TITLE:
An Assessment of Irrigation Water Quality and Selected Soil Parameters at Mutema Irrigation Scheme, Zimbabwe
AUTHORS:
Abel Chemura, Dumisani Kutywayo, Tapiwanashe M. Chagwesha, Pardon Chidoko
KEYWORDS:
Mutema; Irrigation Scheme; Salinity; Irrigation Water Quality; SAR; ESP
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.2,
February
25,
2014
ABSTRACT: Soil salinity and
sodicity are major factors limiting agricultural productivity in irrigation
schemes located in semi-arid areas. A study was conducted to assess the quality
of irrigation water used in Mutema Irrigation Scheme located in south-east
Zimbabwe to understand how irrigation water quality is related to the chemical
quality of soils in the scheme. Irrigation water samples were collected from
groundwater and surface sources in 2012 and their hydrochemistry determined
while soil samples were collected from irrigated and non-irrigated parts of the
scheme in 2006 and 2012 and analysed for selected chemical properties. The
results indicated that the groundwater had high concentrations of Na+ (4.35 mg/l), Mg2+ (4.75 mg/l), Cl- (3.6 mg/l) and Electrical Conductivity (EC) (1729 Msm/cm) compared to the surface
irrigation water source which had 0.72 mg/l Na+, 2.25 mg/l Mg2+, 0.78 mg/l Cl- and 594 Msm/cm EC. The soils in the scheme had
higher levels of pH, Sodium Adsorption Ratio
(SAR), Exchangeable Sodium Percentage (ESP) and EC which in some blocks exceeded
the threshold requirements for cropping. It was found that pH, SAR and ESP were
significantly higher (p ) in
irrigated blocks compared to non-irrigated areas of the scheme, indicating an
influence of irrigation water on soils characteristics in irrigated plots. Mg2+ and Ca2+ in the soils positively correlated with Na+ (r2 = 0.67 and r2 = 0.57 respectively). The results indicated that the
groundwater presents a chloride hazard to the soils in the scheme which are
becoming saline and therefore require proper management and choice of crops to
sustain crop production.