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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #100957
Title: TREATMENT OF SWINE WASTEWATER USING A SATURATED-SOIL-CULTURE SOYBEAN AND FLOODED RICE TREATMENT SYSTEM

Author
item SZOGI, ARIEL - NC STATE UNIV
item Hunt, Patrick
item HUMENIK, FRANK - NC STATE UNIV

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Treatment of animal wastewater is a major problem for both agriculture and the general public. One potential way to treat this wastewater is through the use of constructed wetlands. These wetlands are not natural; they are created on upland sites, and they are dedicated to the treatment of wastewater. However, they generally contain wetland rather than agronomic crops. We evaluated two agronomic crops, saturated-soil (SSC) soybean and flooded rice, in a constructed wetland system used for swine wastewater treatment. Both crop production and treatment efficiency were evaluated as wastewater application rates were gradually increased to obtain rates of 2.0 to 8.8 and 0.5 to 2.2 kg/ha/d for total N and P, respectively. The best soybean grain and dry matter yields were 4.0 and 9.1 Mg/ha, respectively. These were obtained with soybean 'Young' at the lowest application rate. Increasing total N loading rates and the associated higher ammonia concentrations depressed soybean dry matter production. On the other hand, rice grain and dry matter production were stable over the application range; mean values were 4.0 and 10.9 Mg/ha, respectively. Nutrient mass removal values increased linearly with loading rates. In the year with the highest loading rate, the system removed 723 and 167 kg/ha of N and P, respectively. It appears that the SSC soybean and flooded rice system could be useful for liquid manure management in confined livestock production. However, the flooded rice seems to be a more robust component for high wastewater application rates.

Technical Abstract: Constructed wetlands have potential for treatment of livestock wastewater, but they generally contain wetland rather than agronomic crops. We evaluated two agronomic crops, saturated-soil (SSC) soybean and flooded rice, in a constructed wetland system used for swine wastewater treatment. Both crop production and treatment efficiency were evaluated from 1993 to 1996 in two 4-m x 33.5-m constructed wetland cells that were connected in series. The first cell contained SSC soybean - four cultivars planted in a randomized complete block design with four replications. Flood rice 'Maybelle' was planted in the second cell. From the first to fourth year, wastewater application rates were gradually increased to obtain rates of 2.0 to 8.8 and 0.5 to 2.2 kg/ha/d for total N and P, respectively. The best soybean grain and dry matter yields were 4.0 and 9.1 Mg/ha, respectively. These were obtained with soybean 'Young' at the lowest application rate. Increasing total N loading rates and the associated higher NH4-N concentrations depressed soybean dry matter production (y = 10.5 - 0.9NH4, r = 0.95). On the other hand, rice grain and dry matter production were stable over the application range; mean values were 4.0 and 10.9 Mg/ha, respectively. Nutrient mass reductions were good; removal values increased linearly with loading rates (y = 0.45 + 0.69NH4, r = 0.99 and y = 0.20 + 0.45P, r = 0.99). In the year with the highest loading rate, the system removed 723 and 167 kg/ha of N and P, respectively. It appears that the SSC soybean and flooded rice system could be useful for liquid manure management in confined livestock production. However, the flooded rice seems to be a more robust component for high wastewater application rates.