Ontario - Canada Logos
SWEEP Banner

SWEEP Report #18

Effects of Management on Soil Hydraulic Properties

Researchers:
B. O'Neill, R.G. Kachanoski, and D.E. Elrick, Department of Land Resource Science, University of Guelph, Guelph, Ont.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View / Download Final Report  [836 KB pdf]

Associated SWEEP/LSP Research

 

 

List By Number | List By Sub-Program

Completed: September, 1990

Key Words:

run-off, infiltration rate, minimum tillage, moldboard plough, no-till, porosity, Guelph Pressure Infiltrometer, erosion, bulk density

Executive Summary

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:
  1. 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.
  2. 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).
  3. To examine the effects of different cropping/tillage systems on changes in surface hydraulic properties.
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.

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 (D. Lobb's).

The detailed measurements at D. Lobb's site indicated that no-tillage (9 yrs) resulted in:

  1. higher bulk density
  2. lower total porosity
  3. lower macro-porosity
  4. lower saturated hydraulic conductivity
  5. lower field saturated hydraulic conductivity
  6. lower matric flux potential
  7. shorter times to ponding and runoff, and
  8. lower infiltration rates (higher runoff)
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.

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.

 

Evaluation Summary

(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 treatments.

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.

Comments:

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.

Associated SWEEP/LSP Research:

  • 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.
 

 

 

List By Number | List By Sub-Program | LSP Report List
SWEEP Home

 

Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 01:59:14 PM