Use of Azolla as a growing medium component in the nursery production of olive trees

Peat is used in olive-tree nurseries as a component in commercial growing media. Environmental and economic pressures are questioning the use of peat as a component of substrates. In order to remain competitive and to satisfy environmental concerns, it is necessary to identify and evaluate possible alternatives to peat. This study involves the use of Azolla filiculoides, as a growing media component in olive nurseries (Olea europaea L.) for containerized plants. Four treatments were established, based on the addition of increasing quantities of Azolla (0%, 25%, 50%, and 100 %). Were determined some physical and chemical properties of media, the growth, the physiological parameters and nutritional state of olive plants. The physical and chemical properties of the media were significantly affected by the Azolla content. Nursery-produced olive plants grown in substrates supplemented by 50 % Azolla displayed linear growth and the total biomass production greater than those of the control medium. The research indicated that Azolla might be suitable substrate component for olive plants grown in containers

effect of reclamation on the structure of silty clay soils irrigated with saline sodic waters

Abstract The objective of the work was to evaluate, by using the micromorphometric method, the effects of reclamation on porosity of two different clay loam soils irrigated with saline-sodic waters. Soil samples of the Ap horizon were put in cylindrical containers and irrigated with 9 types of saline-sodic waters (3 levels of salinity combined with 3 levels of sodicity). After a 4-year period, correction treatments were initiated by addition of calcium sulphate and leaching until electrical conductivity and sodium absorption ratio values of the drainage water matched 3 dS m-1 and 9, respectively. After 2 years of correction treatments, undisturbed soil samples were taken from the surface layer and soil thin sections for porosity measurements. Both soils did not show critical macroporosity values (> 10%, below this threshold a soil is classified as compact). Nevertheless, the soils exhibited a different behaviour: total porosity of the Pachic Haploxeroll soil was not affected by difference in water salinity and alkalinity; on the contrary, the Udertic Ustochrept soil showed a lower porosity associated with higher salt concentration in the irrigation waters. This may be due to the different iron and aluminium sesquioxides content and, as a consequence, a different effect on soil aggregate stability

Soil slope exposure affects physico-chemical and microbiological properties in soil aggregate size fractions

Slope exposure is known to affect soil biogeochemical processes in mountainous forest ecosystems, but little attention has yet been paid to its influence at a soil aggregate scale. Therefore, we evaluated the effects of slope exposure (north- vs south-facing slope) on the physico-chemical and microbiological properties of bulk soil and dry-sieved and water-stable aggregate size fractions in both organic (OF) and mineral (AE) horizons in an Italian alpine forest. The changes in organic carbon (OC) and nitrogen (ON) fractions were assessed together with a battery of thirteen enzyme activities involved in the main nutrient cycles. In addition, soil biological properties including microbial biomass (estimated as double-stranded DNA content), and microbial activity (assessed as the ratio between the extra-(exDNA) and intracellular (iDNA) fractions of the total soil DNA pool) were determined. The OF horizon at the north-facing slope was enriched in recalcitrant and insoluble OC and ON fractions and characterized by a lower microbial activity, as indicated by the higher exDNA/iDNA ratio with respect to the south-facing slope. On the contrary, exDNA and iDNA contents, microbial biomass, as well as most of the enzyme activities, reached higher levels at the southern exposure in the AE horizon. These exposure-effects were bulk soil- and aggregate size fraction-specific. Overall, lower values of the chemical and microbiological parameters were found in the water-stable fraction. Our findings indicate that slope exposure (and thus topography), soil horizon, and aggregate size distinctly influence soil OC dynamics in mountain ecosystems.Austrian Science Fund | Ref. I989-B16Ministerio de Economía, Industria y Competitividad | Ref. RYC-2016-2123

Soil slope exposure affects physico-chemical and microbiological properties in soil aggregate size fractions

Slope exposure is known to affect soil biogeochemical processes in mountainous forest ecosystems, but little attention has yet been paid to its influence at a soil aggregate scale. Therefore, we evaluated the effects of slope exposure (north- vs south-facing slope) on the physico-chemical and microbiological properties of bulk soil and dry-sieved and water-stable aggregate size fractions in both organic (OF) and mineral (AE) horizons in an Italian alpine forest. The changes in organic carbon (OC) and nitrogen (ON) fractions were assessed together with a battery of thirteen enzyme activities involved in the main nutrient cycles. In addition, soil biological properties including microbial biomass (estimated as double-stranded DNA content), and microbial activity (assessed as the ratio between the extra-(exDNA) and intracellular (iDNA) fractions of the total soil DNA pool) were determined. The OF horizon at the north-facing slope was enriched in recalcitrant and insoluble OC and ON fractions and characterized by a lower microbial activity, as indicated by the higher exDNA/iDNA ratio with respect to the south-facing slope. On the contrary, exDNA and iDNA contents, microbial biomass, as well as most of the enzyme activities, reached higher levels at the southern exposure in the AE horizon. These exposure-effects were bulk soil- and aggregate size fraction-specific. Overall, lower values of the chemical and microbiological parameters were found in the water-stable fraction. Our findings indicate that slope exposure (and thus topography), soil horizon, and aggregate size distinctly influence soil OC dynamics in mountain ecosystems

Soil ecosystem functions in a high-density olive orchard managed by different soil conservation practices

The long-term effects of two different soil management practices, natural grass cover (NC) and conservation tillage (CT), on soil functions (carbon sequestration, habitat for organisms, and water movement and retention) were determined in a high-density, mature olive orchard (Olea europaea L. cv. Frantoio) growing in a sandy loam soil (Typic Haploxeralf) in a Mediterranean environment. Ten years after the beginning of the different soil management, soil samples were collected at 0–10 and 10–20 cm depth and at two distances from the trunk, underneath the olive canopy (UC) and in the inter-row (IR). There were no differences in fruit yield, oil yield, and yield efficiency between the two soil management systems during the 2011–2013 period. CT negatively affected soil organic carbon pools (total and humified), but only at the IR position. The distance from the plant did not significantly influence soil structure and hydrological properties, while NC treatment increased water movement and retention. Tillage reduced the microarthropod abundance, in particular Collembola and eu-edaphic forms, which were the most sensitive groups to soil perturbation. We conclude that natural grass cover was more effective than conservation tillage in maintaining or improving elements of soil functionality

EFFECT OF MANAGEMENT ON TOPSOIL STRUCTURE

This paper aims to show the effectiveness of different soil management strategies for improving soil structure in degraded areas within two vine farms inTuscany(Italy). The management practices adopted were: Composted organic amendment addition (COMP), Green Manure (GM), Dry mulching (DM) and Control (CONTR). Topsoil samples were taken at the beginning of the trial (2015) and two years later, and analyzed for bulk density (BD) and aggregate stability by wet sieving. The strategies adopted to restore the functionality of degraded vineyard soils diversely affected BD and aggregates stability. In both the farms COMP proved to be the best strategy to reduce BD, while GM and DM gave the best results in terms of aggregate stability increase

Soil Physical-Hydrological Degradation in the Root-Zone of Tree Crops: Problems and Solutions

The diffusion of tree crops has continuously increased during the last decades all over the world. The market boost has favored the adoption of intensive and highly mechanized cultivation, often triggering the degradation of the soil physical-hydrological qualities, mainly through enhanced soil erosion and compaction. Several papers have been published on soil degradation and restoration strategies in specific perennial crops and environments. This review paper collects such studies showing the sensitivity of soil under tree crops to the degradation of their physical-hydrological qualities. Then it reports the state of the art on the methodologies used for the evaluation of the physical-hydrological qualities in the field and in the laboratory, also suggesting an improved methodology for estimating the actual available water capacity. Some updated and promising experiences to recover the physical-hydrological qualities of soil are then illustrated. In particular, subsoiling and placement of drainages, spreading of organic amendments, compost, biochar, using of cover crops, and biological inoculants. A key point in applying the restoration practices is that they should not only be specific for the soil and tree rooting system, but also tailored according to the ecosystem functions that need to be improved besides plant health and yield

Soil Physical-Hydrological Degradation in the Root-Zone of Tree Crops: Problems and Solutions

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