• Authors:
    • Adamiade, V.
    • Keller, T.
    • Richard, G.
    • Défossez, P.
    • Govind, A.
    • Mary, B.
  • Source: SOIL & TILLAGE RESEARCH DOI:
  • Volume: 141
  • Year: 2014
  • Summary: Loss of organic matter has been recognized as being a major threat to soils in Europe with important consequences for the physical functioning of soils. We present the result of a numerical analysis of the integrated effects of changes in soil porosity and soil water status, along with decreased soil organic carbon (SOC) and the subsequent changes in the risk of compaction. This study concerns the impact of straw exportation on the risk of soil compaction. We evaluated the risk of compaction of a cultivated Eutric Cambisol in Northern France having a dominant silt loam soil texture, by simulating vehicle wheeling during sugar beet cropping for contrasting soil organic carbon contents (4.7, 11.1 and 23.4gkg-1). To do this, we coupled two models: (1) a crop model (STICS) to calculate the changes in the water content of the 0-30cm depth layer; and (2) a compaction model (COMPSOIL) to calculate soil stresses as a function of vehicle characteristics. Our study suggests that a decrease in SOC reduces the risk of topsoil deformation due to a decrease in soil water content, which tends to augment soil precompression stress. The method requires improvement in the future because it is very sensitive to input parameters for soil physical properties. Nevertheless it provides the first method for evaluating the impact of SOC decline on soil compaction. Its genericity permits it further applications to various soil management practices that decrease SOC. © 2014 Elsevier B.V.
  • Authors:
    • Kim, J.
    • Guillaume, B.
    • Laratte, B.
    • Birregah, B.
  • Source: Science of the Total Environment
  • Volume: 481
  • Year: 2014
  • Summary: This paper aims at presenting a dynamic indicator for life cycle assessment (LCA) measuring cumulative impacts over time of greenhouse gas (GHG) emissions from fertilizers used for wheat cultivation and production. Our approach offers a dynamic indicator of global warming potential (GWP), one of the most used indicator of environmental impacts (e.g. in the Kyoto Protocol). For a case study, the wheat production in France was selected and considered by using data from official sources about fertilizer consumption and production of wheat We propose to assess GWP environmental impact based on LCA method. The system boundary is limited to the fertilizer production for 1 ton of wheat produced (functional unit) from 1910 to 2010. As applied to wheat production in France, traditional LCA shows a maximum GWP impact of 500 kg CO2-eg for 1 ton of wheat production, whereas the GWP impact of wheat production over time with our approach to dynamic LCA and its cumulative effects increases to 18,000 kg CO2-eg for 1 ton of wheat production. In this paper, only one substance and one impact assessment indicator are presented. However, the methodology can be generalized and improved by using different substances and indicators. (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Preudhomme, M.
    • Fourdinier, E.
    • Machet, J.
    • Boizard, H.
    • Demay, C.
    • Ferchaud, F.
    • Cadoux, S.
    • Chabbert, B.
    • Gosse, G.
    • Mary, B.
  • Source: Bioenergy
  • Volume: 6
  • Issue: 4
  • Year: 2014
  • Summary: Biomass from dedicated crops is expected to contribute significantly to the replacement of fossil resources. However, sustainable bioenergy cropping systems must provide high biomass production and low environmental impacts. This study aimed at quantifying biomass production, nutrient removal, expected ethanol production, and greenhouse gas (GHG) balance of six bioenergy crops: Miscanthus * giganteus, switchgrass, fescue, alfalfa, triticale, and fiber sorghum. Biomass production and N, P, K balances (input-output) were measured during 4 years in a long-term experiment, which included two nitrogen fertilization treatments. These results were used to calculate a posteriori 'optimized' fertilization practices, which would ensure a sustainable production with a nil balance of nutrients. A modified version of the cost/benefit approach proposed by Crutzen et al. (2008), comparing the GHG emissions resulting from N-P-K fertilization of bioenergy crops and the GHG emissions saved by replacing fossil fuel, was applied to these 'optimized' situations. Biomass production varied among crops between 10.0 (fescue) and 26.9 t DM ha -1 yr -1 (miscanthus harvested early) and the expected ethanol production between 1.3 (alfalfa) and 6.1 t ha -1 yr -1 (miscanthus harvested early). The cost/benefit ratio ranged from 0.10 (miscanthus harvested late) to 0.71 (fescue); it was closely correlated with the N/C ratio of the harvested biomass, except for alfalfa. The amount of saved CO 2 emissions varied from 1.0 (fescue) to 8.6 t CO 2eq ha -1 yr -1 (miscanthus harvested early or late). Due to its high biomass production, miscanthus was able to combine a high production of ethanol and a large saving of CO 2 emissions. Miscanthus and switchgrass harvested late gave the best compromise between low N-P-K requirements, high GHG saving per unit of biomass, and high productivity per hectare.
  • Authors:
    • Mihalache, M.
    • Fintineru, G.
    • Stan, V.
  • Source: Notulae Botanicae Horti Agrobotanici Cluj-Napoca
  • Volume: 42
  • Issue: 1
  • Year: 2014
  • Summary: Burning crop residues is frequently used by Romanian land users to clean agricultural fields after crop harvest for ease in postharvest soil tillage. Huge amounts of crop residues biomass, on very large areas, were burned in Romania in the last twenty years, as compared to other countries. There are several reasons (e.g. the lack of equipment to gather the crop residues and to transport and store them, the diminishing of the livestock after 1990, the absence of other alternatives, especially in the 1990s, but also the lack of information regarding the good practices) that are evocated to support the use of this method. However, this method is not a sustainable one since it can cause many environmental damages, especially related to soil properties (physical, chemical and biological), greenhouse gas emission and crop yields. Contrary to the above stated, crop residues' addition to the soil may restore damaged soil structure, improve aggregate stability, soil water retention, soil fertility, increase total organic carbon (TOC) and total nitrogen (TN) etc. The purpose of this paper is to make a multicriteria analyze of the effects of crop residue management on the soil, agricultural productivity and environment. At the same time, the use of crop residues biomass as a source of energy is presented as an alternative, given its potential ability to offset fossil fuels and reduce CO 2 emissions.
  • Authors:
    • Lemaire, G.
    • Soussana, J.-F.
  • Source: Agriculture Ecosystems and Enviroment
  • Volume: 190
  • Issue: SI
  • Year: 2014
  • Summary: The C sequestration capacity of grassland soils depends on both the net primary production of the ecosystem that determines the C flows from atmosphere to vegetation and soil, and on the mean residence time of C within the different compartments. Within grassland ecosystems, C and N cycles are strongly coupled by elemental stoichiometry of plant autotrophy and of soil microbial heterotrophy. Plasticity in plant form and function, plant species diversity and regulation of biological N fixation all contribute to stabilize the C:N ratio of organic matter inputs to soil. Soil processes such as the priming effect and nitrate leaching tend to restore stoichiometry by releasing elements in excess. Nevertheless, domestic herbivores tend to uncouple the C and N cycles, by releasing digestible C as CO2 and CH4, and by returning digestible N at high concentrations in urine patches. At low stocking density, herbivores enhance soil N cycling and net primary productivity, leading to an increased soil C sequestration, which however declines at high stocking density. Assuming no overgrazing, the environmental impacts of grassland intensification are therefore controlled by a trade-off between increased C N coupling by vegetation and increased C N decoupling by animals. Stimulation of vegetation by adequate N and P fertilizer applications increases the C flows from the atmosphere to the soil, while increasing stocking density reduces mean C residence time within the system. Intensification of grassland productivity by manipulation of both primary production and stocking density leads to complex responses in terms of environmental impacts: as intensification increases, positive impacts, such as C sequestration are progressively impaired by negative impacts linked to excessive active N forms. Hence, in each unique environmental setting, a threshold level of grassland intensification can be determined above which any additional animal production would be associated with unacceptable environmental risks. Improved grassland management and integration with crop systems may help minimize the harmful environmental effects of C-N decoupling by domestic herbivores, thereby enhancing synergies among food production, biodiversity and various other ecosystem services. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Mary, B.
    • Jeuffroy, M. H.
    • Amosse, C.
    • David, C.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: Nitrogen (N) management is a key issue in livestock-free organic grain systems. Relay intercropping with a legume cover crop can be a useful technique for improving N availability when two cash crops are grown successively. We evaluated the benefits of four relay intercropped legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) on N dynamics and their contribution to the associated and subsequent cash crops in six fields of organic farms located in South-East France. None of the relay intercropped legumes affected the N uptake of the associated winter wheat but all significantly increased the N uptake of the succeeding spring crop, either maize or spring wheat. The improvement of the N nutrition of the subsequent maize crop induced a 30 % increase in grain yield. All relay intercropped legumes enriched the soil-plant system in N through symbiotic fixation. From 71 to 96 % of the N contained in the shoots of the legumes in late autumn was derived from the atmosphere (Ndfa) and varied between 38 and 67 kg Ndfa ha(-1). Even if the cover crop is expected to limit N leaching during wintertime, the presence of relay intercropped legumes had no significant effect on N leaching during winter compared to the control.
  • Authors:
    • Grassini, P.
    • Gayler, S.
    • Sanctis, G. de
    • Deryng, D.
    • Corbeels, M.
    • Conijn, S.
    • Boogaard, H.
    • Biernath, C.
    • Basso, B.
    • Baron, C.
    • Adam, M.
    • Ruane, A. C.
    • Rosenzweig, C.
    • Jones, J. W.
    • Lizaso, J.
    • Boote, K.
    • Durand, J. L.
    • Brisson, N.
    • Bassu, S.
    • Hatfield, J.
    • Hoek, S.
    • Izaurralde, C.
    • Jongschaap, R.
    • Kemanian, A. R.
    • Kersebaum, K. C.
    • Kim, S. H. (et al)
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 7
  • Year: 2014
  • Summary: Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth, and yield. With the goal of analyzing the sensitivity of simulated yields to changes in temperature and atmospheric carbon dioxide concentrations [CO 2], we present the largest maize crop model intercomparison to date, including 23 different models. These models were evaluated for four locations representing a wide range of maize production conditions in the world: Lusignan (France), Ames (USA), Rio Verde (Brazil) and Morogoro (Tanzania). While individual models differed considerably in absolute yield simulation at the four sites, an ensemble of a minimum number of models was able to simulate absolute yields accurately at the four sites even with low data for calibration, thus suggesting that using an ensemble of models has merit. Temperature increase had strong negative influence on modeled yield response of roughly -0.5 Mg ha -1 per °C. Doubling [CO 2] from 360 to 720 mol mol -1 increased grain yield by 7.5% on average across models and the sites. That would therefore make temperature the main factor altering maize yields at the end of this century. Furthermore, there was a large uncertainty in the yield response to [CO 2] among models. Model responses to temperature and [CO 2] did not differ whether models were simulated with low calibration information or, simulated with high level of calibration information.
  • Authors:
    • Richard, G.
    • Grossel, A.
    • Nicoullaud, B.
    • Cellier, P.
    • Rochette, P.
    • Henault, C.
    • Loustau, D.
    • Gu, J.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 98
  • Issue: 1
  • Year: 2014
  • Summary: Modeling nitrous oxide (N2O) emissions from agricultural soils is still a challenge due to influences of artificial management practices on the complex interactions between soil factors and microbial activities. The aims of this study were to evaluate the process-based DeNitrification-DeComposition (DNDC, version 9.5) model and modified non-linear empirical Nitrous Oxide Emission (NOEV2) model with weekly N2O flux measurements at eight sites cropped with winter wheat across a tile-drained landscape (around 30-km(2)) in Central France. Adjustments of the model default field capacity and wilting point and the optimum crop production were necessary for DNDC95 to better match soil water content and crop biomass yields, respectively. Multiple effects of varying soil water and nitrate contents on the fraction of N2O emitted through denitrification were added in NOEV2. DNDC95 and NOEV2 successfully predicted background N2O emissions and fertilizer-induced emission peaks at all sites during the experimental period but overestimated the daily fluxes on the sampling dates by 54 and 25 % on average, respectively. Cumulative emissions were slightly overestimated by DNDC95 (4 %) and underestimated by NOEV2 (15 %). The differences between evaluations of both models for daily and cumulative emissions indicate that low frequency measurements induced uncertainty in model validation. Nonetheless, our validations for soil water content with daily resolution suggest that DNDC95 well represented the effect of tile drainage on soil hydrology. The model overestimated soil ammonium and nitrate contents mostly due to incorrect nitrogen partitioning when urea ammonium nitrate solution was applied. The performance of the model would be improved if DNDC included the canopy interception and foliar nitrogen uptake when liquid fertilizer was sprayed over the crops.
  • Authors:
    • Messina, C. D.
    • Dong, Z. S.
    • Tardieu, F.
    • Harrison, M. T.
    • Hammer, G. L.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 3
  • Year: 2014
  • Summary: Global climate change is predicted to increase temperatures, alter geographical patterns of rainfall and increase the frequency of extreme climatic events. Such changes are likely to alter the timing and magnitude of drought stresses experienced by crops. This study used new developments in the classification of crop water stress to first characterize the typology and frequency of drought-stress patterns experienced by European maize crops and their associated distributions of grain yield, and second determine the influence of the breeding traits anthesis-silking synchrony, maturity and kernel number on yield in different drought-stress scenarios, under current and future climates. Under historical conditions, a low-stress scenario occurred most frequently (ca. 40%), and three other stress types exposing crops to late-season stresses each occurred in ca. 20% of cases. A key revelation shown was that the four patterns will also be the most dominant stress patterns under 2050 conditions. Future frequencies of low drought stress were reduced by ca. 15%, and those of severe water deficit during grain filling increased from 18% to 25%. Despite this, effects of elevated CO 2 on crop growth moderated detrimental effects of climate change on yield. Increasing anthesis-silking synchrony had the greatest effect on yield in low drought-stress seasonal patterns, whereas earlier maturity had the greatest effect in crops exposed to severe early-terminal drought stress. Segregating drought-stress patterns into key groups allowed greater insight into the effects of trait perturbation on crop yield under different weather conditions. We demonstrate that for crops exposed to the same drought-stress pattern, trait perturbation under current climates will have a similar impact on yield as that expected in future, even though the frequencies of severe drought stress will increase in future. These results have important ramifications for breeding of maize and have implications for studies examining genetic and physiological crop responses to environmental stresses.
  • Authors:
    • Katterer, T.
    • Houot, S.
    • Girardin, C.
    • Eglin, T.
    • Bardoux, G.
    • Christensen, B. T.
    • Moyano, F. E.
    • Barre, P.
    • Lefevre, R.
    • Oort, F. van
    • Chenu, C.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 2
  • Year: 2014
  • Summary: The impact of climate change on the stability of soil organic carbon (SOC) remains a major source of uncertainty in predicting future changes in atmospheric CO 2 levels. One unsettled issue is whether the mineralization response to temperature depends on SOC mineralization rate. Long-term (>25 years) bare fallow experiments (LTBF) in which the soil is kept free of any vegetation and organic inputs, and their associated archives of soil samples represent a unique research platform to examine this issue as with increasing duration of fallow, the lability of remaining total SOC decreases. We retrieved soils from LTBF experiments situated at Askov (Denmark), Grignon (France), Ultuna (Sweden), and Versailles (France) and sampled at the start of the experiments and after 25, 50, 52, and 79 years of bare fallow, respectively. Soils were incubated at 4, 12, 20, and 35°C and the evolved CO 2 monitored. The apparent activation energy ( Ea) of SOC was then calculated for similar loss of CO 2 at the different temperatures. The Ea was always higher for samples taken at the end of the bare-fallow period, implying a higher temperature sensitivity of stable C than of labile C. Our results provide strong evidence for a general relationship between temperature sensitivity and SOC stability upon which significant improvements in predictive models could be based.