Bremer, E.

Deng, H.

Hoffman, K.M.

Moore, T.

Sheppard, L.J.

Starzomski, B.

Wang, M.

English

University of Saskatchewan Research Archive

Monitoring Nutrient Enrichment Impacts in Wetlands with PRS Probes   H. Deng1, E. Bremer1, L. J. Sheppard2, K. M. Hoffman3, B. Starzomski3, T. Moore4, and M. Wang4 1 Western Ag Innovations, Inc.; 2 Centre for Ecology and Hydrology, Penicuik; 3 University of Victoria, Victoria; 4 McGill University, Montreal  Key words: PRS probe, Wetland, Nutrient enrichment,   Introduction Wetland ecosystems are sensitive to nutrient enrichment due to naturally low nutrient levels, limitations to plant uptake and high mobility. Ion exchange membranes, such as Plant Root Simulator (PRS™) probes, are useful for measuring soil nutrient bioavailability in situ with minimal disturbance. Three recent studies that utilized PRS probes are presented to highlight the impact of nutrient enrichment in wetland system. N enrichment in an ombrotrophic bog with different N forms PRS-probes were used to measure the impact of 11 years of dry ammonia deposition (circa 6 g N m-2 yr-1) with similar deposition doses as oxidised N (Sodium nitrate) or reduced N (Ammonium chloride), to an ombrotrophic bog, Whim, in southern Scotland. Dry ammonia deposition has completely transformed the vegetation, whereas wet deposited N has only caused dramatic vegetation changes as oxidised N in the presence of additional PK.  Figure 1. N measured in treatment treated with NaNO3 (Nox), NH4Cl (Nred) and Ammonia (Ngas) as PRS™-probe supply rate Dry ammonia deposition has led to a significant increase in NO3--N supply rate. While large change in NH4+-N was also observed in plots with wet application of NH4Cl (Figure 1). This maybe attribute to the vegetation changes induced by the deposition of different N forms.  Effect of nutrient enrichment in open blanket bogs PRS probes were used to understand the impact of nutrient enrichment in minerotrophic bogs (Figure 2) on the central coast of British Columbia as part of a three-year NPK addition experiment where changes to soil microbial and plant communities were examined.    Figure 2. PRS probes installed in a minerotrophic bog. Four nutrient treatments were applied: unamended control, N-enriched (8 urea/m2), P-enriched (100 g triple superphosphate /m2), and K-enriched (18 g muriate of potash/m2).  Two pairs of PRS-probes were installed in four replicates of each treatment from June 23 till September 10, 2013. PRS-probes detected a large impact of nutrient enrichment for N, P and K: measurements varied by two orders of magnitude between treatments (Figure 3).   Figure 3. Effect of nutrient enrichment on PRS-probe N, P, K, Ca and Mg supply rates (logarithmic scale).  Long-term fertilization experiment at Mer Bleue Bog PRS probes were used to understand the N, P, K availability in Mer Bleue, a boreal peatland ecosystem as affected by long-term fertilization and to interpret the nutrient uptake by shrubs and mosses. Treatment applied were 2 controls (C1 and C2), N (NH4NO3)addition rate of 1.6, 3.2 and 6.4 g N m-2 yr-1 (5N, 10N and 20N), N addition with 5 g P m-2 yr-1 and 6.3 g K m-2 yr-1 as KH2PO4 (5NPK, 10NPK and 20NPK) and P, K only (PK). The PRS probes were buried for 4 weeks in the beginning, mid and end of the growing season in 2012. Fertilization was conducted biweekly from the beginning of May to the end of August. Fertilization had large effects on nutrient supply rates at Mer Bleue, especially for P and K addition (Figure 4).   Figure 4. The seasonal pattern of nitrogen (a), phosphorus (b) and potassium (c) availability (µg/10cm2/4 weeks) measured by PRSTM probes in response to long-term fertilization (see background for treatment descriptions).  The nutrient enrichment effect detected was relatively large due to the continuous fertilization from May to August. The availability of N generally returned to the same level as controls, but P and K availabilities in P and K fertilized plots remained higher than the controls one and a half months after the last fertilization.  Conclusions PRS probes can accurately measure the nutrient enrichment effect in wetland systems, taking into account various factors affect the nutrient supply. Using PRS probes to investigate impacts on temporal and spatial patterns would be useful.       • are sensitive to nutrient enrichment due tonaturally low nutrient levels, limitations to plant uptake and highmobility.• Three recent studies that utilized PRS are presented to highlightthe impact of nutrient enrichment in wetland system.Long-term fertilization experiment at Mer Bleue BogPRS probes were used to understand the impact of nutrientenrichment in minerotrophic bogs (Figure 2) on the central coast ofBritish Columbia as part of a three-year NPK addition experiment wherechanges to soil microbial and plant communities were examined.N enrichment in an ombrotrophic bog with different N forms• N PRS-probes were used to measure the impact of 11years of dry ammonia deposition (circa 6 g N m-2 yr-1) withsimilar deposition doses as oxidised N (Sodium nitrate) orreduced N (Ammonium chloride), to an ombrotrophic bog,Whim, in southern Scotland.• Dry ammonia deposition has completely transformed thevegetation, whereas wet deposited N has only caused dramaticvegetation changes as oxidised N in the presence of additional PK.• Dry ammonia deposition has led to a significant increase in NO3--N supply rate. While large change in NH4+-N was also observed inplots with wet application of NH4Cl (Figure 1). This maybeattribute to the vegetation changes induced by the deposition ofdifferent N forms.Monitoring nutrient enrichment impacts in wetlands with PRS probesH. Deng1, E. Bremer1, L. J. Sheppard2, K. M. Hoffman3, B. Starzomski3, T. Moore4, and M. Wang41 Western Ag Innovations, Inc.; 2 Centre for Ecology and Hydrology, Penicuik; 3 University of Victoria, Victoria; 4 McGill University, Montreal;ConclusionsEffect of nutrient enrichment in open blanket bogsResultsBackgroundIntroductionWetland ecosystems Background• Ion exchange membranes, such as Plant RootSimulator (PRS™) probes, are useful formeasuring soil nutrient bioavailability in situwith minimal disturbance.Figure 2. PRS probes installed in aminerotrophic bog.ResultsFigure 3. Effect of nutrient enrichment on PRS-probe N, P, K, Ca and Mg supply rates (logarithmic scale).• Four nutrient treatments wereapplied: unamended control, N-enriched (8 urea/m2), P-enriched(100 g triple superphosphate /m2),and K-enriched (18 g muriate ofpotash/m2). Two pairs of PRS-probes were installed in fourreplicates of each treatment fromJune 23 till September 10, 2013.PRS probes were used to understand the N, P, K availability in MerBleue, a boreal peatland ecosystem as affected by long-term fertilization and tointerpret the nutrient uptake by shrubs and mosses.• Treatment applied were 2 controls (C1 and C2), N (NH4NO3)addition rate of 1.6,3.2 and 6.4 g N m-2 yr-1 (5N, 10N and 20N), N addition with 5 g P m-2 yr-1 and 6.3 gK m-2 yr-1 as KH2PO4 (5NPK, 10NPK and 20NPK) and P, K only (PK).• The PRS probes were buried for 4 weeks in the beginning, mid and end of thegrowing season in 2012. Fertilization was conducted biweekly from the beginningof May to the end of August.BackgroundFigure 4. The seasonal pattern of nitrogen (a), phosphorus(b) and potassium (c) availability (µg/10cm2/4 weeks)measured by PRSTM probes in response to long-termfertilization (see background for treatment descriptions).Results• Fertilization had large effects on nutrient supply rates at Mer Bleue, especially for Pand K addition (Figure 4).• The nutrient enrichment effect detected was relatively large due to the continuousfertilization from May to August. The availability of N generally returned to thesame level as controls, but P and K availabilities in P and K fertilized plots remainedhigher than the controls one and a half months after the last fertilization.• Nutrient enrichment in these wetland systems had a large impact on nutrient supply rates measured with PRS probes. These effects weregreater than observed in most studies.• Further studies would be useful to investigate impacts on temporal and spatial patterns.• PRS-probes detected a large impact of nutrient enrichment for N, P andK: measurements varied by two orders of magnitude betweentreatments (Figure 3).Figure 1. N measured in treatment treated with NaNO3 (Nox), NH4Cl (Nred) and Ammonia (Ngas) as PRS™-probe supply rate

Monitoring nutrient enrichment impacts in wetlands with PRS™-probes

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Monitoring nutrient enrichment impacts in wetlands with PRS™-probes

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