Groundwater quality is an inevitable factor for sustainable
agriculture as a source of irrigation water. Therefore, the study was conducted
in an irrigated sand dune area of northwest Honshu island in Japan to evaluate
the groundwater quality for irrigation. Three observation wells were installed
in the investigated field made of Poly Vinyl Chloride (PVC) pipe with three
plastic tubes to collect groundwater of 2.0, 2.5 and 3.0 m. The sampling was performed
every month from January to November, 2005. Assessment
of groundwater quality was performed on the basis of Total Dissolved Solids
(TDS), concentration of sodium (Na), calcium (Ca) and magnesium (Mg), Sodium
Absorption Ratio (SAR), total hardness (HT) and concentration of phosphate
phosphorus (PO4-P). Total dissolved solids in
groundwater was ranged between 145.5-249.4 mg
L-1 during the investigation period,
revealed that irrigation using groundwater of the study area would not cause
salinity hazards. Cocentrations of Na, Ca and Mg were decreased with depth
throughout the investigation period. The average concentration of Na and SAR
value were 18.8 mg L-1 and 0.81, respectively. Since
groundwater of the study area contained low concentration of Na with low SAR
values, there would not be any possibility of sodium hazards from irrigation
using groundwater. On average groundwater of the study area contained 27.5 mg L-1 Ca and 9.35 mg L-1 Mg, which might contribute to
moderate hardness of groundwater in the study area.