Rory Lewandowski, Extension Educator Wayne County and Crossroads EERA
Pasture is
an important component for many livestock enterprises. Most of our common pasture forage species are
classified as cool season species. This
includes bluegrass, orchardgrass, tall fescue, brome, timothy, white clover and
alsike clover. These forages grow best
when there is adequate moisture, air temperatures in the 50 to 70 degree range
and soil temperatures in the 50 to 65 degree range. I bring this up because our current weather
pattern and the extended forecast are definitely not bringing about conditions
for optimum production. In hot, dry
conditions good pasture management is needed to keep cool season pastures productive.
When the weather is hot and dry it
is critical that pastures not be overgrazed.
In grazing schools we talk about the “take half, leave half”
principle. In most cases, a good
starting grazing height is 8 to10 inches of growth. Remove animals from a pasture paddock when
average pasture forage height is about 4 inches. The remaining leaf area provides the “solar
collector” surface that allows the photosynthetic process to keep going and to
keep the plant growing.
Studies have demonstrated that the percentage
of top growth removed is correlated with root mass and growth below the
surface. When 50% of the top growth is
removed the root mass and growth is only negatively impacted by a few
percentage points. However if 60% of the
top growth is removed, the root mass is reduced by about 50%, significantly
impacting the regrowth of the plant as well as nutrient and water
absorption. If 80% of the top growth is
removed, the root system is shut down and essentially has to start growth all
over.
In hot, dry weather leaving more
plant cover is better. In addition to
keeping the photosynthetic process going and the root system fully functioning,
that leaf cover acts like a mulch to keep the soil temperature cooler and
reduce moisture loss from the soil. This
is important with cool season forage species when a few degrees difference in
soil temperature could determine if the plant will go into dormancy or continue
to grow.
Some pasture managers like to keep seed
heads clipped off the grass plants to keep the plant in the vegetative state
and produce higher quality forage. I
have often seen pastures clipped off at 2 to 3 inches in height. During many of our typical springs with cool
temperatures and good moisture the plant can handle this stress. However, in hot, dry times it is more
important to keep the plant residue so pasture managers may want to tolerate
some seed heads or clip high at around 5 inches.
Hot, dry weather leads to slower
pasture growth. As grass growth slows
down, the temptation is to speed up the pasture paddock rotation. Actually just the opposite is needed. When pasture growth slows down, pasture
rotation must slow down to insure that each paddock has enough time to recover
to a beginning grazing height of 8 to 10 inches. The only way that this can be accomplished
without staying too long in a paddock and overgrazing that paddock is to have
multiple pasture divisions or paddocks.
To protect pastures and manage through hot, dry periods, the livestock
owner needs at least 8 to 10 paddock divisions.
In order to keep cool season
pastures productive the livestock manager must look ahead at pasture growth and
keep an eye on extended weather forecasts.
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