• Authors:
    • Frassanito, A.
    • Gioia, G.
    • Londi, G.
    • Campedelli, T.
    • Florenzano, G.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 213
  • Year: 2015
  • Summary: Steppe habitats are considered to be of great interest in terms of biodiversity conservation, specially for birds, with many rare and endangered species breeding in these habitats. The conversion to crops or other forms of cultivation, is universally recognised as the major threat for the conservation of these habitats and their biodiversity. During the 20th century, particularly in the Mediterranean basin, large areas of natural steppe habitats were plowed, causing a large decline in many bird species. Nowadays, although the economical and social context has deeply changed, many areas of steppe habitats are facing the same threat. In this paper we analysed the effects of different landscape mosaics of crops and steppes on breeding birds in the Alta Murgia National Park, one of the most important steppe areas in Italy. Specifically, we tested the effect of some landscape metrics, descriptive of crops-steppes spatial arrangement, on five Alaudidae species: Calandra lark, Skylark, Greater short-toed lark, Woodlark and Crested lark. Analysis were carried out using MaxEnt. The analyses did not find substantial differences between steppe and cropland, which would seem to be equally suitable habitats for these species. With the only exception of Greater short-toed lark, which shows a degree of ecological plasticity, all other species show a strong preference for landscapes with a high degree of connectivity and low fragmentation. Our results seem to suggest that the co-presence of crops and steppes, if the fragmentation degree at landscape scale is low, does not negatively affect the presence and abundance of steppe species, and represents a highly suitable habitat that can support nationally-important populations of endangered species such as the Calandra lark.
  • Authors:
    • Madejon, E.
    • Murillo, J.
    • Soriano, M.
    • Griffith, D.
    • Carmona, I.
    • Gomez-Macpherson, H.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 213
  • Year: 2015
  • Summary: Conservation agriculture (CA), which is promoted worldwide to conserve soil, water and energy and to reduce production costs, has had limited success in Europe. The objectives of this study were to assess annual crop systems currently managed under CA in southern Spain, identify obstacles to CA adoption, and recommend strategies to overcome those obstacles. We employed the following methods: (i) examination of original government data used to monitor CA; (ii) survey of CA farmers to characterize their practices and perceptions; (iii) agronomic, economic and energy use comparison of minimum tillage (MT) and conventional tillage (CT); and (iv) a stakeholder focus group to identify strategies for improving CA. Farmers selectively implemented some components of CA while disregarding others as a strategy to adapt to local conditions. Although most researchers define CA as a system that combines minimum soil disturbance, maintenance of crop residues, and crop rotation, in practice most farmers and organizations equated CA with direct seeding of cereals without considering residues or crop rotation. Official national statistics did not include all of these CA components either. Examination of government data revealed that only 13% of monitored plots were not tilled consecutively. The most common CA system (50% of farms) was direct seeded wheat rotated with tilled sunflower. This system (classified as MT) and CT were not significantly different with regard to wheat yield, soil quality, net return or energy use in either crop, which was likely due to similar residues management, recurrent soil disturbance in MT, and disuse of moldboards in CT. In wheat, fertilizers represented the largest energy input (68% TEI) in both systems followed by diesel consumption (12% and 19% in MT and CT, respectively). To overcome the most important identified problems in CA, we highlight the need for collaborative research with farmers and other stakeholders to develop appropriate drill technology for spring crops, identify non-cereal crops that are better adapted to CA than sunflower, improve residues management, increase energy efficiency through better fertilizer management, and promote CA among farmer groups excluded by socioeconomic barriers. Finally, international standards to guide data collection and statistical analyses on all components of CA will enable researchers and institutions to compare information and find solutions to common problems.
  • Authors:
    • Merino-de-Miguel, S.
    • Sanchez-Giron, V.
    • Litago, J.
    • Inclan, R.
    • Schmid, T.
    • Uribe, C.
    • Huesca, M.
    • Rodriguez-Rastrero, M.
    • Cicuendez, V.
    • Palacios-Orueta, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 212
  • Year: 2015
  • Summary: The assessment of soil respiration processes in agroecosystems is essential to understand the C balance and to study the effects of soil respiration on climate change. The use of spectral data through remote sensing techniques constitutes a valuable tool to study ecological processes such as the C cycle dynamics. The objective of this work was to evaluate the potential to assess total (Rs) and autotrophic (Ra) soil respiration through spectral information acquired by field spectroscopy in a row irrigated corn crop ( Zea mays L.) throughout the growing period. The relationships between Rs and Ra with leaf area index (LAI), spectral indexes and abiotic factors (soil moisture and soil temperature) were assessed by linear regression models using the adjusted coefficient of determination (Radj 2) to measure and compare the proportion of variance explained by the models. Results showed significant differences and a high variability in the relationships between Rs and Ra with spectral indexes within the corn field during the phenological stages and in measurements under the plants and between the rows. Best results were obtained when assessing Ra during vegetative stages. However, during the reproductive stages, spectral indexes were better related to Rs which could be related to the presence of rhizomicrobial respiration linked to vegetation activity. Spectral indexes contain significant functional information, beyond mere structural changes, that could be related to carbon fluxes. However, specific models should be applied for the different phenological stages and there is a need to be cautious when upscaling remote sensing models. The results obtained confirm that in irrigated crop systems remote sensing data can produce relevant information to assess both Rs and Ra through spectral indexes.
  • Authors:
    • Howden, M.
    • Chapman, S.
    • Zheng, B.
    • Moore, A.
    • Kokic, P.
    • Ghahramani, A.
    • Crimp, S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 211
  • Issue: December 2015
  • Year: 2015
  • Summary: Wheat is one of the main grains produced across the globe and wheat yields are sensitive to changes in climate. Australia is a major exporter of wheat, and variations in its national production influence trade supplies and global markets. We evaluated the effect of climate change in 2030 compared to a baseline period (1980-1999) by upscaling from farm to the national level. Wheat yields and gross margins under current and projected climates were assessed using current technology and management practices and then compared with 'best adapted' yield achieved by adjustments to planting date, nitrogen fertilizer, and available cultivars for each region. For the baseline climate (1980-1999), there was a potential yield gap modelled as optimized adaptation gave potential up scaled yields (tonne/ha) and gross margins (AUD$/ha) of 17% and 33% above the baseline, respectively. In 2030 and at Australian wheatbelt level, climate change impact projected to decline wheat yield by 1%. For 2030, national wheat yields were simulated to decrease yields by 1% when using existing technology and practices but increase them by 18% assuming optimal adaptation. Hence, nationally at 2030 for a fully-adapted wheat system, yield increased by 1% and gross margin by 0.3% compared to the fully adapted current climate baseline. However, there was substantial regional variation with median yields and gross margins decreasing in 55% of sites. Full adaptation of farm systems under current climate is not expected, and so this will remain an on-going challenge. However, by 2030 there will be a greater opportunity to increase the overall water use and nitrogen efficiencies of the Australian wheat belt, mostly resulting from elevated atmospheric CO 2 concentrations.
  • Authors:
    • Zgorelec, Z.
    • Bilandzija, D.
    • Kisic, I.
  • Source: Agriculturae Conspectus Scientificus
  • Volume: 79
  • Issue: 1
  • Year: 2014
  • Summary: Soil carbon stocks are highly vulnerable to human activities (such as tillage), which can decrease carbon stocks significantly. These activities break down soil's organic matter and some carbon is converted to carbon dioxide (CO 2). A part of CO 2 (a greenhouse gas that is one of the main contributor to global warming) is lost from the soil by soil respiration (soil CO 2 efflux). The aim of our study is to determine the soil carbon loss by soil CO 2 efflux under different tillage treatments. The experimental site is characterized by continental climate. Field experiment with six different tillage treatments usually used in this area was set up on Stagnic Luvisols in Daruvar, central lowland Croatia in 1994 with investigation aim on determination of soil degradation by water erosion and later, in 2011, expanded to the research on soil CO 2 efflux. Tillage treatments differed in tools that were used, depth and direction of tillage. Tillage treatments were: black fallow (BF), ploughing up/down the slope to 30 cm (PUDS), no-tillage (NT), ploughing across the slope to 30 cm (PAS), very deep ploughing across the slope to 50 cm (VDPAS) and subsoiling (50 cm) plus ploughing (30 cm) across the slope (SSPAS). Field measurements of soil CO 2 concentrations were conducted during one year (n=14) from November 2011 till November 2012, when cover crop was corn ( Zea mays L.). Preliminary soil sampling for determination of soil total carbon content was conducted in April 2011. This paper presents results of soil total carbon content in the soil surface layer (0-30 cm), the variations of CO 2-C efflux during the year, soil carbon loss by CO 2-C efflux and correlation between soil total carbon content and CO 2-C efflux. The range of soil surface total carbon content varied from 19083.7 kg/ha at BF treatment up to 31073.6 kg/ha at SSPAS treatment. The treatment with the lowest average measured CO 2-C efflux was BF. The average CO 2-C efflux at BF treatment was 7.9 kg CO 2-C/ha/day where CO 2-C efflux varied from 2.3 kg CO 2-C/ha/day up to 22.6 kg CO 2-C/ha/day. The treatment with the highest average measured CO 2-C efflux was NT. Range of CO 2-C efflux at NT treatment varied from 7.8 kg CO 2-C/ha/day up to 65.8 kg CO 2-C/ha/day and the average CO 2-C efflux was 24.4 kg CO 2-C/ha/day. Daily soil total carbon loss by soil respiration ranged from 0.04% at BF treatment up to 0.09% at NT treatment. Soil CO 2-C efflux was fully positively correlated with soil total carbon content (r=0.91). After all mentioned, it can be stated that in these agro-ecological conditions, best tillage practice in sustainable plant production in terms of the lowest daily soil total carbon loss (0.06%) by soil respiration is ploughing to 30 cm (PUDS and PAS). Still, it is necessary to conduct the total soil carbon balance in the future research for better understanding of soil carbon gains and losses.
  • Authors:
    • Acevedo, H.
    • Castanheira, E. G.
    • Freire, F.
  • Source: Applied Energy
  • Volume: 114
  • Year: 2014
  • Summary: The main goal of this article is to assess the life-cycle greenhouse gas (GHG) intensity of palm oil produced in a specific plantation and mill in Colombia. A comprehensive evaluation of the implications of alternative land use change (LUC) scenarios (forest, shrubland, savanna and cropland conversion) and fertilization schemes (four synthetic and one organic nitrogen-fertilizer) was performed. A sensitivity analysis to field nitrous oxide emission calculation, biogas management options at mill, time horizon considered for global warming and multifunctionality approach were also performed. The results showed that the GHG intensity of palm oil greatly depends on the LUC scenario. Significant differences were observed between the LUC scenarios (-3.0 to 5.3 kg CO(2)eq kg(-1) palm oil). The highest result is obtained if tropical rainforest is converted and the lowest if palm is planted on previous cropland, savanna and shrubland, in which almost all LUC from Colombian oil palm area expansion occurred between 1990 and 2009. Concerning plantation and oil extraction, it was shown that field nitrous oxide emissions and biogas management options have a high influence on GHG emissions.
  • Authors:
    • Leu, A.
  • Source: Acta Horticulturae
  • Issue: 1018
  • Year: 2014
  • Summary: Soil carbon sequestration using current organic land management methods has the potential to mitigate a substantial proportion of global greenhouse gas emissions. A published peer review study by the Research Institute of Organic Agriculture (FiBL), found that organic farming practices remove 2,000 kg of carbon dioxide from the air each year and sequester it in a hectare of farmland. There is compelling data that significantly higher levels of CO 2 sequestration can be achieved. The Rodale studies have demonstrated that good organic practices can sequester 3596.6 kg of CO 2 per hectare year for around 30 years however when compost is added this increases to 8220.8 kg of CO 2 per hectare year. Other studies show that increasing the levels of soil carbon improves the resilience of farming systems to the increased frequency extreme weather events, such as droughts and heavy rains, that are linked to climate change.
  • Authors:
    • Mauro, R.
    • Agnello, M.
    • Pesce, G.
    • Sortino, O.
    • Mauromicale, G.
  • Source: Industrial Crops and Products
  • Volume: 57
  • Year: 2014
  • Summary: Increasing the use of renewable energies as biomass offers significant opportunities for Europe to reduce greenhouse gas emission and secure its energy supply. To ensure that bioenergy develops in environmentally-compatible way, the availability of crops, such as perennials, adapted to cropping systems based on minimal production inputs and marginal lands with medium-low soil fertility, is strongly needed. To examine the potential ability in terms of biomass, achenes, and energy yield and the possible role in soil fertility conservation of two botanical varieties (cultivated and wild cardoon) of the C-3 Asteraceae, Cynara cardunculus L, a long-term experiment (seven cropping seasons) was carried out in a marginal farmland of Sicily (Southern Italy), with low soil fertility and without external inputs as fertilization, irrigation, weed and pest control from the second season onward. Under these conditions C. cardunculus improved soil fertility by increasing the soil organic matter content, organic C content, total nitrogen, assimilable P2O5 and exchangeable K, giving an annual harvestable biomass and energy yield of 14.6 t ha(-1) and 275 GJ ha(-1) (cultivated cardoon) and 7.4 t ha(-1) and 138 GJ ha(-1) (wild cardoon). The harvest time, in the third 10-day of August, allowed a very low biomass moisture, about 11% in cultivated cardoon and 7% in wild cardoon. Cultivated cardoon was capable of producing high yields until fifth season, therefore is indicated for medium long-time cropping systems. Wild cardoon showed a most stable yield pattern and plant survival over seasons, suggesting its particular suitability for perennial cropping systems of Mediterranean marginal areas. For these reasons, we have undertaken a breeding program aimed to improve the crop performances in terms of both biomass and energy yield (wild cardoon) and to stabilize the biomass production characteristics during crop ageing (cultivated cardoon). (C) 2014 Elsevier B.V. All rights reserved.
  • Authors:
    • Alvaro-Fuentes, J.
    • Cantero-Martinez, C.
    • Plaza-Bonilla, D.
  • Source: Soil Biology and Biochemistry
  • Volume: 68
  • Year: 2014
  • Summary: Agricultural management practices play an important role in greenhouse gases (GHG) emissions due to their impact on the soil microenvironment. In this study, two experiments were performed to investigate the influence of tillage and N fertilization on GHG production at the macroaggregate scale. In the first experiment, soil macroaggregates collected from a field experiment comparing various soil management systems (CT, conventional tillage; NT, no-tillage) and N fertilization types (a control treatment without N and mineral N and organic N with pig slurry treatments both at 150 kg N ha-(1)) were incubated for 35 days. Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O) production was quantified at regular time intervals by gas chromatography. In the second experiment, the effects of fertilization type and soil moisture on the relative importance of nitrification and denitrification processes in N2O emission from soil macroaggregates were quantified. Nitrate ammonium, macroaggregate-C concentration, macroaggregate water-stability, microbial biomass-C and N (MBC and MBN, respectively) and water-soluble C (WSC) were determined. While NT macroaggregates showed methanotrophic activity, CT macroaggregates acted as net CH4 producers. However, no significant differences were found between tillage systems on the fluxes and cumulative emissions of CO2 and N2O. Greatest cumulative CO2 emissions, macroaggregate-C concentration and WSC were found in the organic N fertilization treatment and the lowest in the control treatment. Moreover, a tillage and N fertilization interactive effect was found in macroaggregate CO2 production: while the different types of N fertilizers had no effects on the emission of CO2 in the NT macroaggregates, a greater CO2 production in the CT macroaggregates was observed for the organic fertilization treatment compared with the mineral and control treatments. The highest N2O losses' due to nitrification were found in the mineral N treatment while denitrification was the main factor affecting N2O losses in the organic N treatment. Our results suggest that agricultural management practices such as tillage and N fertilization regulate GHG production in macroaggregates through changes in the proportion of C and N substrates and in microbial activity. (C) 2013 Elsevier Ltd. All rights reserved.
  • Authors:
    • Gabriel, J. L.
    • Quemada, M.
    • Garcia-Marco, S.
    • Sanz-Cobena, A.
    • Almendros, P.
    • Vallejo, A.
  • Source: Science of The Total Environment
  • Volume: 466
  • Year: 2014
  • Summary: This study evaluates the effect of planting three cover crops (CCs) (barley, Hordeum vulgare L.; vetch, Vicia villosa L.; rape, Brassica napus L) on the direct emission of N2O, CO2 and CH4 in the intercrop period and the impact of incorporating these CCs on the emission of greenhouse gas (GHG) from the forthcoming irrigated maize (Zea mays L.) crop. Vetch and barley were the CCs with the highest N2O and CO2 losses (75 and 47% increase compared with the control, respectively) in the fallow period. In all cases, fluxes of N2O were increased through N fertilization and the incorporation of barley and rape residues (40 and 17% increase, respectively). The combination of a high C:N ratio with the addition of an external source of mineral N increased the fluxes of N2O compared with -Ba and -Rp. The direct emissions of N2O were lower than expected for a fertilized crop (0.10% emission factor, EF) compared with other studies and the IPCC EF. These results are believed to be associated with a decreased NO pool due to highly denitrifying conditions and increased drainage. The fluxes of CO2 were in the range of other fertilized crops (i.e., 1118.71-1736.52 kg CO2-C ha(-1)). The incorporation of CC residues enhanced soil respiration in the range of 21-28% for barley and rape although no significant differences between treatments were detected. Negative CH4 fluxes were measured and displayed an overall sink effect for all incorporated CC (mean values of -0.12 and -0.10 kg CH4-C ha(-1) for plots with and without incorporated CCs, respectively). (C) 2013 Elsevier B.V. All rights reserved.