| Summary: | Preliminary effects of application of dolomitic limestone on growth and nutrient status of two different <i>Camellia sinensis</i> L. (tea) species, and on soil status in two Sri Lankan acid soils were investigated. The concentration of Mg in the leaves of TRI 206 species, grown under low-country climatic conditions, increased but Mg concentration was unaffected in CY9 species, grown under up-country climatic conditions. Dolomitic limestone had no effect on the yield of bud, and first and second leaves which are harvested for the production of made-tea. Ten representative profiles of Sri Lankan acid tea soils overlying dolomitic mineral belts and six profiles from different climatic regions were subjected to a detailed mineralogical investigation. No Mg bearing minerals were found to a depth of 75 cm, even at dolomitic sites. The release of Mg from six Sri Lankan acid tea soils was measured by intensive cropping with ryegrass. A minimum one fifth of total Mg uptake was obtained from non-exchangeable Mg forms in the soil, except St. Coombs top soil. Soils that contained less than 9 mg Mg kg<sup>-1</sup> initial extractable Mg released 2.0 to 13.2 mg non-exchangeable Mg kg<sup>-1</sup> of soil. The effect of Mg and Ca addition supplied in liming and non-liming materials on the growth of <i>Camellia japonica</i> in an acid soil was studied. Magnesium was taken up by <i>Camellia japonica</i> plants in preference to Ca when Mg and Ca were added. The amounts of soil nutrients extracted with mixed resin and ammonium acetate solution were compared with their uptake by <i>Camellia japonica</i> plants. Both methods extracted similar amounts of Mg and Ca but in limed soil the amount of Al taken up by plants was more closely related to ion-exchange resin Al values than ammonium acetate solution adjusted to the pH of the soils.
|
|---|
