Physical and chemical properties of fen peat soils under agricultural use across Europe.

Abstract

<p><span>P</span><span>eat soils offer numerous functions from the global to the local scale: they constitute the biggest terrestrial carbon storage, form important nutrient filters and provide hydrological buffer capacities. They represent a</span><span>n important</span><span> share of soils suitable for agriculture in temperate and boreal Europe, pressurized by increasing demands for production. Cultivated peat soils, however, show </span><span>strong alterations of soil physical and chemical properties, accompanied by </span><span>extreme mineralization rates, </span><span>land surface subsidence, soil and water quality deterioration and thus crop failure.</span></p><p><span>The aim of this study is to </span><span>report</span><span> soil physical and chemical </span><span>properties</span><span> of </span><span>fen </span><span>peat soils </span><span>under </span><span>typical </span><span>agricultural management in six European countries </span><span>in contrast to the technical and economical assessment of the managing farmers.</span><span> We conducted standardized soil mapping, soil physical/chemical analysis, ground water table monitoring and farm business surveys across </span><span>46</span><span> sites in Germany, The Netherlands, Denmark, Estonia, Finland and Sweden.</span></p><p><span>The results show</span><span>ed</span><span> a strong impact of agricultural management on </span><span>fen </span><span>peat soil </span><span>properties</span><span> across Europe. </span><span>Peat depth range</span><span>d</span><span> from -0.2 to -4.7 m below ground (on average -1.1 m). The majority of sites were deeply drained, showing </span><span>annual mean soil water levels of -0.6 m with summer draw downs to</span><span> -0.93 m. </span><span>Soil profiles exhibit</span><span>ed</span><span> strong gradients </span><span>of</span><span> humification with soil depth, </span><span>showing fully degraded topsoils (von Post 10 down to -0.2 m), reaching weaker degradation (<= von Post 7) only below -0.6 m. </span><span>Bulk density, porosity and available field capacity consistently reflect</span><span>ed</span><span> the degradation gradient, </span><span>whereas hydraulic conductivity and penetration resistance showed no trend</span><span>. </span><span>Soil organic carbon </span><span>was</span><span> strongly reduced in the topsoil horizons (25% on average) and reache</span><span>d</span><span> only in horizons below -0.6 m value</span><span>s</span><span> of </span><span>on average </span><span>45%. </span><span>Total nitrogen and pH values show</span><span>ed</span><span> no clear depth gradient. </span><span>The soil carbon stock range</span><span>d</span><span> from 100 to 500 t/ha for the unsaturated horizons and increases up to 2000 t/ha in the permanently saturated subsoil. </span></p><p><span>The economic relevance of organic soils </span><span>varie</span><span>d</span><span> greatly across countries</span> <span>and although farms </span><span>were</span><span> settled in organic soil rich regions, </span><span>72% of farms had an average share of peat soil of only 23%. The main reasons farmers attribut</span><span>ed</span><span> yield losses on organic soils to </span><span>were</span><span> (by importance), high ground water levels, unsuitable water management, and ponding/hydrophobic soils </span><span>independent of the land use, </span><span>strongly contrasting the measured water levels</span><span>. Overall, in the perception of interviewed farmers, the economic success of land use on organic soils in the future will be mostly depended on financial shortcomings due to increasing water logging and inevitably increasing drainage costs agreed on by 65% and 69% of interviewed farmers.</span></p>