The Root-System of Sisal in Some East African Soils

Abstract

During 1937-38 a field investigation was made of the root-system of sisal in relation to some typical soils on which it is grown in East Africa. The root-systems of the plants were excavated by means of water jets provided by a powerful motor-driven pump. A vertical sector of the root-system was obtained by washing away the soil from the roots in the vertical face of a trench extending from the base of the plant to a distance of ten or more feet away. As a check the whole root-system of several plants was excavated, and it was found that the trench isector method gave a reliable indication of the whole. Hand excavation was resorted to if the water method failed owing to the hardness of the soil. -As-the roots were exposed they were pegged in position and drawn to scale with the aid of a string grid of one foot squares. After preliminary trials on plants of various ages, those of the age group 4+ to 5+ years were chosen as having attained their maximum development. In one area, plants of twenty years of age were investigated. Plants were chosen us good specimens for their locality. They had all reached a height of 5 ft. above ground, except on certain poor soils (Nos. 2 and 6). The field spacing in all cases was 2.5 metres x 1 metre. They had all been cleaned twice annually by cutlassing the weeds between the rows.