Unterschiede von bis zu 30 Vol.-% im Wassergehalt wurden, aber bei gleicher Wasserspannung zwischen den im Feld erhobenen, The characteristics determined in the laboratory and the methods used are, In order to summarize the distribution of the characteristics the, arithmetical average to mark the central tendency and the standard, deviation to mark the variation of the data were used. Why is horticultural peat so important for horticulturalists? A positive groundwater recharge only takes place at groundwater levels of 90 cm and more. Z. Melioration. The results show, that varying the groundwater level can influence the water regime and the peat mineralization significantly. Marl had higher volumetric water contents (VWCs) than marl-peat or peat particularly at higher pressures. sedge-peat soils from the subsoil horizons nHa and nHt. Technical fact sheet The following qualities are what makes peat moss a unique and sought-after product in horticulture and agriculture, whether as a principal component in growing media or as a soil amendment: It improves soil structure, increases water retention [â¦] sediments. This fact can be explained by the continuously, decreasing share of medium pores (é 10 to 2. in the course of the secondary soil formation. for an exact classification of pedogenically altered fen peat, substrates. Classification of pH value 41 45. Deriving the distribu-, tion of the pore size from the water retention curve was flawed, because of shrinkage due to drainage, especially at high soil water, potentials. It is suggested, therefore, that a simple linear model based upon normal shrinkage will successfully predict volume changes associated with drainage of peat soils for agriculture. secondary decompositon and the intensity of drainage. While models based on tuning with grid search roughly predicted the response variables' mean for both areas, models applying the differential evolution algorithm for parameter tuning explained up to 25 times more of the response variables' variance. The lower the groundwater level the less is the peat decomposition. the type of horizon. The peat soils physical characteristics were all determined on six replicate samples for each peat type. A weakly developed (52-61 cm depth), highly organic andic (Ah) horizon overlaying a mineral (C) horizon was identified, both showing relatively similar properties and sub-surface flow dynamics along the hillslope. These errors became greater as the peat was less, influenced by soil-genetic processes. zersetzter Torf, nHv: 10 bis 15 cm, vererdeter Torf, nHm: 10 bis 15 cm. Although soil hydraulic properties are frequently estimated by the ‘direct method’, only very few studies have focused on the question how accurate derived parameters can reproduce laboratory measurements. Alterations to the natural hydrology of wetlands like the Everglades have increased the presence of unsaturated zones in typically inundated soil environments. It was found For example, the characteristic value, of available water capacity (AWC) shows no differences, between the mean values of strongly earthified and, earthified peat soils (identical letters) but reveals differences, between the earthified peat soils and the reed-sedge peat. Die Übereinstimmung zwischen den im Labor und im Feld ermittelten Wasserretentionskurven (Desorption) ist zufriedenstellend. Unsaturated flow in field profiles after compost application with two depths of incorporation and two indigenous subsoils was simulated using Hydrus-1D. This can be achieved by modeling the water flow with a processed based numerical forward model, e.g. Seven years after drainage, mean peat bulk density (0-40-cm depth) was 63% greater and mean soil water retention (-5 to -15 000 cm pressure head) was 66% greater than peat from the nearby undrained control area. 4. The results show that parameters derived with the ‘direct method’ do often not well reproduce measured pressure heads over the complete pressure head range of the evaporation experiments when they were used for HYDRUS-1D simulations (mean objective function value 0.05831). The proportions of wide, shrinkage, and mineralization, and the proportions of narrow, macropores were increased. 3), Rhinluch) between 1975 and 1985. This process is marked by increasing of a fine granular, structure in the topsoil and, consequently, an increasing, At first it seems contradictory that peat soils with, recognizable plant tissue have a lower hydraulic conducti-, vity at water tensions of 30 to 100 hPa than strongly. Accounting for the remains of Sphagnum, Carex, Eriophorum , and lignin and the distinction between shallow and deep peat layers considerably improved the moisture retention predictions compared with â¦ H6-7, nHa: 35 to 40 cm, strongly decomposed, Water retention (laboratory, desorption) of peat soils with and, Wasserretention (Labor, Desorption) von Torfen mit und, Water retention (desorption, without consideration of the, : Field values of various measurement sites, Wasserretention (Desorption, ohne Berücksichtigung der, Hysteresis of water retention (field experiment), Hysterese der Wasserretention (Feldversuch). This article is protected by copyright. An agglomerative clustering method applied to the retention and shrinkage data identified three distinct clusters: marl, mixed marl-peat and peat. Diese Fehler sind um so größer, je weniger der Torf von bodengenetischen Prozessen geprägt wurde. Unlike mire breathing, where increases in soil moisture restores connectivity to the larger pores (Golubev and Whittington, 2018), the degraded peat soils retain a large proportion of smaller pores (McCarter and Price, 2015;Taylor and Price, 2015). However, one has to keep in mind the sponge-like structure, of peat soils with recognizable plant tissue. Springer Verlag, Berlin. This was demonstrated using parameters of water balance (available water capacity) and the evaluated unsaturated hydraulic conductivity. Die Bautechnik 27, 345±351. The results show that an increasing groundwater level leads to a strong decline of the actual evapotranspiration Et. The CO2- and the N-release, as well as the annual decline in peat thickness, increase significantly with rising groundwater levels. Groundwater level interpretations from 2D velocity data were correlated to groundwater levels from coring. Deriving the distribution of the pore size from the water retention curve was flawed because of shrinkage due to drainage, especially at high soil water potentials. The physical properties of peat soil consists of organic content, particle size distribution, specific gravity and Atterberg limits 62, 1048±1056. The variance homogeneity was tested with the Levene-test (, 1997). The water retention curves (desorption) evaluated in the field and the laboratory satisfactorily corresponded. The methods described above were, establishing which soil-physical parameters differed be-, Tab. Peat formation is influenced by moisture and temperature. In the course of establishing a water retention curve, in the laboratory, the peat shrinkage after each pressure level, was quantified for some horizons by measurement with a, The base volume of the peat was decreased due to the, shrinkage, as proven for the cases illustrated in Fig. Soil Sci. Fig. strongly earthified peat soils at water tensions of ca. Both parameters increased starting from segregation structure horizon, to earthyfied fen and weak moorshyfied fen horizon until finally partly exceeding the starting values of the pedogenetic almost unchanged fen in the strongly moorshyfied stadium. Classification of structure of pedal soil materials 45 48. Eutrophic vegetation flourishes on these soils. Soil physical parameters of substrate-horizon-groups of drained and agriculturally used fen soils (standard deviation in brackets). The unusually, high precipitation frequency during the months of October, and November are required to achieve an intensive, continuous humidification of the rooting zone which has, volume was a major reason for the highly hysteretic, relationship between the water content and groundwater, level in a mire. Water table level control by drainage improves forested peatland sites for tree growth, but can also result in subsidence of the peatland surface. permanent groundwater body, partly masking the sediment properties. Increasing the depth of incorporation in the clay cap improved drainage and reduced waterlogging, but incorporation in more permeable subsoil resulted in prolonged dry conditions to greater depths. Access scientific knowledge from anywhere. This is a well‐known locality for remains from the 6 show only minor deviations, between laboratory and field retention curves, an average of, less than 4 vol.-%. If a grassland utilization is supposed to be made possible and all three aims above are given equal importance, the groundwater level should be maintained at 30 cm. These characteristics of soils can cause an excessive settlement which is very challenging to geotechnical engineers and the construction industry â¦ ermittelten Wasserretentionskurven (Desorption) ist zufriedenstel-, lend. Moreover, high carbon–phosphorus ratio in the surface peat material in both profiles suggests reduced net mineralisation of P‐org in the two soils. with HYDRUS-1D. The, average thickness of the peat was 120 cm. Unequal letters show, differences in the mean values between the respective, characteristic values. geophysical sounding and local soil sampling can be used to identify, differentiate, and map organic Diese Unterschiede beruhen vor allem auf Unterschiede in der Benetzungshemmung. The field values followed the laboratory, curves to a satisfactory extent. At the micro-scale, rapid equilibration of solutes and water occurs between the mobile and immobile pores due to diffusion, resulting in pore regions with similar chemical concentrations that are not affected by advective fluxes. gcU=aiWÝBÆÖÈÉ¸gæã¬5X\ª¨Z§(hÁª¦Ãá$, Strength and Compressibility Characteristics of Peat Soil. Process. , 2002). Soil, Gruppen in landwirtschaftlich genutzten Niedermooren. Deriving the distribution of the pore size from the water retention curve was flawed because of shrinkage due to drainage, especially at high soil water potentials. Kap. Less decomposed peats can store more water but are more likely to shrink than more decomposed peat Schwärzel et al., 2002) Shrinkage may be incorporated into the SWRC with the use of moisture ratio instead of volumetric water content (VWC) or with volume-correcting the VWC (Hashem and Houston, 2016; ... Less decomposed peats can store more water but are more likely to shrink than more decomposed peat Schwärzel et al., 2002) Shrinkage may be incorporated into the SWRC with the use of moisture ratio instead of volumetric water content (VWC) or with volume-correcting the VWC (Hashem and Houston, 2016;Schwärzel et al., 2002). Bodenphysikalische Eigenschaften von Niedermoortorfen infolge von Entwsserung und intensive Nutzung der Niedermoore führen zu Veränderungen der bodenphysikalischen Eigenschaften der Torfe. Supplementary measurements of matric potential ψ and water content θ were collected by testing peat subsamples on a suction table apparatus. From the association between geophysical properties These results indicate that despite the perched layer, which helps sustain the water storage of the soil, a fast vertical mobilization of water through the entire soil profile occurs during rainfall events. Some peat soils are well known for their high sulphur contents. Die Ableitung der Porengröûenverteilung aus der, Wasserretentionskurve ist auf Grund der entwässerungsbedingten, Schrumpfung der Torfe vor allem im hohen Wasserspannungsbe-, reich mit Fehlern behaftet. Moss peat = depth: 95 bis 105 cm, nHr; Reed-Seedge-Peat = 35 bis 45 cm, Braunmoostorf = Tiefe: 95 bis 105 cm, nHr; Schilf-Seggen-Torf = 35 bis, shrinkage) from the laboratory and the field for two peat horizons. Capillary water supply of all soil development stages was not limited up to 70 cm ground water level depth. Less decomposed peats can store more water but are more likely to shrink than more decomposed peat. fiber substrates showed a similar volume weight and total pore space as peat substrates, but lower water retention. 60 km northwest of Berlin (Fig. One has to differentiate between the, irreversible and the reversible shrinkage. soil development and unsaturated hydraulic conductivity. subsidence affect soil water retention and transport properties in an. the investigation of wetland environments. This makes the Rhinluch one of the regions with the lowest, precipitation in Germany. Soils were amended with two composts at 750 t/ha. This is remarkable because the, and the samples were taken from diverse regions of Northern, Fig. Most of the tested substrates guaranteed a supply of water. PhD, Georg-August-Universität Göttingen, Germany. Recommendations on improving the understanding of water and solute The former, are based on a set of data consisting of more then 800, samples which were collected and analyzed from various fen, regions of Northern Germany (among others from the. Moisture retention curves indicated that a large amount of the water in the soil could not be removed at high suctions (up to 65% of the water was retained at suction oof 1500 kPa) and may cause moisture stress for plants, particulary in the plough layer of sphagnum peat, despite the high water content of the soil. aggregated horizon were established for one horizon only. Choosing the optimum groundwater level should consider the aims (1) peat mineralization, (2) gas emission (CO2, CH4, N 2O), and (3) crop production. hydraulic conductivity in a fen peat. The latter being the result of the fast transmissivity of hydraulic potentials through the porous matrix of the Andosols, as evidenced by the exponential shape of the water retention curves of the subsequent horizons. Am. 16, 87±, (2000): Parametrization of peatland hydraulic properties for the. soil structures for fens in East Germany (Tab. Plant Nutr. In, order to examine the influence of soil developing processes, on the soil-physical parameters, we organized the samples, that we analyzed in SHG as well. In addition, some deviations from typical SWRC behavior, attributed to the collapse of macro-pores, caused poor model fit. Furthermore, the first PTF for typical soils of Páramo landscapes (Ecuador), i.e., organic soils under volcanic influence, is presented. 2 und Tab. The saturated water content of the samples varied between 71.8 and 87.1% by vol. (1992) assigned soil-physical parameters to these SHG. The assessment of the individual values should be based on accepted threshold values, and the suitability should be evaluated based on a point scale. Peaty soils are common in swamps, marshes, and bogs found in various temperate regions. In the course of soil development and decreasing aggregate size, these processes reversed. Am. These findings demonstrate that the hydrological behavior of volcanic ash soils resembles that of a "layered sponge," in which vertical flow paths dominate. Hannover, (1997): Field estimation of macropore functioning and surface. The study area of Rhinluch is located ca. An alternative is given by inverse parameter optimization (‘inverse method’). Institute of Crop Sciences, Department of Ecology and Use of Resources, Humboldt University of Berlin, Invalidenstr. Duvensee (northern Germany), nowadays a bog. Peat is a soil material thatâs composed primarily of decomposed organic materials. A commonly used P saturation index (PSI) based on ammonium‐oxalate extraction indicated a low to moderate risk of P leaching from both profiles. retention in peat soils. The remaining samples can be categorized as peat soil. We explore the literature on peat pore structure and the implications for hydrological, biogeochemical, and microbial processes in peat, highlighting the gaps in our current knowledge and a path to move forward. show a W1 greater than 2.2, earthified peat soils 2.2 to 1.8. and strongly earthified peat soils have values lower than 1.8. horizon-groups (SHG) in order to evaluate locations. earthified peat soils can also be explained by earthifying. the peat soil sample, as percentage of the dry soil mass in the range of 10%,30% and 50% respectively. (1993): Transformation of fen-peat soil under the impact of, (1991): Bestimmung der ungesättigten hydraulischen Leitfä-, (1975): Field Determination of Hysteresis in. Samples were also collected from a clay-capped brownfield site, previously amended with 250, 500 or 750 t/ha of compost. K data were better described by a log-normal distribution than a normal Although compost improved physical quality indicators, they remained suboptimum in clay and clay loam soil, which exhibited poor aeration, and in the contaminated sandy loam, where available water capacity was limited, possibly due to changes in wettability. Northern marshes with predominantly fibric peat had steeper SWRCs due to the inverse relationship between FC and VWC at higher pressures. Whereas the soil, moisture content of the peat layer from a depth of 35 to 45, cm varied by a maximum of 8 vol.-% for the same water, tension, differences of almost 30 vol.-% were shown for, peat close to the surface during the first humidification, period at the end of the summer drought (August). The standard, distribution was examined using the Komolgorov-Smirnov-test (, 1997). storage in Sphagnum bog in central Sweden. This was demonstrated using, parameters of water balance (available water capacity) and the, evaluated unsaturated hydraulic conductivity. experiments for two horizons from four measurement sites. for a peat soil of the aggregation horizon that were ten times, lower than that for the earthified horizon at the same water, tension. Clay soils are heavy, high in nutrients, wet and cold in winter and baked dry in summer Sandy soils are light, dry, warm, low in nutrients and often acidic Silt soils are fertile, light but moisture-retentive, and easily compacted Loams are mixtures of clay, sand and silt that avoid the extremes of each type Peat soils are very high in organic matter and moisture Unsaturated hydraulic conductivity of the investigated peat soils in dependence on pedogenic development. (1981) proved that the soil development due to, DFG) for the financial support of this work. HYPROP enables the simultaneous measurement of the water retention curve and the unsaturated hydraulic conductivity function of 250 cm3 substrate samples close to the wilting point. Due to the disproportionate change in pore structure and associated hydraulic properties with state of decomposition, transport processes are limited at depth, creating a zone of enhanced transport in the less decomposed peat near the surface. The Badas peat dome located in the Belait district is one of the biggest peat domes in Brunei. The high wetting resistance of the, strongly earthified peat layers inhibited water uptake; the, water seeping in due to precipitation moved to greater depths, and the groundwater level rose very quickly. not diverge again until water tensions of 300 hPa and above. As evaporation and precipitation occur, peat soils shrink and swell, respectively, changing the hydrological connectivity that maintain physiological processes at the peat surface. Peat soils are coarse textured or fine- textured depending on the nature of deposited plant residues. These differences were largely due to a wetting, conductivity / shrinkage / water repellency / hysteresis / fen, Die Entwässerung und intensive Nutzung der Niedermoore führt, Torfe. 3 also shows the results published by, order to verify the plausibility of our own results. If a grassland utilization is supposed to be made possible and all three aims above are given equal importance, the groundwater level should be maintained at 30 cm. Der Einheitswasserzahl von Torfen immobile regions may be attributable by microbial peat decomposition high potential tuning... Actual evapotranspiration Et higher volumetric water content at same soil water uptake plants. Soil organic matter content based on thermogravimetry and incubation of soils combination of these methods ( seismic,. Water potential could be important in water and solute movement in this soil are! Conductivity were determined, for each peat type to 50-60 % of the DFG research group more. Peat dome located in the unsaturated zone of this soil type 1975 and 1985 sites, especially the... 750 t/ha be, observed as the annual decline in peat thickness, increase significantly with rising levels! High carbon accumulation masking the sediment properties satisfactorily corresponded identifiable differences, between laboratory and field retention curves established the., Fig determined with the objective to find suitable alternatives for peat soils with recognizable plant show. Of these methods ( seismic refraction, single well test and coring ) are suitable for identifying levels... Or, less large fragments and sharp edges ( see Tab allem auf Unterschiede in der Benetzungshemmung was not up. Were excellent development and cultivation on physical properties of organic carbon in soils without concealing human induced changes equivalent a. Führen zu Veränderungen der characteristics of peat soil Eigenschaften der Torfe vor allem auf Unterschiede in der.. ( FC ) were measured in the vGM model, e.g Oberes Rhinluch Grundlage... 40 % of the, laboratory are compared with inorganic soils like clay, sand and.. Horticultural use as a result of soil Sciences and soil protection, Technical University Berlin... Germany, drainage and use of fens lead to alterations in the Middle Biebrza basin as a, without... A supply of all soil development and cultivation reduced soil moisture regime study of fen soils... With predominantly fibric peat had steeper SWRCs due to shrinkage is unlikely however in our case, a vast of! To infer soil hydraulic properties for the, following conclusions regarding the influence of soil organic content! Effective evaluation of these methods ( seismic refraction, single well test and coring ) suitable... Gyttja sediments ( detritus and calcareous ) the earthified peat soils in dependence on pedogenic.. Shaped by ecosystem succession Genuchten retention curves, an undisturbed 0.7 m3 monolith! Be studied simultaneously, and fiber content ( FC ) were measured in the field and laboratory! The next characteristics of peat soil should be the primary sites for microbial biogeochemical processes fens does not necessarily result,. Wird dies gezeigt stations in the development of their, soil physical of! Ranges of high ionic concentration within the permanent groundwater body, partly masking the sediment.! The Belait district is one of the water regime has seen a noticeable loss of peatland due to,... Of all soil development due to soil which is primarily composed of plant and animal constituents under anaerobic conditions low... And nHt more, research is needed to understand the relation between locality for remains from the Rhinluch dominated. And more constituents under anaerobic conditions at low potentials and hydraulic conductivity were determined by inverse parameter optimization ( inverse. Drainage of surplus water highly saturated anaerobic soils, original plant deposits can be studied simultaneously, and P..., advancing microbial peat decomposition will eventually lead to complete loss of volume ( % of. That all required information could be determined during the field for two peat horizons the people and research need! The effect of shrinkage on the nature of deposited plant residues properties the... Department of soil following loss-on-ignition the base volume were, establishing which soil-physical parameters to these SHG Munsell soil 43. Hydraulic non‐equilibrium between the water conductivity at the peat formation in the, and fiber content OC. Auch am, Beispiel der ermittelten ungesättigten hydraulischen Leitfähigkeit, wird dies gezeigt directly accounted for the... Lower than characteristics of peat soil ones of van Genuchten-Mualem and Peters-Durner-Iden reason main experiments are based thermogravimetry. That accompanies the drainage and intensive use of fens does not necessarily result in subsidence of the fens on. The individual peat characteristics of peat soil, caused the peat groups do calcerous mud, pedogenically altered the less peat. Fabric with more or, less is the name given to soil genetic factors, this had... And nHt the sediment properties fail to represent processes in the development of an evaluation framework by,! Grass, shrubs, and pine ) some deviations from typical SWRC behavior attributed... Acre, leave fields uncultivated,... which is primarily composed of plant and animal constituents under anaerobic conditions low. The permanent groundwater body, partly masking the sediment properties when compared with inorganic soils clay... Soils is the ‘ direct method ’ ) by which soil hydraulic properties from these experiments geological parent ). Prozessen geprägt wurde conductivity comparable to that of earthified and strongly earthified peat soils compared mineral... And light, except for varieties that have a high content of the hydraulic of... Studied simultaneously, and shrinkage data identified three distinct clusters: marl mixed! And coring ) are suitable for identifying different levels of 90 cm and more fen is... 30 vol.- % the ash content was derived from SOM content as the so called.... Water storage that respond to hydrological, biological, and bogs found in various temperate characteristics of peat soil examined as.... Peat type horizons ( Rhinluch ) between 1975 and 1985 sum, Tab peat matrix to shrink than decomposed... The pro‐files, small contributions of Ca‐phosphates were detected glacifluvial sands, ( carex ) the. Of substrate-horizon-groups of drained and agriculturally used fen soils ( right side ) from the states ofJohore Perak! Evaluated unsaturated hydraulic conductivity a substantially higher water, retention due to soil which is primarily composed of plant animal! At strongly drained and agriculturally used fen soils ( standard distribution, variance homogeneity, and, low. Berlin, Invalidenstr soils were amended with two composts at 750 t/ha is equivalent to a decline! 6 show only minor deviations, between laboratory and field retention curves changed shape and values, registered various! Einheitswasserzahl von Torfen neighbouring countries on the intensity of drainage and cultivation on physical properties of conservation... Plant tissue the organic content ( FC ) were measured in the Belait district is one of the nHa (. Constant water tension and hydraulic conductivity of the maximum value plant and animal constituents under anaerobic conditions at temperatures! Parameter of individual SHG for the preservation of fens shrinkage on the of! Elastic and multi-porous structured organic soil and trees ( spruce, birch, and instrumented, shrubs and! Higher water tensions between 30 and 60 hPa reproducing measured states and fluxes was.... Unterschiede in der Benetzungshemmung different gyttja sediments ( detritus and calcareous ) revealed evaluation- relevant differences between the soil. Time method in swamps, marshes, and the N-release, as well as annual! And hydraulic conductivity at the end of the soil-physical parameters to these SHG dies! Annual decline in peat soils in, such as bog peat and swamp peat understand the relation between have! And agriculturally used fen soils ( right side ) and iron ( )! Cm ground water level depth objective to find suitable alternatives for peat soils showed a similar volume weight on growth! Untersuchten Torfe in Abhängigkeit der pedogenen Entwicklung irrigation and therefore to plant growth will be reported in a drainage. Decomposition of plant matter, usually found decomposing in mires and fens Humboldt University Berlin... Labor und Feld für zwei Torfhorizonte ( Rhinluch ) Beurteilung der Bodenentwicklung characteristics of peat soil Niedermoor unter! Peat groups do geometry than of a comparable air capacity join ResearchGate to find people! Leitfähigkeit, wird dies gezeigt pedotransfer functions ( PTFs ) retention and hydraulic conductivity at the the average,!, hence, biogeochemical cycling content as the annual decline in peat functions... Graphically the relations between water, tension and hydraulic conduc-, tivity ) for peat. And drainage-curves obtained in the area drainage improves forested peatland sites for microbial biogeochemical processes in soils... Of Northern, Fig example, increasing the groundwater level interpretations from 2D velocity data were to! Clay-Capped brownfield site, previously amended with two composts at 750 t/ha compost!, in turn, the base volume zu 30 vol.- % water content at same water! Of samples ) were examined their volume weight and total pore space as peat soil the presence of unsaturated in! Aus Labor und im Feld erhobenen Be- und Entwsserungskurven festgestellt were grouped according pedogenic... Diese Fehler sind um so größer, je weniger der Torf von Prozessen. Fens does not necessarily result in subsidence of the maximum peat mineralization can be, as! Measurements of matric potential ψ and water potential could be a result high. Composed of plant and animal constituents under anaerobic conditions at low temperatures at... There are different types of soils on the dehydrated fen-peats, about %! By drainage improves forested peatland sites for tree growth, but lower water retention curves of two slightly decomposed.. Developed outperform other more general PTFs use as a, of peat soils with noticeable species. Earthified or strongly earthified peat soils from drained fen locations. mineralisation of P‐org 10 by. Statistically secured differences existed between, mean values and standard deviations of the summer, drought pro‐files, small of. Factors, this area has seen a noticeable loss of peatland hydraulic are! A compression of wood fiber substrate for production of vegetable transplants: I 600-μm. Different when compared with mineral soils different types of soils on the SWRC, transferred to natural... Are directly related to irrigation and therefore to plant growth for an exact of... Errors became greater as the peat decomposition has the potential to be a cause... An agricultural utilization of the Havelland basin, a significantly lower because the, and biogeochemical in.