Soils In Spain Research Articles

The influence of organic amendment and nickel pollution on tomato fruit yield and quality

The effects of organic fertilization (sludge application) and/or different levels of Ni pollution on tomato fruit yield, quality, nutrition, and Ni accumulation were investigated. The mass loading of sewage sludge solids used in this study for the amendment of a calcareous soil with low organic matter content was 2% (w/w). A control with no sewage sludge amendment was also included (S). Nickel was added to the sludge amended soil at 0, 60, 120 and 240 mg kg‐1 concentrations. Sewage sludge addition to the calcareous soil significantly increased fruit yield but did not adversely affect the quality and nutritional status of the tomato fruit. The results demonstrated that sewage sludge could be successfully used as a horticultural fertilizer. Only the highest addition rate of Ni (240 mg kg‐1) to an organic amended calcareous soil had negative effects on fruit yield and quality, and caused a Ni accumulation in fruit that could be considered as a hazard for human health. Thus, no toxic problems will be encountered in tomato fruit due to Ni pollution provided the total Ni (soil Ni plus Ni incorporated with sludge amendment) concentration is kept below the maximum concentration of Ni allowed for agricultural alkaline soils in Spain (112 mg Ni kg‐1).

A method for the collection of soil monoliths from stony and gravelly soils

Monolith collection of soils with large amounts of coarse fragments, or of wet soils, pose specific problems which are directly related to their lack of physical stability. The purpose of this paper is to outline a procedure for soil monolith collection which is highly appropriate for these cases. A permanent backing is prepared on site with gypsum plaster before detaching the profile from the soil face. The soil is initially stabilized with an aqueous suspension of vinyl latex. A permanent backing is prepared on site by casting a gypsum plaster slurry between the soil section and a backing board. This will fill all voids and anchor the coarse fragments protruding from the soil exposure. Once the plaster has set, the soil monolith can be safely dug out and transported. Little finishing is needed afterwards in the laboratory. The procedure has been successfully demonstrated in a variety of soils in Spain.

Spatial analysis of gypsiferous soils in the Zaragoza province (Spain), using GIS as an aid to conservation

Within the Ebro valley, the Zaragoza province contains the largest area of gypsiferous soils in Spain. Previous mapping of the gypsum outcrops has been the starting point for this study of the soils developed on them. In this paper, gypsiferous soils are differentiated according to geological age, lithological facies and other depositional features. The most abundant gypsiferous soils correspond to Tertiary outcrops, where a typical catena includes Leptosols on the crest of the hillslopes, Regosols on the talus and Gypsisols on the valley bottom. Gypsiferous soils, developed on the Triassic Keuper facies and Quaternary materials, occupy a relatively small area. The gypsiferous soils have been mapped at a scale of 1:200 000. A CAD software package has been used for digitizing the soil units. A digital elevation model of the Zaragoza province has been created from the digitized topography. The geographical information system, IDRISI, has been used to integrate all the spatial information generated and to produce maps of the soil types classified according to slope and precipitation. In the Zaragoza province, the gypsiferous soils (Lithic and Eutric Leptosols, Petric, Calcic and Haplic Gypsisols, Gypsic Regosols, Gypsic Solonchaks) occupy a total area of 229 619 ha (13% of the area of the province). 25% of the gypsiferous soils occur within the semiarid area (annual rainfall<400 mm) indicating that climate is the main limiting factor for soil conservation, because of the fragility of gypsiferous soils, special care must be taken with land use operations on the 18 137 ha with slopes above 10°. The knowledge of the distribution of gypsiferous soils in relation to topographic and climatic factors provides an important basis for soil conservation and management.

Symbiotic effectiveness and bacteriocin production by Rhizobium leguminosarum bv. viceae isolated from agricultural soils in Spain

A collection of twenty wild type strains of Rhizobium leguminosarum bv. viceae was obtained from five different agricultural locations in Granada (Spain) and tested with a commercial cultivar of faba bean ( Vicia faba cv. Alborea) under monoxenic conditions of culture in Leonard jars, in order to study the diversity of symbiotic efficiency among local isolates in terms of nodulation and nitrogenase activity. There were large and significant differences in these symbiotic parameters between the rhizobial strains. Bacteriocin production of Nod + Fix + indigenous isolates of R. leguminosarum bv. viceae was also investigated. Strain Z25 characterized in this study was one of the most effective isolates, according to nodule dry matter accumulation and total ARA results, and showed broad bacteriocinogenic activity on rhizobia, with a high potential to inhibit growth of other strains belonging to the biovar viceae, but not bacteria belonging to other genera. The bacteriocin is produced by strain Z25 under a wide range of culture conditions, and some of the properties of the active compound showed here (non-dialysability, sensitivity to heat and proteolytic enzymes) strongly suggest a proteinaceous nature. Strain Z25 appears to be a promising candidate for use as an inoculant under field conditions.

The influence of aspect and vegetation on seasonal changes in erosion under rainfall simulation on a clay soil in Spain

The seasonal and spatial variability of soil erosion under contrasting slope aspects in southeastern Spain was studied by performing and interpreting 84 rainfall simulation experiments conducted at an intensity of 55 mm h−1 during 1 h. The vegetated soils on the north-facing slope and the upper afforested parts had negligible sediment yield, runoff and erosion, while the bare soils on the south-facing slope had very high runoff rates. Runoff sediment concentration decreased over time during simulated rainfall events on the vegetated areas while it increased on the bare ones. Solute release decreased over time on both surface types. Seasonally, runoff sediment concentration was highest in autumn, decreasing in winter and spring, due to the exhaustion of erodible soil and the vegetation growth. Sediment concentrations increased slightly in summer when runoff and erosion rates where very low. Increasing seasonal variability corresponded with increasing runoff and soil loss rates. Key words: Runoff, soil loss, Mediterranean, erodibility

Mineralogical and chemical modifications in soils affected by a forest fire in the Mediterranean area

We studied the mineralogical and chemical modifications in four soils in Spain produced by a forest fire: two of the soils developed under Quercus pyrenaica and two under Juniperus oxycedrus. Samples were taken 2 and 8 months after the fire. Increases in soil pH, electrical conductivity, exchangeable-bases and total Ca occurred in both soils, but were more evident under Juniperus oxycedrus. The presence of calcite and alteration of vermiculite, were observed in soils beneath Juniperus oxycedrus, but not Quercus pyrenaica. This was due to lower temperatures reached during the fire in the mineral soil under this species. By heating plant and soils samples in the laboratory to 300, 400 and 500°C, the formation of calcite during the burning of Quercus pyrenaica (500°C) and Juniperus oxycedrus (300°C) was confirmed. According to the chemical and mineralogical modifications observed in-vitro, the temperature in the mineral soil under Juniperus oxycedrus reached during the fire was close to 300°C.

Effect of different cultivars, mainly of wheat, on the population densities of Pratylenchus thornei and Merlinius brevidens in dry soils in Spain

Effect of different cultivars, mainly of wheat, on the population densities of Pratylenchus thornei and Merlinius brevidens in dry soils in Spain

Isolation and characterization of Azotobacter chroococcum from the roots of Zea mays

Bacteria showing rapid growth on a nitrogenfree medium and acetylene-reducing activity were isolated from maize roots collected from agricultural soils in Spain. The isolates were Gram-negative motile rods and were identified as Azotobacter chroococcum. Acetylene-reducing activity and microbial counts were determined on root segments from 7- and 30-day-old plants. Rates obtained were in the range of 0.0053–0.848 nmol C 2H 2 · g −1 · h −1. Root populations were 1.4–6.0 × 10 4 micro-organisms · g −1. These results showed that there was an association between A. chroococcum strains and roots of maize planted in some Spanish soils.

Isolation and characterization ofAzotobacter chroococcumfrom the roots ofZea mays

Abstract Bacteria showing rapid growth on a nitrogenfree medium and acetylene-reducing activity were isolated from maize roots collected from agricultural soils in Spain. The isolates were Gram-negative motile rods and were identified as Azotobacter chroococcum . Acetylene-reducing activity and microbial counts were determined on root segments from 7- and 30-day-old plants. Rates obtained were in the range of 0.0053–0.848 nmol C 2 H 2 · g −1 · h −1 . Root populations were 1.4–6.0 × 10 4 micro-organisms · g −1 . These results showed that there was an association between A. chroococcum strains and roots of maize planted in some Spanish soils.

INTERSPERSED SALT-AFFECTED AND UNAFFECTED DRYLAND SOILS OF THE LOWER RIO GRANDE VALLEY

The effects of soluble salts on soil productivity are global. Recent reports present information about saline soils in Spain (1), Iraq (2, 7), Canada (6), Egypt (16), and the United States (8, 10, 15, 19). Although in some areas much has been done towards reclaiming saline soils (5, 9, 17, 19), in other areas plagued by salinity problems (1, 6, 7), little or no progress is evident

New blastomycetes isolated from soils of Spain. I. Schwanniomyces castellii nov. spec.

A new species of Schwanniomyces is described; it was isolated from a soil taken in Spain. This species is named Schwanniomyces castellii nov. spec. in honour of prof. Tommaso Castelli (director of “Istituto di Microbiologia Agraria e Tecnica della Universita di Perugia”).

Agriculture and Horticulture

THE problem of devising a universally applicable system of soil classification calls for a wide knowledge of the soils found in different parts of the world as well as an intimate acquaintance with soils in the field. An attempt at devising such a system is made, by a pedologist with both these qualifications, in Prof, del Villar's work on the soils of Spain and Portugal.

Art. XX.—On the Authorities for the History of the Dominion of the Arabs in Spain

None of the Spanish historians who lived before the present century possessed even the slightest knowledge of the Arabic language, and even they stumbled at every step when they had to treat of the Muhammadan dynasties, and their hostile or friendly relations with the Christians. Casiri alone, in his catalogue of the MSS. in the library of the Escurial, edited and translated some extracts from Arab authors; and this was all that had been done down to 1820, when the first volume of Conde's History appeared, and the world imagined that the light of this newly-risen sun was at length, in a great measure, to dissipate the darkness that had for ages enveloped the doings of the Arab and the Berber on the soil of Spain.