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Sphagnum farming in a eutrophic world : The importance of optimal nutrient stoichiometry

Temmink, Ralph J M; Fritz, Christian; van Dijk, Gijs; Hensgens, Geert LU ; Lamers, Leon P M; Krebs, Matthias; Gaudig, Greta and Joosten, Hans (2017) In Ecological Engineering 98. p.196-205
Abstract

Large areas of peatlands have worldwide been drained to facilitate agriculture, which has adverse effects on the environment and the global climate. Agriculture on rewetted peatlands (paludiculture) provides a sustainable alternative to drainage-based agriculture. One form of paludiculture is the cultivation of Sphagnum moss, which can be used as a raw material for horticultural growing media. Under natural conditions, most Sphagnum mosses eligible for paludiculture typically predominate only in nutrient-poor wetland habitats. It is unknown, however, how the prevailing high nutrient levels in rewetted agricultural peatlands interfere with optimal Sphagnum production. We therefore studied the effect of enriched nutrient conditions... (More)

Large areas of peatlands have worldwide been drained to facilitate agriculture, which has adverse effects on the environment and the global climate. Agriculture on rewetted peatlands (paludiculture) provides a sustainable alternative to drainage-based agriculture. One form of paludiculture is the cultivation of Sphagnum moss, which can be used as a raw material for horticultural growing media. Under natural conditions, most Sphagnum mosses eligible for paludiculture typically predominate only in nutrient-poor wetland habitats. It is unknown, however, how the prevailing high nutrient levels in rewetted agricultural peatlands interfere with optimal Sphagnum production. We therefore studied the effect of enriched nutrient conditions remaining even after top soil removal and further caused by external supply of nutrient-rich irrigation water and (generally) high inputs of atmospheric nitrogen (N) to habitat biogeochemistry, biomass production and nutrient stoichiometry of introduced Sphagnum palustre and S. papillosum in a rewetted peatland, which was formerly in intensive agricultural use. Airborne N was responsible for the major supply of N. Phosphorus (P) and potassium (K) were mainly supplied by irrigation water. The prevailing high nutrient levels (P and K) are a result of nutrient-rich irrigation water from the surroundings. Peat porewater (10 cm below peatmoss surface) CO2 concentrations were high, bicarbonate concentrations low, and the pH was around 4.2. Provided that moisture supply is sufficient and dominance of fast-growing, larger graminoids suppressed (in order to avoid outshading of Sphagnum mosses), strikingly very high biomass yields of 6.7 and 6.5 t DW ha−1 yr−1 (S. palustre and S. papillosum [including S. fallax biomass], respectively) were obtained despite high N supply and biomass N concentrations. Despite high P and K supply and uptake, N:P and N:K ratios in the Sphagnum capitula were still low. Sphagnum mosses achieved high nutrient sequestration rates of 34 kg N, 17 kg K and 4 kg P ha−1 yr−1 from May 2013 to May 2014, which shows that the site acted as an active nutrient sink. Nutrient management still needs further improvement to reduce the competitive advantage of fast growing peatmoss species (cf. S. fallax) at the expense of slower growing but preferred peatmosses as horticultural substrate (S. palustre and S. papillosum) to optimize the quality of biomass yields. In conclusion, Sphagnum farming is well able to thrive under high N input provided that there is a simultaneous high input of P and K from irrigation water, which facilitates high production rates. Due to the lack of suitable, nutrient poor sites, it seems to be useful to remove the topsoil (mainly P removal) prior to start growing Sphagnum mosses. In addition, bicarbonate concentrations have to stay sufficiently low to ensure a low pH, CO2 supply from the peat soil should be sufficiently high to prevent C limitation, and graminoids should be mown regularly.

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author
publishing date
type
Contribution to journal
publication status
published
keywords
Agriculture, Biomass, Nitrogen deposition, Nutrient supply, Paludiculture, Peatland, Rewetting, Stoichiometry
in
Ecological Engineering
volume
98
pages
10 pages
publisher
Elsevier
external identifiers
  • scopus:85003451745
ISSN
0925-8574
DOI
10.1016/j.ecoleng.2016.10.069
language
English
LU publication?
no
id
0329b71e-e4e7-4766-a994-668ca4b2d168
date added to LUP
2017-03-29 14:44:28
date last changed
2017-07-30 05:23:35
@article{0329b71e-e4e7-4766-a994-668ca4b2d168,
  abstract     = {<p>Large areas of peatlands have worldwide been drained to facilitate agriculture, which has adverse effects on the environment and the global climate. Agriculture on rewetted peatlands (paludiculture) provides a sustainable alternative to drainage-based agriculture. One form of paludiculture is the cultivation of Sphagnum moss, which can be used as a raw material for horticultural growing media. Under natural conditions, most Sphagnum mosses eligible for paludiculture typically predominate only in nutrient-poor wetland habitats. It is unknown, however, how the prevailing high nutrient levels in rewetted agricultural peatlands interfere with optimal Sphagnum production. We therefore studied the effect of enriched nutrient conditions remaining even after top soil removal and further caused by external supply of nutrient-rich irrigation water and (generally) high inputs of atmospheric nitrogen (N) to habitat biogeochemistry, biomass production and nutrient stoichiometry of introduced Sphagnum palustre and S. papillosum in a rewetted peatland, which was formerly in intensive agricultural use. Airborne N was responsible for the major supply of N. Phosphorus (P) and potassium (K) were mainly supplied by irrigation water. The prevailing high nutrient levels (P and K) are a result of nutrient-rich irrigation water from the surroundings. Peat porewater (10 cm below peatmoss surface) CO<sub>2</sub> concentrations were high, bicarbonate concentrations low, and the pH was around 4.2. Provided that moisture supply is sufficient and dominance of fast-growing, larger graminoids suppressed (in order to avoid outshading of Sphagnum mosses), strikingly very high biomass yields of 6.7 and 6.5 t DW ha<sup>−1</sup> yr<sup>−1</sup> (S. palustre and S. papillosum [including S. fallax biomass], respectively) were obtained despite high N supply and biomass N concentrations. Despite high P and K supply and uptake, N:P and N:K ratios in the Sphagnum capitula were still low. Sphagnum mosses achieved high nutrient sequestration rates of 34 kg N, 17 kg K and 4 kg P ha<sup>−1</sup> yr<sup>−1</sup> from May 2013 to May 2014, which shows that the site acted as an active nutrient sink. Nutrient management still needs further improvement to reduce the competitive advantage of fast growing peatmoss species (cf. S. fallax) at the expense of slower growing but preferred peatmosses as horticultural substrate (S. palustre and S. papillosum) to optimize the quality of biomass yields. In conclusion, Sphagnum farming is well able to thrive under high N input provided that there is a simultaneous high input of P and K from irrigation water, which facilitates high production rates. Due to the lack of suitable, nutrient poor sites, it seems to be useful to remove the topsoil (mainly P removal) prior to start growing Sphagnum mosses. In addition, bicarbonate concentrations have to stay sufficiently low to ensure a low pH, CO<sub>2</sub> supply from the peat soil should be sufficiently high to prevent C limitation, and graminoids should be mown regularly.</p>},
  author       = {Temmink, Ralph J M and Fritz, Christian and van Dijk, Gijs and Hensgens, Geert and Lamers, Leon P M and Krebs, Matthias and Gaudig, Greta and Joosten, Hans},
  issn         = {0925-8574},
  keyword      = {Agriculture,Biomass,Nitrogen deposition,Nutrient supply,Paludiculture,Peatland,Rewetting,Stoichiometry},
  language     = {eng},
  month        = {01},
  pages        = {196--205},
  publisher    = {Elsevier},
  series       = {Ecological Engineering},
  title        = {Sphagnum farming in a eutrophic world : The importance of optimal nutrient stoichiometry},
  url          = {http://dx.doi.org/10.1016/j.ecoleng.2016.10.069},
  volume       = {98},
  year         = {2017},
}