1
2
3
4
4
1
1
Louis Bolk Instituut
2
Veenweiden Innovatiecentrum
3
WUR Livestock Research
4
WUR Alterra
March 2014

© 2014 Louis Bolk Institute
Effect of submerged drains in peat meadows on soil quality and ecosystem services
March 2014
Joachim Deru (Louis Bolk Institute), Frank
Lenssinck (Veenweiden Innovatiecentrum), Idse
Hoving (WUR-Liverstock Research), Jan van den
Akker (WUR-Alterra), Jaap Bloem (WUR-Alterra)
Nick van Eekeren (Louis Bolk Institute)
Publication number 2014-010 LbD, 36 pages www.louisbolk.nl

The results of a research on the effects of submerged drains on peat soil quality are presented in this report. This research is part of a broader project. In 2009, Stichting Kennisontwikkeling en kennistransfer Bodem (SKB), Dutch provinces Noord-Holland, Zuid-Holland, Utrecht and the
Interdepartementaal Programma Biodiversiteit joined forces to investigate the following:

Phase 1: soil indicators representative for ecosystem services (a. Production; b. Environmental regulation (climate, water quantity and quality) and c. Habitat maintenance (biodiversity) of peat soils;

Phase 2: possibilities for land owners (farmers and nature organizations) to optimize these services with management measures.
From 2010, phase 1 of the research project was performed on forty locations (20 agricultural and 20 natural peat meadows). This resulted in a list of soil indicators for development and optimal use of soil ecosystem services in agricultural and natural peat meadows (see www.bodemveenweiden.nl).
With these results, stakeholder meetings including land owners and decision makers were carried to determined which management measures were appropriate to further research in phase 2 of the project. Three subprojects were defined:
1. Effects of submerged drainage on soil quality and delivery of soil ecosystem services in peat meadows;
2. Effects of different manure types on soil quality and delivery of soil ecosystem services in peat meadows;
3. Effects of liming on soil quality and delivery of soil ecosystem services in peat meadows.
Phase 2 of the project, including the underlying research on submerged drains, is conducted during the period 2013- 2015 and financed by the following Dutch institutions: SKB, Provinces Noord-
Holland, Zuid-Holland and Utrecht, Ministry of Infrastructure and Environment (I&M), Dairy Board
(PZ); LTO Noord Fondsen; WUR-Alterra and Stowa. The project is carried out by the Louis Bolk
Instituut and Veenweiden Innovatiecentrum (VIC).
We would like to thank the farmers who gave us the opportunity to do the measurements on their land: Marinus de Vries, Gijs van Eck, Gertjan Bakker, Jack Steenman and the Research farm at
Zegveld. Matthijs Pleijter, Gerrit van der Wel and Karel van Houwelingen gave us indications for the precise locations to sample. Riekje Bruinenberg, Hans Dullaert, René Groenen, Harm Keidel,
Carmen Versteeg and Manon Kuyper helped us for the sampling and the in situ measurements.
The authors,
March 2014
Foreword
3

Summary
Samenvatting
1 Introduction
1.1
History of peat soils: net accumulation and net oxidation of organic matter
1.2
Agronomical and hydrological effects of submerged drains in peat meadows
1.3
Soil quality and ecosystem services
1.4
Research aim and design
1.5
Hypotheses
2 Material and methods
2.1
Soil sampling and analyses
2.2
Grass production data
2.3
Statistical analyses
3 Results
3.1
Soil chemical properties
3.2
Soil physical properties
3.3
Soil biological properties
3.4
Grass production
4 Discussion
4.1
General and methodological aspects
4.2
Changes in delivery of ecosystem services due to submerged drains
4.2.1
Production
4.2.2
Environmental regulation
4.2.3
Habitat maintenance
5 Conclusions
References
Appendix 1
25
25
26
26
26
27
29
31
35
10
11
11
9
9
9
13
13
16
16
17
17
18
19
22
7
8
Contents
5

Peat meadows cope with land subsidence and emission of greenhouse gasses due to peat oxidation.
This process is enhanced by aerobic soil conditions due to low ditch water and ground water levels especially during summer. The use of submerged drains has shown to decrease land subsidence by increasing water infiltration from the ditch to the soil and levelling up ground water levels during dry periods. Until now, most research focused on hydrological and agronomical effects of submerged drains as used in agriculturally used peat meadows.
The aim of the present study was to get insight in the soil quality of peat meadows as influenced by submerged drains, and their delivery of the ecosystem services ‘production’, ‘environmental regulatio n’ and ‘habitat maintenance’. We selected six peat meadows previously used for agronomical and hydrological research on the effect of submerged drains on peat soil in the Dutch provinces Noord Holland, Zuid Holland and Utrecht. Each meadows was divided in two parts: one without drains (control) and one with submerged drains. We used soil chemical, physical and biological indicators to assess the delivery of ecosystem services in the six meadows (total of 12 plots). Soil measurements were carried out in May 2013. Grass production data from the same meadows but from previous years were used.
The following conclusions were drawn from the experiment:
1. In general, the presence of submerged drains did not have a strong effect on the soil quality variables measured. Due to the large variation between the six locations only a small number of variables differed significantly between the control and the submerged drains.
2. The treatment effect of a number of variables (P-AL, penetration resistance in 0-10 cm, percentage of Marionina enchytraeids, number of fungal feeding nematodes) correlated with the experiment age of the six locations, which varied among the locations between 2 and 9 years.
However, this long term effect of submerged drains on soil quality is only indicative since other location characteristics influence these correlations.
3. The ecosystem service Production was marginally negatively influenced by submerged drains: fertilized grass production, pH and P-AL were slightly lower. A positive change for production was the increase in penetration resistance and load bearing capacity in the top soil at the time of measurements (May).
4. For the ecosystem service Environmental regulation , we found a few indications confirming the positive effect of submerged drains on water quality and decreased peat oxidation. The soil indicators for emission of greenhouse gasses and adaptation to climate change did not differ significantly between submerged drains and control. However, the indicators were measured in the top soil where in general biological activity is highest. We cannot exclude that differences in mineralization and greenhouse gas production occurred deeper in the soil near fluctuating groundwater levels.
5. The measured soil indicators for Habitat maintenance gave no signals for strong changes due to submerged drains. However, the higher species richness of acari (mites) indicated a more stable habitat due to the hydrological buffering by drains and foraging opportunity to meadow birds was slightly altered due to dryer conditions in the top soil.
Summary / Samenvatting
7

Veenweiden hebben te maken met bodemdaling en uitstoot van broeikasgassen als gevolg van veenoxidatie. Dit proces wordt versterkt door aerobe omstandigheden in de bodem vanwege de lage slootwater- en grondwaterpeilen, vooral in de zomer. Het gebruik van onderwaterdrains kan bodemdaling verminderen door een verhoogde infiltratie van water uit de sloot naar de veenweidebodem, waardoor grondwaterstanden tijdens droge perioden minder diep zakken. Tot nu toe heeft het onderzoek zich vooral gericht op hydrologische en landbouwkundige effecten van onderwaterdrains.
Het doel van het onderzoek was om inzicht te krijgen in de bodemkwaliteit van veenweiden onder invloed van onderwaterdrainage, en de levering van de ecosysteemdiensten 'productie',
'milieuregulatie' en 'habitat / biodiversiteit’. Zes veenweidepercelen werden geselecteerd die eerder waren gebruikt voor landbouwkundig en hydrologisch onderzoek naar het effect van onderwaterdrains in de provincies Noord Holland, Zuid Holland en Utrecht. Ieder perceel was verdeeld in twee delen: één zonder drains (controle) en één met onderwaterdrains. We gebruikten bodemchemische, -fysische en -biologische indicatoren om de levering van ecosysteemdiensten in de zes percelen (totaal 12 plots) te beoordelen. Bodemmetingen werden uitgevoerd in mei 2013.
Grasproductiegegevens van dezelfde percelen, maar van voorgaande jaren werden gebruikt.
De volgende conclusies kunnen worden getrokken uit het onderzoek:
1. Over het algemeen had de aanwezigheid van onderwaterdrains geen sterk effect op de bodemkwaliteit. Vanwege de grote variatie tussen de zes locaties was slechts een klein aantal variabelen significant verschillend in de controle- en de onderwaterdrainageplots.
2. Het behandelingseffect van een aantal variabelen (P-AL, indringingsweerstand in 0-10 cm, percentage Marionina potwormen, aantal schimmel-etende nematoden) correleerde met de tijd tussen aanleg van de drains en meting, wat varieerde tussen 2 en 9 jaar. Dit lange termijn effect van onderwaterdrains op bodemkwaliteit is echter slechts indicatief aangezien andere locatiekenmerken deze correlaties beïnvloeden.
3. De dienst productie werd beperkt negatief beïnvloed door onderwaterdrainage: bemeste grasproductie, pH en P-AL waren iets lager. Een positief effect voor productie was de toename van indringingsweerstand en draagkracht in de bovenlaag op het moment van meting (mei).
4. Voor de ecosysteemdienst milieuregulatie vonden we een aantal aanwijzingen die het positieve effect van onderwaterdrainage op waterkwaliteit en een verminderde veenoxidatie bevestigen.
De bodemindicatoren voor uitstoot van broeikasgassen en de aanpassing aan klimaatverandering verschilde niet significant tussen onderwaterdrainage en controle. Echter, de indicatoren zijn in de bovengrond gemeten waar in het algemeen biologische activiteit het hoogst is. We kunnen niet uitsluiten dat er dieper in de bodem (in de buurt van fluctuerende grondwaterstanden) verschillen zijn in mineralisatie en productie van broeikasgassen.
5. De gemeten bodemindicatoren voor habitat/biodiversiteit gaven geen signalen voor sterke veranderingen als gevolg van onderwaterdrainage. Echter, de hogere soortenrijkdom van mijten geven een meer stabiele habitat aan als gevolg van de hydrologische buffering door de drains.
Ook de foerageermogelijkheid voor weidevogels werd enigszins verminderd als gevolg van drogere omstandigheden in de bovengrond.
8
Effect of submerged drains in peat meadows on soil quality and ecosystem services

The peat soils in the western part of The Netherlands were formed between 10.000 and 2.000 years ago by a combination of rise of the sea level, rainfall and a poor drainage in the subsoil. The mostly anaerobic soil conditions in these marshy areas resulted in low decomposition and oxidation rates of the dead plant material (Pons, 1992). Therefore, a net accumulation of organic matter took place and an organic soil layer of several meters thick was being formed.
Agriculture became possible on peat soil with drainage by creating more aerobic growth conditions suitable for crops and grassland and increasing the load bearing capacity for animals, transport and machinery. Drainage was historically done by an infrastructure of ditches and canals through which surface water was removed from the area and groundwater table lowered. With increased technical possibilities, ground water level was lowered more and more during the period from first drainage until now. Most agricultural peat areas in the western part of The Netherlands are nowadays used for dairy farming on basis of permanent grassland.
Due to aerobic conditions in the top soil, a net decrease in organic matter through higher mineralization rates is taking place. This peat oxidation results in soil subsidence. For agriculture, soil subsidence means that enhanced drainage is needed and this will eventually lead to disappearance of the peat layer. Further, large amounts of greenhouse gasses are emitted during this process. Van den Akker et al. (2007 and 2008) calculated that per mm soil subsidence, 2,26 t CO
2
-equivalent ha
-1 is emitted. The social pressure on agriculture to minimize soil subsidence is therefore increasing.
Van den Akker et al. (2007) measured subsidence rates of 5 to 20 mm per year under permanent grassland on in the western peat soils in The Netherlands. Differences were related to the depth of the ground water table during summer. Especially on peat soil, the ground water table is only partly dependent on the ditch water level (which is a controlled factor), because horizontal permeability of peat soil for water is low. The water pressure from the ditches is rapidly decreasing with increasing distance from the ditch. The ground water table at a certain moment is therefore primary a function of the precipitation balance during the previous period (surplus or deficit) and the distance to the ditches. Due to these processes, soil water table is typically concave during summer (when measured in a straight line between the ditches) and convex in the winter.
Since 2005, the effects of submerged drains on the ground water table of peat meadows have been researched (Pleijter and Van den Akker, 2007; Hoving et al, 2008, 2011, 2013; Van den Akker et al.
2013)). Submerged drains are drain pipes that are placed in the soil lower than the ditch water level and thereby increase the horizontal water transport capacity of the soil. During summer (precipitation deficit), an increased water infiltration from the ditch is achieved, resulting in a less concave thus higher ground water table and slower peat mineralization. During winter, net drainage occurs causing
Introduction
9

a less convex curve. The lower ground water table in winter does increase the load bearing capacity but has a minimal effect on organic matter mineralization because this process is strongly influenced by temperature.
Effects on ground water table, soil subsidence and grass production were the main focus of experiments with submerged drains in Dutch peat soils. A variety of factors like ditch water level management strategy (low, high, or alternate according to land use), drain distance (4, 6, 8, 12 m) and meteorological conditions (year effect) were researched in different locations (Pleijter and Van den Akker, 2007; Hoving et al, 2008, 2011, 2013, Van den Akker et al. 2013).
Main conclusions of these experiments were:
1. Submerged drains proved to drain as well as to infiltrate, but the functioning depended on ditch water level, because of differences in water pressure: a low level stimulated draining and a high level stimulated infiltration.
2. The effects were stronger with lower drain distance.
3. Higher ground water level during summer due to submerged drains decreased land subsidence with ca. 50% and the emission of greenhouse gasses related to peat oxidation.
4. Submerged drains can increase ground water level during summer with a relatively small increase in ditch water level, without creating problems with water logging and decreasing load bearing capacity.
5. The response of ground water level to changes in ditch water level was higher with than without drains.
6. Difference in ground water level between drained and non-drained land were strongly influenced by dry versus wet periods and differed therefore per year. Furthermore, differences between locations occurred during dry periods, indicating differences in soil permeability and water supply.
7. Grass dry matter and nitrogen yields tended to be lower with submerged drains but the effects were small and varied per location and year. Lower N supply capacity of the soil due to wetter soil circumstances in the summer probably play a role, as well as a better manure use efficiency due to dryer conditions during wet periods.
8. Load bearing capacity was higher during spring and in September in plots with submerged drains.
Due to the relative simplicity of the technique, low effects on grass production but positive contribution to load bearing capacity, decrease in land subsidence and greenhouse gas emissions, provincial authorities and advisors promote submerged drains among farmers in the peat regions
(e.g. Website Province of Zuid Holland, 2014). In the above-mentioned projects, the research mainly focused on hydrological aspects (water level, transport, quantity and quality), land subsidence and agronomy (grass production and load bearing capacity).
Farmers, advisers, nature organizations and regional policymakers in the peat regions cope with questions about the effects of submerged drains on soil quality in a perspective broader than hydrology and agronomy. In an earlier research conducted in 2010, soil quality indicators were selected for ecosystem services in the peat meadows in the western part of The Netherlands (Deru
10
Effect of submerged drains in peat meadows on soil quality and ecosystem services

et al, 2012). Ecosystem services are the services provided to mankind by an ecosystem. For peat meadow ecosystems, an adaptation from Rutgers et al. (2007) was made in which three main services are distinguished: production, environmental regulation and habitat (biodiversity) maintenance (Table 1
). These main services are divided in ‘sub-services’, which can be quantified with specific measurements on soil chemical, physical and biological quality.
Table 1: Soil ecosystem services: classification specific to peat meadows (adapted from Rutgers et al, 2007) and soil indicators (from Deru et al, 2012)
Ecosystem service Sub-ecosystem service
Production
Environmental regulation
Habitat maintenance
Soil structure maintenance and load-bearing capacity
Nutrient release
Grass production
Pest and disease resistance
Organic matter fragmentation and decomposition
Water quality regulation
Climate mitigation and adaptation
Maintenance of soil faunal biodiversity
Maintenance of botanical biodiversity
Maintenance of meadow bird biodiversity
Soil indicator *
Crumb structures; number of roots; loadbearing capacity; penetration resistance
PMN, P-AL, CEC, Ca-Mg ratio
DM and N yields
PPI
HWC; SOM; endogeic earthworms; enchytraeids
Nitrate; P-AL; number of roots
HWC, DEA
Number of soil species
-
Penetration resistance; number of earthworms in 0-10cm
* abbreviations: see material and methods
To our knowledge, until now only one research has been conduced looking at the effect of submerged drains on soil quality other than for agronomy of hydrology. This study was comparing two locations in the province of Zuid Holland in terms of foraging opportunity for meadow birds by measuring the penetration resistance and the number of earthworms and leatherjackets (larvae of the crane fly) in the top soil (Van der Zijden and Kruk, 2011; Kruk and Van der Zijden, 2012).
Although no statistical judgment could be done on basis of the experiment setup, the authors found very little effect of submerged drains on measured variables. Soil type and clay content was of much greater influence.
The aim of the present study was to get insight the soil quality of peat meadows as influenced by submerged drains, and their delivery of the ecosystem services ‘production’, ‘environmental regulation’ and ‘habitat maintenance’.
We selected peat meadows previously used for agronomical and hydrological research on the effect of submerged drains. We used the soil chemical, physical and biological indicators selected by Deru et al. (2012) to assess the delivery of ecosystem services. Soil measurements were done once.
Historical grass production data was used from the agronomical research.
Compared to non-drained meadows, we hypothesize that drained meadows differ in the delivery of the different ecosystem services. Hypotheses are listed per sub-ecosystem service in Table 2.
Introduction
11

Table 2: Hypotheses for the treatment effect per sub-ecosystem service
Ecosystem service
Production
Environmental regulation
Sub-ecosystem service
Soil structure maintenance and loadbearing capacity
Nutrient release
Grass production
Pest and disease resistance
Organic matter fragmentation and decomposition
Water quality regulation
Hypotheses (effect of submerged drains compared to control)
Dryer conditions during wet periods enhance the load bearing capacity.
During dry periods and fall, we expect no significant effect due to the relatively low ground water level (not assessed in this study).
Wetter conditions during summer and higher ground water table decrease soil organic matter mineralization and available nutrients.
No net effect on production: lower nutrient availability are compensated by better growth conditions during spring and fall (assessed with historical data)
Drainage and soil dryer conditions decrease the occurrence of liver fluke
( Fasciola hepatica ) (not assessed in this study)
Wetter conditions during summer and higher ground water table decrease soil organic matter decomposition and mineralization
Habitat maintenance
Climate mitigation and adaptation
Lower nutrient availability and better growth conditions decrease nutrient concentration in the soil.
Drainage increases water transport from soil matrix to surface water (not assessed in this study).
Dryer top soil increases water infiltration and reduces runoff to the ditches.
Wetter conditions during summer and higher ground water table decrease peat oxidation (CO
2
emission) and soil subsidence.
Emission of other greenhouse gasses (N y
O x
) is lower due to lower availability of mineral N.
No difference expected. Maintenance of soil faunal biodiversity
Maintenance of botanical biodiversity
Maintenance of meadow bird biodiversity
Not assessed in this study.
Availability of earthworms in the top soil is not expected to differ significantly. Dryer soil conditions in the spring give higher penetration resistance in the top soil and decrease foraging ease.
12
Effect of submerged drains in peat meadows on soil quality and ecosystem services

For the present study, we used six existing field experiments on permanent grasslands on peat soil where the effect of submerged drains on grass production was or had been researched.
The six selected grasslands needed to meet the following criteria:

Treatment (submerged drains) and control (no drains) next to each other within one meadow to minimize variety other than treatment effect.

The selected grasslands had a comparable ditch water level, around -50 to -60 cm to ensure comparable hydrological conditions between the locations.

The submerged drains were installed in the soil for at least 2 growing seasons to ensure enough adaptation time for the soil physics, chemistry and biology.

Grass production data available from actual or previous years.

The grasslands were under normal agricultural management.

Peat soil, with SOM in 0-10 cm minimal 25 weight %.

Located within the provinces Utrecht, Noord Holland or Zuid Holland.
As far as we knew, no more locations than the six selected sites met our criteria. Next to the inherent variation in soil quality between the locations due to different geological and agricultural history, the six locations differed in the time between drain installation and soil quality measurements (Table 3).
Table 3: Main characteristics of the six selected experiment locations
Location
Code Place
Experiment owner
Distance between drains
(m)
Mean water level in ditch
(cm)
VR Stolwijk
Province
Zuid-
Holland
WUR-Alterra 6 -50
Z-2
Z-3
Zegveld Utrecht
Zegveld Utrecht
WUR-Livestock
Research
WUR-Livestock
Research
8
8
-60
-60
First year of drainage coordinates
2011
2004
2004
51°56.901N 004°43.421E
52°08.288N 004°50.124E
52°08.320N 004°50.179E
ECK 6 -50 2010 52°12.995N 004°57.378E
BA
ST
Vinkeveen Utrecht
Zeevang
Zeevang
Noord-
Holland
Noord-
Holland
WUR-Alterra
WUR-Livestock
Research
WUR-Livestock
Research
6
6
-60
-60
2006
2006
52°32.217N 004°59.423E
52°32.349N 004°59.711E
All soil sampling and measurements occurred 1 st
and 2 nd
May 2013 in a sampling plot of 8x7 m.
Within one experimental grassland (location), both sampling plots (control and treatment) were situated on an imaginary line parallel to the ditch and at approximately 1/3 of the distance between ditches, to ensure a similar influence of the ditch on the measured variables.
Material and methods
13

The following soil samples were taken:

A field-moist bulk sample of ca. 1 kg (0-10 cm, ø 2.3 cm, ca. 50 cores) was collected randomly, sieved through 1 cm mesh, homogenized and stored at 4°C until analysis. The bulk sample was split into sub-samples for abiotic (soil chemical composition) and biotic (nematodes and microbiology) analysis.

For additional chemical analysis by Hortinova, soil samples were taken in 0-20 cm. Sieved fresh soil was sent to the lab of Soil Tech Solutions (Udenhout, The Netherlands) for analysis.

For soil bulk density, actual moisture content and moisture contents at pF 0.00, 1.00 and 2.00, five undisturbed ring samples containing 100 cm
3
soil were taken in the 2-7 cm layer below the soil surface.

Earthworms were sampled in 2 blocks (20 cm x 20 cm x 20 cm). Each block was horizontally split into 0-10cm and 10-20cm. The blocks were transferred to the laboratory where the whole block was broken down and the earthworms were hand-sorted, counted, weighed and fixed in alcohol prior to identification. Numbers and biomass were expressed per m2. Adults were identified according to species and classified into functional groups (epigeic, endogeic and anecic species) (Bouché, 1977).

Three enchytraeid samples were taken using a separable core sampler of 15 cm length with a diameter of 5.8 cm, holding 6 PVC rings of 2.5 cm high. The enchytraeids were extracted from the soil in the rings with a modified wet extraction method (Didden and Römbke, 2001; Römbke et al., 2006). The organisms were counted, measured and identified using a light microscope.
Adults were identified according to species and juveniles to genus. Based on length, the fresh weight was calculated according to Abrahamsen (1973). The observed species were counted and subdivided into three functional groups (1) Fridericia, (2) Marionina and (3) Enchytraeus
(Didden and Römbke, 2001). In determining the species richness, the lowest identified taxonomical level was taken.

Three samples for micro-arthropods were collected with a core sampler of 15 cm length with a diameter of 5.8 cm, holding 3 PVC rings of 2.5 cm high. Micro-arthropods were extracted from the soil by placing the soil sample rings in a Tullgren funnel (Siepel and Van de Bund, 1988;
Römbke et al., 2006). The temperature in the upper part of the funnel was set at 30 ºC and kept at 5 ºC in the lower part. The organisms moved downwards to escape the heat, dropped through a funnel and collected in a bottle containing 70% ethanol. The total extraction time was one week. Collembola and acari were counted separately and identified. In determining the species richness, the lowest identified taxonomical level was taken.
From the field-moist bulk sample, the following analyses were carried out:

Prior to chemical analysis, samples were oven-dried at 40 °C. Soil acidity of the oven-dried samples was measured in 1 M KCl (pH-KCl). Soil Organic Matter (SOM) was determined by loss-on-ignition (Ball, 1964). Total Carbon (C) was measured by incineration of dry material at
1150 °C, after which the CO2 produced was determined by an infra-red detector (LECO
Corporation, St. Joseph, Mich., USA). Hot Water Extractable Carbon (HWC) was analyzed according to the method of Ghani et al. (2003). Field-moist samples were extracted with 30 ml distilled water for 30 minutes, centrifuged for 20 minutes and filtered. Then a further 30 ml
14
Effect of submerged drains in peat meadows on soil quality and ecosystem services

distilled water was added to the sediments, shaken for 10 seconds and left for 16 hours in a hotwere reduced to N
2
and detected with a thermal-conductivity detector (LECO Corporation, St.
Joseph, Mich., USA). Two phosphorous fractions (aluminum-bound and total P) were determined according to standard methods (Bronswijk et al., 2003).

The BodemBalansAnalyse was carried by Soil Tech Solutions out following the Base-cation saturation ratio (BCSR) method on a Thermo ICP, based on the William Albrecht theory
(Albrecht, 1975; Kinsey and Walters, 2006).

For determination of number and species of nematodes, a sub-sample of 450 g of field moist soil was taken from the bulk sample. Approximately 100 g of this was put in a suspension from which the free-living nematodes were extracted, using the Oostenbrink elutriator (Oostenbrink, 1960).
Total numbers were counted and expressed per 100 g fresh soil. Nematodes were fixed in hot formaldehyde (4%), and at least 150 randomly selected nematodes from each sample were identified according to genus and, whenever possible, to species. The Maturity Index was calculated as the weighted mean of the individual cp-values, in accordance with Bongers (1990) and Bongers et al. (1995) as an index of soil quality. In determining the species richness, the lowest identified taxonomical level was taken.

Potentially mineralizable N (PMN) was determined by anaerobic incubation of a soil sample under water for 1 week at 40 °C (Keeny and Nelson, 1982; Canali and Benedetti, 2006). These warm and anoxic conditions are optimal for a quick mineralization of organic matter by anaerobic bacteria. The lack of oxygen prevents conversion of released NH4+ to NO3- (nitrification) and uncontrolled N losses by denitrification cannot occur.

Denitrification enzyme activity (DEA) was measured as described by Nebert et al. (2011). Fresh soil was placed in an air tight jar with a lid containing two rubber septa. The jars were flushed with N
2
and injected with a degassed solution containing 10 mM KNO
3
and 10 mM glucose to provide an anaerobic environment with nonlimiting amounts of nitrate and a high-energy carbon source. Finally, all jars were injected with C
2
H
2
to inhibit the final enzymatic reduction of N
2
O to
N
2
. The jars were placed on a shaker at room temperature (20°C), and N
2
O was measured using an Innova 1412 photo-acoustic infrared gas analyzer (LumaSense Technologies A/S, Ballerup,
Denmark). The rate of N
2
O accumulation from 1 to 4 h was used as a measure of denitrification enzyme activity.
The following measurements were carried out in situ :

Penetration resistance was measured using an electronic penetrometer (Eijkelkamp, Giesbeek,
The Netherlands) with a cone diameter of 2.0 cm
2
and a 60° apex angle. Cone resistance was recorded per cm of soil depth and expressed as an average value of 10 penetrations per plot in the soil layers 0-10 cm, 10-20 cm, etc. to 70-80 cm.

Load bearing capacity was measured with a penetrometer with a cone diameter of 5.0 cm
2
and a 60° apex angle. Load bearing capacity was recorded at 10 randomly chosen spots plot, and was expressed as the average value of the maximum force (N) needed to push the cone through the sod.

Soil structure was determined in four blocks (20 cm x 20 cm x 10 cm): two in 0-10 cm and two in
10-20 cm depth. The soil in a block was assigned by visual observation of crumbs, sub-angular
Material and methods
15

blocky elements and angular blocky elements (FAO, 2006). These fractions were weighed and expressed as a percentage of total fresh soil weight. On horizontal surfaces (20 cm x 20 cm) at
10 cm and 20 cm depth, the number of roots and the number of macropores were counted and expressed per m
2
.

Water infiltration rate was measured at 3 randomly chosen spots. A PVC pipe of 15 cm high (ø of
15 cm) was driven into the soil to a depth of 10 cm, after which 500 ml of water was poured into the ring. The time it took for the 500 ml water to infiltrate was recorded. From this data, the infiltration rate (mm min
-1
) was calculated.
Grass production measurements were not included in this study, but the most recent available data from the experiments was used (Hoving et al, 2013), Van den Akker et al. (2013) and Hendriks et al.
(2013). For the two locations in Zeevang, only data from 2008 was useful (no missing data) whereas for the other four locations, data from 2011 and 2012 was available. The data from 2008 and a mean of 2011 and 2012 was u sed for the statistical analyses. From the locations ‘VR’ and ‘ECK’, Nfertilized grass production data was available. From the other locations, both N-fertilized and non fertilized grass production was available (Table 4).
Grass production measurements of all locations were carried out by the Experiment Farm Zegveld with a Haldrup harvester. Per year, four to eight grass cuts were harvested and analyzed for dry matter (DM) and N contents.
Table 4: Grass production data per location. N0: unfertilized with N; N1: fertilized with N according agricultural practice.
Location code Place Data from years N level Number of cuts
VR Stolwijk 2011 - 2012 N1 2011: 7; 2012: 5
Z-2
Z-3
ECK
BA
ST
Zegveld
Zegveld
Vinkeveen
Zeevang
Zeevang
2011 - 2012
2011 - 2012
2011 - 2012
2008
2008
N0 and N1
N0 and N1
N1
N0 and N1
N0 and N1
2011: 8; 2012: 5
5
5
4
4
The experiment design consisted of the treatment with two levels: ‘control’ and ‘submerged drains’, replicated within six different grasslands. An ANOVA procedure (Genstat 13.3, VSN international) for testing for treatment effect (control versus submerged drain) was used. Each of the six grasslands in which both treatments were compared was statistically regarded as a block.
The age of the experiments ranged from 2 to 9 years at the time of soil sampling for this study (Table
4). To test whether this had an influence on the treatment effect, we calculated the Pearson
correlations between the treatment effect, as being the value of the submerged drain-plot minus that of the control, and the age of the experiment in years. These correlations are only indicative because the experiment age is not evenly distributed nor independent of the experiment location and project to which the experiment belonged.
16
Effect of submerged drains in peat meadows on soil quality and ecosystem services

Both the soil pH-KCl and the P-AL in the 0-10 cm soil layer were significantly lower in the drained plots, but not the pH-water measured in the 0-20cm. Other measured soil chemical indicators did not differ significantly (Table 5). However, a decreased CEC in plots with submerged drains was found in all locations but Z-2. There was a weak negative correlation of the treatment effect of P-AL with the experiment age (Figure 1; R
2
=0,39, P=0,181).
-3
-4
-5
-6
-7
-8
2
-1
-2
1
0
VR
ECK
ST
BA
R² = 0,3949
Z-2, Z-3
0 2 4 6
Experiment age (yr)
8 10
Figure 1: Correlation between experiment age and treatment effect of P-AL. Treatment effect is calculated per location (n=6) as submerged drains minus control. A positive value means a higher value in the drained plot compared to the control plot.
Table 5: Pvalues, means of ‘control’ and ‘submerged drains’, standard deviation and reference values of the chemical soil quality variables. Reference values from Deru et al. (2012).
Group Variable Unit Pvalue
Means St.dev. Reference
(n=20, 2010)
Control Drains Control Drains Mean St.dev.
0,4 4,8 0,3
3593 20127 4551
BLGG
(0-10cm) pH-KCl
N total
Soil organic matter
C total
C fraction
P total
P-AL
- mg kg
-1
0,025 5,2 g 100 g
-1
0,272 49,3 g 100 g
-1
0,329 26,1 g g
-1
0,793 0,53 mg 100 g
-1
0,319 701 mg 100 g
-1
0,032 52
5,1
0,362 22527 21988 3632
48,1
25,4
0,53
686
49
0,4
5,9
3,5
0,01
101
18
Hortinova pH-w (H) - 0,576 5,6
(0-20cm) CEC (H) 0,125 27,2
Soil organic matter (H) g 100 g -1 0,659 40,7
Ca-Mg ratio (H)
Nitrate-N (H) kg kg
-1 kg ha
-1
0,575
0,566
3,8
116,8
5,5
26,2
40,2
3,9
112,0
0,3
2,9
5,9
0,4
43,5
6,8
4,0
0,02
88
18
0,4
2,3
6,7
0,7
51,7
43,8 8,8
22,4 4,5
0,51 0,02
729 113
53 23
5,4 0,2
25,1 4,1
35,5 8,5
3,9 0,7
68,2 29,1
Results
17

A significant increase in penetration resistance of the top 10 cm soil layer was found in the plots with submerged drains compared to the control plots (P=0.033; Figure 2). Beneath 10 cm depth, no differences were found.
300
250
Control
Submerged drains
200
150
100
50
0
0 10 20 30 40 50
Depth in soil (cm)
60 70 80
Figure 2: Comparison between control plots and plots with submerged drains (n=6): penetration resistance of the soil profile to 80 cm depth.
The treatment effect (calculated as submerged drain minus control) of the mean penetration resistance between 0 and 10 cm depth tended to be positively correlated with the age of the experiment (R
2
=0.64,
P=0.058). The locations VR and ECK showed the least difference (ECK even negative), whereas in the meadows from the older experiments a larger treatment effect was seen (Figure 3).
100
Z-3
80
BA
R² = 0,6363
60
40
Z-2
ST
20
VR
0
ECK
-20
0 2 4 6
Experiment age (yr)
8 10
Figure 3: Correlation between experiment age and treatment effect of penetration resistance in 0-10 cm. Treatment effect is calculated per location (n=6) as submerged drains minus control. A positive value means a higher value in the drained plot compared to the control plot.
18
Effect of submerged drains in peat meadows on soil quality and ecosystem services

The load bearing capacity, which is positively correlated to the mean penetration resistance in 0-
10cm (R
2
=0.83, P=0.001) was not significantly higher in the plots with submerged drains compared to the controls.
The soil moisture content of the top soil, commonly negatively correlated with penetration resistance in the same layer (in our dataset: R
2
=0.45, P=0.017), showed a tendency to be lower in plots with submerged drains (P=0.055; only at ST the was no difference) and the same was seen for the moisture content at pF1.
Other soil physical quality variables did not differ significantly between treatments (Table 6).
However, in a number of variables the treatment effect was similar for all but one location. This is the case for load bearing capacity (all increased, ECK decreased), number of roots at 20 cm (all but Z-3 increased) and water infiltration (all but VR increased) (Table 9 in Appendix).
Table 6: Pvalues, means of ‘control’ and ‘submerged drains’, standard deviation and reference values of the physical soil quality variables. Reference values from Deru et al. (2012).
Variable Unit
Pvalue
Means St.dev.
Reference
(n=20, 2010)
Control Drains Control Drains Mean St.dev.
Penetration resist. (0-10 cm) N 2 cm
-2
Penetration resist. (10-20 cm) N 2 cm
-2
0,033 189
0,358 198
234
210
53
39
51
26
190 41
206 43
Penetration resist. (20-30 cm) N 2 cm -2 0,776 168 164 19 26 176 26
Penetration resist. (30-40 cm) N 2 cm
-2
Penetration resist. (40-50 cm) N 2 cm -2
Penetration resist. (50-60 cm) N 2 cm
-2
Penetration resist. (60-70 cm) N 2 cm -2
0,885
0,510
0,709
132
121
117
0,705 115
Penetration resist. (70-80 cm) N 2 cm
-2
Load bearing capacity
0,814 118
N max
5 cm -2 0,595 662
Crumb structures (0-10cm) weight %
Crumb structures (10-20cm) weight %
Sod thickness
Root density at 10 cm
Root density at 20 cm
Pore density at 10 cm
0,172
0,317
57,8
17,0 cm 1,000 3,4 n 400 cm
-2
0,661 393 n 400 cm
-2
0,136 210 n 400 cm
-2
0,118 2,6
Pore density at 20 cm
Water infiltration
Bulk density
Soil moisture (actual)
Soil moisture (at pF 1)
Soil moisture (at pF 2) n 400 cm
-2
0,235 0,2 mm minute
-1
0,207 6,2 g cm
-3
0,133 0,49 weight % g cm
-3 g cm
-3
0,055
0,091
0,167
55,4
0,76
0,74
131
114
113
119
121
680
12
17
16
24
19
130
63,6 8,1
15,2 6,8
3,4
379
246
0,7
82
99
4,1 2,5
0,5 0,3
11,4 7,5
0,53 0,07
52,8 4,1
0,75 0,01
0,73 0,02
17
15
27
26
23
115
0,6
11,1
0,04
3,3
0,01
0,02
7,5
5,1
0,6
78
75
2,4
131 23
107 13
96
90
88
12
15
19
553 121
78,8 15,3
51,2 17,7
3,8 1,0
306 76
139 68
5,7 4,9
2,1 2,1
3,4 4,5
0,54 0,09
57,6 6,3
0,76 0,03
0,65 0,03
No significant treatment effect was found in the microbiological variables HWC, PMN and DEA.
The total number of earthworms was not significantly different between the treatments. Figure 4 shows the number of earthworms separated into functional groups and soil layer. In the plots with submerged drains, in average more earthworms were found in 10-20 cm depth and the proportion of
Results
19

epigeic worms was higher compared to control (Figure 4). However at one location (VR) the opposite was found, resulting in the non-significant mean increase over the six locations (P=0,065).
800
700
600
500
400
300
Epigeic 0-10 cm
Epigeic 10-20 cm
Endogeic 0-10 cm
Endogeic 10-20 cm
200
100
0
Control Submerged drains
Figure 4: Number of earthworms (n m
-2
), separated into functional group and soil layer. Error bars represent the standard deviation of the total number per treatment level.
The number of enchytraeids tended to be lower in drained plots (P=0,097), especially due to less
Marionina worms (Figure 5) but again, at one location (Z-2) the effect was reversed.
The percentage of Marionina enchytraeids was lower with submerged drains compared to the control at the two ‘young locations’ (VR and ECK). No difference was seen in Polder Zeevang (Noord
Holland), and at Z-2 increased significantly with increasing experiment age (Figure 6; R
2
=0,83,
P=0,012). Compared to the reference of 2010, the number of enchytraeids was lower (Table 7).
25000
20000
15000
10000
5000
Enchytraeus
Marionina
Fridericia
0
Control Submerged drains
Figure 5: Number of enchytraeids (n m
-2
), separated into groups Enchytraeus, Marionina and
Fridericia. Error bars represent the standard deviation of the total number per treatment level.
20
Effect of submerged drains in peat meadows on soil quality and ecosystem services

40
30
20
10
0
-10
-20
-30
-40
-50
VR
ECK
R² = 0,8259
BA, ST
Z-2
Z-3
0 2 4 6
Experiment age (yr)
8 10
Figure 6: Correlation between experiment age and treatment effect of Marionina percentage of enchytraeids. Treatment effect is calculated per location (n=6) as submerged drains minus control. A positive value means a higher value in the drained plot compared to the control plot.
In the drained plots, a significant higher diversity of micro-arthropods was found. Especially the number of acari species was higher in drained plots (Table 7, P=0,007). The micro-arthropod abundance was also higher in drained plots, but this was not significant. In 2010, the number of micro-arthropods counted was ca. 3 times higher than in 2013.
In the nematode variables, no significant differences or trends were distinguished between the treatments. However, differences were found in treatment effect between the locations, with a significant positive correlation with experiment age (Figure 7; R
2
=0,84, P=0,002).
250
200
150
100
50
0
-50
-100
-150
-200
VR
ECK
R² = 0,8448
BA
ST
Z-2
Z-3
0 2 4 6
Experiment age (yr)
8 10
Figure 7: Correlation between experiment age and treatment effect of number of fungal feeding nematodes. Treatment effect is calculated per location (n=6) as submerged drains minus control. A positive value means a higher value in the drained plot compared to the control plot.
Results
21

Table 7: Pvalues, means of ‘control’ and ‘submerged drains’, standard deviation and reference values of the biological soil quality variables. Reference values from Deru et al. (2012).
Group Variable Unit
Pvalue Means St.dev.
Reference
(n=20, 2010)
Control Drains Control Drains Mean St.dev.
µg C g -1 0,498 10837 11113 1332 1932 9309 1852 Microbiology Hot Water extractable Carbon
Potentially
Mineralizable
Nitrogen
Denitrifying
Enzyme Activity
Earthworms Total number mg Nkg
-1
0,368 631 ppm N
2
O
3h -1 n m
-2
0,263 474
0,725 575
599
510
551
75
73
390
66
132
317
465
587
98
318 n m
-2
0,330 542 451 371 209 Total number
(0-10cm)
Total number (10-
20cm)
Epigeic
(adult + juv.)
Endogeic
(adult + juv.)
Fresh biomass n m -2 n m
-2 n m
-2 g m
-2
0,174 33
0,065 102
0,289 386
0,441 149
100
183
333
164
34
79
287
89
135
101
210
59 146 77
0,611 3,8
0,097 19334
3,7 0,8 1,0 4,3 1,2
15621 5865 6299 31642 9967
Diversity (species) n
Enchytraeids Total number n m -2
Fridericia
Marionina n m
-2 n m
-2
Enchyraeus
Biomass n m -2 g m -2
0,908 8999
0,169 7290
0,826 3046
0,338 7,2
8744 1838 5115 15267 7778
4146 4343 842 11589 7106
2731 2637 2021 4786 5152
6,2 5,6 4,7 13,5 5,6
9,3 2,2 0,8 10,3 2,1
32291 12099 25805 81157 33830 Microarthropods
Diversity (species) n
Total number
Acari
Collembola n m -2 n m
-2 n m
-2
0,661
0,438
0,459
0,455
9,0
25904
8187
17717
Diversity (species) n
Diversity
(species acari)
Diversity
(species collembola)
Nematodes Total number n n n 100 g -1
0,048
0,007
0,876
19,7
10,5
9,2
0,388 6113
Total
Maturity Index
(1-5)
Plant Parasitic
Index
Diversity (species) n total soil faunal diversity (species) n
0,491 2,2
0,493
0,129
0,803
2,8
29,2
61,7
9263 4820 5199 47943 27840
23028 8926 22306 33214 13449
22,3
13,3
2,8
3,3
1,5
2,8
24,7
16,3
3,0
2,9
9,0 2,6
5676 708
2,2 0,2
2,7
25,7
61,0
0,1
4,6
6,4
1,4
1043 8598 2267
0,2 2,2 0,2
0,1
2,5
3,0
8,4
2,7
31,2
70,3
1,7
0,1
2,8
4,1
In general, the influence of submerged drains on grass production was weak. The fourth cut resulted in significantly higher DM and N yields in the unfertilized drained plots compared to the control (Table
8). On year basis, this effect was not significant but showed a trend (unfertilized DM yield, P=0,097).
In the fertilized grass, an opposite trend was seen for total DM yield (P=0,076) (Figure 8).
22
Effect of submerged drains in peat meadows on soil quality and ecosystem services

14000
12000
10000
8000
6000
Control
Submerged drains
4000
2000
0
N0 N1
Figure 8: Unfertilized (N0) and fertilized (N1) grass production (kg DM ha
-1
yr
-1
) of control and drained plots. Error bars represent the standard deviation.
Table 8: Pvalues, number of measurements (n), means of ‘control’ and ‘submerged drains’, standard deviation and reference values of grass production. Total year yield and yields from the first 4 cuts are given. Abbreviations: DM: dry matter; N: Nitrogen; N0: without N fertilizer; N1: with
N fertilizer. Reference values from Deru et al. (2012).
Variable Unit
Pvalue n Means St.dev.
Reference
(n=20, 2010)
Control Drains Control Drains Mean St.dev.
DM yield at N0 (year kg DM ha -1 0,097 8 9450 total)
DM yield at N0 (1st cut) kg DM ha
-1
0,153 8 2462
10000 697
2734 700
862
458
10718 1710
DM yield at N0 (2nd cut) kg DM ha -1 0,599 8 2110
DM yield at N0 (3rd cut) kg DM ha
-1
0,203 8 2469
DM yield at N0 (4th cut) kg DM ha
-1
<,001 8 1916
2017
2651
2083
308
650
373
N yield at N0 (year total) kg N ha
-1
N yield at N0 (1st cut) kg N ha
-1
N yield at N0 (2nd cut) kg N ha -1
0,107
0,211
8
8
265,2
62,2
281,2
68,7
17,2
12,3
0,985 8 50,3 50,4 12,6
N yield at N0 (3rd cut)
N yield at N0 (4th cut) kg N ha
-1 kg N ha
-1
0,421 8 71,6
0,017 8 64,5
75,0
69,6
25,2
11,0
DM yield at N1 (year total) kg DM ha
-1
0,077 12 12268
DM yield at N1 (1st cut) kg DM ha
-1
0,439 12 4044
12066
3981
770
780
DM yield at N1 (2nd cut) kg DM ha
-1
0,071 12 2166
DM yield at N1 (3rd cut) kg DM ha
-1
0,926 12 2823
DM yield at N1 (4th cut) kg DM ha
-1
0,978 12 1991
N yield at N1 (year total) kg N ha
-1
N yield at N1 (1st cut) kg N ha -1
N yield at N1 (2nd cut)
N yield at N1 (3rd cut)
N yield at N1 (4th cut) kg N ha
-1 kg N ha
-1 kg N ha
-1
0,186
0,197
0,127
0,448
0,861
12 361,6
12 114,2
12 61,2
12 80,0
12 64,6
2065
2830
1992
355,1
110,7
58,6
81,5
64,9
398
713
455
31,0
8,6
11,7
29,5
11,3
350
516
379
25,2
4,1
13,4
22,2
9,6
884
889
474
676
488
37,9
11,7
14,4
28,3
12,5
263,6 49,8
13111 1236
393,6 36,4
Results
23

In general, the presence of submerged drains in peat meadows did not have a strong effect on the soil quality variables measured. Only a small number of variables differed significantly between the control and the submerged drains. However, the most soil quality indicators used were sensitive enough to differ significantly between 20 agricultural peat meadows and 20 natural peat meadows in the research of Deru et al (2012). In the present study on agricultural meadows only, the differences between treatment levels (submerged drains and control) within one meadow and managed identically were not expected to be as large as between different land use types. The six replicates in combination with a relatively wide geographical distribution might have been too low for enough statistical power to detect significant differences. An indication for this is that most variables had a
(very) significant block effect (blocks being the six individual meadows), reflecting the variability between the locations (see appendix). Soil chemical variables had a stronger block effect than physical and biological variables.
The variation between locations can have different causes. As discussed in Hoving et al. (2013), large differences exist in drainage and infiltration capacity of submerged drains between locations and meadows. Hoving et al (2008) pointed out that even between parcels within the same farm, differences in soil permeability were found, resulting in differences in water infiltration and drainage capacity of fields with submerged drains. For example, drains at Zegveld, and especially at location
Z-2, seemed not to drain as effectively during the last years as they did before. Another possible cause for the variation between locations is the difference in age. At Zegveld and polder Zeevang, drains had been installed 9 and 7 years before soil sampling, respectively, whereas the drains at VR and ECK were only 2 and 3 years old. We found significant correlations between experiment age and treatment effect in some variables (P-AL, penetration resistance 0-10 cm, Marionina enchytraeids, fungal feeding nematodes). However, from the experiment design we cannot exclude that these correlations are caused by differences between locations rather than age.
This study aimed at a broad inventory of the effects of submerged drains on the soil quality and delivery of ecosystem services of peat meadows. Although other studies with specific research questions used repeated measurements during the growing season for earthworms and penetration resistance (Van der Zijden en Kruk, 2011; Kruk and Van der Zijden, 2012) and load bearing capacity
(Hoving et al. 2008), in this study we clustered all measurements during one day at the beginning of the growing season. Most soil quality variables are influenced by crop growth, temperature and moisture and therefore change during the growing season. Also submerged drains can either infiltrate or drain according to the differences in ground water table and ditch water level and thereby influence soil quality differently in different seasons. However, the purpose of this study was to measure the changes in soil quality above the effects within the growing season and some variables are more sensitive to short term changes than other. For example, soil moisture at a given pF is less correlated to actual soil moisture, but actual soil moisture indicates whether submerged drains are draining or infiltrating at a certain moment.
Discussion
25

4.2.1 Production
For the grass production, the collected data was not from the same year for the six locations (Table
4), because we selected the most recent and complete data. From the means, we can conclude that the grass production was not significantly different with submerged drains, and the N supply
(unfertilized grass production; data only from Zeevang and Zegveld) tended to increase. The increase in N supply is surprising, because a lower organic matter mineralization resulting in lower N supply was hypothesized. Hoving et al. (2008 and 2011) concluded in a comparison with more years but partly from the same locations, that the N supply decreased with submerged drains. Apparently, due to large (meteorological) differences between years, the selection of grass production data from a limited number of years can strongly influence the outcome. Further, differences between locations are reported (Hoving et al., 2008, 2011 and 2013; Van den Akker et al, 2013). General conclusions about the effect of submerged drains on grass production should therefore be drawn from long term experiments at different sites.
As for grass production, the soil quality indicators for production (Table 1 in the introduction) did not show many or strong differences between submerged drains and control. P-AL, indicating the phosphate available to grass, was lower with submerged drains. This is in line with our hypothesis and findings of Hoving et al. (2008) for lower N availability due to lower mineralization of organic matter. Penetration resistance in 0-10 cm was higher with submerged drains, which correlates with lower moisture contents. This is an indication that at the time of sampling (1 and 2 May) the submerged drains were mainly draining. Load bearing capacity increased in five out of six locations.
A small decrease in soil pH was seen with submerged drains in 0-10cm. However this was not significant in the layer 0-20 cm. Similarly, the differences in penetration resistance occurred only in the top 10 cm.
4.2.2 Environmental regulation
The overall hypothesis was a lower soil organic matter decomposition and mineralization with submerged drains, leading to less nutrient and greenhouse gas emissions and land subsidence. In the various soil indicators measured for environmental regulation, the only variables with a significant difference between treatments were P-AL (fraction of P-total available to grass) and enchytraeids.
Van den Akker et al (2013) measured the transport of nutrients in ditch water at the locations VR and
ECK and found lower amounts of phosphorus, but not for nitrogen. This is in line with our measurements in the soil. Enchytraeids were among others indicators for organic matter fragmentation and decomposition because they feed on soil organic matter (Schouten et al, 2000).
Except for location Z-2, all locations had a lower number of (Marionina) enchytraeids. No other indications for lower decomposition in drained meadows were found.
26
Effect of submerged drains in peat meadows on soil quality and ecosystem services

Also for climate mitigation, the measured soil indicators (HWC, DEA), did not detect differences although they had given significant differences in the top soil between agricultural and natural meadows in 2010 (Deru et al, 2012). DEA is partly influenced by the amount of nitrate in the soil, and this was not significantly lower with submerged drains (Table 5). However, peat oxidation is a process that not only takes place in the top soil, where we carried out the measurements, but in the total aerobic soil profile. Even beneath the ground water table, anaerobic peat oxidation can happen at places where the peat previously had been in contact with oxygen (Brouns and Verhoeven, 2013).
The largest differences in mineralization, denitrification and greenhouse gas emissions may be expected near the groundwater where levels fluctuate (Van Beek et al. 2009). Since submerged drains reduce fluctuations, also reduced denitrification may be expected. Van Beek et al. (2009) did not find significant effects of submerged drainage but strongly reduced N
2
O emission at higher groundwater levels (40 vs 55 cm below soil surface).
Water infiltration was used as indicator for climate adaptation to more frequent and intensive rainfall.
In our research, all but one location (VR) had a higher infiltration. Water infiltration correlated with soil structure (expressed as percentage of crumb structures) in the study of Deru et al. (2012). In the present study, there was no significant difference in soil structure between the submerged drains and control treatment.
4.2.3 Habitat maintenance
Differences in number of the different soil faunal groups were large, but also their variation.
Therefore, most differences were not significant (Table 7).
We found an increased diversity of acari (mites) in drained meadows, but the abundance was not significantly higher. Species richness is an indication of ecosystem stability (pers. comm. M Bos,
Louis Bolk Institute). The presence of drains can buffer changes in soil moisture conditions (dryer during wet periods and wetter during dry periods) and creates a more stable habitat. The differences in penetration resistance and soil moisture at the time of measuring indicate the draining effect. Also the increase in earthworm abundance in the layer 10-20 cm compared to 0-10 cm can show dryer conditions in the topsoil. However, the lack of other significant differences in diversity variables
(abundance and diversity of other soil faunal groups) do not point out large effects of submerged drains.
Regarding maintenance of meadow bird diversity, we found an weak increase (P=0.065) in epigeic earthworms and penetration resistance in 0-10cm with submerged drains. However, the total number of earthworms in the 0-10 cm soil layer was lower (although not significantly). The negative treatment effect was strongest in the locations in Noord Holland (BA and ST). It is assumed that increased penetration resistance in the top soil is less favorable to meadow birds. From these results we can conclude that foraging opportunity to meadow birds was somewhat altered by submerged drains compared to control.
Discussion
27

1. In general, the presence of submerged drains in peat meadows did not have a strong effect on the soil quality variables measured. Due to the large variation between the six locations only a small number of variables differed significantly between the control and the submerged drains; the effect of location was larger.
2. The treatment effect of a number of variables (P-AL, penetration resistance in 0-10 cm, percentage of Marionina enchytraeids, number of fungal feeding nematodes) correlated with the experiment age of the six locations, showing a long term effect of submerged drains on soil quality. However, this is only indicative since other location characteristics could not be excluded from the correlations.
3. The ecosystem service Production was marginally negatively influenced by submerged drains: fertilized grass production, pH and P-AL were slightly lower. A positive change for production was the increase in penetration resistance and load bearing capacity in the top soil at the time of measurements (May).
4. For the ecosystem service Environmental regulation , we found a few indications confirming the positive effect of submerged drains on water quality and decreased peat oxidation. The soil indicators for emission of greenhouse gasses and adaptation to climate change did not differ significantly between submerged drains and control. However, the indicators were measured in the top soil where in general biological activity is highest. We cannot exclude that differences in mineralization and greenhouse gas production occurred deeper in the soil near fluctuating groundwater levels.
5. The measured soil indicators for Habitat maintenance gave no signals for strong changes due to submerged drains. However, the higher species richness of acari indicated a more stable habitat due to the hydrological buffering by drains and foraging opportunity to meadow birds was slightly altered due to dryer conditions in the top soil.
Conclusions
29

Albrecht WA (1975). The Albrecht papers: Soil fertility and animal health (Volume 2). Acres U.S.A. 192 pp.
Ball DF (1964). Loss-on-ignition as estimate of organic matter + organic carbon in non-calcareous soils.
J. Soil Sci. 15, 84.
Bongers T, (1990). The Maturity Index: an ecological measure of environmental disturbance based on nematode species composition. Oecologia 83, 14-19.
Bongers T, De Goede RGM, Korthals GW, Yeates GW (1995). Proposed changes pf c-p classification for nematodes. Russ. J. Nematol. 3, 61-62.
Bouché MB, Al-Addan F (1997). Earthworms, water infiltration and soil stability: some new assessments.
Soil Biol. Biochem. 29, 441-452.
Bronswijk JBB, Groot MSM, Fest PMJ, Van Leeuwen TC (2003). National Soil Quality Monitoring
Network; results of the first sampling round 1993-1997. Report no. 714801031. RIVM, Bilthoven
(In Dutch, with English summary).
Brouns K, Verhoeven JTA (2013). Afbraak van veen in veenweidegebieden: effecten van zomerdroogte, verbrakking en landgebruik. Eindrapport Kennis voor Klimaat (nr 97/2013), Universiteit Utrecht.
Canali S, Benedetti A (2006). Soil nitrogen mineralization. In: Bloem J., Hopkins, D.W., Benedetti, A.
(Eds), Microbiological Methods for Assessing Soil Quality, pp. 23-49. CABI, Wallingford, UK.
Deru JGC, Van Eekeren NJM, Kloen H, Dijkman W, Van den Akker JJH, De Goede RGM, Schouten T,
Rutgers M, Smits S, Jagers op Akkerhuis GAJM, Dimmers W, Keidel H, Lenssinck F, Bloem J
(2012). Bodemindicatoren voor duurzaam bodemgebruik in de veenweiden: Ecosysteemdiensten van Landbouw- en natuurpercelen in het veenweidegebied van Zuid-Holland, Noord-Holland en
Utrecht. Deel A: Onderzoeksrapportage. Rapport 2012-005 LbD. Louis Bolk Instituut, Driebergen.
115 p.
Didden W, Römbke J (2001). Enchytraeids as indicator organisms for chemical stress in terrestrial ecosystems. Ecotox. Environ. Saf. 50, 25-43.
FAO (2006). Guidelines for Soil Description, Fourth Edition. FAO, Rome, Italy, 97 pp.
Ghani A, Dexter M, Perrott KW (2003). Hot-water extractable carbon in soils: a sensitive measurement for determining impacts of fertilisation, grazing and cultivation. Soil Biology and Biochemistry 35,
1231
–1243.
Hendriks RFA, Van den Akker JJH, Van Houwelingen K, Van Kleef J, Pleijter M, Van den Toorn A
(2013). Pilot onderwaterdrains Utrecht.
Wageningen, Alterra Wageningen UR, Alterra-rapport
2479. 148 blz.
References
31

Hoving IE, André G, Van den Akker JJH, Pleijter M (2008). Hydrologische en landbouwkundige effecten van gebruik ‘onderwaterdrains’ op veengrond. Report 449, Wageningen UR Livestock Research,
Lelystad.
Hoving IE, Van den Akker JJH, Pleijter M, Van Houwelingen K (2011). Hydrologische en landbouwkundige effecten toepassing van onderwaterdrains in polder Zeevang. Report 102,
Wageningen UR Animal Sciences Group, Lelystad.
Hoving IE, Vereijken P, Van Houwelingen K, Pleijter M (2013). Hydrologische en landbouwkundige effecten toepassing onderwaterdrains bij dynamisch slootpeilbeheer op veengrond. Report 719,
Wageningen UR Livestock Research, Lelystad.
Oostenbrink M (1960). Estimating nematode populations by some selected methods. In: Sasser, J.,
Jenkins, W.R. (Eds), Nematology, pp. 85-102. Chapel Hill, University of North Carolina Press.
Keeney DR, Nelson DW (1982). Nitrogen -
Inorganic forms. In “Methods of Soil Analysis”, Part 2. (Black
C.A., Evans D.D., White J.L. Ensminger L.E., Clark F.E., editors). Madison WI: Am Soc Agron, pp. 682-687.
Kinsey N, Walters C (2006). Neal Kinsey's Hands-on Agronomy: Understanding Soil Fertility & Fertilizer.
Acres U.S.A. 391 pp.
Kleijn D, Lammertsma D, Müskens G (2011). Het belang van waterpeil en bemesting voor de voedselbeschikbaarheid van weidevogels pp. 41-60. In: Teunissen WA, Wymenga E (Eds.) 2011.
Factoren die van invloed zijn op de ontwikkeling van weidevogelpopulaties. Belangrijke factoren tijdens de trek, de invloed van waterpeil op voedselbeschikbaarheid en graslandstructuur op kuikenoverleving. SOVON onderzoeksrapport 2011/10. SOVON Vogelonderzoek Nederland,
Nijmegen. A&W-rapport 1532. Bureau Altenburg & Wymenga, Veenwouden. Alterra rapport 2187,
Alterra Wageningen UR, Wageningen.
Kruk M, Van der Zijden A (2012). Effecten van onderwaterdrainage op indringweerstanden en bodemfauna veenbodems - 2012. Landschapsbeheer Zuid-Holland, Waddinxveen
Nebert L, Bloem J, Lubbers I, Van Groenigen JW (2011). Earthworm - denitrifier interactions determine increased nitrous oxide emissions from soil mesocosms amended with crop residue. Applied and
Environmental Microbiology 77, 4097
–4104.
Pleijter M, Van den Akker JJH (2007). Onderwaterdrains in het veenweidegebied. Toelichting op de methode en meetinrichting. Alterra rapport 1586, Alterra Wageningen UR, Wageningen
Pons LJ (1992). Holocene peat formation in the lower parts of the Netherlands. Fens and bogs in the
Netherlands: vegatation, history, nutrient dynamics and conservation (eds J. T. A. Verhoeven).
Kluwer Academics Publishers, Dordrecht.
Rutgers M, Mulder C, Schouten AJ, Bloem J, Bogte JJ, Breure AM, Brussaard L, De Goede RGM, Faber
JH, Jagers op Akkerhuis GAJM, Keidel H, Korthals GW, Smeding FW, Ter Berg C, Van Eekeren
N (2007). Typeringen van bodemecosystemen in Nederland met tien referenties voor biologische bodemkwaliteit. RIVM rapport 607604008 96 pp.
32
Effect of submerged drains in peat meadows on soil quality and ecosystem services

Schouten AJ, Bloem J, Breure AM, Didden WAM, Van Esbroek M, De Ruiter PC, Rutgers M, Siepel H,
Velvis H (2000). Pilot project Bodembiologische Indicator voor Life Support Functies van de bodem. RIVM rapport 607604001.
Siepel H, Van de Bund CF (1988). The influence of management practises on the microarthropod community of grassland. Pedobiologica 31, 179-185.
Van Beek CL, Pleijter M, Jacobs CMJ, Velthof GL, Van Groeningen JW, Kuikman PJ (2009). Emissions of N
2
O from fertilized and grazed grassland on organic soil in relation to groundwater level.
Nutrient Cycling in Agroecosystems 86: 331-340.
Van den Akker JJH, Beuving J, Hendriks RFA, Wolleswinkel RJ (2007). Maaivelddaling, afbraak en CO2 emissie van Nederlandse veenweidegebieden. Leidraad Bodembescherming, Sdu, Den Haag.
Van den Akker JJH, Hendriks RFA, Hoving IE, Meerkerk B, Van Houwelingen K, Van Kleef J, Pleijter M,
Van den Toorn A (2013). Pilot onderwaterdrains Krimpenerwaard.
Wageningen, Alterra
Wageningen UR, Alterra-rapport 2466. 114 blz.
Van den Akker JJH, Kuikman PJ, De Vries F, Hoving I, Pleijter M, Hendriks RFA, Wolleswinkel RJ,
Simões RTL, Kwakernaak C (2008). Emission of CO2 from agricultural peat soils in the
Netherlands and ways to limit this emission. In: Farrell, C and J. Feehan (eds.), 2008.
Proceedings of the 13th International Peat Congress After Wise Use
– The Future of Peatlands,
Vol. 1 Oral Presentations, Tullamore, Ireland, 8 - 13 june 2008. International Peat Society,
Jyväskylä, Finland. pp 645-648
Van der Zijden A, Kruk M (2011). Effecten van onderwaterdrainage op indringweerstanden en bodemfauna veenbodems. Landschapsbeheer Zuid-Holland, Waddinxveen.
Website Province of Zuid Holland (visited 27 th
of March, 2014) http://www.zuidholland.nl/overzicht_alle_themas/c_landschap/thema_groen/c_agrarisch_landschap/c_e_thema_ bodem-onderwaterdrainage.htm
References
33

Table 9: P-values (treatment and location), means of ‘control’ and ‘submerged drains’, standard deviation, reference values and treatment effect of soil quality variables and grass production.
Group Variable Unit P-values Means St.dev.
treatm. location Control Drains Control Drains
Reference (n=20 *) Treatment effect (Submerged drain minus control)
Mean St.dev.
VR Z-2 Z-3 ECK BA ST
Soil chemical variables
BLGG pH-KCl
(0-10cm) N total
Soil organic matter
C total
C fraction
P total
mg kg
-1 g 100 g
-1 g 100 g
-1 g g
-1 mg 100 g -1 mg 100 g
-1
P-al
K total
S total
Hortinova pH-w (H)
(0-20cm) CEC (H)
-
Soil organic matter (H)
Ca-Mg ratio (H) g 100 g
-1 kg kg -1 kg ha
-1
Nitrate-N (H)
Soil physical variables
Penetration resist. (0-10 cm)
Penetration resist. (10-20 cm)
N 2 cm -2
N 2 cm
-2
Penetration resist. (20-30 cm) N 2 cm -2
Penetration resist. (30-40 cm) N 2 cm
-2
Penetration resist. (40-50 cm) N 2 cm
-2
Penetration resist. (50-60 cm)
Penetration resist. (60-70 cm)
N 2 cm
-2
N 2 cm
-2
Penetration resist. (70-80 cm) N 2 cm -2
Load bearing capacity
Crumb structures (0-10cm)
Crumb structures (10-20cm)
Sod thickness
Root density at 10 cm
Root density at 20 cm
N max
5 cm
-2 weight % weight % cm n 400 cm
-2 n 400 cm
-2
Pore density at 10 cm
Pore density at 20 cm
Water infiltration
Bulk density
Soil moisture (actual)
Soil moisture (at pF 1)
Soil moisture (at pF 2)
* from Deru et al. (2012) n 400 cm -2 n 400 cm
-2 mm minute -1 g cm
-3 weight % g cm -3 g cm
-3
0,033 0,027
0,358 0,061
0,776
0,885
0,325
0,816
0,510
0,709
0,705
0,695
0,366
0,217
0,814 0,387
0,595 0,016
0,172
0,317
1,000
0,230
0,019
0,035
0,661 0,087
0,136 0,009
0,118
0,235
0,045
0,322
0,207 0,089
0,133 0,059
0,055
0,091
0,167
0,022
0,152
0,019
0,025 <0,001
0,362 0,001
0,272
0,329
0,793
0,001
0,003
0,238
0,319 <0,001
0,032 <0,001
0,213
0,181
0,576
0,125
0,659
0,004
0,005
0,002
0,006
0,002
0,575 0,090
0,566 0,002
5,2 5,1
22527 21988
49,3 48,1
26,1
0,53
701
52
370
5498
5,6
27,2
40,7
3,8
116,8
25,4
0,53
686
49
331
5118
5,5
26,2
40,2
3,9
112,0
12
17
16
24
19
130
8,1
6,8
0,7
53
39
19
0,3
7,5
0,07
4,1
0,01
0,02
82
99
2,5
131
114
680
63,6
15,2
3,4
113
119
121
234
210
164
0,5
11,4
0,53
52,8
0,75
0,73
379
246
4,1
132
121
662
57,8
17,0
3,4
117
115
118
189
198
168
0,2
6,2
0,49
55,4
0,76
0,74
393
210
2,6
0,4
3632
5,9
3,5
0,01
101
18
147
1097
0,3
2,9
5,9
0,4
43,5
0,4
3593
6,8
4,0
0,02
88
18
132
1309
0,4
2,3
6,7
0,7
51,7
23
13
121
15,3
17,7
1,0
12
15
19
41
43
26
2,1
4,5
0,09
6,3
0,03
0,03
76
68
4,9
131
107
553
78,8
51,2
3,8
96
90
88
190
206
176
2,1
3,4
0,54
57,6
0,76
0,65
306
139
5,7
17
15
27
26
23
115
7,5
5,1
0,6
51
26
26
0,6
11,1
0,04
3,3
0,01
0,02
78
75
2,4
4,8
20127
43,8
22,4
0,51
729
53
273
5127
5,4
25,1
35,5
3,9
68,2
-0,1
340
1,7
0,1
-0,02
2
1
-36
530
0,0
-2,3
-0,5
0,1
15
0,3
4551
8,8
4,5
0,02
113
23
172
1553
0,2
4,1
8,5
0,7
29,1
0,0 -0,1
-300 -2620
-0,2 -4,0
0,5
0,01
-44
-4
-149
-30
-0,1
1,1
0,1
0,1
-4
-3,1
-0,02
-26
-4
30
-1240
0,0
-0,5
0,5
-0,4
0
13,4
-10,3
33,3
27,4
18,5
49,8
49,0
33,2
-0,4
4,7
5,0
0,3
-82,0
76,0
-0,5
-8,0
50,0
0,0
52,0
-46,0
2,0
-0,5
-0,9
1,0
1,1
0,0
1,2
0,1
-2,7
0,0
-2,1
0,1
-3,4
-0,012 -0,005 -0,001
-0,008 0,005 0,001
44,4
23,7
-2,6
15,1
10,3
-13,1
22,2
37,1
16,1
11,2
-5,4
0,3
90,3
10,3
-16,0
-4,9
-28,3
-41,4
-11,0
-18,2
-20,4
1,9
-27,2
-15,8
-12,6
-16,4
-8,0
-3,4
81,5 -125,5
-1,9
-2,6
-1,0
1,8
-4,7
0,3
94,0
94,0
3,5
-64,0
34,0
4,0
-76,0
10,0
0,0
0,0
3,6
0,5
3,4
1,0
22,7
0,0
-0,3
0,1
-7,0
0,0
0,0
0,001 -0,028 -0,010
0,000 -0,023 -0,024
82,2
52,7
25,3
13,7
8,0
81,0
21,2
0,7
0,3
1,8
-4,2
2,1
41,9
22,1
-19,7
-38,6
-48,9
-29,2
-33,3
-25,1
55,5
-1,9
-3,7
0,0
0,2
-1670
-4,5
-2,6
-0,01
42
-2
-60
-490
-0,1
-2,6
-5,6
1,1
-36
0,0
460
-0,9
0,6
0,02
-32
-3
-46
-680
-0,1
-1,3
0,4
0,0
-17
-0,2
560
0,4
0,1
0,00
-27
-7
29
-370
-0,1
-0,4
2,0
-0,2
13
Appendix
35

Table 9 (continued):
Group Variable Unit
Soil biological variables
Microbiology Hot Water exctractable Carbon µg C g -1
Potentially Mineralizable Nitrogenmg Nkg
-1
Denitrifying Enzyme Activity ppm N
2
O 3h
-1
Earthworms Total number
Total number (0-10cm)
Total number (10-20cm)
Epigeic (adult + juv.)
Endogeic (adult + juv.) n m -2 n m
-2 n m
-2 n m -2 n m
-2
Fresh biomass
Diversity (species)
Enchytraeids Total number
Fridericia
Marionina g m -2 n n m
-2 n m -2 n m
-2
Enchyraeus
Biomass
Diversity (species)
Micro-arthropods Total number n m -2 g m
-2 n n m -2
Acari
Collembola
Diversity (species)
Diversity (species acari) n m
-2 n m n n
-2
Diversity (species collembola) n
Nematodes Total number
Maturity Index (1-5) n 100 g
-1
Plant Parasitic Index
Diversity (species) n
Total total soil faunal diversity (species) n
Grass production variables
DM yield at N0 (year total)
DM yield at N0 (1st cut) kg DM ha
-1 kg DM ha
-1
DM yield at N0 (2nd cut)
DM yield at N0 (3rd cut)
DM yield at N0 (4th cut)
N yield at N0 (year total)
N yield at N0 (1st cut)
N yield at N0 (2nd cut)
N yield at N0 (3rd cut) kg DM ha -1 kg DM ha
-1 kg DM ha -1 kg N ha
-1 kg N ha
-1 kg N ha -1 kg N ha
-1
N yield at N0 (4th cut)
DM yield at N1 (year total)
DM yield at N1 (1st cut)
DM yield at N1 (2nd cut)
DM yield at N1 (3rd cut)
DM yield at N1 (4th cut)
N yield at N1 (year total)
N yield at N1 (1st cut)
N yield at N1 (2nd cut)
N yield at N1 (3rd cut)
N yield at N1 (4th cut)
* from Deru et al. (2012) kg N ha -1 kg DM ha
-1 kg DM ha
-1 kg DM ha
-1 kg DM ha
-1 kg DM ha -1 kg N ha
-1 kg N ha -1 kg N ha
-1 kg N ha
-1 kg N ha -1
P-values Means St.dev.
treatm. location Control Drains Control Drains
Reference (n=20 *) Treatment effect (Submerged drain minus control)
Mean St.dev.
VR Z2 Z3 ECK BA ST
0,498
0,368
0,263
0,725
0,330
0,174
0,065
0,289
0,441 0,011
0,611 0,056
0,097 0,031
0,908
0,169
0,407
0,644
0,826
0,338
0,661 0,162
0,438 0,088
0,459 0,018
0,455 0,099
0,048
0,007
0,199
0,006
0,876
0,388
0,271
0,340
0,491 0,173
0,493 0,079
0,129 0,339
0,803 0,314
0,097
0,153
0,599
0,203
<,001 <,001
0,107 0,057
0,211
0,985
0,421
0,008
0,195
0,019
0,003
0,023
0,165
0,089
0,003
0,498
0,002
0,042
0,024
0,173
0,012
0,144
0,040
0,006
0,017 0,002
0,077 <0,001
0,439 <0,001
0,071 <0,001
0,926 <0,001
0,978 <0,001
0,186 <0,001
0,197 0,009
0,127 <0,001
0,448 <0,001
0,861 <0,001
10837
631
474
575
2166
2823
1991
361,6
114,2
61,2
80,0
64,6
11113
599
510
551
386
149
3,8
333
164
3,7
19334 15621
8999 8744
7290
3046
451
100
183
4146
2731
7,2
9,0
6,2
9,3
25904 32291
8187 9263
17717 23028
19,7 22,3
10,5 13,3
9,2 9,0
6113
2,2
2,8
29,2
61,7
542
33
102
5676
2,2
2,7
25,7
61,0
9450 10000
2462 2734
2110
2469
1916
265,2
62,2
50,3
71,6
64,5
2017
2651
2083
281,2
68,7
50,4
75,0
69,6
12268 12066
4044 3981
2065
2830
1992
355,1
110,7
58,6
81,5
64,9
1332
75
73
390
371
34
79
287
89
0,8
5865
1838
4343
2637
5,6
2,2
1932
66
132
317
209
135
101
210
59
1,0
6299
5115
842
2021
4,7
0,8
12099 25805
4820 5199
8926 22306
2,8 1,5
3,3 2,8
2,6 1,4
708
0,2
0,1
4,6
6,4
697
700
308
650
373
17,2
12,3
12,6
25,2
11,0
770
780
398
713
455
31,0
8,6
11,7
29,5
11,3
1043
0,2
0,1
2,5
3,0
862
458
350
516
379
25,2
4,1
13,4
22,2
9,6
884
889
474
676
488
37,9
11,7
14,4
28,3
12,5
9309
465
587
146
4,3
31642
15267
11589
4786
13,5
10,3
81157
47943
33214
24,7
16,3
8,4
8598
2,2
2,7
31,2
70,3
10718
263,6
13111
393,6
1852
98
318
77
1,2
9967
7778
7106
5152
5,6
2,1
33830
27840
13449
3,0
2,9
1,7
2267
0,2
0,1
2,8
4,1
1710
49,8
1236
36,4
161
-5,9
100,3
-140,0
-131,3
-8,8
-25,0
-137,5
-18,0
0,0
-825
9549
-11318
943
-3,5
1,0
40925
4958
35967
4,0
3,0
1,0
-77
0,14
-0,12
-8,0
-3,0
1940
52,6
111,5
10,0
0,0
10,0
12,5
12,5
33,3
-1,0
589 -10021
-4362 -825
3183
1768
-2,1
3,0
9699
2186
7513
3,0
2,0
1,0
-2131
-0,25
0,03
4,0
9,0
-208
-28,3
-7,6
140,0
133,8
6,3
212,5
37,5
77,1
0,0
-2829
-6366
-84,3 -157,2
69,9
-1,8
-1,0
-0,6
-2,0
-1183 -13484
3004
-4187
4,0
6,0
-2,0
-801
0,02
0,01
-8,0
-5,0
321
141,7
-851
-71,3
-260,4
108,3 -358,3 -302,1
33,3 97,9 266,7
66,7 100,0 116,7
-4696
-8788
5,0
2,0
3,0
450
-0,08
-0,13
-4,0
-1,0
83,3 -175,0 -141,7
51,0
0,0
-21,2
1,0
-30,8
-1,0
-1061
354
-2358
-2358
-8606
-3890
-4244
2829 nd nd nd nd nd
-346,4
-211,5 nd nd nd nd nd
-239,2 -197,6 -135,9
-2,2 158,8 272,2
79,8 155,0 -122,6
-17,9
-12,3
-8,3
-8,0
12,6
3,7
-8,1
1,0
2,9
-4,4
5,5
5,9
-1,2
7,8
-0,8
20,6
12,9
1,7
4,1
5,9
6,1
104,9
885,2
483,2
943,0
389,5
68,7 -228,7
254,5
189,7
438,8
150,9 nd nd nd nd nd
30,8 nd
12,2 nd
-1,7 nd
15,4
-4,8
9,1
9,7
2,5 nd nd
6,5
4,6
15,0 -530,0 -290,0
-8,2 -323,8 -92,0
418,0
-149,7
-44,4
366,7
251,2 -460,9
134,9
181,6
-97,9
147,7
-6,9
7,4
-63,3
152,4
-2,8
5,7
-8,9
-54,4
-15,9
-12,0
0,1
-2,0
0,4
-2,5
39,5
-37,7 -239,6 -107,2
2,2
-3,4
-3,0
2,1
-2,8
0,3
-17,6
-90,9
-10,4
-1,4
-1,7
-3,0
-4,3
-589
589
3,1
1,0
-1419
596
-2016
2,0
2,0
0,0
-1076
0,12
0,13
0,0
4,0
-3065
-1650
-0,9
0,0
3785
405
3380
-2,0
2,0
-4,0
1011
-0,28
-0,12
-5,0
-8,0
293
33,8
14,8
-35,4
36
Effect of submerged drains in peat meadows on soil quality and ecosystem services