Some Results of Field Experiments to Test Lime and Phosphogypsum for Aluminium Amelioration

Since 1985 two series of field trials have been conducted or established to assess the value of lime and phosphogypsum for the amelioration of aluminium toxicity. The first series considered their use on weak, coastal sandy soils and the secondconcerned their use on midlands' acid soils with high clay and organic matter contents and under the minimum tillage system. On weak sandy soils the overriding limitingfactorto sugarcane growth wasshown to be parasitic nematodes, and there was little if any response to the application of lime and/or phosphogypsum. In the second series on acid soils there has, to date, been little evidence of responses to lime or phosphogypsum applied as surface, shallow or deep incorporated treatments. Varietal differences may playa role in explaining the lack of response to lime.