Phosphorus speciation in long-term drained and rewetted peatlands of northern germany

Previous studies, conducted at the inception of rewetting degraded peatlands, reported that rewetting increased phosphorus (P) mobilization but long-term effects of rewetting on the soil P status are unknown. The objectives of this study were to (i) characterize P in the surface and subsurface horizons of long-term drained and rewetted percolation mires, forest, and coastal peatlands and (ii) examine the influence of drainage and rewetting on P speciation and distributions using wet-chemical and advanced spectroscopic analyses. The total P was significantly (p < 0.05) different at the surface horizons. The total concentration of P ranged from 1022 to 2320 mg kg−1 in the surface horizons and decreased by a factor of two to five to the deepest horizons. Results of the chemical, solution 31P nuclear magnetic resonance (NMR), and P K-edge X-ray absorption near-edge structure (XANES) indicated that the major proportions of total P were organic P (Po). In the same peatland types, the relative proportions of Po and stable P fractions were lower in the drained than in the rewetted peatland. The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Integrated Use of Farmyard Manure and NP fertilizers for Maize on Farmers’ Fields

A study was initiated in 1997 to introduce the culture of supplementing low rates of NP fertilizers with farmyard manure (FYM) in the maize based farming system of western Oromia. The treatments were 0/0, 20/20, 40/25 and 60/30 kg N/P ha−1 and 0, 4, 8, and 12 t FYM ha−1 in factorial arrangement in a randomized complete block design with three replications. The experiment was conducted at Laga Kalla, Walda, Shoboka, Harato, and Bako Research Center using BH-660 hybrid maize. The FYM used for the experiment was well decomposed under shade and spot applied together with the P fertilizer at planting; N was applied in split form. The residual effects of FYM were investigated for Laga Kalla, Walda and Shoboka during the 1998 cropping season. Statistical analysis revealed that the N/P fertilizers and FYM significantly (p 0.05) increased grain yield in all locations except for Walda in 1997. Interactions of FYM and NP fertilizer rates were significant (p ≤ 0.05) at all locations except for Shoboka. The application of FYM alone at rates of 4, 8, and 12 t ha−1 produced average grain yields of 5.76, 5.61 and 5.93 t ha−1, respectively, compared to 3.53 t ha−1 for the control treatment in 1997. There were significant residual effects of FYM and NP fertilizers applied in 1997 on maize grain yields in 1998. Laboratory analysis confirmed that considerable amounts of macronutrients and small amounts of micronutrients were supplied by FYM. Based on the results of this study, the integrated use of properly managed FYM and low rates NP fertilizers could be used for maize production in the areas under consideration. Moreover, sole applications of FYM on relatively fertile soils like Walda and Harato are useful in maintaining soil fertility and are encouraging for resource poor farmers

Editorial: Soil health, functions, and ecosystem services: insights into soil parameters and methods of integration

editorial reviewe

Long-Term Rewetting of Three Formerly Drained Peatlands Drives Congruent Compositional Changes in Pro- and Eukaryotic Soil Microbiomes through Environmental Filtering

Drained peatlands are significant sources of the greenhouse gas (GHG) carbon dioxide.Rewetting is a proven strategy used to protect carbon stocks; however, it can lead to increasedemissions of the potent GHG methane. The response to rewetting of soil microbiomes as drivers ofthese processes is poorly understood, as are the biotic and abiotic factors that control communitycomposition. We analyzed the pro- and eukaryotic microbiomes of three contrasting pairs ofminerotrophic fens subject to decade-long drainage and subsequent long-term rewetting. Abiotic soilproperties including moisture, dissolved organic matter, methane fluxes, and ecosystem respirationrates were also determined. The composition of the microbiomes was fen-type-specific, but allrewetted sites showed higher abundances of anaerobic taxa compared to drained sites. Based onmulti-variate statistics and network analyses, we identified soil moisture as a major driver ofcommunity composition. Furthermore, salinity drove the separation between coastal and freshwaterfen communities. Methanogens were more than 10-fold more abundant in rewetted than in drainedsites, while their abundance was lowest in the coastal fen, likely due to competition with sulfatereducers. The microbiome compositions were reflected in methane fluxes from the sites. Our resultsshed light on the factors that structure fen microbiomes via environmental filtering

Understanding metrics for effective environmental measures under the Agricultural Reform Programme for Scotland

To deliver climate change mitigation and adaptation, nature restoration and high quality food production, the Scottish Government produced their vision for agriculture, along with the next steps, to encourage sustainable and regenerative farming in Scotland. A programme of work is underway to reform agricultural payments with a greater emphasis placed on delivering environmental outcomes with a proposed structure of four payment tiers tied to a suite of potential measures that will deliver tangible outcomes. This study identified the most suitable metrics that could be used to monitor the success of the proposed measures in the agricultural reform programme against environmental outcomes. This includes consideration of cost-effectiveness, practicalities and the skills and capabilities of those tasked with monitoring

From Understanding to Sustainable Use of Peatlands: The WETSCAPES Approach

Of all terrestrial ecosystems, peatlands store carbon most effectively in long-term scales of millennia. However, many peatlands have been drained for peat extraction or agricultural use. This converts peatlands from sinks to sources of carbon, causing approx. 5% of the anthropogenic greenhouse effect and additional negative effects on other ecosystem services. Rewetting peatlands can mitigate climate change and may be combined with management in the form of paludiculture. Rewetted peatlands, however, do not equal their pristine ancestors and their ecological functioning is not understood. This holds true especially for groundwater-fed fens. Their functioning results from manifold interactions and can only be understood following an integrative approach of many relevant fields of science, which we merge in the interdisciplinary project WETSCAPES. Here, we address interactions among water transport and chemistry, primary production, peat formation, matter transformation and transport, microbial community, and greenhouse gas exchange using state of the art methods. We record data on six study sites spread across three common fen types (Alder forest, percolation fen, and coastal fen), each in drained and rewetted states. First results revealed that indicators reflecting more long-term effects like vegetation and soil chemistry showed a stronger differentiation between drained and rewetted states than variables with a more immediate reaction to environmental change, like greenhouse gas (GHG) emissions. Variations in microbial community composition explained differences in soil chemical data as well as vegetation composition and GHG exchange. We show the importance of developing an integrative understanding of managed fen peatlands and their ecosystem functioning.

Phosphorus Speciation in Long-Term Drained and Rewetted Peatlands of Northern Germany

Previous studies, conducted at the inception of rewetting degraded peatlands, reported that rewetting increased phosphorus (P) mobilization but long-term effects of rewetting on the soil P status are unknown. The objectives of this study were to (i) characterize P in the surface and subsurface horizons of long-term drained and rewetted percolation mires, forest, and coastal peatlands and (ii) examine the influence of drainage and rewetting on P speciation and distributions using wet-chemical and advanced spectroscopic analyses. The total P was significantly (p &lt; 0.05) different at the surface horizons. The total concentration of P ranged from 1022 to 2320 mg kg&minus;1 in the surface horizons and decreased by a factor of two to five to the deepest horizons. Results of the chemical, solution 31P nuclear magnetic resonance (NMR), and P K-edge X-ray absorption near-edge structure (XANES) indicated that the major proportions of total P were organic P (Po). In the same peatland types, the relative proportions of Po and stable P fractions were lower in the drained than in the rewetted peatland. The results indicate that long-term rewetting not only locks P in organic matter but also transforms labile P to stable P fractions at the surface horizons of the different peatland types

Dissolved organic matter concentration, molecular composition, and functional groups in contrasting management practices of peatlands

About 91,300 ha of peatlands has been rewetted in western Europe since the mid‐1990s. Still, it is unknown how long‐term rewetting alters the dissolved organic matter (DOM) concentration, molecular composition, and functional groups. We examined these DOM characteristics in three peatland types subjected to 47‐ to 231‐yr drainage and 18‐ to 24‐yr rewetting to address this knowledge gap. Cold water‐extractable DOM was characterized by pyrolysis field ionization mass spectrometry (Py‐FIMS) and X‐ray absorption near‐edge structure (XANES) spectroscopy. The dissolved organic carbon (DOC) concentration in the rewetted forest peatland was 2.7 times higher than in the drained forest peatland. However, rewetting decreased the DOC concentrations by 1.5 and 4 times in the coastal peatland and percolation mire, respectively, compared with their respective drained peatlands at the topsoil horizons. The Py‐FIMS analysis revealed that all nine DOM compound classes' relative abundances differed between the rewetted and drained forest peatland with the lower relative abundances of the labile DOM compound classes in the rewetted forest peatlands. However, most DOM compound classes' relative abundances were similar between the rewetted and drained coastal peatlands and percolation mires. The XANES also revealed nine carbon and seven nitrogen functional groups with no apparent differences between the two contrasting management practices. The influence of drainage and rewetting on DOC concentration and molecular composition depends on peatland type, drainage period, rewetting intensity, and peat degradation status that should be considered in future research for understanding DOM transformation and transportation from degraded and restored peatland ecosystems.Core Ideas: Dissolved organic matter (DOM) concentrations and molecular compositions depend on degradation status in drained peatlands. Rewetting effects on DOM concentrations and molecular compositions differ with peatland types. Pyrolysis field ionization mass spectrometry reveals management effects on DOM molecular compositions compared with X‐ray absorption near‐edge structure

Peat Formation in Rewetted Fens as Reflected by Saturated <i>n</i>-Alkyl Acid Concentrations and Patterns

The conversion of cultivated fen peat soils into rewetted soils can mitigate global climate change. Specifically, carbon in newly formed peat can store atmospheric CO2 for a long time in soil, but alterations in the quality of soil organic matter are not well known. To shed light on the complex processes of peat degradation or new formation under dry or rewetting conditions, we investigated and quantified saturated n-alkyl acids as an indicator compound class of peatlands response to the contrasting management practices. The concentrations of saturated n-alkyl acids from two soil layers of the drained and rewetted were determined in two soil layers of drained and rewetted fenland types such as Alder Carr forest, coastal peatland, and percolation mire. The analytical methods were solvent extraction, methylation with tetramethylammonium hydroxide, and gas chromatography/mass spectrometry. The saturated n-alkyl acid distribution pattern showed that the concentrations of long C-chain lengths were larger by factors of up to 28 relative to the short C-chain lengths. The effect of rewetting was reflected by the ratios of the summed concentrations of long (n-C21:0 to n-C34:0) to short (n-C10:0 to n-C20:0) C-chain saturated n-alkyl acids for drained and rewetted peat soil samples. These ratios were consistently lower in samples from the rewetted sites, indicating a higher input of microbial bio- and necromass to soil organic matter, likely from algae and anaerobic bacteria, under rewetting. The results suggest that the enrichment of microbial biomass and necromass in rewetted soils may be an important contributor to the formation of new peat in fenlands, irrespective of fenland type