diff --git a/include/osgTerrain/GeometryPool b/include/osgTerrain/GeometryPool
index e166875f5..8cf2e5992 100644
--- a/include/osgTerrain/GeometryPool
+++ b/include/osgTerrain/GeometryPool
@@ -110,6 +110,9 @@ class OSGTERRAIN_EXPORT GeometryPool : public osg::Referenced
 
         void applyLayers(osgTerrain::TerrainTile* tile, osg::StateSet* stateset);
 
+        void setUseGeometryShader(bool flag) { _useGeometryShader = flag; }
+        bool getUseGeometryShader() const { return _useGeometryShader; }
+
     protected:
         virtual ~GeometryPool();
 
diff --git a/src/osgTerrain/GeometryPool.cpp b/src/osgTerrain/GeometryPool.cpp
index 242e367bc..267b58059 100644
--- a/src/osgTerrain/GeometryPool.cpp
+++ b/src/osgTerrain/GeometryPool.cpp
@@ -44,6 +44,19 @@ const osgTerrain::Locator* osgTerrain::computeMasterLocator(const osgTerrain::Te
 GeometryPool::GeometryPool():
     _useGeometryShader(false)
 {
+    const char* ptr = 0;
+    if ((ptr = getenv("OSG_TERRAIN_USE_GEOMETRY_SHADER")) != 0)
+    {
+        if (strcmp(ptr,"OFF")==0 || strcmp(ptr,"Off")==0 || strcmp(ptr,"off")==0 ||
+            strcmp(ptr,"FALSE")==0 || strcmp(ptr,"False")==0 || strcmp(ptr,"false")==0)
+        {
+            _useGeometryShader = false;
+        }
+        else
+        {
+            _useGeometryShader = true;
+        }
+    }
 }
 
 GeometryPool::~GeometryPool()