Nutrient Removal by Grasses Irrigated with Wastewater and Nitrogen Balance for Reed Canarygrass
- Ulrika Geber *
To develop complementary wastewater treatment systems that increase nutrient reduction and recycling, an experiment was conducted to evaluate the efficiency of three grass species as catch crops for N, P, and K at Surahammar wastewater treatment plant (WWTP) in the southern part of Sweden. Another objective was also to assess soil accumulation of N, P, and K and the risk of N leaching by drainage. Three grasses—reed canarygrass (Phalaris arundinacea L.), meadow foxtail (Alopecurus pratensis L.), and smooth bromegrass (Bromus inermis Leyss.)—were irrigated with a mixture of treated effluent and supernatant at two levels of intensity [optimum level (equal to evapotranspiration) and over-optimal level] and at two nutrient levels, approximately 150 and 300 kg N ha−1. There were small differences in dry matter (DM) yield between grass species and no difference in N removal among species. The amount of N removed in harvested biomass to N applied was 0.58 in 1995 and 0.63 in 1996. The amount of N removed increased with increased nutrient load. Applied amounts of P were the same as P in harvested biomass. All species removed K amounts several times greater than applied amounts. Increased nutrient load increased overall K removal. The low amount of mineral N and especially NO−3-N in the soil profile in autumn samplings indicate the risk for leaching is small. Soil water NO−3 contents were also low, <2.5 mg NO−3-N L−1 during the growing season, with a mean value of <1 mg NO−3-N L−1.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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