Premium
Soil Salinity and Exchangeable Cations in a Wastewater Irrigated Area, India
Author(s) -
Biggs Trent W.,
Jiang BinBin
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0247
Subject(s) - salinity , soil salinity , wastewater , irrigation , environmental science , soil water , agronomy , groundwater , cation exchange capacity , sodic soil , hydrology (agriculture) , environmental engineering , geology , soil science , biology , oceanography , geotechnical engineering
The salinity and cation composition of water and soil were documented in a large (98 km 2 ) wastewater‐irrigated area (WIA) downstream of Hyderabad, India. The wastewater, which flows in a river that passes through the city, had a high to very high salinity hazard (EC = 1.1–3.0 dS m −1 ) that increased with distance from the city. The EC of soil irrigated by wastewater sampled within 8 km of the city was 6.2 to 8.4 times the EC of soil irrigated by uncontaminated groundwater. Between 57 to 100% of soil samples in the upper 10 cm within 8 km of the city exceeded the salinity tolerance of rice ( Oryza sativa L.). Soil salinity fell rapidly after 8 km downstream and changed most in the upper 0 to 5 cm of the soil, indicating retention of cations in the upper soil horizon. The effect of wastewater irrigation on soil exchangeable cations was most evident for Na + (Exch‐Na) near the city (<8 km downstream), where Exch‐Na averaged 20 to 22 times the Exch‐Na in soils irrigated by groundwater outside the WIA. Exchangeable Mg + and K + correlated with clay percentage, though both still had higher concentrations near the city controlling for clay content. Near the city, where salinity and Exch‐Na concentrations were highest, farmers had replaced rice with para grass [ Brachiaria mutica (Forsk.)], which has higher salinity tolerance and expanding demand as a fodder crop. Salinity may constrain rice production in wastewater‐irrigated areas of India and elsewhere.