| Popis: |
Effect of soil compaction on the growth and activity of coconut (Cocos nucifera L.) roots in two soil series, namely, Andigama series (gravelly soil) and Madampe series (sandy loam soil) was studied. The effective root zone of coconut in relation to water absorption process under natural soil compaction were also investigated. Soil compaction and soil moisture absorption ability was determined using cone penetrometer and neutron scattering methods, respectively. Coconut root distribution in Andigama and Madampe series showed that 75%-80% of roots of adult coconut palms were localised in a depth ranging from 20 cm to 100 cm. About 5% of the roots were located beyond the 100 cm depth and 15%-20% was confined to the top layer (0-20 cm) of soil. Root growth of coconut in the two series did not show any significant differences. However, the root activity in the Madampe series, with respect to moisture absorption was higher than that of the Andigama series due to low compaction of the former. Results also showed that soil compaction higher than 250 N/cm2 restricted the activity of coconut roots in the Andigama series for moisture absorption up to a distance of 2 m away horizontally from the base of the tree and the highest moisture extraction was observed at 1 m distance. High moisture extraction by coconut roots was confined to a depth ranging of 20 to 120 cm and of 20 to 250 cm in soils of Aruligama and Madampe series, respectively, due to differences in soil compaction levels. It was concluded that soil compaction limits the water absorption ability of coconut roots vertically from the base of the tree, rather than coconut root growth and penetration. |
