Abstract:
Twenty surface soils representing four major rice soil types of Keraia viz., the
Kari, Karapadom, Kayal and low level laterites were extracted with different extractants
viz.. one normal potasium chloride at different soil solution ratios, one
normal ammonium acetate adjusted to different pH values and water and the
alluminium estimated. Based on the results, one normal potasium chloride with
a soil solution ratio of 1 :10and water were adjudged to be good for predicting
toxic levels of Al in this soils. The result obtained further indicate that most
of the Al extracted is of the exchangeable type in the case of Kayal and low
level laterite soils, while it is not so in the case of Kari and Karapadom soils.
The results of the present investigation thus project the need for a very
systematic evaluation of the extractable Al content of the highly acid rice soils
of Kerala in relation to the existence of Al toxicity to the rice crop.
