Soil permeability in the Eastern Gezira

Abstract

An account is given of studies of moisture content in the field. The results are in agreement with Joseph's (1) view that the relation between salt content and fertility is chiefly due to the effect of sodium salts on soil texture. At the Gezira Research Farm a single watering moistens only the top 3 ft. of soil, although in the course of an irrigation season some small percolation continues below this depth. The water requirement of cotton in this region is extremely high and danger of water strain is correspondingly acute. The effect of 14 days' flooding is taken as a measure of permeability in the field and this test was applied with confirmatory results to two areas whose agricultural value had previously been gauged both by laboratory studies and by field observation of the soil profile. The genesis of the Gezira soil is briefly discussed with regard to the relation between salb content and fertility and with regard to the use of gypsum as a corrective. Marked improvements in permeability have been brought about by applications of this substance. I am indebted to Dr A. F. Joseph, under whose direction this work was done, for his useful suggestions and for facilities placed at my disposal.