THE IMPACT OF ACID FORMING MATERIALS ON PLANT-GROWTH ON RECLAIMED MINESOIL

A field study showed that reclaimed minesoil that produced high forage yield contained zones of soil with pH values below that considered op timum for good plant growth. Minesoil that produced lower dry matter y ield had lower soil pH values and higher plant tissue Al and Mn concen trations. An intensive soil sampling scheme provided a dataset (>4500 soil samples) that quantitatively evaluated variation in soil acidity and root distribution in the field. More than 16% of the samples in a high yield plot had pH values below 5.5 and few roots. There was consi derable microvariability in pH readings for a high yield plot, due to oxidation of FeS2 or application of CaCO3. Geostatistical analyses of the data indicated short order variation of soil acidity and plant roo t distribution in minesoil. Field results show that plant roots will a void zones of high soil acidity and that adequate yields of crops can be obtained if the soil acidity is randomly distributed and occupies a relatively low proportion of the total minesoil volume.