Further results of studies on the rejuvenation of exhausted soils in humid districts by incorporating basalt dust.
O. D’Hotman de Villiers
ABSTRACT:
Results are republished of the 1938-41 experiments conducted in Mauritius with powdered basalt and heavy NPK fertilizer applications on sugar-cane crops grown in exhausted lateritic soil. With these are compared the results of the 2nd series of experiments (1944-47) on the same plots, in which, after a bare fallow of 23 months, moderate N and minimum P and K applications were combined with 10 metric tons/arpent of powdered basalt. The 1937 basalt dressings had been 10, 30 and 90 metric tons.
Results show a striking residual benefit, especially from the highest basalt application, affecting both cane and sugar yields. This was in spite of very heavy rainfall during the long fallow, and disastrous cyclones during the 2nd series. The conclusions are that the silica of the basalt, through chemical and biological action, formed non-leaching compounds with the sesquioxides of the soil and that hydrolysis of some of the fine basalt particles provided readily available minerals for the crop roots. Even in the 8th year after the original heavy application, residual benefits were by no means exhausted.
