• Authors:
    • Syp,A.
    • Faber,A.
    • Borzecka-Walker,M.
    • Osuch,D.
  • Source: Polish Journal of Environmental Studies
  • Volume: 24
  • Issue: 5
  • Year: 2015
  • Summary: Data envelopment analysis (DEA) has been recognized as a suitable tool for efficiency assessment of the economic and environmental performance of multiple similar units in the agri-food sector. In the present study, DEA methodologies were applied to 55 winter wheat farms in three farm sizes in Poland to benchmark the level of operational efficiency for each producer. Next, the potential reduction in the consumption levels of inputs were defined, and the environmental profits linked to these reduction targets were calculating. Our results indicate that 55% of the analysed farms operated efficiently. The technical efficiency scores of inefficient farms were 0.72 for small farms and 0.84 for medium and large ones. The production of 1 kg winter wheat results with average greenhouse gas (GHG) emissions of 0.448, 0.481, and 0.411 kg CO 2 eq. per kg of grain, for small, medium, and large farms, respectively. The performed analysis shows that GHG emissions per hectare depend on farm size and ranged from 2,378 kg CO 2 eq. for the small farms to 2,759 kg CO 2 eq. for large farms. The reduction of material input in inefficient farms, converted into environmental gains, resulted in GHG emissions reduction of 25.7, 29.0, and 28.6% for small, medium, and large farms, respectively. The estimated potential reduction of global warming potential (GWP) according to the DEA for the whole sample ranged from 7 to 18%, and was dependent on farm size. The major contributor to GWP was nitrous oxide field emissions (49-52%), followed by nitrogen fertilizer (31-33%), and diesel (11-13%). Raising operational efficiency is recommended for potential environmental improvement in the surveyed region.
  • Authors:
    • Peridy, N.
    • Zouabi, O.
  • Source: Article
  • Volume: 133
  • Issue: 2
  • Year: 2015
  • Summary: North African countries (NACs) are particularly concerned with climate change because of their geographical position (close to deserts) and their economic dependence on agriculture. We aim to provide additional insight into the impact of climate on agriculture for NACs, through the example of Tunisia. We first use disaggregated data, both at the geographical level (for 24 regions in Tunisia) and at the product level (cereals, olives, citrus fruit, tomatoes, potatoes and palm trees). Second, through spatial panel data analysis, we explore both the time and spatial dimensions of the data. This makes it possible to consider spatial interactions in agricultural production and the role of climate in these spatial spillover effects. Finally, the model not only includes direct climate variables, such as temperature and precipitation, but also indirect climate-related variables such as the stock of water in dams and groundwater. Results show that Tunisian agriculture is strongly dependent on the direct effects of temperature and precipitation for all the products considered at the regional level. The presence of dams and groundwater generally has a positive effect on agricultural production for irrigated crops with interesting spillover effects with neighboring regions. However, this impact is still considerably lessened in the case of detrimental climate conditions (indirect effect). These results raise the question of the sustainability of the growth in agricultural production in Tunisia in the case of significant climate change.
  • Authors:
    • Jeuffroy, M. H.
    • Hombert, N.
    • Pelzer, E.
    • Makowski, D.
  • Source: AGRONOMY JOURNAL
  • Volume: 106
  • Issue: 5
  • Year: 2014
  • Summary: Numerous studies have been performed to study the effect of N fertilization on cereal-legume intercrops, and their results are sometimes conflicting. Our objective was to do a meta-analysis on cereal-legume intercrops testing the effects of N fertilization on land equivalent ration (LER; partial and total LER), yield ratio, and proportion of legume in the mixture of crop grains. This analysis was based on 17 published studies reporting the results of experiments performed in 15 countries on six species of cereals and 10 species of legumes. Experiments were generally based on replacement (50-50, i.e., in the intercrop, each species is sown at half the sowing rate used for the sole crop) or full substitutive (100-100, i.e., the sowing rate for each crop in the intercrop is identical to that for sole crops) designs. Nitrogen fertilization rates ranged from 0 to 180 kg N ha -1. The effect of N fertilization and its inter-study variability were analyzed with mixed-effect statistical models, including study as a random effect. Results showed that N fertilization had non-significant effects on average LER and average yield ratio but that the inter-study variability of these effects was large. Nitrogen fertilization was found to significantly decrease the grain proportion of the legume in the mixture and the partial LER of the legume in studies based on C 3 cereal intercrops. The database used for the meta-analysis is freely available (http://www6.versailles-grignon.inra.fr/agronomie/Meta-analysis-in-agron omy/Datasets/Dataset-Intercrop).
  • Authors:
    • Silva, E. de O.
    • de Carvalho, C. A. C.
    • Bezerra, M. A.
  • Source: Revista Caatinga
  • Volume: 27
  • Issue: 1
  • Year: 2014
  • Summary: Over the past few years, the increased use of fossil fuels as well as the unsustainable use of land, through the reduction of native forests has increased the greenhouse gas emissions, contributing definitively to the rise in temperature on earth. In this scenario, two environmental factors, directly related to the physiology of crop production, are constantly being changed. The first change is the increase in the partial pressure of carbon dioxide (CO 2), which directly affects photosynthetic efficiency and the associated metabolic processes. The other change is the temperature increase which affects all the physiological and metabolic processes mediated by enzymes, especially photosynthesis and respiration. Therefore, this review aims to discuss the main effects caused by increased CO 2 pressure and the temperature rise in the physiology, productivity and post-harvest quality of plants with photosynthetic metabolism C3, C4 and CAM. Based on physiological evidence, the increased atmospheric CO 2 concentration will benefit net photosynthesis, stomatal conductance and the transpiration of C3 plants, however in hot, dry and saline environments, the C4 and CAM species present an advantage by having low photorespiration. Studies show controversial conclusions about the productivity of C3 and C4 plants, and the quality of their fruits or grains under different CO 2 concentrations or high temperatures. Thus, there is a need for more testing with C3 and C4 plants, besides of more research with CAM plants, in view of the low number of experiments carried out in this type of plants.
  • Authors:
    • Rebetzke, G. J.
    • Watt, M.
    • Kirkby, C. A.
    • Hunt, J. R.
    • Conyers, M. K.
    • Kirkegaard, J. A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 187
  • Issue: April
  • Year: 2014
  • Summary: Adoption of conservation agriculture (CA) principles in Australia increased rapidly during the 1990s and it now boasts the highest adoption rates worldwide. These principles of (1) diverse rotations (2) reduced (or no-) till systems and (3) the maintenance of surface cover make good sense in extensive, mechanised, rain-fed cropping systems on erosion-prone, structurally-unstable soils. Indeed reduced fuel and labour costs, soil conservation and moisture retention are the most commonly stated reasons for adoption of CA principles by farmers in Australia. Yet even in Australia, while broadly applicable, the adaptation and application of CA principles within specific farming systems remains pragmatic due to the diverse biophysical and socio-economic factors encountered. Most "no-till" adopters continue some strategic tillage (similar to 30% cropped area) for a range of sound agronomic reasons, intensive cereal systems dominate, and partial removal of crop residues as hay or by grazing livestock is commonplace within the largely mixed-farming systems. Although this challenges the notion of "ideal" CA principles (zero-till with no soil disturbance, full stubble retention and >3 species in rotations) this high degree of flexibility in CA principles as practiced in southern Australian mixed farming systems makes sense to optimize both economic and environmental outcomes. In addition, some proposed ecosystem service benefits of CA such as soil carbon sequestration and energy efficiency have been recently questioned. Though the socio-economic factors of small-holder farming systems in Africa and south Asia are more diverse and clearly different to Australian farms, some of the biophysical challenges and economic realities are shared (infertile soils, variable and extreme climates, relatively low input levels, integrated crop-livestock systems, small profit margins, highly variable income). It is therefore useful to consider from a biophysical standpoint why a pragmatic approach to CA principles has been necessary, even in a relatively high-adopting country like Australia, and why we should expect similarly 'imperfect' adoption of CA (if at all) in the diverse smallholder systems of Sub-Saharan Africa and South Asia. We review aspects of CA adoption in Australia in an effort to draw out important lessons as CA principles are adapted elsewhere, including the smallholder farming systems of Sub-Saharan Africa and South Asia. (C) 2013 Elsevier B.V. All rights reserved.
  • Authors:
    • Mukherjee, A.
    • Lal, R.
  • Source: Soil Research
  • Volume: 52
  • Issue: 3
  • Year: 2014
  • Summary: Any strategy towards widespread adoption of biochar as a soil amendment is constrained by the scarcity of field-scale data on crop response, soil quality and environmental footprint. Impacts of biochar as a soil amendment over a short period based on laboratory and greenhouse studies are often inconclusive and contradictory. Yet biochar is widely advocated as a promising tool to improve soil quality, enhance C sequestration, and increase agronomic yield. While substantial reviews exist on positive aspects of biochar research, almost no review to date has compiled negative aspects of it. Although biochar science is advancing, available data indicate several areas of uncertainty. This article reviews a range of negative impacts of biochar on soil quality, crop yield, and associated financial risk. This review is important because advances in biochar research demand identification of the risks (if any) of using biochar as a soil amendment before any large-scale field application is recommended. It is the first attempt to acknowledge such issues with biochar application in soil. Thus, the aims of this review are to assess the uncertainties of using biochar as a soil amendment, and to clarify ambiguity regarding interpretation of research results. Along with several unfavourable changes in soil chemical, physical and biological properties, reduction in crop yield has been reported. Relative to controls, the yield for biochar-amended soil (application rate 0.2-20% w/w) has been reduced by 27, 11, 36, 74, and 2% for rice (Oryza sativa L.) (control 3.0 Mg ha(-1)), wheat (Triticum spp. L.) (control 4.6 Mg ha(-1)), maize (Zea mays L.) (control 4.7 Mg ha(-1)), lettuce (Lactuca sativa L.) (control 5.4 Mg ha(-1)), and tomato (Solanum lycopersicum L.) (control 265 Mg ha(-1)), respectively. Additionally, compared with unamended soils, gaseous emissions from biochar-amended soils (application rate 0.005-10% w/w) have been enhanced up to 61, 152 and 14% for CO2 (control 9.7 Mg ha(-1) year(-1)), CH4 (control 222 kg ha(-1) year(-1)), and N2O (control 4.3 kg ha(-1) year(-1)), respectively. Although biochar has the potential to mitigate several environmental problems, the data collated herein indicate that a systematic road-map for manufacturing classification of biochars, and cost-benefit analysis, must be developed before implementation of field-scale application.
  • Authors:
    • Wynn, S. C.
    • Kindred, D. R.
    • Sylvester-Bradley, R.
    • Thorman, R. E.
    • Smith, K. E.
  • Source: The Journal of Agricultural Science
  • Volume: 152
  • Issue: 1
  • Year: 2014
  • Summary: Fertilizer nitrogen (N) accounts for the majority of the greenhouse gas (GHG) emissions associated with intensive wheat production, and the form of fertilizer N affects these emissions. Differences in manufacturing emissions (as represented in the current carbon accounting methodologies) tend to favour urea, even when using the best available manufacturing technologies (BAT), whereas differences in fertilizer N efficiency and emissions of ammonia tend to favour ammonium nitrate (AN). To resolve these differences, data from 47 experiments in two large UK studies conducted from 1982 to 1987 and from 2003 to 2005 were reanalysed, showing that on average urea efficiency was 0 center dot 9 of AN (although mean ammonia emissions in 10 subsidiary experiments indicated an efficiency difference of 0 center dot 2); treating urea with a urease inhibitor (TU; AGROTAIN((R)), active ingredient N-(n-butyl) thiophosphoric triamide (n-BTPT)) brought its efficiency almost in line with AN; however, a significantly greater mean optimum N amount for TU (+0 center dot 1 of AN) was not fully explained. A standard response function relating wheat yield to applied AN was modified for degrees of relative inefficiency, thus enabling yields and GHG intensities (kg CO(2)e/tonne (t) grain) to be calculated using a PAS2050 compatible model for GHG emissions for any N amount of any N form. With AN manufactured by average European technology (AET), the estimated GHG intensity of wheat producing 8 t/ha was 451 kg/t; whereas with urea or TU made by AET it was 0.87-0.99 or 0.84-0.86 of this respectively. Using BAT for fertilizer manufacture, the grain's GHG intensity with AN and TU was 368kg/t, but was 1 center dot 03-1 center dot 17 of this with untreated urea. The range of effects on GHG intensities arose mainly from remaining uncertainties in the inefficiencies of the N forms. Generally, economic margins and GHG intensities were not much affected by adjustments in N use for relative inefficiencies or different prices of urea-based fertilizers compared with AN. Overall, TU appeared to provide the best combination of economic performance and GHG intensity, unless the price for N as TU exceeded that for N as AN.
  • Authors:
    • Wassmann, R.
    • Sharma, D. K.
    • Sharma, P. C.
    • Kumar, V.
    • Sharma, S.
    • Gathala, M.
    • Rai, M.
    • Tirol-Padre, A.
    • Ladha, J.
  • Source: Global Change Biology
  • Volume: 20
  • Issue: 1
  • Year: 2014
  • Summary: Rapid, precise, and globally comparable methods for monitoring greenhouse gas (GHG) fluxes are required for accurate GHG inventories from different cropping systems and management practices. Manual gas sampling followed by gas chromatography (GC) is widely used for measuring GHG fluxes in agricultural fields, but is laborious and time-consuming. The photo-acoustic infrared gas monitoring system (PAS) with on-line gas sampling is an attractive option, although it has not been evaluated for measuring GHG fluxes in cereals in general and rice in particular. We compared N2O, CO2, and CH4 fluxes measured by GC and PAS from agricultural fields under the rice-wheat and maize-wheat systems during the wheat (winter), and maize/rice (monsoon) seasons in Haryana, India. All the PAS readings were corrected for baseline drifts over time and PAS-CH4 (PCH4) readings in flooded rice were corrected for water vapor interferences. The PCH4 readings in ambient air increased by 2.3ppm for every 1000mgcm(-3) increase in water vapor. The daily CO2, N2O, and CH4 fluxes measured by GC and PAS from the same chamber were not different in 93-98% of all the measurements made but the PAS exhibited greater precision for estimates of CO2 and N2O fluxes in wheat and maize, and lower precision for CH4 flux in rice, than GC. The seasonal GC- and PAS-N2O (PN2O) fluxes in wheat and maize were not different but the PAS-CO2 (PCO2) flux in wheat was 14-39% higher than that of GC. In flooded rice, the seasonal PCH4 and PN2O fluxes across N levels were higher than those of GC-CH4 and GC-N2O fluxes by about 2- and 4fold, respectively. The PAS (i) proved to be a suitable alternative to GC for N2O and CO2 flux measurements in wheat, and (ii) showed potential for obtaining accurate measurements of CH4 fluxes in flooded rice after making correction for changes in humidity.
  • Authors:
    • Bozorgi, H. R.
    • Moraditochaee, M.
    • Azarpour, E.
  • Source: Journal of Applied Science and Agriculture
  • Volume: 9
  • Issue: 4
  • Year: 2014
  • Summary: Background: The suitability of the Life Cycle Assessment (LCA) methodology to analyze the environmental impact of agricultural production is investigated. Objective: This study was conducted to assess the impact of wheat production on environment under rain fed and watered farming systems in north of Iran. Life cycle assessment (LCA) was used as a methodology to assess all environmental impacts of wheat production through accounting and appraising the resource consumption and emissions. Data were collected from 72 farms by used a face to face questionnaire method during 2011 year in Guilan province. Results: In rain fed farming system, total green house gases emissions for wheat production were calculated to be 440.4 kg CO2 eq ha -1 calculated. In watered farming system, total green house gases emissions for wheat production were calculated to be 570.7 kg CO2 eq ha -1. Conclusion: Life cycle assessment (LCA) is defined as the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product system throughout its life cycle. Thus, LCA is a tool for the analysis of the environmental burden of products at all stages in their life cycle.
  • Authors:
    • Katterer, T.
    • Oborn, I.
    • Sundberg, C.
    • Tidaker, P.
    • Bergkvist, G.
  • Source: Agricultural Systems
  • Volume: 129
  • Year: 2014
  • Summary: Rotational perennial grass/clover has multiple effects in cropping systems dominated by cereals. This study evaluated the environmental impact of rotational grass/clover ley for anaerobic digestion in a cereal-dominated grain production system in Sweden. Life cycle assessment (LCA) methodology was used to compare two scenarios: (i) a cropping system including only spring barley and winter wheat; and (ii) a cropping system including 2-year grass/clover ley in combination with spring barley and winter wheat. The functional unit was one tonne of grain. The two main functions of the grass/clover crop were to provide feedstock for biogas production and to act as an organic fertiliser for allocation among the cereal crops in the rotation. Special consideration was given to nitrogen (N) management and the rotational effects of the grass/clover ley. In total, 73% of the N requirement of cereals in the ley scenario was met through symbiotic N fixation. Replacing diesel with biogas and mineral fertiliser with digested grass/clover biomass (digestate) reduced the use of fossil fuels substantially, from 1480 MJ per tonne in the reference scenario to -2900 MJ per tonne in the ley scenario. Potential eutrophication per tonne grain increased in the ley scenario, mainly owing to significantly higher ammonia emissions from spreading digestate and the larger area required for producing the same amount of grain. Potential acidification also increased when N mineral fertiliser was replaced by digestate. Crops relying on symbiotic N fixation are a promising feedstock for reducing the use of non-renewable energy in the production chain of farm-based bioenergy, but careful handling of the N-rich digestate is required. Replacing cereals intended for feed or food with bioenergy crops leads to indirect land use changes (iLUC) when the displaced crops must be produced elsewhere and the benefits obtained when biofuels replace fossil fuels may thereby be outweighed. In this study, the iLUC factor assumed had a critical effect on global warming potential in the ley scenario. However, carbon sequestration and the higher yield potential of subsequent cereal crops can mitigate greenhouse gas emissions from iLUC to a varying extent. We recommend that crop sequences rather than single crops be considered when evaluating the environmental impact of production systems that include perennial legumes for food, feed and bioenergy.