density
A new and particularly useful field instrument, the Guelph Pressure Infiltrometer
has been developed for determining in situ measurements of soil hydraulic
properties. The objectives of this study were to assess the effects of management
on changes in surface hydraulic properties. Specific objectives were:
Measurements were taken on 5 Tillage-2000 sites and also at the Elora Research
Station, Univ. of Guelph. At the field scale sites, paired benchmarks were
selected to cover the major soil and topographic changes in the field. A
pressure infiltrometer attachment for the Guelph permeameter was used to
obtain measurements of field saturated hydraulic conductivity Kfs
and metric flux potential [phi]m on each of the tillage/soil
landscape combinations. Undisturbed soil cores were taken to determine bulk
density, total porosity, saturated hydraulic conductivity, moisture retention
curves, and an estimate of macro-porosity.
- To further test the relationship between rainfall runoff (from rainfall
simulation experiments) and predicted runoff using measurements of Kfs
[phi]m, [capital delta][theta], and Tp from the pressure infiltrometer.
- To examine the temporal changes in hydraulic properties measured with
the pressure infiltrometer under two tillage systems and compare them
to temporal changes in surface runoff (simulated).
- To examine the effects of different cropping/tillage systems on changes
in surface hydraulic properties.
At three of the T-2000 sites rainfall simulation studies were also carried
out as part of a Ministry of Environment project. The rainfall simulation
trials gave steady runoff, infiltration rates, and soil loss rates to compare
to the pressure infiltrometer and undisturbed core measurements. Detailed
measurements at three times during the year were taken at one of the sites
The detailed measurements at D. Lobb's site indicated that no-tillage
(9 yrs) resulted in:
compared to a moldboard treatment. The results were consistent across all
measurement times. Similar effects of no-tillage compared to a minimum tillage
treatment were also observed at a second site. No significant differences
between no-till and other tillage systems were found at the remaining sites.
Comparisons of minimum tillage and moldboard tillage treatments also indicated
no influence of tillage on surface hydraulic properties.
- higher bulk density
- lower total porosity
- lower macro-porosity
- lower saturated hydraulic conductivity
- lower field saturated hydraulic conductivity
- lower matric flux potential
- shorter times to ponding and runoff, and
- lower infiltration rates (higher runoff)
At every site where both rainfall simulation and Guelph pressure infiltrometer
measurements were taken, the data from both methods were comparable. Thus,
the pressure infiltrometer should be a reliable, cost-effective instrument
for evaluating management effects on hydraulic properties. The portability
and minimum site disturbance of the permeameter make it a good choice for
small plot experiments.
The data suggest that there is a risk of increased surface runoff on
no-tillage plots. The main factors resulting in decreased soil loss in no-till
appear to be increased surface protection and decreased particle detachment,
not decreased runoff. The risk of increased surface water runoff may be
significant for the movement of non-adsorbed chemicals or soil additions
(such as manure).
The increased runoff and decreased infiltration rates in the no-till
does not support the hypothesis that no-till increases the risk of movement
of chemicals to the groundwater.
(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)
Previous U.S. research has shown conflicting results regarding the effect
of conventional tillage on infiltration, saturated hydraulic conductivity
values and run-off.
The purpose of the study was to further the development of the Guelph
Pressure Infiltrometer as a tool to accurately assess the effects of tillage
systems on soil hydraulic properties.
Detailed measurements were taken three times during the year using the
Guelph Pressure Infiltrometer, intact soil cores, and rainfall simulation.
At one long-term no-till site (9 years), the measurements showed that the
no-till had a higher bulk density, lower total porosity, lower macro-porosity,
lower saturated hydraulic conductivity, shorter time to ponding and lower
infiltration rates compared to the moldboard treatment. Similar observations
were made at a second site comparing no-till and minimum tillage. While
the run-off from no-till sites was higher due to decreased infiltration,
the amount of soil loss was lower than either the minimum till or the moldboard
There were no differences in surface hydraulic properties between no-till
and other tillage systems or between minimum till and moldboard tillage
at the four remaining sites.
The Guelph Pressure Infiltrometer was shown to be a good in situ method
for determining the effect of management on surface hydraulic properties.
The title was misleading as the study mainly focused on the development
of the Guelph Pressure Infiltrometer. The collection of data on the effects
of management on soil hydraulic properties was secondary. The effect of
tillage on soil hydraulic properties may be site specific and vary depending
on factors such as soil type, organic matter level, earthworm populations,
crop rotations, etc.
- SWEEP Report #30 - The Response of Soil Microflora
and Fauna to Spring Plowing of Zerotill and Pasture Soils
Future Research: ( ) indicates reviewers suggestion for
priority, A - high, C - low.
(A) Further research is needed to determine the effect of tillage on infiltration,
run-off, macroporosity and other soil hydraulic properties at different
locations with varying soil types, management histories, etc.
Thursday, May 19, 2011 01:59:14 PM