Wettabifity of Soil under Different Plant Covers

Alluvial soils (Typic Eutrochrepts) under six different plantations, viz. Leucaena (Subabul), teak, chir, bamboo, sal and eucalyptus were characterized for their wettability using the indices such as waterdrop penetration time, liquid-solid contact angle and critical surface tension. Soils undereucalyptus plantations exhibited water repellent characteristics whereas those under Leucaena were highly wettable. Organic mattet extract from soils under eucalyptus when added to other soils rendered them water repellent. The greater fraction of insoluble humic acids as compared with lower amount of water soluble fulvic acids in soils undereucalyptus and the fatty acids present in the waxy leaves of eucalyptus making complexes with exchangeable ions and coating soil particles seem to be causes of water repellency in soils.