Two weeks after irrigation there was a temporary water-table between 30 and 127 cm. below the soil surface in four different parts of a grapefruit orchard. As the temporary water-table rose closer to the soil surface the percentage of soil water in the root zone increased and tree size, number of leaves per branch, and leaf size all decreased. Shallow water-tables also induced more die-back and reduced yields significantly. Analyses of soils at various sites indicated that there was no problem of salinity or alkalinity, but physical soil analyses showed that the percentage of clay increased with increased shallowness of the water-table, in line with the soil moisture characteristic curves.
(Accepted December 14 1973)
p1 Present address: Department of Horticulture, Faculty of Agriculture, University of Khartoum, Sudan.
p2 Present address: University of Alexandria, Egypt (temporarily at Agricultural Research Corporation, Sudan).
p3 Present address: Department of Horticulture, Faculty of Agriculture, University of Khartoum, Sudan.