Late in 1961, the Arrowhead Country J Club in San Bernardino County requested Extension Service assistance in its program of green replacements and repair. Two greens had a characteristic surface soil stratification, traffic compaction, impaired root penetration and health. The anaerobic soil condition was sufficiently severe that the cores developed a strong odor after exposure to the atmosphere for 20 to 30 minutes. One green was selected for replacement, and the other, Green No. 4, was selected for repair and rejuvenation tests.