Can salt increase oversowing
success on south facing
hill country?
Agriculture Group
Lincoln University
edwardsg@lincoln.ac.nz
Results
Background
• Shorter pastures with fewer seedheads and more bare
ground where salt applied. Effects persist for more than
12 months.
• Pasture sodium (Na) levels in
herbage DM in inland areas are often
less than the 0.07% required for
sheep maintenance.
• More balansa clover and plantain where salt applied,
although both remain at a low proportion in the pasture.
• Sheep are attracted to Na-deficient
pasture fertilized with salt (NaCl).
• Pasture quality of south facing slopes
is often poor due to low grazing
intensity.
Pasture responses to salt application in the two experiments
Experiment 1
• Oversowing success is limited by
competition from ungrazed tall
grass.
Hypothesis: Application of salt
increases grazing intensity in Nadeficient pasture and this leads to
better pasture quality and more
seedlings establishing.
Methods
Conclusions
• Two experiments conducted in Nadeficient pasture on Mt Grand
(Hawea). Pastures grazed by merino
ewes and lambs.
• Sheep graze intensively where
salt is applied.
• Experiment 1: Salt applied at 0 and
150 kg NaCl/ha in December 2003.
Annual clover seeds (balansa and
subterranean) oversown into each
plot in March 2004.
- shorter resident pasture
• Experiment 2: Salt (0, 100 kg
NaCl/ha) and seed (no seed, mixture
of Caucasian clover, Lotus
pedeunculatus and plantain) spread
in late September 2004.
Ben Gillespie,
Dick Lucas,
Derrick Moot,
Grant Edwards
Experiment 2
Salt rate (kg/ha)
0
150
0
100
Botanical composition (%)
Resident grasses
White clover
Sub clover
Balansa clover
Annual legumes
Plantain
Litter
Dicot weeds
Bare ground
53
14
1
1
12
9
4
4
53
11
1
2
10
8
6
9
63
9
1
0.1
19
3
4
49
12
1
2.3
10
4
22
Balansa flowering plants/m2
7
25
-
-
65
52
117
1
1
10
Seed heads/m2
Cocksfoot
Tall oat grass
Sweet vernal
• Establishment of some species
will be enhanced by
- more bare ground
- seed trampled into the
ground.
• Salt topdressing on
undergrazed, mid slope, shady
aspect pastures will help pasture
improvement in tandem with
subdivision, fertilizer and
grazing management.
CHRISTCHURCH
NEW ZEALAND
www.lincoln.ac.nz
Acknowledgements
Dominion Salt Ltd and Miss EA Hellaby Indigenous Grassland Trust for financial support.
Gordon Meikle, Mt Grand Farm manager.