Twelve soils derived respectively from basalt,granite and marine deposit in the western parts of Guangdong Province were collected and for planting grass (Coastcross-1 Bermuda grass) in the greenhouse.Magnesium deficiency symptoms with chlorotie spots appeared in grass growing in the soils derived from granite and marine deposit,and plants responded well to magnesium fertilizer.Grass growing in soils derived from basalt showed no symptoms of magnesium deficiency,and did not respond to magnesium fertilizer.Incipient symptoms of magnesium deficiency appeared when the grass contained 0.15% Mg or less.Magnesium fertilizer had no strong influence on N,P and K concentration in the grass.But in magnesium deficient soils it made the grass grow well and increased the total N,P and K uptake of the grass significantly.