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Correzione di terreni irrigati con acque salino-sodiche. Risposta della coltura di fagiolo borlotto.
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Impiego di fanghi compostati di qualità come ammendante. effetti sulla patata (Solanum tuberosum L.
No full textSpatial distribution of roots and cracks in soils cultivated with sunflower
No full textThe aim of this research was to investigate the spatial distribution of roots and cracks in two clay soils cropped with sunflower under different inter-row spacing in order to identify the optimal management. A latin square experimental design was applied to compare bare soil and soil cropped with sunflower, with three plant densities, obtained by keeping constant the number of plants on the row (3 plants m−1) and varying the row spacing (0.4, 0.6, 0.8 m). The presence of the crop and the different distance between rows influenced soil moisture content as well as the root spatial distribution and thus the structural features of cracks. Increasingly lower values of moisture were found in both soils as the distance between rows decreased; an opposite trend was observed for both root density and crack size. The volume of cracks in the soil grown with sunflower at 0.4 m row spacing was 201.4 m3 ha−1, thus 8 times higher than the value on the bare soil and 2.5 times higher compared to the one grown at 0.8 m between rows. Optimal results in terms of root density, soil moisture and crack size were obtained with an inter-row spacing of 0.6 m
Leaching effect of rainfall on soil under four-year saline water irrigation
Full text linkIn the context of the overall competition for water resources it is important to understand the complex dynamics of crop water management including evapotranspiration, water quality, and leaching requirement, each of them depending on the site-specific conditions. The research started with grain maize and continued with sunflower, grain maize, and wheat, at the experimental field. On both grain maize and sunflower, 10 irrigation treatments were compared that resulted from the factorial combination of two types of water (fresh and brackish water) with five irrigation regimes; the scheduled treatments were applied by furrow irrigation. The amount of salts brought into the soil with the irrigation water during the three irrigation seasons of our trial increased shifting from the lowest to the highest irrigation regime and with the increase of salinity in the irrigation water. From the study of salt distribution in the soil it follows that at the end of the irrigation season the salt concentration increased by passing from the middle of the furrow, a zone more subject to leaching during irrigation, to the intermediate zone between the furrow and the ridge, and in the middle of the ridge between two contiguous furrows, an area of confluence of the wetting and salt accumulation fronts. The leaching water supplied during the irrigation season was poorly efficient in leaching the salts brought in through irrigation, whereas the rainfall water of the autumn-winter period after the irrigation season ensured a good control of soil salinit
Indirect measurement of electrical conductivity and exchangeable cations on soil water extracts: Assessing the precision of the estimates
No full textThe electrical conductivity of saturated soil paste extracts withrespect to the electrical conductivity of extracts obtained applying differentsoil-water dilution ratios (from 1:1 to 1:5) was estimated considering 194soil samples of different texture, salinity, and pH. A smaller data set com-posed by 50 samples was used to estimate exchangeable sodium percentage(ESP) values from the concentration of soluble cations determined on 1:2water extracts. Both estimation procedures were carried out applying a lin-ear multivariate model, according to a“stepwise”approach. The dilutionratio 1:2 provided the best estimates, although all the dilution ratios gavereasonable results. The ESP prediction model included the concentrationof soluble sodium; the addition of electrical conductivity and pH valuesof the 1:2 soil-water extracts improved precisio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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