Treatment of swine wastewater using a saturated-soil-culture soybean and flooded rice system
Constructed wetlands have potential for treatment of livestock wastewater, but they generally contain wetland plants rather than agronomic crops. The authors evaluated two agronomic crops, saturated-soil-culture (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. Flooded 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 wastewater application rate. Increasing total N loading rates and the associated higher NH{sub 4}-N concentrations depressed soybean seed yield and dry matter production. On the other hand, both rice grain and dry matter production were stable over the application range; mean values were 4.0 and 10.9 Mg ha{sup {minus}1}, respectively. Nutrient mass reductions were good; removal values increased linearly with loading rates (y = 0.69N load + 0.45, R{sup 2} = 0.99 and y = 0.45P load + 0.20, R{sup 2} = 0.95). At the highest loading rate, the system removed 751 and 156 kg/ha yr 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. The system produced comparable treatment to systems with natural wetland plants; moreover, the soybean and rice are marketable crops. However, the flooded rice seems to be the more robust component for high wastewater application rates.
- Research Organization:
- Dept. of Agriculture, Florence, SC (US)
- OSTI ID:
- 20080251
- Journal Information:
- Transactions of the ASAE, Vol. 43, Issue 2; Other Information: PBD: Mar-Apr 2000; ISSN 0001-2351
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rye-soybean double-crop: planting method and N fertilization effects in the North Central US
Mississippi State Biodiesel Production Project