|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
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 at: http://www.ars.usda.gov/is/AR/archive/aug05/sylvan0805.htm