Effect of various soil amendments on soil pH and exchangeable Ca at different depths in the identification of a suitable liming material for tannia (Xanthosoma sagittifolium L. Schott) in an Ultisol, Kerala, India

Abstract

Tannia (Xanthosoma sagittifolium L. Schott) is an important tropical tuber crop coming under the groupof aroids. It is usually grown as intercrop in plantations and fetches good remuneration. When thiscrop is grown in the acid laterite soils (Ultisols), widespread occurrence of Mg deficiency was verycommon resulting in the complete devastation of the crop. The reason attributed was the acidity due toexcess Al3+ions in the subsoil layers which causes the decay of roots and hence adversely affecting theabsorption of water and nutrients. This crop being an indicator plant for Mg deficiency, the symptomis manifested as interveinal chlorosis coupled with drying of the whole plant. The present study wasundertaken to screen a better soil amendment to tackle the problem of subsoil acidity induced multinutrient disorder in tannia. The present study was done using five liming materials viz., calcite, dolomite,gypsum, calcium silicate and calcium oxalate at quantities ranging from 50-1000g both under controlledcondition in lysimeter and in field. After application of treatments, soil samples drawn continuously for6-7 months from four different depths viz., 0-15, 15-30, 30-45 and 45-60 cm were analysed for pH,CEC and exchangeable Ca. The data generated were statistically analysed for the independent andinteraction effect of treatments (liming materials, rate of application, depth of sampling and intervalafter application) and results on the mean effect, changes over initial and at the end of 6-7 months ofapplication with respect pH and exchangeable Ca for the above treatments were described. The resultsfrom both situations revealed that, calcite, dolomite and gypsum were equally effective. Among thethree, dolomite being a source of both Ca and Mg, even at lower quantities as 250 g was found betterin enhancing both pH (1.54 units over initial) and exchangeable Ca (1.559 cmol (+) kg soil-1 overinitial) to the maximum extent especially at lower depths up to 60 cm to a period of 4-5 months afterapplication.