Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2017
Publication Date: 7/11/2017
Citation: Logsdon, S.D. 2017. Nutrient leaching when soil is part of plant growth media. Water. 9(7):501. https://doi.org/10.3390/w9070501.
Interpretive Summary: Engineered plant growth media is used in greenhouses, golf courses, and urban bioretention cells. Commerical waste products have been used to reduce leaching of phosphorus, but these waste products may be toxic to plants or interact negatively with other components of plant growth media. This study showed that some soils (high in aluminum or calcium) are able to keep phosphorus within the plant growth media and reduce phosphorus leaching. This information is of interest to urban planners, as well as operators of greenhouses.
Technical Abstract: Soils can serve as sorbents for phosphorus (P) within plant growth media, negating the need for artificial sorbents. The purpose of this study was to compare soils with different properties, as part of plant growth media, for their effect on nutrient levels in effluent. Four soils were mixed with sand and packed into columns 0.5 m long, with or without compost on the surface. Infiltration and effluent concentrations were measured before and after growing plants [Buffalo (Buchloe dactyloides (Nutt.) Engelm.) and blue grama grasses (Bouteloua gracilis H.B.K.) and red clover (Trifolium pratense L.)]. The growth media with compost at the surface had higher nutrient levels than the media without the compost, but column effluent nutrient levels were not significantly increased. The final effluent nitrate concentrations after harvest were significantly lower for columns with the compost blanket (59 vs. 86 mg L-1). All of the nitrate concentrations were high (> 10 mg L-1, many > 100 mg L-1) due to mineralization and nitrogen fixation. The final effluent P concentrations before planting were significantly higher in the soil with the most sand (0.71 mg L-1), and after harvest in the mixture that contained the high soil P levels (0.58 mg L-1). Some soils (high in aluminum or calcium) were adequate sorbents for P without additions of other sorbents, but soils often generated too much nitrate in effluent.