Spring Recovery of Constructed Wetland Plants Affects Nutrient Removal From Nursery Runoff

Abstract

Abstract The nursery/greenhouse industry is the fastest growing segment of United States agriculture. Consumer demand for excellent product quality requires luxury applications of water and agricultural chemicals. These cultural practices tend to yield significant volumes of runoff rich in nutrients and pesticides. A capture and recycle system at the Nursery/Floral Crops Research and Education Center at the Texas A&M University was fitted with 12 sub-surface flow (SSF) and 12 free-surface flow (FSF) wetland cells. A single pass of runoff through constructed wetland cells provided substantial reduction of runoff nutrient concentrations, particularly NO3-N, without increasing electrical conductivity (EC), an indicator of salinity. Nitrate-N concentration reductions were greater in the FSF cells than SSF cells, while the greatest reductions in ammonium and nitrites were obtained with SSF cells. Growth of Iris pseudacorus L. and Canna x generalis L.H. Bailey during spring growth was greater in the FSF wetland cells, while that of Colocasia sp. Fabr. was greater in the SSF wetland cells. Equisetum hyemale L. grew equally well in both cell types. Interactions among irrigation water sources and container media types for growth indices occurred for Juniperus procumbens (Endl.) Miq. ‘Green Mound’ and Ilex vomitoria Ait. ‘Nana’, but not for Raphiolepis indica L. ‘Carmelita’.