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United States Department of Agriculture

Agricultural Research Service

Research Project: Conservation Systems Research for Improving Evnironmental Quality and Producer Profitability

Location: National Soil Dynamics Laboratory

Title: Short-term soil nutrient impact in a real-time drain field soil moisture controlled SDI wastewater disposal system

Authors
item He, Jiajie -
item Dougherty, Mark -
item Arriaga, Francisco
item Fulton, John -
item Wood, Charles -
item Shaw, Joey -
item Lange, Clifford -

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2011
Publication Date: June 14, 2011
Citation: He, J., Dougherty, M., Arriaga, F.J., Fulton, J., Wood, C.W., Shaw, J.N., Lange, C.R. 2011. Short-term soil nutrient impact in a real-time drain field soil moisture controlled SDI wastewater disposal system. Irrigation Science. 9 pages. doi:10.1007/s00271-011-0292-2. Available: http://www.springerlink.com/content/j0t0342721075257/.

Interpretive Summary: The Alabama Black Belt area has soils that expand and contract depending on moisture conditions, creating soil cracks. These soils are generally unsuitable for conventional septic systems; nonetheless, systems of this type have been widely used in this region for decades. In order to explore alternatives for these conventional septic systems, a real-time soil moisture controlled subsurface drip irrigation wastewater disposal system was tested in these soils for one year. This automated disposal system effectively limited wastewater disposal during unfavorably wet drain field conditions. However, the resulting nutrient supply into the soil was observed to be in surplus to crop needs. Soil samples taken at the conclusion of the one-year study indicated evidence of nitrate and phosphorus leaching. Phosphorous in the soil increased below the drip line, which may be attributed to soil cracking that was not properly controlled with the irrigation system. Despite potential deficiencies, integrating timing of wastewater disposal with soil moisture conditions can supplement existing municipal or decentralized community wastewater treatment disposal systems.

Technical Abstract: The Alabama Black Belt area is widespread of Vertisols that are generally unsuitable for conventional septic systems; nonetheless, systems of this type have been widely used in this region for decades. In order to explore alternatives for these conventional septic systems, a real-time soil moisture controlled subsurface drip irrigation wastewater disposal system was integrated and field tested in a Houston Vertisol for one year. This automated disposal system effectively limited wastewater disposal during unfavorably wet drain field conditions. However, the resulting nutrient supply into the drain field was observed to be in surplus to crop growth requirements. Soil cores taken at the conclusion of the one-year study indicated evidence of nitrate and phosphorus leaching. Available nitrates in the top 100 cm of soil showed a decreasing trend but were higher than all other parallel controls. Soil crop available phosphorous in the soil increased below the drip line, as result which may be ascribed to soil cracking that was not properly controlled at the test site. Despite the demonstrated deficiencies, integrating timing of wastewater disposal with soil moisture conditions can supplement existing municipal or decentralized community wastewater treatment disposal systems.

Last Modified: 4/19/2014
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