Transcript Prairie Grass management - Dairy Fertility Investigator

Lydia Turner
The Secrets of Prairie Grass Revealed
Question
Prairie grass can help fill the summer feed gap but how do I manage it to optimise yield
and persistence ?
Investigation
Findings
The study showed that after
prairie grass plants were cut,
energy reserves moved to
leaves first, roots second and
tillers third. Root growth
stopped when plants were cut
and recommenced at the 3-leaf
stage of regrowth. New tillers
emerged at the 4-leaf stage of
regrowth.
Conclusions
Stubble WSC (g/kg DM)
A glasshouse study was carried out to measure the changes that take place in prairie
grass during regrowth. Water soluble carbohydrate (WSC) energy reserves, tiller number
and plant yield were measured when each new leaf appeared (leaf stage).
400
Tillers
350
Roots
300
250
200
150
100
50
0
Pre
1
2
3
4
5
6
Leaf regrowth stage (leaves/tiller)
Diagram showing the increase in stubble WSC
energy reserves, and timing of root growth and
tillering during regrowth.
Grazing prairie grass pastures repeatedly before the 3-leaf stage of regrowth is detrimental
for plant persistence, as it is likely that root growth has not restarted (limiting plant
anchorage and uptake of nutrients and water) and tillering has not occurred (limiting
reproductive capacity).
The secret to maintaining productive
and persistent prairie grass pastures is
grazing management.
Grazing at the 4-leaf stage of regrowth,
combined with allowing the pasture to
set seed in spring every second or third
year will optimise the potential of
prairie grass as a dairy pasture species.