BIOLOGICAL STUDIES OF SOILS IN PAIRED OLD AND NEW LAND SITES GROWING SUGARCANE

The growth of sugarcane in soils from land monocultured with sugarcane , and from land which had either never been cropped with sugarcane, or just recently cropped, was compared under glasshouse conditions. In g eneral, cane growth in new land soils was greater than in monocultured soil (shoot growth 7.4%, root growth 21.4%). Responses to soil pasteu risation were investigated in some soils and were greater in monocultu red soils suggesting that root growth constraints were larger in the m onocultured soil (210% response in monocultured soils v. 64% in new la nd soils). Assays for sugarcane root pathogens suggested that Pachymet ra chaunorhiza was a major contributor to the old/new land growth resp onses, but it is unlikely that Pythium spp. were factors in the growth differences. Monitoring of other groups of organisms in soil from one site suggested that sugarcane monoculture may affect populations in t he broader biological community.