Use of Disturbed Western Rangelands as Dedicated Biosolids Beneficial use Sites
Abstract:Biosolids land application represents a cost effective approach for improving the environmental health and productivity of disturbed rangelands. The Utah Division of Water Quality (Salt Lake City, UT) in conjunction with the US Environmental Protection Agency (EPA) Region VIII (Denver, CO) and Utah State University (Logan, UT) has evaluated the potential benefits of land applying aerobically digested and lime stabilized biosolids to enhance the vegetative production on disturbed rangelands in Skull Valley, UT.
Biosolids land applied at rates significantly greater that the nitrogen-based agronomic rate was found to increase vegetative biomass production above that which was observed for control plots. For example, while the control plot recorded an average vegetative growth of 366.6 lbs per acre (wet basis), plots receiving lime-stabilized biosolids at 10X the agronomic rate and aerobically digested biosolids at 20X the agronomic rate reported maximum biomass yields of 2043.7 and 1688.0 lbs per acre (wet basis), respectively. Preliminary ecological analysis indicated that the dominant plant species found on the control test plots was Bromus tectorum (cheat grass) while the dominant vegetative species found on the sites amended with biosolids was Hordeum marinum gussoneanum (seaside barley).
Soil sampling indicated that nitrate concentrations in all test plots including control increased with increasing soil depth. While nitrate concentrations in the control plots ranged from 7.5 mg/kg (at 0.75 feet below the ground surface) to 88.0 mg/kg (at 5.0 feet below ground surface), soils receiving biosolids had soil nitrate concentrations that ranged from 12.0 mg/kg (at 0.75 ft below the ground surface) to 183.6 mg/kg (at 5.0 feet below ground surface).
In all but two cases, soil ammonia concentrations biosolids amended soils were found to be statistically equivalent to the control plots. This observation was not surprising as the alkaline soil conditions would facilitate ammonia volatilization. The only exceptions to this behavior was observed in lime stabilized and aerobically digested biosolids test plots that received 10X and 20X the estimated agronomic rate, respectively. At a measured soil depth of 0.75 feet, the ammonia concentrations at these sites were much larger than that observed within the control. These observations suggest the possibility that ammonia mass transfer limitations associated with unassimilated land applied biosolids may exist.
Document Type: Research Article
Publication date: 2006-01-01
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