|August 11, 2005,
ARS News Service: Giving forage plants, as well
as animals, some shade from trees could be profitable
for farmers, especially those farming marginal lands.
Soil scientist Charlie Feldhake, agronomist Dave Belesky
and animal scientist Jim Neel of the Agricultural Research
Service (ARS) are in their fourth year of raising lambs
on oak and conifer silvopastures, combinations of forages
and trees growing together on the same land. Belesky
heads the team of scientists at the ARS Appalachian
Farming Systems Research Center in Beaver, W.Va.
The scientists have found that some plants do better
under moderate shade than in traditional open pastures.
For example, Neel found that moderately shaded forage
has more protein than forages on open pasture during
the heat of July and August.
Silvopastures also seem to buffer drought and other
seasonal extremes. Feldhake found that this buffering
includes helping forage plants warm up about two weeks
earlier than usual in the spring and to stay warm enough
in late fall to hold off the hard frost for about two
weeks. These effects are greatest under conifers.
This means silvopastures could provide another four
weeks of forage growth and grazing time. The extra warmth
in cool seasons comes from thermal radiation trapped
and returned by the tree canopy.
The silvopastures are designed carefully, from the
size of the trees to the amount and quality of sunlight
allowed to reach the forest floor. The sites have instruments
to monitor light, soil temperature, wind speed, precipitation
and soil moisture.
The amount of light-buffering from tree shade has to
be just right--not too much or too little. Researchers
in other regions have found that tall fescue and orchardgrass
grown in moderate shade yield better than those grown
in heavy shade. Neel has found that pasture plants do
best in up to 25 percent tree shade in the frequently
cloudy Appalachian Region.
Read more about the research in the August 2005 issue
of Agricultural Research magazine, available online