1
|
Bleken MA, Rittl TF, Nadeem S, Hansen S. Roots and other residues from leys with or without red clover: Quality and effects on N 2O emission factors in a partly frozen soil following autumn ploughing. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 831:154582. [PMID: 35367262 DOI: 10.1016/j.scitotenv.2022.154582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/11/2022] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
Revised IPCC guidelines assume that a constant share of N in decomposing crop residues is directly emitted as N2O (emission factor: EFN2O), and calculate the amount of nitrogen (N) in non-removable residues of temporary grasslands proportionally to the average annual herbage yield. However, EFN2O depends on the intrinsic quality of the residues and their interactions with environmental conditions. Only a few field studies on N2O emissions from grassland renewal are available, and none have simultaneously quantified the N amount and quality of non-removable residues (roots and stubble). To gain insight into the effect of non-removable residue quality on EFN2O, we studied the amount and quality of roots and stubble and their effect on EFN2O following the ploughing of three-year-old swards. The measured amount of N in non-removable residues was approximately 20, 25, and 31 kg N per 1 Mg average annual dry matter yield in grass, red clover-grass, and red clover, and 70-83% of it was below ground. However, the EFN2O of non-removable residues measured over 252 days was lower (0.24%, SE = 14% for grass and red clover-grass) than the IPCC default value (0.6%, CV: 50%) for wet regions, although within the uncertainty margin, and was significantly lower than the EFN2O of incorporated herbage, which was related to differences in EFCO2. We advocate for more specific studies that separate the effects of belowground and aboveground residues (AGR), considering the possibility of simplifying the accounting of N2O emissions from belowground residues while improving that of non-removable AGR from temporary grasslands and other green crops. We observed the accumulation of N2O in the frozen soil under snow, which was released during diurnal percolation of meltwater. N2O emissions from frozen soil accounted for 30% or more of the total emissions.
Collapse
Affiliation(s)
- Marina Azzaroli Bleken
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1432 Ås, Norway.
| | - Tatiana Francischinelli Rittl
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1432 Ås, Norway; Presently Norwegian Centre for Organic Agriculture, 6630 Tingvoll, Norway..
| | - Shahid Nadeem
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences (NMBU), 1432 Ås, Norway
| | - Sissel Hansen
- Norwegian Centre for Organic Agriculture, 6630 Tingvoll, Norway..
| |
Collapse
|
2
|
Poeplau C, Don A, Schneider F. Roots are key to increasing the mean residence time of organic carbon entering temperate agricultural soils. GLOBAL CHANGE BIOLOGY 2021; 27:4921-4934. [PMID: 34228862 DOI: 10.1111/gcb.15787] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 06/13/2023]
Abstract
The ratio of soil organic carbon stock (SOC) to annual carbon input gives an estimate of the mean residence time of organic carbon that enters the soil (MRTOC ). It indicates how efficiently biomass can be transformed into SOC, which is of particular relevance for mitigating climate change by means of SOC storage. There have been few comprehensive studies of MRTOC and their drivers, and these have mainly been restricted to the global scale, on which climatic drivers dominate. This study used the unique combination of regional-scale cropland and grassland topsoil (0-30 cm) SOC stock data and average site-specific OC input data derived from the German Agricultural Soil Inventory to elucidate the main drivers of MRTOC . Explanatory variables related to OC input composition and other soil-forming factors were used to explain the variability in MRTOC by means of a machine-learning approach. On average, OC entering German agricultural topsoils had an MRT of 21.5 ± 11.6 years, with grasslands (29.0 ± 11.2 years, n = 465) having significantly higher MRTOC than croplands (19.4 ± 10.7, n = 1635). This was explained by the higher proportion of root-derived OC inputs in grassland soils, which was the most important variable for explaining MRTOC variability at a regional scale. Soil properties such as clay content, soil group, C:N ratio and groundwater level were also important, indicating that MRTOC is driven by a combination of site properties and OC input composition. However, the great importance of root-derived OC inputs indicated that MRTOC can be actively managed, with maximization of root biomass input to the soil being a straightforward means to extend the time that assimilated C remains in the soil and consequently also increase SOC stocks.
Collapse
Affiliation(s)
| | - Axel Don
- Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany
| | - Florian Schneider
- Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany
| |
Collapse
|
3
|
Filling gaps in models simulating carbon storage in agricultural soils: the role of cereal stubbles. Sci Rep 2021; 11:18299. [PMID: 34526561 PMCID: PMC8443642 DOI: 10.1038/s41598-021-97744-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/27/2021] [Indexed: 11/08/2022] Open
Abstract
Carbon (C) input is a prerequisite for the formation of soil organic matter and thus for soil organic C (SOC) sequestration. Here we used the C-TOOL model to simulate SOC changes in a long-term field experiment (1932-2020) at Askov, Denmark, which involved four different levels of nutrients added in mineral fertilizer (0, 0.5, 1, 1.5 NPK) and a four-crop rotation. The C input into soils consists of belowground and aboveground plant biomass and was estimated using allometric functions. The simulation showed that modelled SOC based on standard allometric functions of C input from crop residues did not adequately matched measured SOC contents. However, applying modified allometric functions based on current and the previously measured results for aboveground and belowground C inputs in winter wheat and grass clover in rotations provided much better match between simulated and measured SOC contents for fertilized treatments at normal and high level of fertilization. This improved indicators of C-TOOL model performance (e.g. yielding RMSE of 2.24 t C ha-1 and model efficiency of 0.73 in 1.5 NPK treatment). The results highlight that standard allometric functions greatly overestimates the amount of C in winter wheat stubble left after harvest in treatments dressed with NPK compared with modified functions. The results also highlight further needs for improvement of allometric functions used in simulation models for C-accounting in agroecosystems.
Collapse
|
4
|
Hirte J, Walder F, Hess J, Büchi L, Colombi T, van der Heijden MG, Mayer J. Enhanced root carbon allocation through organic farming is restricted to topsoils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:143551. [PMID: 33190899 DOI: 10.1016/j.scitotenv.2020.143551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/29/2020] [Accepted: 10/31/2020] [Indexed: 06/11/2023]
Abstract
Soils store significant amounts of carbon (C) and thus can play a critical role for mitigating climate change. Crop roots represent the main C source in agricultural soils and are particularly important for long-term C storage in agroecosystems. To evaluate the potential of different farming systems to contribute to soil C sequestration and thus climate change mitigation, it is of great importance to gain a better understanding of the factors influencing root C allocation and distribution. So far, it is still unclear how root C allocation varies among farming systems and whether the choice of management practices can help to enhance root C inputs. In this study, we compared root C allocation in three main arable farming systems, namely organic, no-till, and conventional farming. We assessed root biomass, vertical root distribution to 0.75 m soil depth, and root-shoot ratios in 24 winter wheat fields. We further evaluated the relative importance of the farming system compared to site conditions and quantified the contribution of individual management practices and pedoclimatic drivers. Farming system explained one third of the variation in topsoil root biomass and root-shoot ratios, both being strongly positively related to weed biomass and soil organic C content and negatively to mineral nitrogen fertilization intensity. Root C allocation was significantly higher in organic farming as illustrated by an increase in root biomass (+40%) and root-shoot ratios (+60%) compared to conventional farming. By contrast, the overall impact of no-till was low. The importance of pedoclimatic conditions increased substantially with soil depth and deep root biomass was largely controlled by precipitation and soil texture, while the impact of management was close to zero. Our findings highlight the potential of organic farming in promoting root C inputs to topsoils and thereby contributing to soil organic matter build-up and improved soil quality in agroecosystems.
Collapse
Affiliation(s)
- Juliane Hirte
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland.
| | - Florian Walder
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland.
| | - Julia Hess
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland
| | - Lucie Büchi
- Agroscope, Plant Production Systems, Route de Duillier 50, CH-1260 Nyon, Switzerland; University of Greenwich, Natural Resources Institute, Central Avenue, UK-ME4 4TB Chatham, United Kingdom of Great Britain and Northern Ireland
| | - Tino Colombi
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland; Swedish University of Agricultural Sciences, Department of Soil and Environment, Box 7014, SE-750 07 Uppsala, Sweden
| | - Marcel G van der Heijden
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland; University of Zürich, Department for Plant and Microbial Biology, CH-8057 Zurich, Switzerland; Utrecht University, Plant-Microbe Interactions, Department of Biology, NL-3508 TB Utrecht, the Netherlands
| | - Jochen Mayer
- Agroscope, Agroecology and Environment, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland
| |
Collapse
|
5
|
Farina R, Sándor R, Abdalla M, Álvaro-Fuentes J, Bechini L, Bolinder MA, Brilli L, Chenu C, Clivot H, De Antoni Migliorati M, Di Bene C, Dorich CD, Ehrhardt F, Ferchaud F, Fitton N, Francaviglia R, Franko U, Giltrap DL, Grant BB, Guenet B, Harrison MT, Kirschbaum MUF, Kuka K, Kulmala L, Liski J, McGrath MJ, Meier E, Menichetti L, Moyano F, Nendel C, Recous S, Reibold N, Shepherd A, Smith WN, Smith P, Soussana JF, Stella T, Taghizadeh-Toosi A, Tsutskikh E, Bellocchi G. Ensemble modelling, uncertainty and robust predictions of organic carbon in long-term bare-fallow soils. GLOBAL CHANGE BIOLOGY 2021; 27:904-928. [PMID: 33159712 DOI: 10.1111/gcb.15441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/26/2020] [Indexed: 06/11/2023]
Abstract
Simulation models represent soil organic carbon (SOC) dynamics in global carbon (C) cycle scenarios to support climate-change studies. It is imperative to increase confidence in long-term predictions of SOC dynamics by reducing the uncertainty in model estimates. We evaluated SOC simulated from an ensemble of 26 process-based C models by comparing simulations to experimental data from seven long-term bare-fallow (vegetation-free) plots at six sites: Denmark (two sites), France, Russia, Sweden and the United Kingdom. The decay of SOC in these plots has been monitored for decades since the last inputs of plant material, providing the opportunity to test decomposition without the continuous input of new organic material. The models were run independently over multi-year simulation periods (from 28 to 80 years) in a blind test with no calibration (Bln) and with the following three calibration scenarios, each providing different levels of information and/or allowing different levels of model fitting: (a) calibrating decomposition parameters separately at each experimental site (Spe); (b) using a generic, knowledge-based, parameterization applicable in the Central European region (Gen); and (c) using a combination of both (a) and (b) strategies (Mix). We addressed uncertainties from different modelling approaches with or without spin-up initialization of SOC. Changes in the multi-model median (MMM) of SOC were used as descriptors of the ensemble performance. On average across sites, Gen proved adequate in describing changes in SOC, with MMM equal to average SOC (and standard deviation) of 39.2 (±15.5) Mg C/ha compared to the observed mean of 36.0 (±19.7) Mg C/ha (last observed year), indicating sufficiently reliable SOC estimates. Moving to Mix (37.5 ± 16.7 Mg C/ha) and Spe (36.8 ± 19.8 Mg C/ha) provided only marginal gains in accuracy, but modellers would need to apply more knowledge and a greater calibration effort than in Gen, thereby limiting the wider applicability of models.
Collapse
Affiliation(s)
- Roberta Farina
- Research Centre for Agriculture and Environment, CREA - Council for Agricultural Research and Economics, Rome, Italy
| | - Renata Sándor
- Centre for Agricultural Research, Agricultural Institute, Martonvásár, Hungary
- Université Clermont Auvergne, INRAE, VetAgro Sup, UREP, Clermont-Ferrand, France
| | | | | | | | | | | | - Claire Chenu
- Université Paris Saclay, INRAE, AgroParisTech, Paris, France
| | - Hugues Clivot
- INRAE, BioEcoAgro, Barenton-Bugny, France
- Université de Lorraine, INRAE, LAE, Colmar, France
| | | | - Claudia Di Bene
- Research Centre for Agriculture and Environment, CREA - Council for Agricultural Research and Economics, Rome, Italy
| | | | | | | | | | - Rosa Francaviglia
- Research Centre for Agriculture and Environment, CREA - Council for Agricultural Research and Economics, Rome, Italy
| | - Uwe Franko
- Helmholtz Centre for Environmental Research, Halle, Germany
| | - Donna L Giltrap
- Manaaki Whenua - Landcare Research, Palmerston North, New Zealand
| | - Brian B Grant
- Ottawa Research and Development Centre, Agriculture and Agri-Food, Ottawa, ON, Canada
| | - Bertrand Guenet
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
- Laboratoire de Géologie de l'ENS, PSL Research University, Paris, France
| | | | | | - Katrin Kuka
- JKI - Federal Research Centre for Cultivated Plants, Braunschweig, Germany
| | | | - Jari Liski
- Finnish Meteorological Institute, Helsinki, Finland
| | - Matthew J McGrath
- Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, Gif-sur-Yvette, France
| | | | | | | | - Claas Nendel
- Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
- University of Potsdam, Potsdam, Germany
| | - Sylvie Recous
- Université de Reims Champagne Ardenne, INRAE, FARE, Reims, France
| | | | - Anita Shepherd
- University of Aberdeen, Aberdeen, UK
- formerly Rothamsted Research, North Wyke, UK
| | - Ward N Smith
- Ottawa Research and Development Centre, Agriculture and Agri-Food, Ottawa, ON, Canada
| | | | | | - Tommaso Stella
- Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
| | | | - Elena Tsutskikh
- Leibniz Centre for Agricultural Landscape Research, Müncheberg, Germany
| | - Gianni Bellocchi
- Université Clermont Auvergne, INRAE, VetAgro Sup, UREP, Clermont-Ferrand, France
| |
Collapse
|
6
|
Sykes AJ, Macleod M, Eory V, Rees RM, Payen F, Myrgiotis V, Williams M, Sohi S, Hillier J, Moran D, Manning DAC, Goglio P, Seghetta M, Williams A, Harris J, Dondini M, Walton J, House J, Smith P. Characterising the biophysical, economic and social impacts of soil carbon sequestration as a greenhouse gas removal technology. GLOBAL CHANGE BIOLOGY 2020; 26:1085-1108. [PMID: 31532049 PMCID: PMC7079085 DOI: 10.1111/gcb.14844] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 08/21/2019] [Indexed: 06/01/2023]
Abstract
To limit warming to well below 2°C, most scenario projections rely on greenhouse gas removal technologies (GGRTs); one such GGRT uses soil carbon sequestration (SCS) in agricultural land. In addition to their role in mitigating climate change, SCS practices play a role in delivering agroecosystem resilience, climate change adaptability and food security. Environmental heterogeneity and differences in agricultural practices challenge the practical implementation of SCS, and our analysis addresses the associated knowledge gap. Previous assessments have focused on global potentials, but there is a need among policymakers to operationalise SCS. Here, we assess a range of practices already proposed to deliver SCS, and distil these into a subset of specific measures. We provide a multidisciplinary summary of the barriers and potential incentives towards practical implementation of these measures. First, we identify specific practices with potential for both a positive impact on SCS at farm level and an uptake rate compatible with global impact. These focus on: (a) optimising crop primary productivity (e.g. nutrient optimisation, pH management, irrigation); (b) reducing soil disturbance and managing soil physical properties (e.g. improved rotations, minimum till); (c) minimising deliberate removal of C or lateral transport via erosion processes (e.g. support measures, bare fallow reduction); (d) addition of C produced outside the system (e.g. organic manure amendments, biochar addition); (e) provision of additional C inputs within the cropping system (e.g. agroforestry, cover cropping). We then consider economic and non-cost barriers and incentives for land managers implementing these measures, along with the potential externalised impacts of implementation. This offers a framework and reference point for holistic assessment of the impacts of SCS. Finally, we summarise and discuss the ability of extant scientific approaches to quantify the technical potential and externalities of SCS measures, and the barriers and incentives to their implementation in global agricultural systems.
Collapse
Affiliation(s)
| | | | - Vera Eory
- Scotland's Rural College (SRUC)EdinburghUK
| | | | - Florian Payen
- Scotland's Rural College (SRUC)EdinburghUK
- School of GeosciencesThe University of EdinburghEdinburghUK
| | | | | | - Saran Sohi
- School of GeosciencesThe University of EdinburghEdinburghUK
| | - Jon Hillier
- Global Academy of Agriculture and Food SecurityThe University of EdinburghMidlothianUK
| | - Dominic Moran
- Global Academy of Agriculture and Food SecurityThe University of EdinburghMidlothianUK
| | - David A. C. Manning
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle‐upon TyneUK
| | - Pietro Goglio
- School of Water, Energy and EnvironmentCranfield UniversityBedfordUK
| | - Michele Seghetta
- School of Water, Energy and EnvironmentCranfield UniversityBedfordUK
| | - Adrian Williams
- School of Water, Energy and EnvironmentCranfield UniversityBedfordUK
| | - Jim Harris
- School of Water, Energy and EnvironmentCranfield UniversityBedfordUK
| | - Marta Dondini
- Institute of Biological & Environmental SciencesUniversity of AberdeenAberdeenUK
| | - Jack Walton
- Institute of Biological & Environmental SciencesUniversity of AberdeenAberdeenUK
| | | | - Pete Smith
- Institute of Biological & Environmental SciencesUniversity of AberdeenAberdeenUK
| |
Collapse
|
7
|
Smith P, Soussana J, Angers D, Schipper L, Chenu C, Rasse DP, Batjes NH, van Egmond F, McNeill S, Kuhnert M, Arias‐Navarro C, Olesen JE, Chirinda N, Fornara D, Wollenberg E, Álvaro‐Fuentes J, Sanz‐Cobena A, Klumpp K. How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal. GLOBAL CHANGE BIOLOGY 2020; 26:219-241. [PMID: 31469216 PMCID: PMC6973036 DOI: 10.1111/gcb.14815] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 08/22/2019] [Indexed: 05/19/2023]
Abstract
There is growing international interest in better managing soils to increase soil organic carbon (SOC) content to contribute to climate change mitigation, to enhance resilience to climate change and to underpin food security, through initiatives such as international '4p1000' initiative and the FAO's Global assessment of SOC sequestration potential (GSOCseq) programme. Since SOC content of soils cannot be easily measured, a key barrier to implementing programmes to increase SOC at large scale, is the need for credible and reliable measurement/monitoring, reporting and verification (MRV) platforms, both for national reporting and for emissions trading. Without such platforms, investments could be considered risky. In this paper, we review methods and challenges of measuring SOC change directly in soils, before examining some recent novel developments that show promise for quantifying SOC. We describe how repeat soil surveys are used to estimate changes in SOC over time, and how long-term experiments and space-for-time substitution sites can serve as sources of knowledge and can be used to test models, and as potential benchmark sites in global frameworks to estimate SOC change. We briefly consider models that can be used to simulate and project change in SOC and examine the MRV platforms for SOC change already in use in various countries/regions. In the final section, we bring together the various components described in this review, to describe a new vision for a global framework for MRV of SOC change, to support national and international initiatives seeking to effect change in the way we manage our soils.
Collapse
Affiliation(s)
- Pete Smith
- Institute of Biological & Environmental SciencesUniversity of AberdeenAberdeenUK
| | | | | | - Louis Schipper
- Environmental Research InstituteUniversity of WaikatoHamiltonNew Zealand
| | | | | | | | | | | | - Matthias Kuhnert
- Institute of Biological & Environmental SciencesUniversity of AberdeenAberdeenUK
| | | | | | | | | | - Eva Wollenberg
- CGIAR CCAFS ProgrammeUniversity of Vermont (UVM)BurlingtonVTUSA
| | | | - Alberto Sanz‐Cobena
- Research Center for the Management of Environmental and Agricultural Risks (CEIGRAM)Universidad Politécnica de MadridMadridSpain
| | | |
Collapse
|
8
|
Morais TG, Teixeira RF, Domingos T. Detailed global modelling of soil organic carbon in cropland, grassland and forest soils. PLoS One 2019; 14:e0222604. [PMID: 31536571 PMCID: PMC6752864 DOI: 10.1371/journal.pone.0222604] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 09/03/2019] [Indexed: 12/22/2022] Open
Abstract
Assessments of the global carbon (C) cycle typically rely on simplified models which consider large areas as homogeneous in terms of the response of soils to land use or consider very broad land classes. For example, "cropland" is typically modelled as an aggregation of distinct practices and individual crops over large regions. Here, we use the process-based Rothamsted soil Carbon Model (RothC model), which has a history of being successfully applied at a global scale, to calculate attainable SOC stocks and C mineralization rates for each of c. 17,000 regions (combination of soil type and texture, climate type, initial land use and country) in the World, under near-past climate conditions. We considered 28 individual crops and, for each, multiple production practices, plus 16 forest types and 1 grassland class (total of 80 classes). We find that conversion to cropland can result in SOC increases, particularly when the soil remains covered with crop residues (an average gain of 12 t C/ha) or using irrigation (4 t C/ha), which are mutually reinforcing effects. Attainable SOC stocks vary significantly depending on the land use class, particularly for cropland. Common aggregations in global modelling of a single agricultural class would be inaccurate representations of these results. Attainable SOC stocks obtained here were compared to long-term experiment data and are well aligned with the literature. Our results provide a regional and detailed understanding of C sequestration that will also enable better greenhouse gas reporting at national level as alternatives to IPCC tier 2 defaults.
Collapse
Affiliation(s)
- Tiago G. Morais
- MARETEC–Marine, Environment and Technology Centre, LARSyS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Ricardo F.M. Teixeira
- MARETEC–Marine, Environment and Technology Centre, LARSyS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Tiago Domingos
- MARETEC–Marine, Environment and Technology Centre, LARSyS, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| |
Collapse
|
9
|
Modern Wheat Varieties as a Driver of the Degradation of Spanish Rainfed Mediterranean Agroecosystems throughout the 20th Century. SUSTAINABILITY 2018. [DOI: 10.3390/su10103724] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The high grain yield of modern varieties (MV) respond to the increase in fossil-based inputs, and the widespread belief that they are more productive than old varieties (OV) is biased. This belief focuses only on marketable biomass, without considering the consequences on agroecosystem sustainability of the reductions in other portions of NPP. Additionally, field comparisons of OV and MV were normally conducted under industrialized farming conditions, which is detrimental for OV performance. Both trials carried out in this study comparing wheat OV and MV show that, under Mediterranean rainfed conditions and traditional organic management, aerial and belowground biomass production of OV is higher than that of MV, without significantly decreasing yield and enabling a better competition against weeds. From the data of our trials, bibliographic review and information from historical sources, we have reconstructed the NPP and destinations of biomass of Spanish wheat fields (1900–2000). Varietal replacement entailed the reduction in residues and unharvested biomass (UhB), which involved soil degradation in rainfed cereal fields and undermining heterotrophic trophic webs. Our results suggest that OV can increase the sustainability of rainfed Mediterranean agroecosystems at present through the improvement of soil quality, the reduction of herbicides use, and the recovery of biodiversity.
Collapse
|
10
|
Aguilera E, Guzmán GI, Álvaro-Fuentes J, Infante-Amate J, García-Ruiz R, Carranza-Gallego G, Soto D, González de Molina M. A historical perspective on soil organic carbon in Mediterranean cropland (Spain, 1900-2008). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 621:634-648. [PMID: 29202285 DOI: 10.1016/j.scitotenv.2017.11.243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 06/07/2023]
Abstract
Soil organic carbon (SOC) management is key for soil fertility and for mitigation and adaptation to climate change, particularly in desertification-prone areas such as Mediterranean croplands. Industrialization and global change processes affect SOC dynamics in multiple, often opposing, ways. Here we present a detailed SOC balance in Spanish cropland from 1900 to 2008, as a model of a Mediterranean, industrialized agriculture. Net Primary Productivity (NPP) and soil C inputs were estimated based on yield and management data. Changes in SOC stocks were modeled using HSOC, a simple model with one inert and two active C pools, which combines RothC model parameters with humification coefficients. Crop yields increased by 227% during the studied period, but total C exported from the agroecosystem only increased by 73%, total NPP by 30%, and soil C inputs by 20%. There was a continued decline in SOC during the 20th century, and cropland SOC levels in 2008 were 17% below their 1933 peak. SOC trends were driven by historical changes in land uses, management practices and climate. Cropland expansion was the main driver of SOC loss until mid-20th century, followed by the decline in soil C inputs during the fast agricultural industrialization starting in the 1950s, which reduced harvest indices and weed biomass production, particularly in woody cropping systems. C inputs started recovering in the 1980s, mainly through increasing crop residue return. The upward trend in SOC mineralization rates was an increasingly important driver of SOC losses, triggered by irrigation expansion, soil cover loss and climate change-driven temperature rise.
Collapse
Affiliation(s)
- Eduardo Aguilera
- Agro-ecosystems History Laboratory, Universidad Pablo de Olavide, 41013 Sevilla, Spain.
| | - Gloria I Guzmán
- Agro-ecosystems History Laboratory, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - Jorge Álvaro-Fuentes
- Departamento de Suelo y Agua, Estación Experimental de Aula Dei, Consejo Superior de Investigaciones Científicas (EEAD-CSIC), 50059 Zaragoza, Spain
| | - Juan Infante-Amate
- Agro-ecosystems History Laboratory, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | - Roberto García-Ruiz
- Departamento de Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, 23071 Jaén, Spain
| | | | - David Soto
- Agro-ecosystems History Laboratory, Universidad Pablo de Olavide, 41013 Sevilla, Spain
| | | |
Collapse
|
11
|
Hirte J, Leifeld J, Abiven S, Oberholzer HR, Hammelehle A, Mayer J. Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter. FRONTIERS IN PLANT SCIENCE 2017; 8:284. [PMID: 28298919 PMCID: PMC5331040 DOI: 10.3389/fpls.2017.00284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/16/2017] [Indexed: 06/06/2023]
Abstract
Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial "DOK." We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0-0.25, 0.25-0.5, 0.5-0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations of the climate change mitigation potential of soils.
Collapse
Affiliation(s)
- Juliane Hirte
- Department of Natural Resources and Agriculture, Institute for Sustainability Sciences, AgroscopeZurich, Switzerland
- Department of Geography, University of ZurichZurich, Switzerland
| | - Jens Leifeld
- Department of Natural Resources and Agriculture, Institute for Sustainability Sciences, AgroscopeZurich, Switzerland
| | - Samuel Abiven
- Department of Geography, University of ZurichZurich, Switzerland
| | - Hans-Rudolf Oberholzer
- Department of Natural Resources and Agriculture, Institute for Sustainability Sciences, AgroscopeZurich, Switzerland
| | | | - Jochen Mayer
- Department of Natural Resources and Agriculture, Institute for Sustainability Sciences, AgroscopeZurich, Switzerland
| |
Collapse
|