by P.A. Dalton and P.N.V. Truong
University of Southern Queensland and Queensland Department of Primary Industries,
AUSTRALIA.
Soil moisture competition between Vetiver hedges and crop could affect crop yield. To date
conflicting results have been stated and very few quantitative studies on this topic have
been reported.
This paper presents the effects of Vetiver hedges on soil moisture and sorghum yield under
various growing conditions. Treatments include hedge maturity (mature and newly planted),
soil types (Vertisol and Alfisol) and moisture regimes (dryland and irrigated).
Gravimetric soil moisture and sorghum yield was recorded for each single row.
Under irrigated conditions on both soil types, mature hedges depleted more soil moisture
than the sorghum crop and newly established hedges, but sorghum yield was not
significantly affected by the presence of either mature or young Vetiver hedges.
Under dryland conditions on Vertisol soil, the presence of a mature hedge significantly
depressed sorghum yield of the first two rows adjacent to the hedges. Yield of row 3 and
further was not affected.
The above results indicate that moisture competition does occur between mature hedge and
the first few rows. However crop yield is only affected when soil moisture availability is
very low. Under irrigation or adequate soil moisture conditions, yield of adjacent rows
was not adversely affected by Vetiver hedges.