AN IMPROVED METHOD FOR MEASURING THE GERMINABLE SOIL SEED BANKS OF TROPICAL PASTURES

The accuracy of 2 methods for determining germinable soil seed banks w as compared in soil cores containing known seed loads of 5 tropical gr asses placed on sand columns in pots. A sprayed method watered soil co res for 30 minutes per day, and a capillary method watered cores by ca pillary action from shallow trays. The sprayed method produced signifi cantly (P<0.05) higher seedling emergence than the capillary method an d gave more reliable estimates of seed load. In a second pot experimen t, using soil cores from a grazing experiment, the sprayed method agai n resulted in significantly (P<0.05) higher seedling emergence than th e capillary method. We consider that the sprayed method more closely s imulates the natural process in a field situation, where seeds are sub jected to daily fluctuations in moisture potential rather than being c ontinuously wet, as occurs with the capillary method.