Short-term effects of chemical and mechanical cover management and decomposition processes in a grassland soil.
In a randomized plot experiment on Festuca arundinacea grassland on alluvial loam soil during 1968, plots were mowed and raked bi-weekly, mowed and sprayed with dalapon (to kill shoots and roots) or merely sprayed with dalapon. Sapro-phytic mites were unaffected by cover manipulations, but soil Apterygota and predatory-parasitic mites were apparently reduced in number by the high temperatures and low moisture content occurring in soil of denuded plots. On plots where fescue was killed, irrespective of whether the dead cover was removed, soil bacteria increased in number corresponding to enhanced rates of organic-matter decomposition. Evidence was found that living fescue produces toxic substances, explaining in part the proliferation of bacteria when the vegetation is killed. This suggests that a factor of primary importance in the responses of soil organic-matter decomposition to cover management is the presence or absence of vegetation producing bacterial-inhibiting compounds. The elimination of such plants by management techniques, may greatly accelerate the decomposition of organic matter, possibly accelerating mineralization processes.