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| Project Name: | Early Warning Indicators of Ground Water Contamination in Soils with Variable Charge Clays |
| ASO Log No.: | 96-121 |
| Start/End Date: | June 1997 to January 1998 |
| Federal Funds: | $95,652.00 |
| Matching Funds: | $75,612.00 |
| Contractor: | Goro Uehara University of Hawaii – CTAHR Department of Agronomy and Soil Science 1910 East-West Road, Honolulu, HI 96822 Phone: (808) 956-6593 |
| Background/ Overview: |
For the past century, agriculture in central Oahu has been dominated by plantation crops, like sugarcane and pineapple. Heavy nitrogen fertilization of these crops has acidified the soils. These soils are dominated by variable charge minerals that acquire increasing amounts of positive surface charge as the soil is acidified. The physics and chemistry of these soils indicated that a significant amount of nitrate-nitrogen should now be adsorbed on the positively charged clay surfaces in the subsoil. The conversion of former plantation land to diversified ag will require the addition of lime to the soil to reduce soil acidity. |
| Objectives/Goals: | To investigate the consequence of high input diversified agriculture on the charge characteristics of variable charge soils and its impact on the fate of nitrate absorbed on positively charged subsoil materials. The project focused on the extent and distribution of nitrate accumulation in the sugarcane and pineapple fields in the target area and the potential hazard to the ground water from neutralizing these soils for growing acid intolerant diversified crops. |
| Methods Employed: | Assess the extent and distribution of nitrate accumulation in the sugarcane and pineapple fields in the target area. Assess the potential hazard to the ground water from neutralizing these soils for growing acid intolerant diversified crops. |
| Pollutants of Concern: | Nitrate |
| Watershed: | Poamoho Watershed, island of Oahu |
| Size of Project: | Former and current sugar and pineapple lands located in the saddle between the Waianae and Koolau mountain ranges, island of Oahu |
| Affected Water Bodies: | Not described in report |
| Deliverables: | Final report contains the results of the three studies carried out to assess the nitrate situation |
