• Authors:
    • Skiba, U.
    • Baggs, E. M.
    • Lloyd, C. R.
    • Finch, J. W.
    • Drewer, J.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: It is important to demonstrate that replacing fossil fuel with bioenergy crops can reduce the national greenhouse gas (GHG) footprint. We compared field emissions of nitrous oxide (N2O), methane (CH4) and soil respiration rates from the C-4 grass Miscanthus x giganteus and willow (salix) with emissions from annual arable crops grown for food production. The study was carried out in NE England on adjacent fields of willow, Miscanthus, wheat (Triticum aetivum) and oilseed rape (Brassica napus). N2O, CH4 fluxes and soil respiration rates were measured monthly using static chambers from June 2008 to November 2010. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured by eddy covariance on Miscanthus from May 2008 and on willow from October 2009 until November 2010. The N2O fluxes were significantly smaller from the bioenergy crops than that of the annual crops. Average fluxes were 8 and 32 mu g m(-2) h(-1) N2O-N from wheat and oilseed rape, and 4 and 0.2 mu g m(-2) h(-1) N2O-N from Miscanthus and willow, respectively. Soil CH4 fluxes were negligible for all crops and soil respiration rates were similar for all crops. NEE of CO2 was larger for Miscanthus (-770 g C m(-2) h(-1)) than willow (-602 g C m(-2) h(-1)) in the growing season of 2010. N2O emissions from Miscanthus and willow were lower than for the wheat and oilseed rape which is most likely a result of regular fertilizer application and tillage in the annual arable cropping systems. Application of N-15-labelled fertilizer to Miscanthus and oil seed rape resulted in a fertilizer-induced increase in N2O emission in both crops. Denitrification rates (N2O + N-2) were similar for soil under Miscanthus and oilseed rape. Thus, perennial bioenergy crops only emit less GHGs than annual crops when they receive no or very low rates of N fertilizer.
  • Authors:
    • Walling, D. E.
    • Russell, M. A.
    • Taylor, P.
    • Ficken, K. J.
    • Blake, W. H.
  • Source: Geomorphology
  • Volume: 139
  • Year: 2012
  • Summary: A Compound Specific Stable Isotope (CSSI) sediment tracing approach is evaluated for the first time in an agricultural catchment setting against established geochemical fingerprinting techniques. The work demonstrates that novel CSSI techniques have the potential to provide important support for soil resource management policies and inform sediment risk assessment for the protection of aquatic habitats and water resources. Analysis of soil material from a range of crop covers in a mixed land-use agricultural catchment shows that the carbon CSSI signatures of particle-reactive fatty acids label surface agricultural soil with distinct crop-specific signatures, thus permitting sediment eroded from each land-cover to be tracked downstream. High resolution sediment sampling during a storm event and analysis for CSSI and conventional geochemical fingerprints elucidated temporal patterns of sediment mobilisation under different crop regimes and the specific contribution that each crop type makes to downstream sediment load. Pasture sources (65% of the catchment area) dominated the sediment load but areal yield (0.13 +/- 0.02 t ha(-1)) was considerably less than that for winter wheat (0.44 +/- 0.15 t ha(-1)). While temporal patterns in crop response matched runoff and erosion response predictions based on plot-scale rainfall simulation experiments, comparison of biomarker and geochemical fingerprinting data indicated that the latter overestimated cultivated land inputs to catchment sediment yield due to inability to discriminate temporary pasture (in rotation) from cultivated land. This discrepancy, however, presents an opportunity since combination of the two datasets revealed the extremely localised nature of erosion from permanent pasture fields in this system (estimated at up to 0.5 t ha(-1)). The novel use of CSSI and geochemical tracers in tandem provided unique insights into sediment source dynamics that could not have been derived from each method alone. Research into CSSI signature development (plant and soil processes) and the influence of cultivation regimes are required to support future development of this new tool. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Saran, S.
  • Source: Science
  • Volume: 338
  • Issue: 6110
  • Year: 2012
  • Summary: Biochar is the solid, carbon-rich product of heating biomass with the exclusion of air (pyrolysis or “charring”). If added to soil on a large scale, biochar has the potential to both benefit global agriculture and mitigate climate change. It could also provide an income stream from carbon abatement for farmers worldwide. However, biochar properties are far from uniform, and biochar production technologies are still maturing. Research is beginning to point the way toward a targeted application of biochar to soils that maximizes its benefits.
  • Authors:
    • Sims, B. G.
    • Eliis-Jones, J.
  • Source: Agriculture for Development
  • Issue: 14
  • Year: 2011
  • Summary: This paper describes the experience of one successful no-till farm in the UK. It highlights the improved wheat yields and reduced production costs the farm has achieved over time since implementing no till; describes how it achieves no till planting and weed control; and discusses the benefits to the soil and the other environmental benefits associated with no till.
  • Authors:
    • Blanco-Canqui, H.
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 1
  • Year: 2011
  • Summary: Soil water repellency (SWR) is an intrinsic and dynamic soil property that can influence soil hydrology and crop production. Although several land use systems have been shown to induce water repellency in soil, the specific effects of no-till cropping on SWR are poorly understood. This article reviews the impacts of no-till on SWR and identifies research needs. No-till cropping generally induces 1.5 to 40 times more SWR than conventional tillage, depending on soil type. This may result from near-surface accumulation of hydrophobic organic C compounds derived from crop residues, microbial activity and reduced soil disturbance. While large SWR may have adverse impacts on soil hydrology and crop production, the level of SWR under no-till relative to conventional tillage may contribute to aggregate stabilization and intra-aggregate C sequestration. More research is needed to discern the extent and relevance of no-till induced SWR. This includes: (1) further assessment of SWR under different tillage systems across a wide range of soil textures and climates, (2) comparison of the various methods for measuring SWR over a range of water contents, (3) inclusion of SWR in routine soil analysis and its use as a parameter to evaluate management impacts, (4) assessment of the temporal and spatial changes in SWR under field conditions, (5) further assessment of the impacts of the small differences in SWR between no-till and conventionally tilled soils on crop production, soil hydrology and soil C sequestration, and (6) development of models to predict SWR for different tillage systems and soils.
  • Authors:
    • Yahuza, I.
  • Source: International Journal of Biosciences (IJB)
  • Volume: 1
  • Issue: 5
  • Year: 2011
  • Summary: Intercropping (growing two or more crops together simultaneously) is increasing being adopted worldwide, probably because there have been suggestions that the system is beneficial in terms of land use efficiency compared to sole cropping. There are several indices for estimating intercrop performance compared to the component sole crops, but as reviewed in this paper, the land equivalent ratio (LER) is the most widely adopted. Yet the LER is constrained because it is not able to account for the relative duration each component in the intercrop spent in the field may have had on intercropping performance. Area time equivalency ratio (ATER) appears to have solved this problem well. However, neither ATER nor LER can account for the physiological or physical basis for the intercropping performance. The crop performance ratio (CPR) is more appropriate in this regard, even though CPR 'adjusted for time', (CPRT) is more efficient where the component crops differ in growth duration. In addition, particularly for intercrops with commercial value, there may be a need to compute a monetary advantage (MA) for intercropping. This paper concludes that in addition to the LER, for certain intercrops such as wheat/faba bean system that has not been widely adopted, there may be a need to use other indices such as ATER, CPR, CPRT and MA as may be applicable in order to understand more fully the nature of intercrop benefits that may exist. Indeed such type of information may help to attract potential growers.
  • Authors:
    • Leifert, C.
    • Critchley, C. N. R.
    • Eyre, M. D.
    • Wilcockson, S. J.
  • Source: European Journal of Agronomy
  • Volume: 34
  • Issue: 3
  • Year: 2011
  • Summary: A survey of 128 plots, in 2008, of a trial where the effects of crop protection can be separated from those of fertility management, generated weed cover data within six crops (winter wheat, winter barley, spring barley, potatoes, cabbages and a grass/clover ley). The effects of the 2008 crop types, of the two preceding crops and of organic and conventional crop protection and fertility management, were assessed using mixed-effects models and constrained ordination. Cover data for 22 weed species and for monocotyledon, dicotyledon, annual, perennial and total weed cover were used. Cover of 15 weed species, and of the five weed groups, was significantly affected by 2008 crops, with cover highest in spring beans and cabbage. Nine and four weed species 2008 cover were significantly related to crops grown in 2007 and 2006 respectively, as were dicotyledon, annual and total weed cover, but not monocotyledon or perennial cover. Cover of 15 species, and the five groups, was significantly higher in plots with organic crop protection, but only eight species and annuals were significantly affected by fertility management. Crop:crop protection produced the most significant interactions with most cover in organically managed plots. Five species, perennials and total weed cover produced significant three-factor models. The greatest weed cover was in organic crop protected but conventionally fertilised spring barley and the least in totally conventional winter barley. Other factors such as crop density and mechanical weeding also affected 2008 weed cover. The ordination indicated that most of the 22 species were strongly associated with crops from all three years. The sequence of crops in the rotation had a profound effect on weed cover. Where three spring-sown, difficult to weed, crops were grown in sequence (spring beans, potatoes and vegetables, spring barley) weed cover increased. However, cover was limited in grass/clover and some cereal plots with different preceding crops. Models predicting weed cover may need to take into account crop sequences within crop rotations, as well as the more usual management inputs. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Eskandari, H.
    • Ghanbari, A.
  • Source: Notulae Scientia Biologicae
  • Volume: 2
  • Issue: 4
  • Year: 2010
  • Summary: An experiment was conducted in University of London, Kent, UK during the year 2003. The aim of experiment was to investigate the effects of planting pattern on performance of wheat and bean intercrops. A complete randomized block design with four replications was employed to compare the treatments. Treatments included wheat sole crop (W), Bean sole crop (B), within row intercropping (M 1), row intercropping (M 2) and mix cropping (M 3). The density of intercropping was according to replacement design (one wheat replaced by three bean plants). The results showed that total dry matter achieved by intercrops was significantly higher than those achieved by either wheat or bean sole crop. Regarding to weed control, intercrops were more effective than sole crops, especially bean sole crop. Crops performance in terms dry weight, height and percentage of leaf, stem pod and ear was affected by cropping systems depending on crop species, where wheat showed more changes compared to bean. Grain yield, harvest index and thousand grain weights of wheat were decreased in intercropping while bean had reduction only in grain yield.
  • Authors:
    • Eskandari, H.
    • Ghanbari, A.
  • Source: Notulae Scientia Biologicae
  • Volume: 2
  • Issue: 3
  • Year: 2010
  • Summary: Wheat ( Triticum aestivum) and bean ( Vicia faba L.) sole crops and their mixture in three planting pattern (M 1: alternate-row intercrop, M 2: within-row intercrop, M 3: mixed intercrop) were used to investigate the amount of resource consumption in terms of PAR interception and nutrient uptake. The experiment was carried out as randomized complete block design with four replications. The results showed that intercropping systems had a significant effect on environmental resources consumption, where intercropping systems had more nutrient uptake and light interception compared to sole crops, suggesting the complementarity effect of intercropping components in resources consumption. The ability of wheat and bean was different in intercropping systems in absorbing nutrients because of their differences in root morphology and cation exchange capacity.
  • Authors:
    • Fritsche, U. R.
    • Fehrenbach, H.
    • Wiegmann, K.
    • Savy, C.
    • Semroc, B.
    • Hewson, J.
    • Haye, S.
    • Dragisic, C.
    • Hennenberg, K. J.
  • Source: Conservation Biology
  • Volume: 24
  • Issue: 2
  • Year: 2010
  • Summary: The sustainable production of bioenergy is vital to avoiding negative impacts on environmental goods such as climate, soil, water, and especially biodiversity. We propose three key issues that should be addressed in any biodiversity risk-mitigation strategy: conservation of areas of significant biodiversity value; mitigation of negative effects related to indirect land-use change; and promotion of agricultural practices with few negative impacts on biodiversity. Focusing on biodiversity concerns, we compared principles and criteria set to address biodiversity and other environmental and social issues in seven standards (defined here as commodity-based standards or roundtables, or relevant European legislation): five voluntary initiatives related to bioenergy feedstocks, the Renewable Transport Fuel Obligation (United Kingdom), and the European Renewable Energy Source Directive. Conservation of areas of significant biodiversity value was fairly well covered by these standards. Nevertheless, mitigation of negative impacts related to indirect land-use change was underrepresented. Although the EU directive, with its bonus system for the use of degraded land and a subquota system for noncrop biofuels, offered the most robust standards to mitigate potential negative effects, all of the standards fell short in promoting agricultural practices with low negative impacts on biodiversity. We strongly recommend that each standard be benchmarked against related standards, as we have done here, and that efforts should be made to strengthen the elements that are weak or missing. This would be a significant step toward achieving a bioenergy industry that safeguards Earth's living heritage.