Runoff phosphorus retention in vegetated field margins on flat landscapes

Abstract

, J. 2006. Runoff phosphorus retention in vegetated field margins on flat landscapes. Can. J. Soil Sci. 86: 871-884. Vegetated buffer strips (VBS) are often recommended as a management practice that farmers can use to help mitigate the environmental effects of runoff from agricultural fields. Previous research has shown that VBS can be effective at trapping phosphorus (P) and other farm-sourced environmental contaminants. This project measured the effectiveness of established vegetated strips at decreasing P in runoff from agricultural fields in Manitoba. Paired samples of runoff, taken at the field edge and in the vegetated strip, indicated that in 11 of the 22 cases sampled (50%), P concentrations in the runoff decreased (on average 30%) as the flow passed through the vegetated strip. In 7 of the 22 case (32%) there was no difference; however, in four of the 22 cases (18%), runoff P concentrations increased, indicating the vegetated strip had become a source of runoff P. Soil samples from the VBS showed high available P concentrations at positions within the vegetated strip along the runoff flow path, and in 7 of 10 cases these concentrations were higher (33% on average) than in the field soil. Although the observations and numerical results suggest that VBS can be effective at removing P in runoff, perhaps the major limitation in this flat-land region is that runoff tends to flow through rather small portions of the VBS, and these may not have sufficient capacity to retain the runoff P in the longer term. Le projet devait établir l'utilité de telles bandes de végétation pour réduire la concentration de P dans les eaux de ruissellement issues des cultures, au Manitoba. Les couples d'échantillons d'eau de ruissellement prélevés en bordure des champs et dans la bande enherbée indiquent que la concentration de P dans les eaux de ruissellement diminue (d'en moyenne 30 %) dans 11 cas sur 22 (50 % des échantillons) lorsque l'eau traverse la bande de végétation. Aucune variation n'a été notée dans sept cas (32 %) alors que dans quatre autres (18 %), les auteurs ont relevé une hausse de la concentration de P, signe que la bande enherbée devenait elle-même une source de P lors du ruissellement. Les échantillons de sol tirés des bandes enherbées révèlent une concentration élevée de P disponible aux endroits situés le long du trajet suivi par les eaux et, dans sept cas sur dix, la concentration était plus élevée (d'en moyenne 33 %) que dans le sol cultivé. Bien que ces observations et les données quantitatives laissent croire à l'efficacité des bandes enherbées pour retenir le P présent dans les eaux de ruissellement, le principal problème de cette région au relief plat est peut-être que les eaux ont tendance à ruisseler à travers de petites sections des bandes de végétation, dont la capacité de rétention pourrait s'avérer insuffisante à plus long terme.

Crops and garden products near Olkiluoto repository site

“…Also the fraction of the "bioavailable" concentrations of the total element concentrations across all sampling plots are given (mean ± s.e.). [2,4], it can be observed that in most cases our concentration ratios are within an order of magnitude of them. The nearly two order of magnitude difference to the IAEA values [2] in case of Sr to the barley ears may be due to the IAEA value to grains of several cereals; on the other hand, our value here is close to that of the Canadian study [4].…”

“…[2,4], it can be observed that in most cases our concentration ratios are within an order of magnitude of them. The nearly two order of magnitude difference to the IAEA values [2] in case of Sr to the barley ears may be due to the IAEA value to grains of several cereals; on the other hand, our value here is close to that of the Canadian study [4]. The rather large value, by a factor of 280, compared to the IAEA data on Ag to the lettuce leaves may be similarly arising from the inclusion of all leafy vegetables to the IAEA value (derived from only five data points).…”

“…Element composition of the plant samples was determined with a total elemental analysis (ICP-SFMS) after drying at 50 • C and digestion with HNO 3 /HF (trace). The soil samples were analysed for "bioavailable" element concentrations after an NH 4 Ac extraction: 1M NH 4 Ac extraction (ratio 1 : 10) was done at pH 4.5 with ICP-MS/ICP-OES techniques. For analyses, 3 g of dried and homogenised soil was weighed.…”

How to combat cyanobacterial blooms: strategy toward preventive lake restoration and reactive control measures

“…Surface flow systems like sewage farms, mash zones, wetlands, vegetated buffer strips, and sedimentation ponds are easy to maintain and have little chance of hydraulic failure. They might have some P removal properties, but might in worst cases also act as P sources (Sheppard et al 2006;Ballantine and Tanner 2010). Vymazal (2011) reviewed various approaches of constructed wetlands and concluded that wetlands are usually not designed for P removal.…”

“…This makes size, design, and management crucial for P removal efficiency. Such efficiencies might vary from 0.3 up to[0.9 (Sheppard et al 2006;Ballantine and Tanner 2010;Groenenberg et al 2013;Penn et al 2014). Provided there is ample hydraulic head, especially for subsurface flow or drains, the sorbing beds can be implemented below the surface in wetlands and drains without additional hardware, fully integrating into the natural surroundings.…”