Suchergebnisse

This study presents the analysis of the suitability of three native species of annual plants, Bromus rubens, Medicago truncatula and Anthemis arvensis, as cover crops in Andalusia, Southern Spain. We used experimental data from two agricultural years to calibrate and validate degree-day-based phenological models for these cover crop species. From these developed models, we determined the seed maturity dates for the three species for seven locations in Andalusia for two different date assumptions regarding conditions for seed germination: fixed on October 20 or with the first significant rainfall (25 mm on four consecutive days) in late summer or early autumn, using an 18 year dataset of daily temperature and precipitation. This analysis enabled us to determine the probability distribution of seed maturity dates for the three plant species at each location, and determine an empirical linear regression model to calculate the average seed maturity date for each species in the region. This empirical model enabled us to calculate a regional map of maturity dates for the three cover crop species based on long-term average daily temperatures across the region. The analysis showed how the management of a temporary cover crop needs to be regionalised and adapted to the specific edaphoclimatic conditions of each orchard. Thus, whereas in the western part of the Guadalquivir river valley the three species can produce viable seeds in early April, especially A. arvensis and M. truncatula, in the rest of the region management of these cover crops needs to be adapted to combine seed production for self-seeding with minimising the risk of competition for soil water with the trees. This can be done with systems allowing partial killing of the cover crop in late winter, leaving a tiny fraction of the cover alive to produce seed for the next year. Our analysis suggests that new cover crop species with shorter cycles are needed, particularly grasses. In this search another key trait should be ease of seed dispersal. Our thermal time phenological models and approach may be directly applicable to similar areas in the Mediterranean or re-calibrated for different conditions or plant species with relatively simple experiments. ; This work was supported by the AGL2012-40128-C03-01 (Spanish Ministry of Economy and Competiveness), P12-AGR-931 projects (Andalusian Government), and EU‒FEDER funds, whose support is gratefully acknowledged. ; Peer reviewed

Trabajo desarrollado bajo la financiación del proyecto "Soil Hydrology research platform underpinning innovation to manage water scarcity in European and Chinese cropping Systems" (773903), coordinado por José Alfonso Gómez Calero, investigador del Instituto de Agricultura Sostenible (IAS). ; This manuscript presents a questionnaire-based study aimed to provide a detailed analysis on the different soil management carried out by olive farmers in two representative olive-growing areas in southern Spain (Cordoba and Estepa), their perceptions on cover crop use and the possible influence of the different types of farms and farmers' typologies on these perceptions. Our results show a relatively large variability of soil management, with fourteen options, as a result of a combination of different alternatives for bare soil and cover crops with the use or not of pruning residues, but with a great similarity between both areas. The results indicate a high adoption of soil conservation measures in the two study areas, with 63% of farmers using cover crops and 80% a mulch of pruning residues, higher than that reported in previous studies in Southern Spain, and a trend of lower use of these techniques by less experienced and younger farmers. This high penetration of soil conservation measures resulted in a significant reduction of soil erosion risk, as indicated by the relatively low values for the cover and management factor (C) of RUSLE, also calculated and presented in this study, but also the possibility of focusing further efforts on farmers with less experience. Our results indicate the persistence of a minor, but relevant, percentage of farmers using bare soil management (37%) and no mulching (20%), with a moderate concern on the impact of soil erosion on soil degradation and provision of ecosystem services. This suggests the need to concentrate efforts also on this cluster of farmers to enhance the success of what seems to be a remarkable expansion of the use of soil conservation measures in recent decades in Southern Spain, but also in similar areas in the Mediterranean basin. ; This work was supported by P12-AGR-0931 (Andalusian Government), AGL2015-65036-C3-1-R and PID2019-105793RB-I00 (Spanish Government), SHui (European Commission Grant Agreement number: 773903) and EU-FEDER funds, as well as by the cooperative agreement between the DOP Estepa and the University of Cordoba. All this support is gratefully acknowledged. ; Peer reviewed

19 pages, 3 figures, 5 tables, 36 references. ; The failure of a tailing pond dam at the Aznalco´ llar pyrite mine (SW Spain) in April 1998 released a toxic spill affecting approximately 4300 ha along the Agrio and Guadiamar valleys.T wo years later, we have studied yield and concentration of mineral nutrients and trace elements in sunflower plants grown in the spill-affected soil, and in an adjacent unaffected soil as comparison.The study has been carried out in plants at seedling (V4) and mature (R8) stages.Shoot and root biomass of sunflower seedlings was significantly smaller in the affected soil than in the unaffected soil, but there was no significant difference at the mature stage.Oil production was greater in the spillaffected plants.W e have not detected any 'fertilising' effect caused by the acid waters of the spill on the main nutrient (N, P and Ca) acquisition, as documented in 1998 for sunflower plants flooded by the spill.Sunflower plants growing in the spill-affected soil reached adequate levels of nutrients.None of the trace elements measured—As, Cd, Cu, Pb and Tl—reached levels either phytotoxic or toxic for humans or animals in seeds and the above-ground part of the spill-affected plants.W e evaluate the potential use of sunflower plants for phytoremediation. The potential for phytoextraction is very low; however, it may be used for soil conservation.The production of oil (usable for industrial purposes) may add some value to this crop. ; This study was carried out in the framework of the 'Programa de Investigación del Corredor Verde (PICOVER)', supported with funds of the 'Consejería de Medio Ambiente' of the Regional Government (Junta de Andalucía), Spain. ; Peer reviewed

14 páginas.-- 1 figuras.-- 6 tablas.-- 62 referencias.-- Appendix A. SSupplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.agee.2015.07.028 ; 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. © 2015 Elsevier B.V. ; This study was supported by the Spanish Ministry of Economy and Competitiveness (Projects: AGL2010-22050, AGL2013-49062 and 201440E100) and FEDER funds. We thank the Consejería de Agricultura Pesca y Desarrollo Rural (Junta de Andalucía) for providing original data on the area of direct seeded crops. J.J. Pérez and AEAC/SV helped identify farmers practicing CA in western Andalusia and R. Gil facilitated the focus group. M. Panettieri, R. Luque, R. Gutierrez and M. Salmoral provided technical support in field measurements and laboratory analyses. We are grateful to the farmers for their collaboration in this study. ; Peer reviewed