Effectiveness of Vegetated Buffer Strips in Controlling Legacy Phosphorus Exports from Agricultural Land

Abstract

The continued phosphorus (P) impairment of freshwaters and the associated risk of eutrophication raise questions regarding the efficiency of current beneficial management practices (BMPs) for improving water quality. Vegetated buffer strips (VBSs) are widely encouraged BMPs for reducing P export from agricultural land. However, there is a lack of evidence regarding the longterm efficiency of VBSs for reducing legacy P losses. This research used soil analyses to investigate the P removal efficiency of an unmanaged VBS for controlling P loss from agricultural land in Manitoba, Canada, between 1954 and 2011. The results showed statistically significant retention of total P, Olsen extractable P, and 0.01 M CaCl 2 extractable P by a 5-m wide VBS compared with field soils. We found that surface soils at 5-m into the VBS had a significantly greater P sorption capacity and a smaller degree of P saturation (DPS) than adjacent field soils. The elevated DPS in field soils is likely associated with gradual P enrichment as a result of manure or fertilizer application over time and the strong affinity of P compounds for soil. Although P stratification in the VBS over 57 yr resulted in a significant increase (?11%) in DPS of VBS topsoil compared with VBS subsoil, our findings do not support the saturation of VBS soils with P. However, cutting and removal of vegetation from VBS could be a useful strategy to remove P from VBS and minimize possible P remobilization associated with vegetation senescence, especially where the climate is cold and runoff is dominated by snowmelt.

Phosphorus Pool Composition in Soils and Sediments of Transitional Ecotones under the Influence of Agriculture

“…3a), which suggests contribution of P from adjacent farmland. An increase in TP and labile Pi of buffer strip soil compared with adjoining cropland was previously described by Habibiandehkordi et al (2019) and Roberts et al (2012). Furthermore, DPS values were highest in buffer strip soil (reaching up to 27%; Supplemental Table S3).…”

Effectiveness of Riparian Vegetated Filter Strips in Removing Agricultural Nonpoint Source Pollutants in Agricultural Runoff from the Liao River Area, China

“…The plants also play an important role in intercepting agricultural non-point source pollutants. The interception efficiency of pollutants depends mainly on the vegetation type [37]. The reason why the sweet clover had high nitrogen retention efficiency was because it was a legume, which has good nitrogen fixation ability.…”

Current Insights into the Effectiveness of Riparian Management, Attainment of Multiple Benefits, and Potential Technical Enhancements

“…The longer‐term functioning of VBSs for storage of sediment and P has been questioned in the international literature, with the concern being that buffers may become a future P source due to decreasing soil P sorption capacities with age and P loading (Hoffmann et al, 2009; Stutter et al, 2009). In their study of a 57‐yr‐old unmanaged VBS, Habibiandehkordi et al (2019) found significantly higher mean masses of sediment and P in surface soils at the border of the VBS (6966 kg total P ha −1 and 10702 Mg sediment ha −1 ) than either 5 m upslope into the field (3956 kg total P ha −1 and 5346 Mg sediment ha −1 ) or 5 m into the VBS (2776 kg total P ha −1 and 3992 Mg sediment ha −1 ). They also found that surface soils at 5 m into the VBS had a significantly greater P sorption capacity and a smaller degree of P saturation than adjacent field soils, the latter attributed to P enrichment in the field resulting from manure or fertilizer application.…”

“…Hille et al (2019) quantified the effects of annual vegetation harvesting to deplete the accumulated pools of soil P as P‐enriched fines were trapped over years in the buffer. Habibiandehkordi et al (2019) observed that the P saturation of VBS topsoil as compared with subsoil had increased as little as ∼11% over the 57‐yr period, and the authors concluded that their sites did not support the hypothesis of saturation of VBS topsoils with P. It would be advantageous to bring in knowledge of P sorption and saturation in different soil types that is well developed in the agronomic literature to support recommendations for reducing P in differing buffer soil matrices.…”

“…Habibiandehkordi et al (2019) studied how effective Canadian buffer strips were in controlling P exports according to levels of P saturation attained in the buffers. Although their investigated buffers were not sufficiently P saturated to pose major leaching risks, they proposed that cutting and removal of vegetation could be a useful strategy to remove P for delaying possible P saturation and losses in the long term.…”