• Authors:
    • Kankanen, H.
    • Lemola, R.
    • Valkama, E.
    • Turtola, E.
  • Source: Agronomy Journal
  • Volume: 203
  • Year: 2015
  • Summary: The growing of catch crops aims to prevent nutrient leaching in autumn after harvest and during the following winter, but due to competition, catch crops may also reduce yields of the main crop. We used meta-analysis to quantitatively review 35 studies conducted in Denmark, Sweden, Finland and Norway over the past four decades. These studies assessed the effect of both non-legume and legume catch crops undersown in spring cereals on nitrogen (N) leaching loss or its risk as estimated by the content of soil nitrate N(NO3--N) or its sum with ammonium N(NH4+-N) in late autumn. The meta-analysis also included the grain yield and N content of spring cereals. To identify sources of variation, we studied the effects of soil texture and management (ploughing time, the amount of N applied), as well as climatic (annual precipitation) and experimental conditions (duration of experiments, lysimeter vs. field experiments, the decade in which the experiment took place). Compared to control groups with no catch crops, non-legume catch crops, mainly ryegrass species, reduced N leaching loss by 50% on average, and soil nitrate N or inorganic N by 35% in autumn. Italian ryegrass depleted soil N more effectively (by 60%) than did perennial ryegrass or Westerwolds ryegrass (by 25%). In contrast, legumes (white and red clovers) did not diminish the risk for N leaching. Otherwise, the effect on N leaching and its risk were consistent across the studies conducted in different countries on clay and coarse-textured mineral soils with different ploughing times, N fertilization rates (<160 kg ha -1), and amounts of annual precipitation (480-1040 mm). Non-legume catch crops reduced grain yield by 3% with no changes in grain N content. In contrast, legumes and mixed catch crops increased both grain yield and grain N content by 6%. Therefore, in spring cereal production, non-legume catch crops represent a universal and effective method for reducing N leaching across the varieties of soils and weather conditions in the Nordic countries. Moreover, the trade-off between potential grain yield loss and environmental benefits seems tolerable and can be taken into account in environmental subsidy schemes.
  • Authors:
    • Heimonen,Kaisa
    • Valtonen,Anu
    • Kontunen-Soppela,Sari
    • Keski-Saari,Sarita
    • Rousi,Matti
    • Oksanen,Elina
    • Roininen,Heikki
  • Source: Climatic Change
  • Volume: 131
  • Issue: 2
  • Year: 2015
  • Summary: Boreal forests might be challenged by increased herbivory pressure in the future due to global warming, since warming is predicted to increase the abundance of herbivorous insects and to lead to shifts in their distribution towards higher latitudes where they might face more palatable food sources. We studied the effect of the latitudinal translocation of silver birch (Betula pendula Roth) on herbivore damage to 26 micropropagated genotypes originating from six populations ranging from 60 to 67 degrees N in Finland in two growing seasons, 2011 and 2012. The genotypes were planted at three sites located in southern (60 degrees N), central (62 degrees N) and northern (67 degrees N) Finland. The genotypes translocated to lower latitudes from their latitudes of origin were experiencing higher intensity of herbivore damage compared to the genotypes translocated to higher latitudes in 2011, but not in 2012. All genotypes were experiencing herbivore damage by local herbivores of each study site. These results suggest that, as many herbivore species are predicted to shift their ranges towards higher latitudes, they can feed on novel host plant genotypes and may face more palatable food sources than at their present range. This suggests that future climate change will increase herbivore damage to young silver birch. Increased herbivory, in turn, might affect the growth of birch and therefore should be considered when making predictions about the boreal forest composition in the future.
  • Authors:
    • Brady,M. V.
    • Hedlund,K.
    • Rong-Gang Cong
    • Hemerik,L.
    • Hotes,S.
    • Machado,S.
    • Mattsson,L.
    • Schulz,E.
    • Thomsen,I. K.
  • Source: Agronomy Journal
  • Volume: 107
  • Issue: 5
  • Year: 2015
  • Summary: Soil biodiversity through its delivery of ecosystem functions and attendant supporting ecosystem services - benefits soil organisms generate for farmers - underpins agricultural production. Yet lack of practical methods to value the long-term effects of current farming practices results, inevitably, in short-sighted management decisions. We present a method for valuing changes in supporting soil ecosystem services and associated soil natural capital - the value of the stock of soil organisms - in agriculture, based on resultant changes in future farm income streams. We assume that a relative change in soil organic C (SOC) concentration is correlated with changes in soil biodiversity and the generation of supporting ecosystem services. To quantify the effects of changes in supporting services on agricultural productivity, we fitted production functions to data from long-term field experiments in Europe and the United States. The different agricultural treatments at each site resulted in significant changes in SOC concentrations with time. Declines in associated services are shown to reduce both maximum yield and fertilizer-use efficiency in the future. The average depreciation of soil natural capital, for a 1% relative reduction in SOC concentration, was 144 Euro ha -1 (SD 47 Euro ha -1) when discounting future values to their current value at 3%; the variation was explained by site-specific factors and the current SOC concentration. Moreover, the results show that soil ecosystem services cannot be fully replaced by purchased inputs; they are imperfect substitutes. We anticipate that our results will both encourage and make it possible to include the value of soil natural capital in decisions.
  • Authors:
    • Soimakallio, S.
    • Koponen, K.
  • Source: The International Journal of Life Cycle Assessment
  • Volume: 20
  • Issue: 11
  • Year: 2015
  • Summary: As proposed by United Nations Environment Programme (UNEP)-Society for Environmental Toxicology and Chemistry (SETAC) Life Cycle Initiative (MilA i Canals et al., Int J Life Cycle Assess 18:1265-1277, 2007 and Koellner et al., Int J Life Cycle Assess 18:1188-1202, 2013), the impacts of land occupation should be studied in comparison to a baseline. Regardless of these guidelines, a land use baseline is often ignored in agro-bioenergy life cycle assessment (LCA) studies. This paper tests the appropriateness and significance of applying natural regeneration as a land use baseline for assessing the greenhouse gas (GHG) balances of agro-bioenergy in Finland. In the land use baseline applied, the land is assumed to be left to regenerate toward its natural state, which, in Finland, would most probably be some sort of forest. The foregone carbon stock of the natural regeneration baseline was estimated based on the literature. The GHG balances were studied by comparing the cumulative warming impacts of the dynamic biomass carbon cycle of the agro-bioenergy production system and the defined baseline over a given time horizon varying from 0 to 100 years. The significance of the results is illustrated by comparing them to other GHG emissions related to bioenergy. The results depend significantly on the agro-bioenergy yields and the carbon sequestration rate assumed in the natural regeneration baseline scenario. The GHG balances may be of the same magnitude as GHG emissions due to indirect land use changes resulting from market-mediated impacts, life cycle emissions of fossil fuels, and relative reduction in carbon stocks due to forest harvesting for bioenergy. Ignoring a dynamic land use baseline results in misleading conclusions on the GHG balances of land occupation, including agro-bioenergy, due to ignorance of foregone carbon sequestration. Thus, the interpretation of the results and conclusions provided in the vast number of agro-bioenergy LCA studies relying on biomass carbon neutrality should be reassessed. Besides bioenergy, the issue of land use baseline is relevant for any provision service function of land occupation. The foregone carbon sequestration is, however, highly uncertain and thus speculative.
  • Authors:
    • Myllys, M.
    • Sheehy, J.
    • Regina, K.
  • Source: Article
  • Volume: 20
  • Issue: 8
  • Year: 2015
  • Summary: Cultivated organic soils are a remarkable source of greenhouse gases (GHG) in many countries. Keeping the ground water table as high as possible could lower the mineralization rate of the peat and thus the emissions of carbon dioxide (CO2) and nitrous oxide (N2O) from these soils. We studied the effect of raised water table on the emissions of N2O, CO2 and methane (CH4) from undisturbed peat soil profiles of six different Finnish cultivated organic soils during a 5-week outdoor mesocosm experiment. The aim was to determine an optimum water table that would enable grass cultivation but lower the net gas balance of the soil. Raised water table decreased the GHG emissions from each peat type ranging from weakly decomposed Sphagnum peat to highly humified Carex peat. Based on the results, the optimum water table would be 30 cm below the soil surface. The average reduction of the total net emissions with a raise of water table from a typical drainage depth of 70 to 30 cm was 42 % in the outdoors mesocosm experiment and 23 % at a constant temperature (+6 A degrees C). The emissions of both CO2 and N2O declined and the net consumption of CH4 changed to net production as the water table rose. The results were confirmed by long-term measurements at one of the sampled sites. As a conclusion, we see that promoting drainage systems enabling raising of the ground water table and cultivation of crops capable of producing good yields also in wet conditions would be beneficial for the GHG mitigation in agriculture.
  • Authors:
    • Soimakallio, S.
    • Holma, A.
    • Helin, T.
  • Source: International Journal of Life Cycle Assessment
  • Volume: 19
  • Issue: 4
  • Year: 2014
  • Summary: A framework for the inclusion of land use impact assessment and a set of land use impact indicators has been recently proposed for life cycle assessment (LCA) and no case studies are available for forest biomass. The proposed methodology is tested for Scandinavian managed forestry; a comparative case study is made for energy from wood, agro-biomass and peat; and sensitivity to forest management options is analysed. The functional unit of this comparative case study is 1 GJ of energy in solid fuels. The land use impact assessment framework of the United Nations Environment Programme and the Society of Environmental Toxicology and Chemistry (UNEP-SETAC) is followed and its application for wood biomass is critically analysed. Applied midpoint indicators include ecological footprint and human appropriation of net primary production, global warming potential indicator for biomass (GWP(bio)-100) and impact indicators proposed by UNEP-SETAC on ecosystem services and biodiversity. Options for forest biomass land inventory modelling are discussed. The system boundary covers only the biomass acquisition phase. Management scenarios are formulated for forest and barley biomass, and a sensitivity analysis focuses on impacts of land transformations for agro-biomass. Meaningful differences were found in between solid biofuels from distinct land use classes. The impact indicator results were sensitive to land occupation and transformation and differed significantly from inventory results. Current impact assessment method is not sensitive to land management scenarios because the published characterisation factors are still too coarse and indicate differences only between land use types. All indicators on ecosystem services and biodiversity were sensitive to the assumptions related with land transformation. The land occupation (m(2)a) approach in inventory was found challenging for Scandinavian wood, due to long rotation periods and variable intensities of harvests. Some suggestions of UNEP-SETAC were challenged for the sake of practicality and relevance for decision support. Land use impact assessment framework for LCA and life cycle impact assessment (LCIA) indicators could be applied in a comparison of solid bioenergy sources. Although forest bioenergy has higher land occupation than agro-bioenergy, LCIA indicator results are of similar magnitude or even lower for forest bioenergy. Previous literature indicates that environmental impacts of land use are significant, but it remains questionable if these are captured with satisfactory reliability with the applied LCA methodology, especially for forest biomass. Short and long time perspectives of land use impacts should be studied in LCA with characterisation factors for all relevant timeframes, not only 500 years, with a forward-looking perspective. Characterisation factors need to be modelled further for different (forest) land management intensities and for peat excavation.
  • Authors:
    • Gundersen, P.
    • Stefansdottir, H. M.
    • Vesterdal, L.
    • Kiar, L. P.
    • Barcena, T. G.
    • Sigurdsson, B. D.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 8
  • Year: 2014
  • Summary: Northern Europe supports large soil organic carbon (SOC) pools and has been subjected to high frequency of land-use changes during the past decades. However, this region has not been well represented in previous large-scale syntheses of land-use change effects on SOC, especially regarding effects of afforestation. Therefore, we conducted a meta-analysis of SOC stock change following afforestation in Northern Europe. Response ratios were calculated for forest floors and mineral soils (0-10 cm and 0-20/30 cm layers) based on paired control (former land use) and afforested plots. We analyzed the influence of forest age, former land-use, forest type, and soil textural class. Three major improvements were incorporated in the meta-analysis: analysis of major interaction groups, evaluation of the influence of nonindependence between samples according to study design, and mass correction. Former land use was a major factor contributing to changes in SOC after afforestation. In former croplands, SOC change differed between soil layers and was significantly positive (20%) in the 0-10 cm layer. Afforestation of former grasslands had a small negative (nonsignificant) effect indicating limited SOC change following this land-use change within the region. Forest floors enhanced the positive effects of afforestation on SOC, especially with conifers. Meta-estimates calculated for the periods 30 years since afforestation revealed a shift from initial loss to later gain of SOC. The interaction group analysis indicated that meta-estimates in former land-use, forest type, and soil textural class alone were either offset or enhanced when confounding effects among variable classes were considered. Furthermore, effect sizes were slightly overestimated if sample dependence was not accounted for and if no mass correction was performed. We conclude that significant SOC sequestration in Northern Europe occurs after afforestation of croplands and not grasslands, and changes are small within a 30-year perspective.
  • Authors:
    • Poskitt, J.
    • McNamara, N. P.
    • Briones, M. J. I.
    • Crow, S. E.
    • Ostle, N. J.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 9
  • Year: 2014
  • Summary: Partially decomposed plant and animal remains have been accumulating in organic soils (i.e. >40% C content) for millennia, making them the largest terrestrial carbon store. There is growing concern that, in a warming world, soil biotic processing will accelerate and release greenhouse gases that further exacerbate climate change. However, the magnitude of this response remains uncertain as the constraints are abiotic, biotic and interactive. Here, we examined the influence of resource quality and biological activity on the temperature sensitivity of soil respiration under different soil moisture regimes. Organic soils were sampled from 13 boreal and peatland ecosystems located in the United Kingdom, Ireland, Spain, Finland and Sweden, representing a natural resource quality range of C, N and P. They were incubated at four temperatures (4, 10, 15 and 20°C) at either 60% or 100% water holding capacity (WHC). Our results showed that chemical and biological properties play an important role in determining soil respiration responses to temperature and moisture changes. High soil C : P and C : N ratios were symptomatic of slow C turnover and long-term C accumulation. In boreal soils, low bacterial to fungal ratios were related to greater temperature sensitivity of respiration, which was amplified in drier conditions. This contrasted with peatland soils which were dominated by bacterial communities and enchytraeid grazing, resulting in a more rapid C turnover under warmer and wetter conditions. The unexpected acceleration of C mineralization under high moisture contents was possibly linked to the primarily role of fermented organic matter, instead of oxygen, in mediating microbial decomposition. We conclude that to improve C model simulations of soil respiration, a better resolution of the interactions occurring between climate, resource quality and the decomposer community will be required.
  • Authors:
    • Stoddard, F. L.
    • Makela, P.
    • Simojoki, A.
    • Tammeorg, P.
    • Alakukku, L.
    • Helenius, J.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 191
  • Year: 2014
  • Summary: Poor water retention capacity (WRC) and nutrient deficiency commonly limit crop yields in sandy soils. The use of biochar as a soil amendment has been previously reported to improve these limiting factors in subtropical and temperate soils. We studied the effects of biochar on soil properties and yield formation of spring wheat ( Triticum aestivum L.) when applied together with inorganic fertiliser or meat bone meal (MBM) to an Endogleyic Umbrisol with a loamy sand texture in boreal conditions. In a two-year field experiment, biochar was applied at 0, 5, 10, 20 and 30 t ha -1 combined with three fertiliser treatments (unfertilised control, MBM and inorganic fertiliser) providing equal amounts of nitrogen (N), phosphorus (P) and potassium (K). Soil WRC and fertility as well as wheat yield, yield components and quality were analysed. Soil moisture content, leaf area index and leaf chlorophyll values (SPAD) were monitored during the experiment. Biochar increased the plant-available water content of the topsoil in the first year and reduced the bulk density in the second year after application. It also increased the contents of easily soluble K and soil organic C (SOC) in the 20 cm of topsoil, but had no effects on other soil nutrients, pH or moisture content. Biochar amendment decreased the soil NO 3--N content below control values in the first year but increased it significantly in the second year. The addition of biochar did not significantly affect the nitrogen uptake, grain yield or quality of wheat, possibly because of its low nutrient availability and the high organic matter content of the soil.
  • Authors:
    • Zhong, Q. C.
    • Zhang, C.
    • Hyvonen, N.
    • Wang, K. Y.
    • Shurpali, N. J.
    • Kellomaki, S.
    • Gong, J. N.
    • Martikainen, P. J.
  • Source: AGRICULTURAL AND FOREST METEOROLOGY
  • Volume: 198
  • Year: 2014
  • Summary: In this study, a process-based model (RCG-C) was developed, parameterized and calibrated for studying the annual and seasonal dynamics of the ecosystem CO2 exchange (NEE) in a cutaway peatland (Linnansuo, eastern Finland) cultivated with a perennial bioenergy crop (Phalaris arundinaceae, L., RCG). Based on a number of prior studies and an environmentally controlled experiment, RCG-C emphasized several key processes beyond the generality of previous diplotelmic models for pristine peatlands. These processes included the effects of management (e.g., drainage, peat extraction, tilling, harvesting and fertilization) on the soil hydrology and the cycling of carbon and nitrogen, the influence of climatic factors on photosynthesis and the phenological cycle and phenological and soil-moisture controls on biomass production and canopy development. The model was validated based on continuous measurements of meteorological parameters, energy and CO2 fluxes (eddy covariance system) performed at the site from 2005 to 2010, including variation associated with both wet and dry years. The results showed that the model captured the seasonal and annual trends of the latent heat flux and NEE during the six-year period. Moreover, the simulated values for the total C sink capacity, accumulation of rhizome biomass and peat formation from RCG obtained during the six-year period also agreed well with the field measurements. Based on the FINADAPT climate scenarios, a sensitivity analysis of the model showed that the potential increases in the atmospheric CO2 concentration (Ca) and air temperature (Ta) could be the main forces driving the changes in NEE. The model simulation suggested that the effects of Ta tend to offset those of Ca and lead to a decrease in the total C sink capacity of the site during the main rotation period (4-15th year of cultivation). This decrease tends to become more intensive toward the end of the 21st century. During the period from 2060 to 2099, the total CO2 sink capacity could decrease by 79% during the main rotation period at the Linnansuo site.