- L. Leskiw, A. Laycock, Can-Ag Enterprises, Guelph, Ontario
Evaluation Summary (Tech. Transfer Report Summaries)
View / Download Final Report [1104 KB pdf]
Associated SWEEP/LSP Research
Completed: September, 1990
post-emergence subsoiling, B.C. Sub-mulcher, corn, yields, compaction,
Twelve farmers from Kent County in southwestern Ontario co-operated in this
study to observe the effect of subsoiling on corn yields and soil conditions.
(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)
This study focused on the subsoiler performance in the soil layer below
the plow depth (i.e. about 15 to 30 cm below ground surface). This region
within the soil profile is where compaction can occur. Soil compaction may
include one or more of these conditions: degraded soil structure; reduced
size, abundance and continuity of vertical cracks and pores; smearing; increased
soil bulk density; layering; and, altered rooting pattern and depth. These
conditions tend to reduce the soils' ability to produce abundant crops due
to deterioration of root zone quality. Soil permeability is also reduced
and this results in increased runoff and erosion.
A previous Can-Ag compaction study indicated that about 50 to 70 percent
of the clay to clay loam soils in several southwestern Ontario counties
are affected. Of this total, about 25% are severely compacted and 75% are
moderately affected resulting in crop yield reduction, increased soil erosion,
and increased phosphorus loadings to the Great Lakes.
The purpose of the study was to evaluate the B.C. Sub-mulcher, a narrow
shank subsoiler, pulled through corn rows at depths of 18 and 31 cm in June
of 1988. Not only did we look at the soil and plant response to the subsoiling,
but also to determine what other management practices may affect soil compaction
Measurements of Compaction
Several methods are used to measure soil compaction and five of the more
popular ways were used in this study: visual observations of a combination
of factors, bulk density determinations, hand and cone penetrometer measurements
and detailed descriptions of soil peds and pores (tubular and planar).
The degree of compaction was assessed using two kinds of statistical analyses;
a Pearson Correlation matrix and an analysis of variance. The ANOVA established
differences among subsoiling treatments with respect to yields and measured
soil properties. The Pearson Correlation matrix was made to examine correlations
among various parameters measured and described.
The 1988 growing season lacked significant rainfall which contributed to
below average yields. These abnormally dry conditions were excellent for
the subsoiling operation but caused some yield loss in the subsoiling test
Results indicate that shallow (18 cm) subsoiling was detrimental to yields:
deeper subsoiling did not, on the average, have any effect. However, in
the sites determined to be severely compacted, yields responded very favourably
to deep subsoiling.
Subsoiling improved soil conditions, though these improvements were confined
to a 20 cm width centred over the shank path.
An interesting management correlation showed an increase in yields with
an increase in field operations, even though this has the potential to increase
compaction. The dry season probably was the major factor for this observation.
Since there was not any extensive periods of wet soil conditions during
critical times for field operations, compaction associated with these operations
did not occur. This points out the importance of proper timing of field
operations in conjunction with soil conditions.
A few recommendations arising from this study concern the use of a post
emergence subsoiler, especially in a dry year. These include:
- pulling a packer behind the subsoiler to close the openings left by
the subsoiler shanks to reduce moisture loss through evaporation;
- the use of a subsoiler after wheat harvest where the soil is dry and
there is no resulting moisture stress on a crop; and
- further research on subsoiling timing and effects of implement design.
A one year subsoiling trial was conducted in June 1988 in corn at two depths,
18 cm and 31 cm using a B.C. Sub-mulcher in the Kent County area. Five different
methods were used to assess soil compaction including visual observations,
bulk density, hand and cone penetrometer measurements and detailed descriptions
of soil peds and pores.
Soil conditions were dry at the time of subsoiling and continued dry
for the remainder of the growing season. Shallow subsoiling (18 cm) reduced
corn yields while deeper subsoiling did not, on average, have any effect.
Two sites were determined to be severely compacted, yields did increase
with the deep subsoiling. Soil conditions were improved in a 20 cm wide
strip in the area of the shank path.
This study was limited to one season only. Other compaction studies would
suggest that improvements in soil conditions as a result of subsoiling are
normally short lived.
The effect of subsoiling is highly dependent on soil moisture conditions
at the time of subsoiling and during the following growing season.
- SWEEP Report #4 - Assessment of Soil Compaction
and Structural Degradation in the Lowland Clay Soils
- SWEEP Report #24 - Investigation of Soil and
Crop Response to Fall Subsoiling in Southwestern Ontario
- LSP 7002 - Management of Fine Textured
Poorly Drained Soils for Intensive Agriculture
- LSP 7006 &
LSP 7007 - Management of Fine Textured
Poorly Drained Soils For Intensive Agriculture: Characterization of a Forage
Factor which Enhances the Growth of Corn in Rotation - Parts I and II
- LSP 7012 - Improving the Degraded
Structure of Fine Textured Soils with Deep Tillage and Grass and Legume
- LSP 7013 - Improving the Degraded
Structure of a Clay Loam Soil with Deep Tillage and Grass and Legume Crops
- LSP 7015 - Crop Production with a
No-Traffic Tillage System
Future Research: ( ) indicates reviewers suggestion for
priority, A - high, C - low.
Thursday, May 19, 2011 01:55:43 PM