Improving the Degraded Structure of a Clay Loam Soil
with Deep Tillage and Grass and Legume Crops
Researchers: W. Curnoe, KCAT, J. Culley, L. Heslop and N.
McLaughlin, Agriculture Canada, Principal Researchers
- To develop agronomic practices which restore the productivity
of fine textured soils which have been seriously degraded as a result
of continuous corn cropping with conventional tillage.
- To provide primary producers with good quality information from
which they will be able to evaluate benefits and costs related to
crop-based and tillage-based remedial measures for improving degraded
A no-tillage system was imposed on a structurally degraded fine-texture
soil (Humic Gleysol) that had been under continuous corn with moldboard
tillage for more than 20 years. After 3 years of no-tillage, several
soil structural properties were compared with the conventional tillage
treatment to assess whether the soil structure had improved.
No significant difference (P < 0.05) was found between tillage treatments
for the saturated hydraulic conductivity, porosity and penetration resistance
in the surface 5 cm. Measurements of soil penetration resistance and
in situ saturated hydraulic conductivity (Kwp) using the
well permeameter method were sensitive structural changes that had occurred
at 5-20 cm depth. The Kwp at this depth was significantly
greater in the moldboard treatment than in the no-tillage treatment.
Resistance measurements indicated significantly greater soil strengths
at 10-20 cm under no-tillage. Aggregate stabilities were assessed by
wet sieving twice during the growing season. No-tillage resulted in
larger soil aggregates, especially at the surface, compared with the
These data suggest that degraded soils with low structural stability
may initially suffer further deterioration with the elimination of tillage,
owing to the loss or reduction of mechanically formed pores.
Tuesday, May 10, 2011 12:55:49 PM