New Zealand Journal of Agricultural Research abstracts
Effects of cattle treading and natural amelioration on soil physical properties
and pasture under dairy farming in Southland,
New Zealand
J. J. DREWRY
AgResearch
C/- Soil and Physical Sciences Group
Soil, Plant and Ecological Sciences Division
P. O. Box 84
Lincoln University
Canterbury, New Zealand
R. J. PATON
AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
Abstract The effects of current dairy cow grazing practice,
reduced levels of grazing, and stock exclusion on soil physical properties and
pasture dry matter production were investigated under dairy farming in
Southland. Current grazing practice involves rotational grazing with dairy cows
from September to May each year, with no grazing during winter. For the reduced
grazing treatments, cattle were excluded during the 3rd, or combined 3rd, 4th,
and 5th grazing cycles, or for half-day grazing intervals to reduce grazing
intensity. Macroporosity increased by 70% in the ungrazed treatment compared
with current grazing practice (control) within four months of dairy cow
exclusion. Air permeability was increased by over two orders of magnitude 18
months after trial commencement, and saturated hydraulic conductivity increased
by 200% to the 10-cm soil depth. Macroporosity, air permeability, and hydraulic
conductivity for the reduced grazing treatments were intermediate between the
control and ungrazed treatments. Relationships between macroporosity and
pasture relative yield are presented. At 97% relative pasture yield, the level
of macroporosity was 11.5-11.7% (v/v) in three silt loams.
Keywords compaction; treading; macropores; air permeability;
hydraulic conductivity; pugging; cattle
New Zealand Journal of Agricultural Research, 2000, Vol 43: 377-386
0028-8233/00/4303-0377 $7.00/0 (c) The Royal Society of New Zealand
2000
PDF file of entire paper: medium quality (754K); (scanned from paper original: notes about this process)
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