Rory Lewandowski,
Extension Educator Wayne County
With the
arrival of summer we can generally expect warm to hot temperatures and less
frequent rainfall. The vast majority of
pastures managed for grazing in our area are composed of cool season grass
species that grow best when temperatures are cool to warm and moisture is
plentiful. Thus, we have the summer
slump in pasture productivity. Although
summer weather conditions are not conducive to high yields with cool season
grasses there are some grazing management practices that can help to increase
summertime productivity. These practices
can be summarized as the four “R’s”.
The first
“R” is remove seed heads. Clipping off
seed heads in late June will return grass plants to vegetative growth and
improve the quality of the forage that is grazed. The second “R” is right starting height. Do not let livestock into a pasture paddock
where grass height is too short because this is almost certain to lead to
overgrazing. What is the right
height? It depends upon the predominant
grass in the pasture mix. Perennial
ryegrass should be grazed when it reaches the 6 to 8 inch height. Orchardgrass and endophyte free or novel
endophyte tall fescue grass should be grazed starting at an 8 to 10 inch
height. Endophyte infected tall fescue
and Kentucky bluegrass should be grazed when the height reaches 5 to 6 inches.
The third
“R” is residual leaf area. Do not
overgraze pasture paddocks. Pull
livestock out of pasture paddocks while there is still sufficient leaf area for
the plant to continue to photosynthesize.
The general principle that is taught in grazing schools is to take half
the plant and leave half the plant.
Leaving sufficient leaf residual has several benefits. When more than half the plant is grazed or
clipped off root growth is drastically affected and the plant takes longer to
recover from defoliation. Leaving half
the plant allows root growth and function to continue with very minimal
reduction and the plant recovers rapidly from the grazing defoliation. Leaving more residual leaf area helps to
shade the soil. In the summer heat this
can mean cooler soil temperatures and less moisture loss from the soil,
important considerations to keep grass growing.
In general, do not graze below 3 inches in height for perennial
ryegrass, below 4 inches in height for orchardgrass, endophyte free or novel
endophyte tall fescue and do not graze below 2 inches in height for Kentucky
bluegrass and endophyte infected tall fescue.
The fourth “R” is rest period. After a grazing pass allow enough time for
that plant to regrow back to the right grazing height. The length of this rest period is affected by
how much leaf residual has been left, the air and soil temperature, and soil
moisture. Summer pasture rotations need
to slow down because the grass is growing slower. For example, during the favorable
temperatures and moisture conditions of spring and early summer grass is
growing fast and it may have been possible to get back to a pasture paddock
within an 18 to 25 day period for another grazing pass. In the summer the rest period required for
that same plant to regrow to the right grazing height may be anywhere from 30
to 50 or more days. During last summer’s
drought when plants just quit growing in many pastures, the only way to avoid
overgrazing was to stop rotating between paddocks and keep livestock in a
sacrifice area. The only way to maintain
the longer rest periods needed during summer weather is to have enough pasture
paddocks or divisions. Most of the
experienced graziers that I know have at least 10 pasture paddocks or run
multiple pasture divisions as they strip graze across a pasture. I have yet to hear an experienced grazier say
that they regret putting in another pasture division or paddock.
Summer weather can negatively
affect cool season pastures, but following good grazing management practices
can minimize those negative effects. For
more information about pasture and grazing management, contact a member of the
OSU Integrated Forage Team.
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