SPANISH JOURNAL OF AGRICULTURAL RESEARCH

Published by Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria
Online ISSN: 2171-9292
Publications
Article
This paper examines the export performance of Spanish tomatoes in the European Union (EU). The origins and destinations of Spanish tomato exports are examined: Almeria is the main exporting province and Germany the biggest client. The performance of Spain’s North African competitors in the tomato market (mainly Morocco) is also examined, and the structural competitiveness of the countries that export tomatoes to the EU is analysed. Spain has the greatest advantage in this respect, and the largest inter-industry trade. An export model is developed. This model shows that the export of tomatoes from Almeria is not much influenced by shipments from Morocco.
 
Distribution functions' parameters and correlation matrix (yields are in kg/ha; losses are expressed in relative terms to total liability)
Comparison of the Crop-specific insurance and Whole-farm insurance results
Certainty equivalents for both farms and 6 levels of relative risk aversion
Article
Time and value are related concepts that influence human behaviour. Although classical topics in human thinking throughout the ages, few environmental economic non-market valuation studies have attempted to link the two concepts. Economists have estimated non-market environmental values in monetary terms for over 30 years. This history of valuation provides an opportunity to compare value estimates and how valuation techniques have changed over time. This research aims to compare value estimates of benefits of a protected natural area. In 1978, Nadgee Nature Reserve on the far south coast of New South Wales was the focus of the first application of the contingent valuation method in Australia. This research aims to replicate that study using both the original 1978 contingent valuation method questionnaire and sampling technique, as well as state of the art non-market valuation tools. This replication will provide insights into the extent and direction of changes in environmental values over time. It will also highlight the impact on value estimates of methodological evolution. These insights will help make allocating resources more efficient.
 
Maximum likelihood estimates of the stochastic frontier model for olive farms in Spain, 1999-2002 
Mean technical efficiency by year and farms 
Article
The concept of technical efficiency is critical to measuring the firm performance, determining the degree of innovative technology adoption and the overall production efficiency. Traditionally, technical efficiency has been measured as the ratio of observed output to maximum feasible output. Stochastic frontier models have been widely utilized to assess this issue. Our research evaluates technical efficiencies in the Spanish olive sector. Specifically, the main objective of this study is to estimate a stochastic frontier production model by using a farm- level panel of data. The non- negative technical efficiency effects are assumed to be a function of firm- specific variables. A sample of Spanish farms observed from 1999 to 2002 is obtained from the FADN dataset and used in the estimation of the model. Maximum- likelihood methods are applied in the estimation of the parameters of the model. A primal approach is used to decompose Total Factor Productivity (TFP) growth. Results indicate that farm location, age of manager, tenure regimes of land and whether the farm has adopted organic farming techniques affect efficiency levels . Technical efficiency change, allocative efficiencies and scale effects are found to be the main sources of TFP growth, while technical change seems to be of minor importance. Results also suggest that Spanish olive farms are less efficient relative to other EU farms. This suggests that improvements in the Spanish olive productive capacity after the accession to the EU were not fully implemented in the period of analysis. This may be due to a decline in olive farm incomes as a result of a decline in both public subsidies and in output prices after the mid 1990s.
 
Article
El normalmente bajo contenido de cobalto en vinos trae aparejado problemas en su cuantificación, tanto en absorciometría molecular como en espectrometría de absorción atómica corriente, no solo en el tratamiento previo de las muestras sino también en el aspecto instrumental. El objetivo del trabajo fue aplicar un método altamente sensible y selectivo que usa 4-(5-Br-2 pyridylazo)-1,3-diaminobenzeno (5-Br-PADAB) para la determinación de cobalto en vinos. Su exactitud y precisión fueron comparables a los obtenidos por espectrometría de absorción atómica. La absortividad molar del complejo de Co-5-Br-PADAB fue de 116.000 L mol-1 cm-1. Las interferencias debidas a Fe (III) y Cu (II) fueron resueltas por enmascaramiento con fluoruro y cuprón respectivamente. The typically low content of cobalt in wines hinders its quantification by molecular absorptiometry and atomic absorption spectrometry (AAS); difficulties arise both in the preparation of samples and cobalt detection. This work proposes a highly sensitive and selective extraction-spectrometry method that uses 4-(5-Br-2 pyridylazo)-1,3- diaminobenzene (5-Br-PADAB) for the determination of cobalt in this medium. Its accuracy and reproducibility are comparable to those of flame AAS. The molar absorptivity of the complex was 116,000 L mol-1 cm-1. Interference from Fe (III) and Cu (II) ions was resolved by masking them with fluoride and cupron respectively.
 
Article
The use of rootstocks is widespread in modern viticulture; non-grafted Vitis vinifera vines are now grown in only a handful of places with very specific conditions. Since the need to graft vine-scions onto American rootstocks, a lot of work has been performed in which different aspects of the relationship between the vine and the rootstock have been studied. Despite this there are still many open questions, which remained unanswered. The present paper reports a study performed on five ¿Albariño¿clones (MBG-1, MBG-2, MBG-7, MBG-9 and MBG-10), in which the influence of rootstock type (110- R and SO4) on a number of agronomic variables was examined. The results show that these rootstocks have no influence on many of the variables which were studied (phenology, cluster size and weight, fertility, yield, and berry size and weight), although they do influence variables such as the probable alcohol content, the quantity of free-run juice, must total acidity and weight of pruned wood. Therefore it is possible to conclude, that rootstocks influence agronomic parameters.
 
Article
Germline chimaerism (intra or interspecific) is a technique of great potential in aquaculture. It allows specimens to be obtained that produce gametes whose origins lie in the cells of the donor organism. Chimaerism is usually performed at the mid blastula transition (MBT) stage since this is the last in which embryonic cells remain completely totipotent. Zebrafish are photoperiodic in their egg-laying behaviour and show rapid embryonic development. For chimaerism to be successful, it is of interest to establish the maximum time over which embryonic development can be reversibly arrested. This paper reports the effect on survival of subjecting zebrafish embryos at different stages of development to a water temperature of 16°C for different lengths of time. The maximum exposure time after which these embryos were able to resume development following low-temperature-induced developmental arrest became shorter as the embryonic stage exposed became earlier. At the MBT stage, the maximum safe exposure time was 2 h; longer exposure times led to problems in development and survival.
 
Article
La industria de la producción de camarón es una de las industrias acuícolas que se encuentra en más crecimiento en la actualidad. Los estudios para encontrar marcadores genéticos son muy efectivos para la mejora de sus propiedades y de gran interés para los productores de camarón. En este trabajo se utilizaron seis individuos de una población de Litopenaeus vannamei, donde se encontraron cuatro polimorfismos de nucleótido único (SNPs) en el gen 5HT1R (5-hidroxitriptamina receptor1) y un SNP en el gen STAT (transductor de señal y activador de la transcripción). Sin embargo, el polimorfismo en el gen STAT resultó ser homocigoto en una población diferente utilizada para análisis de asociación. Los presentes análisis revelaron que el alelo C, en dos polimorfismos SNP (C109T y C395G) del gen 5HT1R, tiende a estar asociado con el aumento del peso corporal. Consideramos que hay necesidad de hacer nuevos estudios utilizando una muestra más amplia y diversa de la población en cuestión. Shrimp aquaculture is one of the growing animal industries. Breeding stocks with high disease-resistance and growth rate are of particular interest to shrimp breeders. Association studies are useful to find genetic markers for marker assisted selection of animals. Using six Litopenaeus vannamei individuals from a sample population, four single nucleotide polymorphisms (SNPs) were found in the 5HT1R (5-hydroxytryptamine receptor1) gene and one SNP in the STAT (signal transducer and activator of transcription) gene. However, the SNP in the STAT gene was homozygous in a different population used for association analyses. The association analyses revealed that allele C of two SNPs, C109T and C395G in 5HT1R, tended to be associated with increased body weight. Further studies need to be conducted using a large and diverse population sample.
 
Article
The control of Trialeurodes vaporariorum on tomato with Encarsia formosa is influenced by the use of insecticides. Nine days after allowing E. formosa adults to lay their eggs in T vaporariorum nymphs on tomato plants, insecticide solutions (abamectin, mineral oil, acetamiprid, an industrial detergent and imadacloprid) were applied at the highest recommended dosages to tomato leaflets in Petri dishes using a Potter tower (four replicates, each involving 20 parasitized nymphs). Adult parasitoids began to emerge on day 7 post-application; this lasted 3-4 days, peaking on day 9 post-application. All the tested products killed the E. formosa pupae (an effect significantly different [P <= 0.05] to that achieved with the water control). The products with the greatest toxicity were the detergent (62.99% mortality) and mineral oil (49.55% mortality; no significant difference). The effect of abamectin, the third most toxic agent (33.05% mortality), was not statistically different to that of the mineral oil. Imidacloprid (20.17% mortality) and acetamiprid (20.71% mortality) were the least toxic treatments and could be used (along with abamectin to a lesser extent) in integrated whitefly management programmes involving E. formosa pupae. At the concentrations used, the mineral oil and industrial detergent are not recommended for use in such programmes given their high toxicity to E. formosa pupae.
 
Values of isotherm adsoption variables for powdered (PAC) and granular (GAC) activated carbon
Fruit properties at harvest for all three tomato cultivars 1
Article
The aims of this work were to study the ethylene adsorption capacity of different types and masses of activated carbon, to predict the performance of the ethylene adsorption process, to improve the removal of ethylene by impregnating granular activated carbon (GAC) with palladium, and to analyse the effect of this product on the removal of ethylene released from tomatoes. In an in vitro system, both GAC and powdered activated carbon (PAC) effectively absorbed exogenous ethylene; GAC was the most effective. Maximum adsorption was achieved with carbon masses of 1.25 g L-1 or greater. The best model describing the adsorption of ethylene by GAC was the Langmuir isotherm. To increase ethylene removal, a system involving an adsorbent (GAC) and a catalyst (1% palladium) was developed. This was tested in an in vivo experiment involving the removal of ethylene produced by three tomato cultivars inside sealed jars. Ethylene removal led to a delay in tomato ripening; smaller changes in fruit firmness and colour were observed compared to controls. This system could provide a useful way of eliminating ethylene from storage areas and thus maintaining tomato fruit quality, which can be negatively affected by ethylene.
 
Article
The effect of the weed Abutilon theophrasti M. (common name: velvetleaf) on the growth of cotton grown in the Guadalquivir Valley, was studied by examining the influence of weed density on growth of the weed and that of cotton. Velvetleaf impeded normal cotton growth caused production losses as a result of the stress the cotton was subjected to. Additionally there was competition among velvet leaf plants at high velvet leaf densities. The influence of velvetleaf density in coexistence with cotton has been also studied evaluating weed effect on the biomass of cotton and its production. Additional determinations included the velvetleaf seed production capacity per unit area and seed production per plant. These determinations were adjusted to hyperbolic, inverse linear and logistic models. Last, the economic damage threshold (EDT) was calculated using the efficiency level in control of velvetleaf in cotton. In this calculation the treatment cost and losses caused by the weed, in the crop, were taken into account. The EDT varied between 0.1-0.5 velvetleaf plant m-2, depending on the control methods used.
 
Location of the three trials, and local climate and soil characteristics
Means for the measured variables (see Material and Methods) in the 44 sainfoin accessions grown at three locations: Latre (Lat), Lagueruela (Lag) and Zaragoza (Zar)
Correlation matrix for 12 characteristics measured in Spanish sainfoin grown at Latre (Huesca), Lagueruela (Teruel) and Zaragoza
Article
La esparceta (Onobrychis viciifolia Scop.) es una leguminosa forrajera plurianual, apreciada por su valor nutritivo y rusticidad. Existen dos tipos caracterizados por su hábito de crecimiento y persistencia: �común�, que no florece el año de siembra, y �gigante�, que sí florece. Con el fin de determinar su grado de pertenencia a uno de los dos tipos, se estudió la variabilidad de 38 procedencias nacionales y seis extranjeras de la esparceta. El estudio se realizó en plantas individuales, utilizando 36 plantas por procedencia en dos localizaciones de secano y una de regadío en el noreste de la Península Ibérica, durante 2002-2004. Los parámetros analizados fueron: porcentaje de plantas florecidas a lo largo del año de siembra, desarrollo otoñal y capacidad de rebrote después del primer corte. El análisis cluster distribuyó las 44 entradas en dos grandes grupos, definidos como �común� y �gigante�. Estos grupos pudieron dividirse a su vez en tres subgrupos, según el grado de contaminación o de cruzamientos habidos entre dichos grupos. Dos de los caracteres evaluados, el porcentaje de plantas florecidas el año de siembra y la rapidez del rebrote tras el corte de primavera, pueden contribuir a clasificar las plantas como de uno u otro tipo y facilitar la selección de cultivares.
 
Number of deaths in the agricultural sector from 2004 to 2008 collected by the Labour and Social Affaires Spanish Minister (MTAS) and by the authors 
Decease distribution throughout the year 
Fatalities distribution accoring to age of dead people 
Risk factors 
Article
Many fatal accidents happen in agriculture and some of them are not off icially recorded. The aim of this research was to compare official to real data about fatal accidents in agriculture and to characterize and evaluate the main risk factors associated with them. A comparative study of 388 fatal accidents related to agricultural machinery, occurred in Spain during the last five years, has been conducted. Official records only account for 61.85% of the deaths. Older people are the social group with the highest risk but children and nonfarmers are risk groups too. The main cause of death was the overturn of tractors lacking roll-over protective structures (ROPS) since from 272 fatal overturns detected; only one occurred in tractors equipped with homologated ROPS. Many overturns happened while tractor driving along roads and tracks. Terrain conditions as slopes, ditches and obstacles are also risk factors. A total of eleven risk factors have been characterized but the concurrence of at least two of them is required to cause a fatal accident. Most accidents are caused by the overlapping of three or more risk factors. Therefore, accidents are preventable when trying to circumvent all described risk factors because the probability of concurrence of at least two decreases.
 
Physical and chemical properties of the soil at the experimental field site 
Article
Humic acids are the most active components of soil organic matter and have been shown to have an hormone-like activity thus stimulating plant growth. The objective of this work was to verify the quantitative and qualitative yield responses of the table grape cv. Italia after the application of a humic acid at various phenological stages. The humic acid used in this study has been extracted from a clay soil of the Apulia region and was applied at a concentration of 100 mg L�1 in four different times: pre-bloom (I), full-bloom (II), fruit set (III) and veraison (IV) and in two years, 2007 and 2008. The following parameters were measured at harvesting: berry size, °Brix, pH and titratable acidity. Finally, the °Brix/titratable acidity ratio has been calculated. Soil Plant Analysis Development (SPAD) readings were performed every 30 days up to harvesting time on the leaves of the middle shoots. No statistical differences were observed between the two years for all the parameters examined. The humic acid applied at full-bloom (II) induced a significant increase of berry size (width and weight) and a significant improvement of the other quality parameters (titratable acidity and °Brix/titratable acidity) with respect to the control. This study confirmed that humic acids, if applied at full-bloom, can induce significant increase of qualitative and quantitative parameters in table grape and can find a positive application in an organic and sustainable viticulture. Los ácidos húmicos son los componentes más activos de la materia orgánica del suelo y se ha demostrado que tienen una actividad similar a las hormonas, estimulando así el crecimiento de las plantas. El objetivo de este trabajo fue verificar los incrementos en el rendimiento cuantitativo y cualitativo de la uva de mesa cv. Italia después de la aplicación de un ácido húmico en diferentes etapas fenológicas. El ácido húmico se extrajo de un suelo arcilloso de la región de Apulia y se aplicó a una concentración de 100 mg L�1 en cuatro momentos diferentes: pre-flor (I), plena floración (II), fruto (III) y envero (IV), y en dos años, 2007 y 2008. Se midieron los siguientes parámetros en la época de la cosecha: tamaño de la baya, °Brix, pH, acidez titulable y ratio °Brix/acidez titulable. Cada 30 días hasta la época de cosecha se realizaron lecturas SPAD sobre las hojas de los brotes medios. Para todos los parámetros examinados no se observaron diferencias estadísticas entre los dos años. El ácido húmico aplicado en plena floración (II) indujo un aumento significativo del tamaño de las bayas (anchura y peso) y una mejora significativa de los demás parámetros de calidad (acidez titulable y °Brix/acidez) con respecto al control. Este estudio confirmó que los ácidos húmicos, si se aplican en plena floración, pueden inducir un aumento significativo de los parámetros cualitativos y cuantitativos en la uva de mesa y se puede encontrar una aplicación positiva en una viticultura ecológica y sostenible.
 
Article
The juices of five grapevine cultivars cultivated in a typical Mediterranean climate were analyzed for sugars, organic acids, and phenols at four distinct stages of berry development. When the unripe berries were almost in full size, the glucose and fructose contents, based on HPLC detection, ranged from 13.3 to 30.7 g L-1 and from 8.3 to 23.7 g L-1 for 'Muscat of Alexandria' and 'Muscat of Hamburg', respectively. At this stage, tartaric acid concentration was between 10.3 ('Italia') and 12.3 g L-1 ('Muscat of Alexandria'), while the level of total phenols was low. Up to véraison, there were slight reductions in organic acids, while sugar content increased slightly. However, dramatic changes in all genotypes were apparent after véraison. Slight reductions were determined in the glucose and fructose levels of 'Italia' prior to final analysis, possibly indicating this cultivar's sensitivity to late harvest. In the final analysis, glucose and fructose content varied from 86.4 ('Italia') to 107.0 g L-1 ('Muscat of Hamburg'), and from 73.1 ('Italia') to 94.1 g L-1 ('Alphonse Lavallée'), respectively. Tartaric acid content of ripe berries was between 3.8 ('Alphonse Lavallée') and 5.2 g L-1 ('Isabella') with a mean value of 4.6 g L-1, and phenol content of mature berries ranged from 2,253 to 2,847 mg L-1. This study provides valuable information for further understanding the sugar, acid and total phenol changes that occur in some grape cultivars during berry maturation. Therefore, these results will be useful for future research on the biochemistry of the grape berry.
 
Emergence pattern curves for common dry (above left), common wet (below left), Cornwall dry (above right) and Cornwall wet (below right). 13d, 20d, 27d, 41d, 48d, and 55d: symbols and lines for 13, 20, 27, 41, 48 and 55 day-storage at 4°C, respectively.
Article
The effect of temperature and moisture on the activation of two forms of Oxalis latifolia Kunth bulbs - common and Cornwall - was studied. Gaining knowledge about the conditions needed for their activation may contribute to the control of this weed. Bulbs were kept in a refrigerator at +4°C for 13, 20, 27, 41, 48 and 55 days. At each sampling date, three sets of 30 bulbs of both forms were transferred from 4°C to 21°C; 15 were kept under dry conditions and 15 under wet conditions. For both forms, and under both wet and dry conditions, activation occurred over a prolonged period of time. Dry bulbs were activated earlier than the wet bulbs, and the common form was activated earlier than the Cornwall form. Two different patterns of activation behavior were observed: dry bulbs of the common form usually followed a logarithmic activation pattern, while those subjected to the wet treatment were activated in a linear fashion. Bulbs of the Cornwall form were activated exponentially in the majority of cases. The mean time required for activation after cold storage was constant in the common form, while in the Cornwall form, activation was faster the longer the period of cold storage the bulbs had been previously subject to.
 
Chemical composition of E. globulus essential oils
Mite and bee mean mortality (%) after 24, 48 and 72 h for different concentrations of essential oils of E. glo- bulus from two different geographic locations (CL: Conla- ra. MdP: Mar del Plata)
LC 50 (µL Petri dish -1 ) estimated for V. destructor and A. mellifera for essential oils and fluvalinate from Conlara and Mar del Plata
Article
The biological activity of Eucalyptus globulus essential oils derived from plant material obtained from different geographic areas was analyzed in in vitro experiments on Paenibacillus larvae, Varroa destructor, and Apis mellifera. The physicochemical properties, composition, antimicrobial, and bioactivity of these essential oils were studied. The bioactivity against P. larvae was analyzed by means of two in vitro techniques (tube dilution and bioautography). Mite and bee lethality were estimated using a complete exposure method test with oils at different concentrations. Essential oils differed in their composition, albeit their similar physicochemical properties. The minimal inhibitory concentrations range for E. globulus essential oil lay between 600-700 μg mL-1 for Mar del Plata and 900-1,200 μg mL-1 for Valle de Conlara essential oils against all P. larvae strains. The bioautography method determined that limonene accounted for the greatest antimicrobial activity with respect to the other compounds. The complete exposure method at 24, 48, and 72 h yielded lower LC50 values for mites exposed to E. globulus essential oils from Conlara. LC50 values for acari after 72 h of treatment with E. globulus from Mar del Plata and Conlara were 47.1 and 11.7 μL capsule-1, respectively; whilst those for bees was > 20 μL capsule-1 for both oils. The E. globulus essential oils tested in this study featured high efficiency against V. destructor, yet their antimicrobial activity against P. larvae proved to be lower, and innocuous to bees. The present experience promotes the use of active compounds for American fouldbrood and Varroosis management.
 
Description of the different crop frequency maps considered in the present research for comparison with land suitabili- ty categories
Article
The present research aims to obtain a better insight into the agreement between land evaluation results and actual crop spatial distribution by comparing biophysical land suitability with different crop frequency parameters and with crop rotations derived from multi-year crop maps. The research was carried out in the Flumen district (33,000 ha), which is located in the Ebro Valley (northeast Spain). Land evaluation was based on a 1:100,000 soil survey according to the FAO framework for the main crops in the study area (alfalfa, winter cereals, maize, rice and sunflower). Three crop frequency maps and a crop rotation map, derived from a time-series of Landsat TM and ETM+ images of the period 1993-2000 were used for comparison with land suitability maps. The relationships between the two types of variables were analyzed by means of statistical tests (Pearson chi-square (χ2), Cramer's V, Gamma and Somers' D). The results show the existence of a significant (P=0.001) relationship between crops' location and land suitability, except for opportunist crops as sunflower, which is very much influenced by subsidies in the study period. The alfalfa-based rotations show the highest distribution percentages (52%) on the land most suitable for agriculture in the area. The present multitemporal analysis approach offers a more realistic insight than the comparison between a land evaluation map and static year crop map in assessing the degree of agreement of land evaluation recommendations with crops actually cultivated by farmers.
 
Frequencies of detection of studied factors (IAPV and Fipronil) in colonies showing depopulation symptoms or asymptomatic
Article
This study is presented in order to determine the presence and impact of some factors related with honeybee colony losses such as Israeli Acute Paralysis virus (IAPV) and certain pesticides. Samples (house worker bees and stored pollen from brood chamber) were selected from one hundred apiaries, half of them with a clear underpopulation, in accordance with region and time of the year. Total prevalence of IAPV either in spring or in autumn was 18% (CI95% = 9.9-26.0; p < 0.0001), no relationship between IAPV and depopulated colonies was established. Fipronil was only detected in two samples of stored pollen from asymptomatic colonies and imidacloprid was not detected in any sample. Like IAPV, neither fipronil nor imidacloprid appeared to be directly related with the generalized problem of colony death and honey bee losses in professional Spanish apiaries. Se llevó a cabo un estudio para determinar la presencia y el impacto de algunos factores relacionados con las pérdidas de colonias de abejas, como el virus IAPV (virus israelita de parálisis aguda) y ciertos pesticidas. Se incluyeron en el estudio muestras (abejas adultas y polen almacenado de la cámara de cría) procedentes de 100 colmenares profesionales, la mitad de ellas con claros síntomas de despoblamiento de acuerdo con la región y el momento del año. La prevalencia total del virus IAPV fue del 18% (CI95% = 9,9-26,0; p < 0,0001), tanto en otoño como en primavera y su presencia no estaba directamente relacionada con la manifestación del síntoma de despoblamiento en las colonias de abejas. El fipronil se detectó solo en dos muestras de polen almacenado en la cámara de cría de las colmenas, en ambos casos en colonias asintomáticas. No se detectó imidacloprida en ninguna muestra. Nuestros resultados sugieren que IAPV, fipronil e imidacloprida no están relacionados con las muertes masivas de colonias de abejas detectadas en colmenares profesionales en España.
 
Article
Spanish bee samples were analyzed for the presence of Israel Acute Paralysis Virus (IAPV). Some of these samples were collected from colonies presenting compatible symptoms with the colony collapse disorder (CCD, 240 out of 484) and the rest were asymptomatic. Only one of these samples was diagnosed as positive to IAPV by employing a one step RT-PCR that targets the ORF 2 of the IAPV genome. Specificity of the RT-PCR assay was evaluated by sequence analysis of size specific amplification products. IAPV nucleotide sequences already published in GeneBank were used to construct a phylogenetic tree that included the new Spanish IAPV sequence (FJ821506). They segregated in two main lineages and the Spanish isolate was mainly related with the American ones. As IAPV was detected in Spain in a very low frequency, no causal relation between IAPV and CCD in Spain was found. Se analizaron muestras de abejas españolas para detectar el virus de la parálisis aguda israelita (IAPV). Parte de las muestras (240 de 484) procedían de colmenas que mostraban síntomas compatibles con el síndrome de despoblamiento (SDC), el resto de las muestras eran asintomáticas. Solo una de las muestras fue diagnosticada como positiva frente a IAPV utilizando la técnica RT-PCR, que amplifica una parte del ORF 2 del genoma viral. La especificidad de la prueba fue confirmada por secuenciación del producto amplificado que presentaba el tamaño específico. Se emplearon secuencias de IAPV ya publicadas en GeneBank para construir un árbol filogenético que incluye la secuencia de IAPV detectada en muestras españolas (FJ821506). Se observaron dos grupos principales y la muestra española está agrupada con varias americanas. Debido a que en España IAPV fue detectado en muy baja frecuencia, no se encuentra relación causal entre el SDC y la presencia de IAPV.
 
Article
La mayor parte de los modelos climáticos de invernaderos son formulados y verificados para aquellas condiciones concretas en que fueron definidos, como son el tipo de invernadero, el cultivo y las características climáticas. Para aplicarlos en condiciones distintas, los coeficientes de los modelos deben ser calibrados, proceso seguido de la los valores medidos y simulados fue bueno, lo cual prueba que el modelo puede ser usado para estimar el clima interior del invernadero, en función de las condiciones climáticas externas y de las características del sistema invernadero- cultivo.correspondiente validación del modelo adaptado. El objetivo principal del presente trabajo fue la aplicación de un modelo climático dinámico formal, definido y validado para invernaderos calefactados del interior de España con clima continental, a invernaderos no calefactados de la costa de Portugal con clima templado. La metodología empleada en este estudio permitió identificar los problemas del proceso de adaptación, modificando el modelo de una forma sistemática, para después determinar su comportamiento mejorado. El nuevo modelo climático incluye nuevas propiedades para algunos componentes de contorno, nuevos submodelos para la ventilación y la resistencia estomática del sistema invernadero-cultivo, y nuevas expresiones para los coeficientes de transferencia convectiva de calor. Para el proceso de validación, se compararon las predicciones y las mediciones de las variables ambientales del invernadero de una forma gráfica y mediante el empleo de estadísticos. El modelo fue validado con datos representando diferentes situaciones climáticas, operaciones del sistema de ventilación y condiciones del cultivo de tomate. El ajuste entre
 
Article
The germination of stored Diplotaxis erucoides seed was studied under controlled conditions of temperature and light by conducting germination tests over three years after collection. The D. erucoides seed was not dormant at harvest, but secondary dormancy appeared during storage as indicated by reduced germination 12 months after collection (from 92% down to 39%). This could be overcome by prolonged storage or by the use of gibberellic acid. Such shifts between dormancy and non-dormancy can be interpreted in terms of the soil seed bank dynamics in relation to intraspecific competition and/or with its adaptation as an annual weed in periodically disturbed soil in cultivated areas. Se estudió la evolución de la germinación/dormición de semillas de Diplotaxis erucoides mediante ensayos periódicos en condiciones controladas (temperatura y luz), durante tres años desde el momento de su recolección. Las semillas recién recolectadas no presentaron dormición, pero a los 12 meses apareció una dormición secundaria (la germinación disminuyó de un 92% a un 32%), desapareciendo posteriormente durante el almacenamiento o mediante aplicaciones exógenas de ácido giberélico. Los cambios entre estado no durmiente y durmiente de las semillas se interpretan como una dinámica de las semillas en el banco del suelo, como posible estrategia relacionada con la competición intraespecífica y su adaptación como mala hierba anual.
 
Effect of quebracho administration on the evolution of ruminal pH and concentrations of ammonia-N and total VFA at 0, 1, 3, 6 and 9 h after administration of the morning feed. 
Article
This work was carried out with the aim of studying the effect of the administration of commercial quebracho extract (76% condensed tannins, CT) to sheep, for 70 days. Ten ruminally cannulated ewes were distributed into two experimental groups (control and quebracho). Zero (placebo) or 0.75 g of quebracho tannins extract per kg of live weight and day were intra-ruminally administered to the animals. The nylon bag technique was used to examine alfalfa hay in situ dry matter (DM), nitrogen (N) and neutral-detergent fiber (NDF) disappearances. In vivo digestibility, pH and ammonia-N and volatile fatty acid (VFA) concentrations were also measured. The daily ruminal administration of quebracho extract did not affect rumen fermentation parameters such as pH and ammonia-N and VFA concentrations, but reduced significantly the alfalfa hay DM potentially degradable fraction and the fractional rate of N degradation. Only on day 8 of the experiment were the DM and NDF disappearance values, after 24 h of in situ incubation, significantly lower in the animals treated with quebracho. No differences were observed on any other day of the experiment. Furthermore, the quebracho CT extract significantly decreased the in vivo digestibility of the following diet components: DM, crude protein and NDF. To carry out this work, Gonzalo Hervás received a grant from the Ministries of Education and Culture (MEC, Spain) and Science and Technology (MCyT, Spain). This work was financed by the Inter-Ministerial Commission of Science and Technology (CICYT, Spain; project AGF98-0874). Peer reviewed
 
Estimated probit models of adoption of soil conservation practices: partial derivatives and elasticities
Article
This paper presents some results from a survey carried out in 2004 among 223 olive tree farmers from mountainous areas in the Spanish Southern provinces of Granada and Jaén regarding the adoption of soil conservation and management practices. Olive tree groves in mountainous areas are subject to a high risk of soil erosion and incur a higher cost of soil conservation. This results in greater difficulty to comply with the requirements of the new single payment scheme (cross-compliance) and to benefit from agri-environmental schemes. The main objectives of this study are to analyze the current adoption level of soil conservation practices in this area and to address which socioeconomic and institutional factors determine such adoption. Three probit models are estimated. Dependent variables are three different soil conservation practices, namely tillage following contour lines, maintenance of terraces with stonewalls, and non-tillage with weedicides. Results show a significant increase in the adoption of several soil conservation measures in the last 15 years, especially of non-tillage practices. Some factors positively related with the adoption of soil conservation practices are farm profitability, the presence of young farmers, and continuity of the farming activity by relatives and the use of family labour.
 
Location of study areas in the Bursa-Karacabey plain, Turkey.
State of production and productive values in Karacabey Plain in the years 1990, 1996 and 1998
A) Logit regression estimates of coefficients of variables affecting adoption of land consolidation. See text for explanation of variables. B) Logit model predictions of adoption of consolidation vs observed adoption A)
Article
Ownership of agricultural land is very fragmented in Turkey, as is the case in countries within central Europe. This prevents agricultural efficiency from reaching desired levels. Land consolidation involves redistributing land ownership so that individual farmers own fewer, larger, more compact and more contiguous land parcels. In Turkey, generally voluntary land consolidation projects are performed, while some financial limitations and political conditions prevent land consolidation reach to its desired level. For this reason, only 2.2% of the agricultural areas have been consolidated so far. Ideally, farmers adopt consolidation and are pleased by its results; this helps maintain the sustainability of the land structure formed by consolidation and accelerate acceptance of consolidation in other areas. In this study, the factors that are effective on farmers' adopting land consolidation and their contentment were investigated. For this purpose, the results of the survey carried out in the selected villages within the Bursa- Karacabey plain were assessed using a logit model. According to the results obtained from this consolidation study, the criteria farmers value are the utilization of the irrigation system, reduction of inter-farmer conflicts, shaping parcels into a form proper for mechanized agriculture, and forming parcels of large dimensions by consolidating parcels. A higher level of contentment was observed among the farmers who were provided with above mentioned factors.
 
Article
Wheat bugs are widely distributed in various areas of Europe, Asia and North Africa. Species belonging to the genus Eurygaster and Aelia pierce wheat kernels affecting protein quality. The effects of these insects'feeding activity have been studied mainly in bread wheat (Triticum aestivum L.). This study provides information on the degradation of prolamin proteins (glutenins and gliadins) of bug-damaged durum wheat (Triticum turgidum L. var durum) in six cultivars grown in Sardinia (Italy). Samples of whole flour mixture of 70% sound wheat and 30% damaged wheat were hydrated and incubated at two temperatures (45 and 4°C), for different periods of time (0, 1 and 3 h). Glutenin and gliadin content was analysed using free zone capillary electrophoresis. The presence of bug-damaged kernels had influence on the quality of durum wheat proteins. Glutenins were rapidly degraded independently to incubation temperature. Gliadin degradation, however, took place with dependence on temperature and incubation time. Therefore glutenin degradation was possibly not due solely to the activity of proteolytic enzymes but also to some other as yet unknown factor linked to wheat bugs' feeding activity.
 
Article
Soil degradation increased incessantly in the Pampas region of Argentina, due to the intensification of agricultural activities, when carried out with conventional tillage (CT) systems. No-tillage system was adopted as conservation practices by the farmers. The objectives of this study were: a) to determine the macrofauna taxa and their relative abundance under CT and NT in two different seasons; and b) to evaluate soil tillage and seasonal effects on the density of the main macrofauna taxa. The study was conducted from 2002 to 2004 in 46 production farms, in Balcarce, Argentina. Ten soil monoliths (25.2 cm side; 30 cm depth) ramdomly directed field at July-August; and at October-November to determine the number of individuals of macrofauna and Enchytraeidae. Soil macrofauna density did not differ between tillage systems. Oligochaeta Megadrilli density was generally not affected by the tillage system (P > 0.05) except in 2004 when it was greater under CT in July-August (P = 0.0002). Chilopoda density was greater in soils under NT, with significant differences in 2002 in October-November (P = 0.0070). In July-August of 2003 it was higher in CT (P = 0.0109). Diplopoda were more abundant only under NT in July-August 2004 (P = 0.0010). In July-August a significantly (P < 0.05) higher density of Enchytraeidae was found in CT than NT fields. No differences were observed in the taxonomic composition and the relative abundance of the macrofauna when comparing CT and NT. It can be then concluded that in the study region tillage systems affected slightly soil macrofauna and significantly Enchytraeidae.
 
Article
Elevated trace element concentrations in soils can affect the solubility and uptake of essential elements, resulting in nutrient deficiencies in plant tissues. The present paper deals with nutrient composition of pastures established on polluted and remediated soils (Green Corridor of the Guadiamar river Valley), in order to check the potential nutritional disorders that could derive from the soil pollution. In addition, nutrient composition of a representative grass, Cynodon dactylon, collected in 1999 and 2008 was compared in remediated and non-remediated sites of the polluted area. In general, nutrient concentrations of pastures were similar or even higher in polluted sites compared to 'control' sites. Therefore, the estimated potential ingestion of main nutrients by horses (the most abundant animals in the area) was also greater in the polluted and remediated soils and covered their nutritional requirements (more than 300 (N), 70 (S), 35 (P), 400 (K), 175 (Ca) and 30 (Mg) mg kg-1 body weight day-1 in spring and autumn). Temporal evolution of nutrients and physiological ratios (N/S, Ca/P, K/Na, K/Ca+Mg) in C. dactylon showed a significant variation from 1999 to 2008, especially in the non-remediated area, leading to a recovery of the nutritional quality of this grass. The reasonable nutritional quality of pastures and the absence of negative interactions between nutrients and trace elements seem to indicate a stabilisation of soil pollutants in the affected area.
 
Article
Physical properties are essential for the development of silos, transport calculations, separation and classification of grain and seeds. The present work evaluates the influence of the parchment on the drying and physical properties of coffee grains. The true density (ρ t), bulk density (ρ b) and porosity (ε) were evaluated for coffee grains (cv. Catuaí Amarelo) with and without parchment. Four mathematical models (Chung-Pfost, GAB, Modified Henderson and Oswin) were fitted to the experimental data to acquire desorption isotherms. The drying treatment was conducted in a factorial scheme with four levels of temperature (20, 35, 45 and 55°C) and five levels of relative humidity of the drying air (30, 40, 50, 60 and 80%) in a completely randomized design. The respective equilibrium moisture contents of the coffee grains were measured for each drying condition. No differences were observed among the products on the desorption isotherms. The pulped coffee with parchment (PP) had higher ε values than the pulped coffee without parchment (PR). The true density was higher for the PP coffee, but as the moisture content (X) increased, the true densities became more similar for the two samples. The ρ b was higher for the PP coffee than for the PR coffee. Higher initial and final values of ρ b were found for the PR and PP coffee, respectively. The Guggenheim-Anderson-de Bôer model was the model that best represented the experimental data for the drying process.
 
Article
Concern regarding the relationship between diet and health is growing among consumers. As an answer to this concern, the food industry has developed functional foods, a market with an increasing demand both in volume and expenditure. New functional products are being developed for which market potential must be investigated. This paper centres on one of this products, a wine with increased levels of resveratrol, a natural compound which has been found to be positively related to the reduction in the risk of inflammatory diseases. The market potential of this new product is assessed using a survey of wine consumers in the city of Granada (Spain). Consumers are asked for the probability of purchasing this new wine in order to identify «potential consumers» and factors influencing belonging to this category are identified. A significant proportion of the sample is found to belong to the «potential consumers» category with cognitive, affective and situational variables as the main factors affecting inclusion within this category.
 
Article
An experiment was conducted to study the effect of a reduction in dietary sodium content on performance and nutrient digestibility, in rabbits weaned at 25 days of age. Two diets with the same composition and only differing in the supply of sodium chloride content (0.5 or 0%) were used. A reduction on the dietary sodium content from 2.7 to 0.6 g kg¿1 DM decreased the ileal and faecal apparent digestibility of dry matter, crude protein and the ileal apparent digestibility of every amino acid studied with the exception of the phenylalanine, and reduced daily weight gain, feed intake and feed efficiency. These results indicate that a reduction of the dietary sodium content up to 0.6 g kg¿1 DM results excessive and insufficient to assure a correct absorption of nutrients and to maintain the growth performance in growing rabbit. Se realizó un experimento para estudiar el efecto de una reducción de sodio en la dieta de gazapos destetados a 25 días. Se utilizaron dos piensos con la misma composición y que sólo diferían en el contenido de cloruro sódico añadido (0,5 y 0%). La reducción del contenido en sodio de la dieta del 2,7 a 0,6 g kg¿1 MS disminuyó la digestibilidad ileal y fecal aparente de la materia seca y la proteína bruta, y la digestibilidad ileal aparente de todos los aminoácidos estudiados con la excepción de la fenilalanina. También empeoró el consumo y la ganancia media diaria y la eficacia alimenticia. Estos resultados indican que una reducción de sodio de la dieta hasta 0,6 g kg¿1 MS resulta excesiva e insuficiente para asegurar una correcta absorción de los nutrientes y para mantener los rendimientos productivos en gazapos de cebo.
 
Article
Mycotoxicosis, particularly that caused by aflatoxins and ochratoxins, is a serious problem for the poultry production industry. The aim of this study was to determine the total aflatoxin and ochratoxin A levels in liver and plasma, and kidneys and plasma, respectively, of chickens for fattening fed experimentally contaminated diets, and to assess the impact of these toxins on body weight increase and the feed conversion ratio (FCR). Forty eight 21 day-old Ross breeder chickens (n = 12 x four treatments) were fed diets containing different levels of mycotoxins: grower diet + ochratoxin A (200 mg kg -1 of feed) + total aflatoxin in different concentrations (T1 = 60 μg kg-1 of feed; T = 50 μg kg-1; T3 = 30 μg kg-1). Control chickens (T4) were fed only the grower diet. No significant differences were seen in the weight increase of chickens subjected to the different treatments. However, lower FCRs were seen in those exposed to T1 and T2. In general, the amount of total aflatoxin and ochratoxin A found in the liver, kidneys and plasma (determined by ELISA) were directly related to the amounts added to the experimental diets and feed consumption. Plasma ochratoxin A was always higher than kidney levels; this relationship was not seen for total aflatoxin.
 
Determination of resistance level 
Article
A 3 year screening of 25 long staple cotton cultivars for resistance to African cotton mosaic virus (ACMoV) conducted in northern Nigeria during the 1999-2001 wet seasons indicated that no cultivar was immune or resistant. Two cultivars, Pima S1 and Pima S4 were moderately resistant (16% infection), four cultivars Pima S2, Pima S3, Giza 45 and Giza 69 were moderately susceptible (31% infection), while the remaining 19 cultivars were highly susceptible. The moderately resistant cultivars are high yielding, have high quality lint characteristics such as crin percentage, bundle strength, and micronaire fineness. They can be used to reduce the menace caused by ACMoV on cotton in Nigeria.
 
Article
The agronomic performance of different proportions of mixtures of coconut fibre (CF) pith and spent mushroom substrate (SMS) was studied for their use as casing material in mushroom cultivation. After chemical and biological characterisation of the casing substrates qualitative and quantitative production parameters were evaluated in a cycle of Agaricus production. An increase in the proportion of SMS reduced the number of carpophores and overall yield; while the first flush was delayed, mushroom size tended to increase and the mushrooms had a higher dry matter content and a better texture, although their colour was worse. Combinations of CF pith and SMS of 4:1 and 3:2 (v/v) gave biological efficiencies of 92.9 and 82.6 kg 100 kg-1 compost, respectively. These values compare well with that obtained from the commercial casings used as a control. The high electrical conductivity of the mixture containing the highest proportion of SMS would limit its use. However, the results indicate the viability of reusing SMS as an ingredient of casing material for mushroom cultivation. This alternative could be considered to partially replace the organic substrates normally used for mushroom cultivation, with the double advantage of decreasing cost and reducing the environmental impact of waste disposal.
 
Article
The effect of the ageing method (bone-in or boneless), ageing period (7 or 14 days), cooking method (grilling or water bath preparation) and sample thickness (1, 2 or 4 cm) on the meat texture characteristics of the longissimus thoracis muscle of six young, commercial bulls was measured using a texture analyser incorporating compression and Warner-Bratzler devices. The sarcomere length of the raw meat and cooking losses were also recorded. The ageing method and ageing period had more influence on the textural properties studied than either the cooking method or sample thickness. Cooking losses were, however, mainly influenced by the cooking method. Although the cooking method had no significant effect on meat toughness, the meat tended to be tougher when grilled than when prepared in a water bath. Meat tenderness mainly improved during the first week of storage.
 
Ordinary least squares regressions on the influence of members' characteristics on the objectives
Ordinary least squares regressions on the influen- ce of member characteristics on satisfaction
Article
This manuscript examines the member-agricultural cooperative relationship from the point of view of the agency and the property rights theories. The sample analysed includes 277 personal surveys completed by members of agricultural cooperatives in the Region of Murcia (Spain). Results show that in all questions related to objectives and level of satisfaction, members value them with an average of 6.9 out of 10 or higher in all cases. For both objectives and satisfaction, the directors and the cooperative members who depend upon agricultural activity for a large percentage of their income have higher scores, compared with non-board members and members who are less dependent on agricultural activity (with a statistical significance of 1% and 5%, respectively). We also find that members who agree in more with the admission of new members, who think it is easy to recover their investments and who want to stay longer in the cooperative are those who are more willing to invest and to exert control. Furthermore, we find that members that prefer to have a participation in the assembly proportional to their contribution and that prefer that the cooperative diversifies more are those who are more willing to invest. In addition, control is favoured by members pertaining to the cooperative for a large period and for those members who think that investing in the cooperative is a high risk and who prefer long-term investments. Finally, directors are more willing to invest and to exert control.
 
Some physical and chemical properties of the soils studied 
Wet aggregate stability values for different soils and aggregate sizes after different numbers of freeze-thaw cycles 
Article
Freezing and thawing affect soil aggregate stability. Understanding the effects of freezing and thawing processes on aggregate stability is necessary for the development of strategies for managing saline-sodic soils. This study was performed to determine the effects of freezing and thawing cycles (two, four, and six) on wet aggregate stability in six soils of different salinity and sodicity (54 dS m-1, 11.7%; 49 dS m-1, 11.8%; 53 dS m-1, 31.7%; 85 dS m-1, 39.7%; 59 dS m-1, 13.9%; 68 dS m-1, 36.8%, respectively) and three different aggregate sizes (< 1, 1-2, and 2-4 mm). The experiments were conducted under laboratory conditions using disturbed and non-cropped soil samples. In soils with a high percentage of exchangeable sodium and high electrical conductivity, the effect of freeze-thaw cycles on the wet aggregate stability was not significant. However, when the electrical conductivity was high and the percentage exchangeable sodium relatively low, wet aggregate stability was significantly reduced by the freeze-thaw cycles. Moreover, for aggregate sizes of 1-2 and 2-4 mm, a significant reduction (P < 0.01) was seen in the wet aggregate stability of samples that underwent six freeze-thaw cycles compared to those that underwent two cycles.
 
Article
El presente trabajo expone la incidencia de diferentes intensidades de tránsito sobre el suelo de un sistema frutícola, para evaluar la distribución vertical de la compactación inducida. Se utilizaron un tractor ligero y otro pesado, los cuales pasaron una, cinco y diez veces sobre un suelo previamente arado hasta una profundidad de 200 mm. El suelo, de textura arcillosa, tenía una humedad promedio de 23 %. Los parámetros físicos cuantificados para evaluar la compactación fueron densidad aparente e índice de cono. El índice de cono del suelo sin tránsito se incrementó significativamente con el primer pase de cualquiera de los dos tractores. El primer pase de ambos vehículos originó más del 75 % de la densificación máxima alcanzada luego de pasar 10 veces. La presión en el área de contacto rueda/suelo fue la responsable de la compactación superficial cuando los tractores circularon una y cinco veces.
 
Summary of the model performance on estimating evaporation an water temperature
Annual and monthly evaporation with (E C ) and without the cover (E), relative im- portance of monthly evaporation with respect to the annual value and evaporation reduction factors (F R )
Net margin per m 3 of irrigation water for most usual crops in the Segura River Basin (Segura et al., 2006)
Article
Agricultural water reservoirs (AWRs) are commonly used to guarantee water supply throughout the whole irrigation season in arid and semiarid areas. An important fraction of the total stored water is lost through evaporation, substantially decreasing overall irrigation efficiency. In this study, the effects of suspended shade cloth covers (SSCCs) on reducing evaporation and on the quality of the stored water have been experimentally assessed. To this aim, an AWR located in south-eastern Spain was monitored during two consecutive years. During the first year, the AWR remained uncovered, while during the second year it was covered with a black polyethylene SSCC. The evaporation rate, the water temperature profile and the driving meteorological variables determining evaporation were measured to assess the technical viability of the cover. Evaporation measurements for covered conditions were compared with estimations obtained from an openwater evaporation model which was validated during the first year of experimentation. A reduction close to 85% in the evaporation rate was found. To assess the effects on water quality, water samples and measurements with a multiparametric instrument were monthly collected during the two-year experimental period. Electrical conductivity, chlorophyll concentration and turbidity were measured using this equipment. Results indicate that the reduction in solar radiation (1% transmission through the cover) dramatically reduced the photosynthetic activity; hence algal bloom was highly limited. Finally, the main benefits and costs associated with the cover installation were identified in order to analyse economic viability under different scenarios representative of the current irrigated farming situation in south-eastern Spain.
 
Gain of cereal area BLUP estimator with respect to the DE estimator currently used in ESYRCE
Article
This article aims to be a contribution to the improvement of agricultural and environmental official statistics. Methods are applied to integrate information from state agency registers regarding crop area with ground data observed in random area samples. To improve the precision of crop area estimates in small areas (municipalities), methods using ground survey and remote sensing are applied. To improve temporal resolution of crop area estimators, methods based on time series analysis are applied. Agro-meteorological models are applied to improve crop yields statistics. A method is shown whereby crop rotation models may be a useful tool to forecast changes in the dynamics of the use of natural resources (soil, water and air) by agriculture and to foresee their environmental impact. Finally, a method to update and disaggregate information from territorial censuses on land uses is applied. These methods and models are illustrated in the framework of an information system belonging to the Spanish Ministry of the Environment and Rural and Marine Affairs. The relative improvement offered by each method is assessed by evaluating the precision gain of the proposed crop area estimates versus those currently used by the aforementioned information system.
 
Properties of diesel fuel and different fuel blends with methyl ester
Methyl ester analysis
Engine power (kW) for different fuel blends and different OECD engine testing points
Engine torque (N m) for different fuel blends and different OECD engine testing points
Break specific fuel consumption (BSFC) (g kw -1 h -1 ) for different fuel blends and OECD engine testing points
Article
This paper shows the results of an investigation carried out to assess the application of different fuels produced by blending diesel fuel with methyl ester obtained from mixture of 75% (v/v) sunflower oil and 25% (v/v) used cooking oil on a Kubota agricultural indirect injection diesel engine, natural aspirated, and with a rated horsepower of 19.7 kW. Seven fuels, namely diesel fuel; 90:10, 80:20, 70:30, 50:50, 25:75 and 0:100 (%v/v) blends were prepared and tested for the performance of the diesel engine in accordance with the standardised OECD test code 2. The test results showed that the performance of the engine was satisfactory without a significant reduction in power output and torque with blends smaller than 50%. Fuel consumptions with biodiesel were higher than that when fuelled with diesel but differences were not very marked up to 30% blends. As the reduction of the engine thermal efficiency was less than the corresponding reduction in heating value of the different biodiesel blends, the latter resulted in a more complete combustion in comparison with diesel fuel. The oxides of nitrogen (NOx) emissions were found to be reduced as the biodiesel concentration increase, particularly with 70% and 100% blends. The emissions of carbon monoxide (CO) were lower and increased at a lower rate with the oxygen concentration of the exhaust as the biodiesel blends were equal or higher than 50%.
 
Evolution of citrus insurance contracts in Spain in the period 1998-2006
Statistics of the analysed variables
Bi-variate correlation coeff icients among the analysed variables (Rho of Spearman)
Summary of the model and parameter estimations.Insurance premium = f (Risk)
Article
Agricultural insurance has an essential role as a tool for risk reduction. This is especially important in a changing and uncertain environment as in agriculture. Insurance acts as a compensating mechanism of loss and risk transference between insured and insurer. This paper aims to find if there is a concluding relationship amongst the rates applied by insurance companies; the insurance premium applied to the insured farmers; the real risk level that farms face and the indemnifications that farmers get after a disaster. There were 418 citrus tree farms analysed in Murcia region (Spain) in the period 2002-2006. They were in the line called «Multicultivo de Cítricos y Complementario» (Citrus Multi-crop and Complementary). The correlation coefficients of the different analyses are close to zero (between 0.047 and 0.053). This indicates no relation between the real risk and the rate that insurance companies use. The rate is almost a constant, with no dependence on the risk of suffering damage. The main conclusion is that the present agricultural insurance system is not discriminating enough and the settlement of insurance premiums that insurance companies apply does not maintain any relation to the essential element that should direct an insurance contract: the risk that a disaster has occurred.
 
Estimates of the Ordered Probit Models postulated to explain individuals' opinion on different attributes of multifunctional agriculture
Article
This paper aims to contribute further research on the conceptualization of agricultural multifunctionality through quantitative methods. The empirical analysis is based on a large dataset (Agrobarometre of Andalusia) consisting of self-reported measures of individual opinions on multifunctionality. Ordered probit models are proposed to analyze the extent to which individuals' perceptions of multifunctionality can be explained not only by individual and regional characteristics, but more importantly, by the preferences individuals have for a given type of agriculture. Results indicate that individuals are aware of the multi-dimensional nature of agriculture as a provider of private and public goods and services, although a big fraction of the population still focuses its demand on private goods production. It is not surprising that individuals' perceptions about the multifunctionality concept are site-specific, depending on the surrounding farming systems. Given their stated preference for a type of agricultural multifunctionality, the proposed quantitative method highlights those attributes of the concept which do not fully satisfy individuals' expectations. Overall, this manuscript provides a useful empirical tool for policy-makers concerned with improving satisfaction on the perception of multifunctionality in the agricultural sector.
 
Distribution of farms in Galicia according to size classes. The size of a dairy farm is measured in terms of the numbers of cows on the farm
Percentage of farms for each first-order combination with two land uses
Distribution of farm type in Galicia according to size class for the 1989 and 1999 census of agriculture (corn silage was not considered in the 1989 census)
Article
Agricultural activity in Galicia, North West Spain, is carried out on farms that are characterized by a diversity of land use and production models, a variety of farm sizes, and considerable geographical dispersion. Any attempt of Agricultural Production Planning aimed at characterizing production models requires a method of analysing data and obtaining technicaleconomic results from farms in the different areas. Models based on average statistical data are limited because they represent farms that do not exist in reality. This study develops a methodology to characterize and group dairy farms into different types according to the following basic variables: land use, size classes and production systems. The information used in this study was microdata from the 1999 Census of Agriculture. The methodology developed was also applied to microdata from the 1989 Census of Agriculture, thus obtaining significant information about the evolution of agricultural activity. The tools used in the analysis were Microsoft Access and Excel, and an application that was developed using Microsoft Visual Basic. The methodology presented can be used to analyse the evolution of the sector or to model future trends.
 
Variables in the used tractor database
Remaining value by year for different tractors sizes with respect to value in the fourth year.
Article
This work analyses the market value of second hand agricultural tractors in Spain for the period 1999-2002, with the aims of obtaining the most appropriate valuation models (through the use of ordinary least squares regression) and proposing an empirical model that estimates the true depreciation of these vehicles. Differences in tractor depreciation were studied in terms of the three horsepower groups normally employed (< 60, 60-90, > 90 hp), as well as in terms of a new power classification (< 80, 80-133 and > 133 hp) that appears to better reflect the influence of horsepower on the change in market value. The results show tractor depreciation to be exponential, with larger, more powerful tractors depreciating more quickly than smaller machines En el presente trabajo se analiza el valor de mercado de los tractores agrícolas de segunda mano en España, durante el periodo 1999-2002, con el fin de obtener, por métodos de regresión mínimos cuadrados, los modelos de valoración más apropiados y proponer un método empírico de amortización que estime la depreciación real. Asimismo, se estudian diferencias de comportamiento de los tractores según los tres grupos de potencia utilizados normalmente en el mercado ( <60, 60-90, > 90 CV) y se propone una nueva clasificación de potencias (< 80, 80-133, > 133 CV) que refleja mejor los cambios del valor. Se demuestra que la depreciación es de tipo exponencial y mayor en los tractores de mayor tamaño o potencia que en los pequeños
 
The relationship between V 15 and V 200 for open pan (OP), single layer of black polyethylene (1-BPE) shade and double layer of black polyethylene (2-BPE) shade.
The daily pattern of the surface-to-air vapour pressure gradient, ∆e s , for open pan (OP), single layer of black polyethylene (1-BPE) shade and a double layer of black polyethylene (2-BPE) shade. Data are hourly values averaged over a period of several sunny days (average day).
Article
The potential use of shade covers to reduce evaporation from agricultural reservoirs motivated this study on the effect of black polyethylene shade on the evaporation rate from a small water body (Class-A pan) and of its driving variables. Evaporation was measured hourly in two pans during the summer in Cartagena (Spain), along with the measurements of air temperature and humidity, water temperature, solar radiation and wind speed. The first pan was uncovered whereas the second pan was covered with black polyethylene shade as either a single or double-layer. The main factors influencing reduced evaporation (mass transfer coefficient and surface-to-air vapour pressure deficit) were analyzed, focusing on the changes in the uncovered pan. In the shaded pan there was a decrease in daily evaporation of 75 and 83% for single and double-layer shade respectively. Condensation on the shade was considerable and was 14 and 21% of the daily evaporation losses for the single and double-layer shade respectively. It was concluded that (i) black polyethylene shade appears to be an efficient way to reduce evaporative loss from agricultural reservoirs, and (ii) an economic analysis of their implementation under the current scarce water supply, for agriculture, in southern Spain justified their use.
 
Description of the variables used in the analysis 
Results of the Tobit models 
Article
The reuse of treated water for agricultural irrigation is considered a promising option in regions facing water scarcity problems and there is an increasing number of reuse projects going on in southern European countries. The aim of this paper is to estimate the non-market benefits that society attaches to the use of reclaimed wastewater for agricultural purposes, as part of the economic assessment needed to evaluate the viability of this water management option. For this purpose, a contingent valuation study has been developed in the Segura River Basin in south-eastern Spain, interviewing 352 individuals from a representative sample of the basin's population. Results show that the use of reclaimed wastewater for irrigation has significant non-market environmental benefits (mean willingness to pay of €5.13 per month per household, which adds up to a total annual value of €23.3 million). In terms of volume, these benefits represent €0.31 m-3. Therefore, it can be concluded that the non-market benefits of using reclaimed wastewater for agriculture justify its implementation, as they overcome the average treatment costs of €0.16-0.26 m-3. Additionally, the analysis of preference heterogeneity suggests that the use of reclaimed wastewater in agriculture is more acceptable to people if they are made aware of their current payment for water sanitation. The inclusion of these non-market benefits in the overall assessment of water policy options will lead to better informed and more efficient water management decisions.
 
Article
A great number of flood irrigation districts which have low irrigation efficiency due to the high permeability of their soils cannot undertake a generalised changeover to pressurized irrigation systems in the short term. This work seeks to study the effects which the changeover of the irrigation system in the Irrigation District Nº V of Bardenas (Spain) would have on the hydric regime of the Miralbueno aquifer; also to evaluate different alternatives to improve water management based on the use of groundwater. For this, a model of the aquifer was made with the help of the Modflow 2000 software and different scenarios were simulated. The results indicate that generalised conversion to pressurized irrigation systems will cause a decrease in the average phreatic level (1.20 m) and in the volume of water drained by the ditches (49% less). Until this measure is taken, the irrigation efficiency of the agrarian system could be increased notably by intensifying the reuse of groundwater by means of: a) the construction of intercepting drainages to reuse groundwater in flood irrigation again, and b) the construction of appropriately distributed wells for drip irrigation of the current area of vegetables.
 
Mergers of Spanish Agrifood Cooperatives between 1995-2005
(cont.). Mergers of Spanish Agrifood Cooperatives between 1995-2005
Economic and financial mean and median ratios prior to and following the merger process and statistical test results
Article
Mergers have become the most widely accepted formula for business growth among many different sectors. However, these processes do not always contribute to obtaining the expected results, particularly from an economic viewpoint. In light of these reflections, this study attempts to establish whether mergers carried out between Spanish agrifood cooperatives during the period 1995-2005 have contributed to reaching some of the objectives they were set out to achieve: improving the economic-financial situation of the companies involved, increasing income and reducing costs. To do so, mergers that took place during this period were analyzed in four autonomous communities (Andalusia, Navarra, La Rioja and the Basque Country). Despite the considerable variability observed following the time-based analysis of the economic-financial situation of cooperatives prior to and after merger, statistically significant differences were only found in four of the fifteen variables studied. These were operating profit (a 99% reduction), financial income (an increase of 240%), extraordinary income (400% increase) and cost of goods sold (16% reduction), of all of which are calculated with respect to production value. The results obtained generally indicate that the objectives that were originally the motivation for initiating the merger processes have not been reached, as the financial situation of the cooperatives has not, by and large, undergone any significant improvement, nor have average unit costs been reduced. Performance and profitability have not improved either and the firms involved have found themselves at lower levels than the average for the sector.
 
List of 31 sweet and sour cherry cutivars examined in this study with their origin
Comparison of petiole length, blade length and leaf width in sweet cherry cultivars 'Garafal Napoleón' (improved, left) and 'Del Valle' (local, right). Scale in cm.  
Main parameters of flower, leaf and fruit in sweet (P. avium), duke (P. × gondouinii) and sour (P. cerasus) cherry species A posteriori species assignation
Comparison of the drooping vegetative habit of cherry cultivars 'Guindo del País 1' (left) and the intermediate vegetative habit of 'Guindo Tomatillo 2' (right).
Tree habit in sweet (sw) (P. avium L.) and sour (so) (P. cerasus L.) cherry cultivars
Article
Thirty-one traditional cultivars [26 sweet cherry (Prunus avium L.), four duke cherry (Prunus × gondouinii Rehd.), and one sour cherry (Prunus cerasus L.)] from Sierra de Francia and Arribes del Duero in Central-Western Spain were surveyed and characterized agromorphologically. A total of 37 descriptors, mainly defined by the International Plant Genetic Resources Institute and the International Union for the Protection of New Varieties of Plants were used to describe flowers, leaves, fruits and the tree itself over a 3 consecutive years. This made possible the unequivocal identification of 25 cultivars. A dendrogram gave a clear separation between the sour, duke and sweet cherry cultivars and showed existing synonymies and homonymies. This work is an important step in the conservation of genetic cherry resources in the province of Salamanca (Spain), which show distinctive and interesting agronomical characters such as low susceptibility to fruit cracking, high levels of soluble solids, early fruit maturity and great rusticity.
 
Article
The yield response to limited irrigation is a major concern where water resources are limited. The objective of the work was to know the agronomic response of 12 maize hybrids cultivars under full and limited irrigation levels. Full irrigation consisted in 5 to 7 furrow irrigations events (90 mm) applying a total depth of 450-630 mm. In the limited irrigation treatment, three irrigations (90 mm) were applied, beginning 2-3 weeks before silking and ending 3-5 weeks after it. Results indicated a mean yield loss of 17% due to limited irrigation. The main effect of limited irrigation was a reduction of the ears per plant and 1,000 kernel weight. Maize yield decreased as season length was reduced. The main effect of season length reduction was a reduction of kernels per ear. Limited or regulated deficit irrigation is one way of maximizing productivity of total applied water (PAW); thus, the limited irrigation treatment reached a higher PAW value (2.66 kg nr3) than full irrigation (1.90 kg m3). In both irrigation levels, PAW was higher as the growth cycle increased. It can be concluded that, in the conditions of Southern Spain, reduced irrigation provided larger yields when applied to long cycle cultivars (FAO 700-800), with increased PAW values.
 
Top-cited authors
Gonzalo Hervás
  • Spanish National Research Council
Angel R Mantecón
  • Spanish National Research Council
F. Javier Giráldez
  • Spanish National Research Council
Azucena Gracia
  • Centro de Investigación y Tecnología Agroalimentaria de Aragón
Tiziana de magistris
  • Centro de investigacion y tecnologia agroalimentaria de Aragon