• Authors:
    • Dang,Y. P.
    • Seymour,N. P.
    • Walker,S. R.
    • Bell,M. J.
    • Freebairn,D. M.
  • Source: Soil & Tillage Research
  • Volume: 152
  • Year: 2015
  • Summary: Development of no-tillage (NT) farming has revolutionized agricultural systems by allowing growers to manage greater areas of land with reduced energy, labour and machinery inputs to control erosion, improve soil health and reduce greenhouse gas emission. However, NT farming systems have resulted in a build-up of herbicide-resistant weeds, an increased incidence of soil- and stubble-borne diseases and enrichment of nutrients and carbon near the soil surface. Consequently, there is an increased interest in the use of an occasional tillage (termed strategic tillage, ST) to address such emerging constraints in otherwise-NT farming systems. Decisions around ST uses will depend upon the specific issues present on the individual field or farm, and profitability and effectiveness of available options for management. This paper explores some of the issues with the implementation of ST in NT farming systems. The impact of contrasting soil properties, the timing of the tillage and the prevailing climate exert a strong influence on the success of ST. Decisions around timing of tillage are very complex and depend on the interactions between soil water content and the purpose for which the ST is intended. The soil needs to be at the right water content before executing any tillage, while the objective of the ST will influence the frequency and type of tillage implement used. The use of ST in long-term NT systems will depend on factors associated with system costs and profitability, soil health and environmental impacts. For many farmers maintaining farm profitability is a priority, so economic considerations are likely to be a primary factor dictating adoption. However, impacts on soil health and environment, especially the risk of erosion and the loss of soil carbon, will also influence a grower's choice to adopt ST, as will the impact on soil moisture reserves in rainfed cropping systems. (C) 2015 Elsevier B.V. All rights reserved.
  • Authors:
    • Fiore,A.
    • Dichio,B.
    • Celano,G.
    • Modarelli,A.
    • Palese,A. M.
    • Quinto,G.
    • Pergola,M. T.
    • Xiloyannis,C.
  • Source: Acta Horticulturae
  • Volume: 1084
  • Year: 2015
  • Summary: The most recent and recognised standards for carbon footprint (CFP) ISO 14067:2013 requires the inclusion of land based emissions (CO2 fluxes from soil organic carbon change and field emissions from fertilization) into greenhouse gas accounting. These two categories of emissions are often disregarded from CFP studies of fruit products. In the present paper a simple methodology to include land-based emissions into greenhouse gas (GHG) accounting of fruit product from perennial crops is tested on a case study, and the results compared to experimental measurement from literature in order to evaluate its point of strength and weakness; this methodology is based on IPCC guidelines for national GHG inventories (IPCC, 2006). All fossil (anthropogenic) and biogenic emissions arising from all agricultural operations during orchard life cycle have been accounted according ISO 14067:2013. Fertilization resulted to be the most impacting agricultural operation, together with the production of materials constituting the irrigation pipe system and its supporting structure (metal and cement poles, wire). The most innovative aspect of the tested methodology consists in considering the sink role of soil in fruit orchards managed according to sustainable agronomical practices (increasing of internal and external carbon input to soil). Comparison with measurements data from literature revealed that the simple methodology tested can be improved in order to improve the accuracy of the estimates according to pedoclimatic conditions and crop specificities. © 2015 ISHS.
  • Authors:
    • Hao,Xiying
  • Source: Geomicrobiology Journal
  • Volume: 32
  • Issue: 7
  • Year: 2015
  • Summary: This study investigated CO2 and N2O emissions from soil receiving long-term cattle feedlot manure applications under rainfed and irrigated conditions in semi-arid southern Alberta, Canada. Soil available N and CO2 and N2O fluxes were measured after fall crop harvesting and prior to next spring's seeding from plots that had received 0 and 60 t ha(-1)yr(-1) cattle feedlot manure application with (Mi0 and Mi60) or without irrigation (Mr0 and Mr60) for 27years. Both CO2 and N2O fluxes varied considerably over the 7-month nongrowing season. Cumulative CO2 emissions from manured treatments (Mr60 at 2.20 t ha(-1) and Mi60 at 2.36 t ha(-1)) were 2.6times values from nonmanured treatments (Mr0 at 0.83 t ha(-1) and Mi0 at 0.92 t ha(-1)). Similarly, cumulative N2O emission from manured treatments (Mr60 at 4.54kg ha(-1) and Mi60 at 5.34kg ha(-1)) were 8-12times values from nonmanured treatments (Mr0 at 0.40kg ha(-1) and Mi0 at 0.70kg ha(-1)). Growing season irrigation had no effect on CO2 and N2O emission over the nongrowing season.
  • Authors:
    • Lubbers,Ingrid M.
    • van Groenigen,Kees Jan
    • Brussaard,Lijbert
    • van Groenigen,Jan Willem
  • Source: Scientific Reports
  • Volume: 5
  • Year: 2015
  • Summary: Concerns about rising greenhouse gas (GHG) concentrations have spurred the promotion of no-tillage practices as a means to stimulate carbon storage and reduce CO2 emissions in agro-ecosystems. Recent research has ignited debate about the effect of earthworms on the GHG balance of soil. It is unclear how earthworms interact with soil management practices, making long-term predictions on their effect in agro-ecosystems problematic. Here we show, in a unique two-year experiment, that earthworm presence increases the combined cumulative emissions of CO2 and N2O from a simulated no-tillage (NT) system to the same level as a simulated conventional tillage (CT) system. We found no evidence for increased soil C storage in the presence of earthworms. Because NT agriculture stimulates earthworm presence, our results identify a possible biological pathway for the limited potential of no-tillage soils with respect to GHG mitigation.
  • Authors:
    • Mereu,Valentina
    • Carboni,Gianluca
    • Gallo,Andrea
    • Cervigni,Raffaello
    • Spano,Donatella
  • Source: Climatic Change
  • Volume: 132
  • Issue: 2
  • Year: 2015
  • Summary: Climate change impact on the agricultural sector is expected to be significant and extensive in Sub-Saharan Africa, where projected increase in temperature and changes in precipitation patterns could determine sensible reductions in crop yields and concerns for food security achievement. This study presents a multi-model approach to analysing climate change impacts and associated risks for staple food crops in Nigeria. Previous attempts to evaluate climate change impacts in Nigeria had mainly focused on a reduced number of crops, with analysis limited to single experimental fields or specific areas, and in many cases considering only a limited number of climate models. In this work, crop simulation models implemented in the DSSAT-CSM software were used to evaluate climate change impacts on crop production in different Agro-Ecological Zones, considering multiple combinations of soils and climate conditions, varieties and crop management. The climate impact assessment was made using an ensemble of future climate projections, to include uncertainty related to climate projections. Even if precipitations could increase in most parts of Nigeria, this is not likely to offset the crop yield reduction due to the increase in temperatures, particularly over the medium-term period (2050), with yield decreases projected especially for cereals. The short-term effects are more uncertain and yields for cassava and millet might actually increase by 2020. Moreover, yield reductions are only partially mitigated by the direct effect of increased CO2 atmospheric concentration enhancing crop yield. In both periods and for all crops, there is a higher risk that crop yields may fall below the actual risk threshold.
  • Authors:
    • Mouazen,Abdul Mounem
    • Palmqvist,Martin
  • Source: Sustainability
  • Volume: 7
  • Issue: 7
  • Year: 2015
  • Summary: Although controlled traffic farming (CTF) is an environmentally friendly soil management system, no quantitative evaluation of environmental benefits is available. This paper aims at establishing a framework for quantitative evaluation of the environmental benefits of CTF, considering a list of environmental benefits, namely, reducing soil compaction, runoff/erosion, energy requirement and greenhouse gas emission (GHG), conserving organic matter, enhancing soil biodiversity and fertiliser use efficiency. Based on a comprehensive literature review and the European Commission Soil Framework Directive, the choice of and the weighting of the impact of each of the environmental benefits were made. The framework was validated using data from three selected farms. For Colworth farm (Unilever, UK), the framework predicted the largest overall environmental benefit of 59.3% of the theoretically maximum achievable benefits (100%), as compared to the other two farms in Scotland (52%) and Australia (47.3%). This overall benefit could be broken down into: reducing soil compaction (24%), tillage energy requirement (10%) and GHG emissions (3%), enhancing soil biodiversity (7%) and erosion control (6%), conserving organic matter (6%), and improving fertiliser use efficiency (3%). Similar evaluation can be performed for any farm worldwide, providing that data on soil properties, topography, machinery, and weather are available.
  • Authors:
    • Openshaw,K.
  • Source: Advances in Building Energy Research
  • Volume: 4
  • Issue: 1
  • Year: 2015
  • Summary: The energy value of biomass depends on its carbon and hydrogen contents, its non-combustibles and the water content. For unprocessed biomass, namely wood, residues and dung, the C and H contents are more or less constant for each group of fuels on an ash-free and moisture-free basis. Using this information, a method is given to calculate the low heat values of unprocessed biomass at different moisture and ash contents. While most wood species have an ash content of about 1%, the ash content of crop residues vary according to species from about 1 to 20%. Similarly dung varies from about 20 to 30% ash. However, moisture is the most important factor when determining the available energy. Tables and graphs are given of unprocessed biomass energy at different ash and moisture contents. Charcoal is the most important processed biomass. A method to calculate the energy value of charcoal from biomass is given. The energy values of other forms of biomass are also given. Finally, the role of biomass as a renewable energy (RE) source as well as it being an important tool to capture and reduce greenhouses gases (GHG) is discussed.
  • Authors:
    • Plaza,E. H.
    • Navarrete,L.
    • Gonzalez-Andujar,J. L.
  • Source: Agriculture, Systems and Environment
  • Volume: 207
  • Year: 2015
  • Summary: Disturbances have a prominent role in structuring plant communities. However, in agroecosystems, the long-term effect of disturbances on determining trait distributions within weed communities remains little studied. We analyzed the effect of three tillage treatments, which differ in the intensity of soil disturbance, on the mean, the range and the distribution of four response traits within weed communities. We aim to test whether tillage acts as a filter restricting the range and the distribution of response traits within weed communities and leads to reduced response trait diversity or whether tilling may have a diversifying effect, creating opportunities for more phenotypes to coexist and increasing response trait diversity. To test this idea, we used data on weed abundance recorded over 24 years from an experiment in which conventional tillage (CT), minimum tillage (MT) and no-tillage (NT) systems were compared. We selected four response traits, maximum height, specific leaf area (SLA), seed weight and seed output, and computed the community weighted mean (CWM) of each trait, as well as four multi-trait metrics related to a different aspect of functional diversity. We found that soil disturbance increases available niche opportunities for weeds especially in terms of regenerative traits. CT, the greater soil disturbance, leads to a greater range and even distribution of the studied traits and that abundant weed species from CT plots hold more divergent trait values than those from MT and NT plots. Our results may be explained by the idiosyncrasy of our disturbance treatments that affect weed seed placement in the soil layers as well as the stratification and availability of soil nutrients. We also found that NT system selected for lower CWM of seed weight (and higher seed output) than MT and CT systems. NT places weed seeds mostly on the soil surface, where having a large seed output may be necessary to avoid the risk of decay or depredation. Conversely, MT and CT systems offer some advantage to other strategies such as larger seed sizes useful to germinate from depth. CWM of SLA was higher in NT and MT than in CT plots and this could be related to greater soil nutrient content in NT systems. In addition our results showed a general trend over experimental time for weed communities to increase in height (and slightly in SLA and seed production) while reducing in seed size. These features are generally associated with intensive farming systems.
  • Authors:
    • Sastre,C. M.
    • Gonzalez-Arechavala,Y.
    • Santos,A. M.
  • Source: Applied Energy
  • Volume: 154
  • Year: 2015
  • Summary: This paper aims to provide more accurate results in the life cycle assessment (LCA) of electricity generation from wheat straw grown in Spain through the inclusion of parameter uncertainty and variability in the inventories. We fitted statistical distributions for the all the parameter that were relevant for the assessment to take into account their inherent uncertainty and variability. When we found enough data, goodness of fit tests were performed to choose the best distribution for each parameter and, when this was not possible, we adjusted triangular or uniform distributions according to data available and expert judge. To obtain a more complete and realistic LCA, we considered the consequences of straw exportation for the agricultural system, specially the loss of soil organic carbon and the decrease of future fertility. We also took into account all the inputs, transformations and transports needed to generate electricity in a 25 MWe power plant by straw burning. The inventory data for the agricultural, the transport and the transformation phases were collected considering their most common values and ranges of variability for the Spanish case. We used Monte Carlo simulation and sensitivity analysis to obtain global warming potential (GWP) and fossil energy (FOSE) consumption of the system. These results were compared with those of the electricity generated from natural gas in Spanish power plants, as fossil reference energy system. Our results showed that for the majority of the simulations electricity from wheat straw biomass combustion produced less greenhouse gases (GHG) emissions and consumed less fossil energy than electricity from natural gas. However, only 58% of the simulations achieved the sustainability threshold of 60% GHG savings proposed by the European Union (EU). Our analysis showed that agricultural field works and the loss of soil organic carbon due to straw exportation were the most important phases for FOSE consumption and GWP respectively. According to parameters sensitivity analysis, the loss of soil organic carbon was completely dependent on the isohumic coefficient and the soil carbon content factor values. Due to this fact, local and specific estimates of these parameters are relevant tasks to be performed in order to reduce uncertainties and provide a definitive answer to the compliance of the EU sustainability criteria. (C) 2015 Elsevier Ltd. All rights reserved.
  • Authors:
    • Vaccari,F. P.
    • Maienza,A.
    • Miglietta,F.
    • Baronti,S.
    • Lonardo,S. di
    • Giagnoni,L.
    • Lagomarsino,A.
    • Pozzi,A.
    • Pusceddu,E.
    • Ranieri,R.
    • Valboa,G.
    • Genesio,L.
  • Source: Agriculture, Ecosystems and Environment
  • Volume: 207
  • Year: 2015
  • Summary: Biochar addition to soil is a promising option for climate change mitigation and is recognized to exert beneficial effects on soil fertility. However, recent meta-analysis documented controversial effects on soil-plant interactions and on crop yields response. The data presented in this paper are the results of a field experiment on a processing tomato crop aiming to enhance the knowledge on the real applicability of biochar at farm scale in a high fertility alkaline soil. The effects of two biochar types on soil properties and on quantitative and qualitative parameters of processing tomato were evaluated. Biochar application significantly increased the soil carbon content, the soil cation exchange capacity and the availability of NH 4+, P and K. Moreover, it stimulated plant growth and N, P and base cation contents at harvest, reducing the leaf water potential in the warmer period. These results demonstrate that also intensive cultivations in fertile soil can benefit from biochar amendment.