Impact of Organic-amended Surface and Sub-surface Soil Layers on Cumulative Evaporation, Water Redistribution and Conservation in Sandy Soil Columns*

Abstract

A glass house sandy soil column experiment was conducted for
three months to investigate the impact of organic amendments on
cumulative evaporation, water redistribution and conservation. The
treatments consisted of a control and three organic amendments: chicken
manure (CHM); dry sewage sludge (DS) and farm yard manure (FYM),
each incorporated in two soil depths: 0-5 and 25-30 cm, at a rate of 20
ton/ha. The treatments were arranged in a randomized complete block
design with three blocks and seven treatments. The results show that the
weekly, monthly and overall rate of evaporation was consistently in the
following order: control > sub-surface organic-amended layer > surface
organic-amended layer. Consecutively, the surface and subsurface organic
amendments significantly (P  0.05) reduced the overall cumulative
evaporation (TEc) by 38.5% and 31.9% for CHM, 37.9% and 29.1% for
DS, and 36.5% and 33.5% for FYM. The soil moisture distribution in the
control columns depicted initial increase in moisture content followed by
leveling off thereafter, whereas that of the surface organic-amended soil
columns were mirror image of that of the control columns. The subsurface organic amendment showed a distribution curve with maximum
soil moisture content at the amended depth. The soil water conserved in
the soil columns ranged between154% and 171% due to surface
application and between 199% and 324% due to subsurface application of
organic amendments. Farm yard manure proved to be superior because of

*
Part of an M.Sc. thesis submitted by the second author to the University of Khartoum
2
Professor of Soil Physics
3
Former M.Sc. student