• Authors:
    • Menendez, S.
    • Castellon, A.
    • Artetxe, A.
    • Merino, P.
    • Aizpurua, A.
    • Estavillo, J. M.
  • Source: Soil & Tillage Research
  • Volume: 123
  • Year: 2012
  • Summary: Nitrous oxide is a greenhouse gas contributing to global warming. Biocrops have been proposed as an alternative for energy production. Nevertheless, the use of biofuels could be a counterproductive approach to mitigate global warming, as the fuel energy gained from biofuel crops might be offset against the nitrogen inputs and associated N2O emissions. The objective of this work was to determine the warming potential of a rapeseed crop in northern Spain caused by direct N2O emissions and CO2 emitted during farm machinery operations. Mineral fertilizer was applied at a rate of 180 kg N ha(-1) Fluxes of N2O were measured year round. The emission factor of direct N2O losses was determined, together with the relative warming with regard to plant N content and the CO2 emissions from farm equipment operation. The emission factor from direct N2O losses from rapeseed crop was 2.54%. Emissions of CO2 produced by farm machinery in rapeseed crop represented 8.5% of the CO2 equivalents in terms of N2O emitted by the crop. Thus, rapeseed grown in our conditions leads to N2O emissions whose warming effect is compensated by the "saved fossil CO2" of biofuel production. (C) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • Carbonell-Bojollo, R.
    • Ordóñez-Fernández, R.
    • Veroz-González, O.
    • González-Sáncheza, E. J.
    • Gil-Ribes, J. A.
  • Source: Soil & Tillage Research
  • Volume: 122
  • Year: 2012
  • Summary: Conservation agriculture (CA) helps to mitigate climate change. Firstly, the modifications introduced by CA on the carbon dynamics in the soil directly result in an increase of the carbon (C) in the soil fraction. Secondly, CA drastically reduces C oxidation processes by diminishing the mechanical manipulation of the soil. Spain's position in relation to the Kyoto Protocol must be improved, as is one of the European countries in a non-compliance situation. With the aim of providing knowledge about the potential of CA as C sink in Spain, 29 articles on this subject were reviewed. According to 2010 CA uptake, the results demonstrated that conservation practices have the potential to promote the fixation in soil of about 2 Gg year(-1) more C than traditional tillage (TT) systems. As indicated by Tebrugge (2001), 3.7 Mg of CO2 are generated from 1 Mg of C through microbial oxidation processes taking place in the ground, meaning that through CA almost 7.5 Gg of CO2 could be sequestered from the atmosphere every year until the equilibrium is reached. C fixation was found to be irregular over time. C fixation rates were high in newly implemented systems during the first 10 years, reaching top values of 0.85 Mg ha(-1) year(-1) for no-tillage (NT) and 1.54 Mg ha(-1) year(-1) for cover crops (CC) implemented in-between perennial tree rows. After those first 10 years, it followed a period of lower but steady growth until equilibrium was reached. Nevertheless, C decreases of 0.16 Mg ha(-1) year(-1) in the first 10 years may be expected when practicing minimum tillage (MT). C sequestration rate resulted higher in case farmers do crop rotations in NT and MT rather than monoculture. In woody crops, studies reported higher C fixation values for native species when compared to sowed CC. Also, climate conditions seem to affect C sequestration rate in Spain. Although in NT differences observed between maritime and continental climates are not pronounced, as approximately 25% of the values recorded in both climates are equal, in the case of MT about 75% of maritime climate values result higher than the continental situation. (c) 2012 Elsevier B.V. All rights reserved.
  • Authors:
    • García-Jiménez, J.
    • Botella-Rocamora, P.
    • Vicent, A.
    • Bascón, J.
    • de la Roca, E.
    • López-Quílez, A.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 3
  • Year: 2012
  • Summary: Phytophthora branch canker, caused by Phytophthora citrophthora, has been an increasing problem in clementine ( Citrus reticulata) production in Spain during last years. The disease was particularly severe in the new citrus-growing areas of the southwestern coastal areas in Huelva Province. Recent studies revealed that disease emergence was not related to either genetic drift or host specificity changes in P. citrophthora population. Therefore, the possible association of agronomic factors with the disease was investigated. A total of 110 orchards were selected arbitrarily from the main citrus-growing areas in Huelva Province. The presence of branch cankers together with agronomic factors including soils, cultivars, rootstocks, irrigation, pruning, techniques to improve fruit production, fungicide treatments, presence of brown rot of fruit and frost damage were recorded. Logistic regression analysis was used to detect correlations between the agronomic factors studied and disease prevalence. Phytophthora branch canker was significantly associated with mature clementine orchards. Sweet orange and hybrid cultivars as well as young clementine orchards were less affected by the disease. Although disease was less frequent in Salorthid soils, alternative high resolution procedures are required to draw conclusions about the effect of soil properties on disease prevalence. As in other Phytophthora-induced diseases, soil flooding during the rainy season was correlated positively with the prevalence of branch cankers. Improving fruit production by branch scoring showed a strong positive correlation with Phytophthora branch canker. This is the first time that girdling has been associated with Phytophthora disease epidemics on a fruit tree crop, but further research is needed to determine the cause of this relationship. Cultural practices including pruning, regulated deficit irrigation, additional phosphonate sprays, and abiotic and disease factors such as frost damage and presence of brown rot of fruit were not significantly correlated with disease prevalence.
  • Authors:
    • Melero, S.
    • Panettieri, M.
    • Madejon, E.
    • Gomez Macpherson, H.
    • Moreno, F.
    • Murillo, J. M.
  • Source: Soil & Tillage Research
  • Volume: 112
  • Issue: 2
  • Year: 2011
  • Summary: Long-term no-till practices (NT) have a positive effect on recovery and improving soil fertility and decreasing soil erosion. Nevertheless, long term no-till practices may also cause some inconveniences, such as soil compaction, water infiltration and problems in seed germination. Thus, in the present work we assess the effects of the implementation (October 2008) of a traditional tillage (mouldboard ploughing) (TT) and reduced tillage (chiselling) (RT) on soil quality in a dryland calcareous soil (Leptic Typic Xerorthent) after 8 years of soil no-till management (NT) in SW Spain. The results were compared to those found under no-till. We hypothesised that C fractions and biological properties would be adequate indicators of soil quality changes. To test the hypothesis soil samples were collected at three depths (0-5, 5-10 and 10-25 cm) and in three sampling periods, after tillage and sowing (January 2009) after harvesting (June 2009) a vetch crop ( Vicia sativa, L) and after tillage and sowing (January 2010) of a wheat crop ( Triticum aestivum, L). Total organic carbon (TOC) and carbon labile fractions (active carbon (AC) and water soluble carbon (WSC)) were determined. Biological status was evaluated by the analysis of soil microbial biomass carbon and nitrogen (MBC and MBN) and enzymatic activities [dehydrogenase activity (DHA), and beta-glucosidase activity (Glu)]. The implementation of chiselling did not cause depletion in most of the studied soil properties compared to no-till in the first 5 cm of soil. However, the application of traditional tillage reduced 23% of TOC, 27% of WSC, 12% of AC, 19% of MBC, 44% of MBN, 37% of DHA and 51% of Glu in the upper layer of the soil (0-5 cm depth) with respect to no-till. Soil organic carbon and microbial parameter values decreased as depth increased, particularly in conservation tillage systems (RT and NT) in all sampling periods. Under our conditions, dryland Mediterranean areas, the mouldboard ploughing is not considered a suitable soil tillage system since it showed an early negative effect on soil organic fractions and biochemical quality. Although further studies would be necessary, the use of chiselling could be a solution in case of problems related to no-till.
  • Authors:
    • Martinez-Ruiz, C.
    • Marrs, R.
    • Alday, J.
  • Source: Journal of Vegetation Science
  • Volume: 22
  • Issue: 6
  • Year: 2011
  • Summary: Question: Does the course of succession on a coal mine restored by hydroseeding converge with a reference community in terms of species composition and vegetation structure? What is the rate of succession on restored areas? How does the balance between local colonization and extinction rates change during succession? Which species group (native or hydroseeded) determines the successional process? Location: Large reclaimed coal mine in the north of Palencia province, northern Spain (42degrees50′N, 4degrees38′W). Methods: Between 2004 and 2009 we monitored annually vascular plant species cover in nine permanent plots (20 m 2 each) at a restored mine; these plots were structured to account for site aspect (north, south and flat). Three identical permanent plots were established in the surrounding reference community and monitored in 2004 and 2009. We used detrended correspondence analysis to assess successional trends and rates of succession, generalized linear mixed models to derive patterns of vegetation structural changes and turnover through time, and Huisman-Olff-Fresco modelling to illustrate response of individual species through time. Results: The three restored mine areas exhibited a successional trend towards the reference community through time, although speed of convergence differed. However, after 6 years the restored sites had diverged considerably and this was greater than the dissimilarity reduction with respect to the reference community. Richness, diversity and native species cover increased linearly through time, whereas hydroseeded species cover decreased. Success of hydroseeded species initially differed in the three areas, and this was negatively related with native species colonization rates. Response patterns through time of ten hydroseeded and 20 most common native species are described. Conclusions: Vegetation structural parameters rapidly converged with the reference community, whereas compositional convergence needed much longer. At the same time, successional composition trajectories and rates were related to site properties (here aspect).
  • Authors:
    • Emeran, A. A.
    • Shtaya, M. J. Y.
    • Fernandez-Aparicio, M.
    • Allagui, M. B.
    • Kharrat, M.
    • Rubiales, D.
  • Source: Crop Protection
  • Volume: 30
  • Issue: 8
  • Year: 2011
  • Summary: Chocolate spot incited by Botrytis fabae is a serious faba bean disease of worldwide distribution. The increasing interest in sustainable tools for disease control, together with the lack of sufficient levels of genetic resistance triggered our interest in the use of intercropping as a tool for the management of this disease. The effect of intercropping on chocolate spot severity was studied in field experiments performed in Egypt, the Palestinian Territories, Spain and Tunisia, in which a susceptible faba bean cultivar was grown as a monocrop or with two mixed species intercrops of either barley, oat, triticale, wheat, pea or common vetch, or with three mixed species intercrops of wheat and berseem clover. Chocolate spot was significantly reduced when faba bean was intercropped with cereals, but not when intercropped with legumes. Suppressive effects can be ascribed to a combination of host biomass reduction, altered microclimate and physical barriers to spore dispersal.
  • Authors:
    • Jimenez-Munoz, J.
    • Sobrino, J.
    • Julien, Y.
  • Source: International Journal of Applied Earth Observation and Geoinformation
  • Volume: 13
  • Issue: 5
  • Year: 2011
  • Summary: Several previous studies have shown that the inclusion of the LST (Land Surface Temperature) parameter to a NDVI (Normalized Difference Vegetation Index) based classification procedure is beneficial to classification accuracy. In this work, the Yearly Land Cover Dynamics (YLCD) approach, which is based on annual behavior of LST and NDVI, has been used to classify an agricultural area into crop types. To this end, a time series of Landsat-5 images for year 2009 of the Barrax (Spain) area has been processed: georeferenciation, destriping and atmospheric correction have been carried out to estimate NDVI and LST time series for year 2009, from which YLCD parameters were estimated. Then, a maximum likelihood classification was carried out on these parameters based on a training dataset obtained from a crop census. This classification has an accuracy of 87% (kappa=0.85) when crops are subdivided in irrigated and non-irrigated fields, and when cereal crops are aggregated in a single crop, and performs better than a similar classification from Landsat bands only. These results show that a good crop differentiation can be obtained although detailed crop separation may be difficult between similar crops (barley, wheat and oat) due to similar annual NDVI and LST behavior. Therefore, the YLCD approach is suited for vegetation classification at local scale. As regards the assessment of the YLCD approach for classification at regional and global scale, it will be carried out in a further study.
  • Authors:
    • Robles, A. B.
    • Garcia, P. A.
    • Altieri, M. A.
    • Ramos, M. E.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 7
  • Year: 2011
  • Summary: We evaluate the forage yield and quality, species composition, and carrying capacity of oats and oat-vetch as fodder-cover crops, grown in almond orchards, under mineral or organic fertilizer and three harvesting regimes ("grazing," "hay," and "grain plus straw"). Also, we show preliminary results of almond yield. Differences in yield due to mineral and organic fertilization were only 9%. The carrying capacity was similar for all treatments. The almond yield was greater when the cover crop was removed early as "grazing." Therefore, oats and oat-vetch could be used as cover crops in almond orchards if removed early by livestock grazing.
  • Authors:
    • Alvaro-Fuentes, J.
    • Paustian, K.
  • Source: Plant and Soil
  • Volume: 338
  • Issue: 1/2
  • Year: 2011
  • Summary: Climate change is projected to significantly impact vegetation and soils of managed ecosystems. In this study we used the ecosystem Century model together with climatic outputs from different atmosphere-ocean general circulation models (AOGCM) to study the effects of climate change and management on soil organic carbon (SOC) dynamics in semiarid Mediterranean conditions and to identify which management practices have the greatest potential to increase SOC in these areas. Five climate scenarios and seven management scenarios were modeled from 2010 to 2100. Differences in SOC sequestration were greater among management systems than among climate change scenarios. Management scenarios under continuous cropping yielded greater C inputs and SOC gain than scenarios under cereal-fallow rotation. The shift from rainfed conditions to irrigation also resulted in an increase of C inputs but a decrease in the SOC sequestered during the 2010-2100 period. The effects of precipitation and temperature change on SOC dynamics were different depending on the management system applied. Consequently, the relative response to climate and management depended on the net result of the influences on C inputs and decomposition. Under climate change, the adoption of certain management practices in semiarid Mediterranean agroecosystems could be critical in maximizing SOC sequestration and thus reducing CO 2 concentration in the atmosphere.
  • Authors:
    • Intrigliolo, D.
    • Castel, J.
    • Ballester, C.
    • Castel, J.
  • Source: Agricultural Water Management
  • Volume: 98
  • Issue: 6
  • Year: 2011
  • Summary: The effects of mid-summer regulated deficit irrigation (RDI) treatments were investigated on Clementina de Nules citrus trees over three seasons. Water restrictions applied from July, once the June physiological fruit drop had finished, until mid September were compared with a Control treatment irrigated during all the season to match full crop evapotranspiration (ET c). Two degrees of water restrictions were imposed based on previous results also obtained in Clementina de Nules trees ([Ginestar and Castel, 1996] and [Gonzalez-Altozano and Castel, 1999]). During the RDI period, deficit irrigation was applied based on given reductions over the ET c, but also taking into account threshold values of midday stem water potential (psi s) of -1.3 to -1.5 MPa for RDI-1 and of -1.5 to -1.7 MPa for RDI-2. Results showed that water savings achieved in the RDI-2 treatment impaired yield by reducing fruit size. On the contrary, the RDI-1 strategy allowed for 20% water savings, with a reduction in tree growth but without any significant reduction in yield, fruit size nor in the economic return when irrigation was resumed to normal dose about three months before harvest. Water use efficiency (WUE) in the RDI trees was similar or even higher than in Control trees. RDI improved fruit quality increasing total soluble solids (TSS) and titratable acidity (TA). In conclusion, we suggest that the RDI-1 strategy here evaluated can be applied in commercial orchards not only in case of water scarcity, but also as a tool to control vegetative growth improving fruit composition and reducing costs associated with the crop management.