Silvopastures on marginal sites

[Brett Chedzoy]

A friend recently inquired if it would be possible to convert her low site-index oak/white pine woods into silvopatures to expand the grazeable acreage on her cattle farm.  Most any site can be managed to grow forages and browse for livestock grazing, but not every site can grow enough food to make the investment worthwhile.  Another consideration is the senstivitiy of the site, particularly in the case of steep slopes or poorly drained areas. 

One approach to answering the question "should I?" is to conservatively estimate all of the likely benefits (increased grazing days, increased shaded grazing, improved timber management, invasives control, greater production to amortize fixed costs, etc) as well as an honest estimate of all of the costs (fencing, water, net thinning costs, etc).  If the ratio appears to be positive, then it probably makes sense to develop a given wooded area into silvopasture.  However, there may be additional barriers on low-quality sites that are difficult to overcome.  On poorly-drained sites, for example, the "window" for suitable ground conditions may be so narrow that total forage growth over the course of the season can't be efficiently harvested by livestock and the site may become overgrown with undesirable plant species due to low grazing pressure.  There may also be added risks such as increased incidence of foot rot or deer worm.

On the other hand, a droughty, low-pH site with low soil fertility (such as the oak/pine stands mentioned above) may need soil ammendments and disturbance of the oak leaf litter in order to grow enough quality forage - and will there be enough soil moisture to grow the forage when it's really needed?  These are all case-by-case decisions that have to be made.