Giovanna Cucci

Improvement of soil properties by application of olive oil waste

Wet olive pomace is an organic lignocellulosic material, a by-product of the olive milling process, a typical and traditional activity in many Mediterranean countries. Wet olive pomace has difficult commercialization due to its high moisture content of 55–65%, that causes a noticeable increase in oil extraction costs. However, it could be conveniently reused in agriculture as a valid soil amendment to improve soil fertility and structure. Here, we studied the effects of the application of increasing amounts of non-fermented wet pomace on the fertility of a silty-clay soil, grown with 3 crops in succession: sunflower-wheat-wheat. The experiments were conducted at the Agricultural Faculty of Bari, Italy, on a Pachic Hoploxeroll soil characterized by illite and kaolinite and large amounts of Fe and Al sesquioxides. We compared the effect of wet pomace applied at amounts ranging from 0 to 210 Mg ha−1, incorporated 60 days prior to sunflower sowing. In the wheat late season of the second year, average samples from the 0–0.60 m layer were taken and tested for structural stability, organic matter, total nitrogen, available phosphorus, exchangeable potassium, pH and saturation extract electrical conductivity. The results indicate that the application of wet pomace induces a general improvement in soil fertility. In particular, the incorporation of increasing amounts of wet pomace improved nutrient content. For instance, an application of 210 Mg ha−1 of wet pomace increased soil organic matter by +84%, total N by +0.90 g kg−1, available P by +79.40 mg kg−1 and exchangeable K by +80 mg kg−1. We also observed an improvement in soil structure, which is of particular importance in hot, arid environments and in sustainable agricultural systems.

Kaolin influences tomato response to salinity: physiological aspects

Environmental stress as salinity can negatively affect the physiology of tomato plants. Conditions leading to a reduction of transpiration can contribute to greater tolerance to salinity. Use of kaolin-based particle film technology (PFT) may be an effective tool to control stomatal conductance and transpiration rate, thus mitigating the detrimental effect of salinity. The present three-year study has investigated the effects of kaolin application on leaf gas exchange, leaf water potential, leaf and canopy temperature of field-grown tomato, irrigated with brackish water by drip method, in southern Italy. Treatments were: (1) three salinity levels of irrigation water (electrical conductivity of water = 0.5, 5 and 10 dS m−1); (2) tomato plants treated or not with kaolin; and (3) two cultivars in each year. The increase in salinity caused the reduction of leaf water potential, stomatal conductance, net photosynthesis and transpiration rate, and the increase of leaf and canopy temperature. Kaolin has resulted in an improvement of leaf water potential, and the reduction in gas exchange variables in low-salinity conditions. Under high salinity, kaolin was effective in limiting the reductions in net photosynthesis and reducing leaf and canopy temperature. These latter variables were slightly affected by kaolin, in different ways in respect to the saline treatments; while in non-saline conditions were 0.2–0.5°C higher in the kaolin-treated plants, the situation was reversed in more saline treatment. The variation of leaf and canopy temperature shows that kaolin influences the thermal balance mainly for the dual effect of reflection of the incident radiation and partial occlusion of the stomata. Kaolin mitigated detrimental effects of salinity also on yield, contributing to the improvement of income for the farmers. The use of kaolin-based PFT may be an effective tool to alleviate salinity stress in tomato production under arid and semi-arid conditions.

Geostatistical modelling of within-field soil and yield variability for management zones delineation: a case study in a durum wheat field

The paper proposes a geostatistical approach for delineating management zones (MZs) based on multivariate geostatistics, showing the use of polygon kriging to compare durum wheat yield among the different MZs (polygons). The study site was a durum wheat field in southern Italy and yield was measured over three crop seasons. The first regionalized factor, calculated with factorial cokriging, was used to partition the field into three iso-frequency classes (MZs). For each MZ, the expected value and standard deviation of yield were estimated with polygon kriging over the three crop seasons. The yield variation was only in part related to soil properties but most of it might be ascribable to different patterns of meteorological conditions. Both components of variation (plant and soil) in a cropping system should then be taken into account for an effective management of rainfed durum wheat in precision agriculture. The proposed approach proved multivariate Geostatistics to be effective for MZ delineation even if further testing is required under different cropping systems and management.

Leaching effect of rainfall on soil under four-year saline water irrigation

Cucci G., Lacolla G., Mastro M.A., Caranfa G. (2016): Leaching effect of rainfall on soil under four-year saline water irrigation. Soil & Water Res., 11: 181−189. In 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 salinity.

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.

Effect of composted sewage sludge on morpho-physiological growth parameters, grain yield and selected functional compounds of barley.

BACKGROUND Several studies have evaluated the effects of composted sewage sludge on barley and found a positive influence on crop productivity. No studies have investigated the effects of composted sewage sludge on functional compounds of the caryopsis, such as phenolics and β-glucans. The former play a role in plant defence mechanisms and both could be influenced by variations of kernel size related to fertilization intensity. The present study aimed to evaluate the effect of different doses (3-12 mg ha-1 ) of composted sewage sludge applied alone or in combination with mineral fertilization on morpho-physiological and yield qualitative parameters, especially phenolics and β-glucans contents of grains, in barley. RESULTS Increasing fertilization rates, irrespective of fertilizer type, improved morpho-physiological and yield parameters, whereas the phenolic compounds and the related antioxidant activity significantly decreased (P < 0.05). The β-glucans and the main color indices did not show significant differences. The combined application of 6 mg ha-1 sewage sludge and nitrogen was not significantly different from mineral fertilization. Morpho-physiological and qualitative parameters, as well as bioactive compounds, were all significantly correlated with nutrient levels, with higher r values for nitrogen. CONCLUSION Composted sewage sludge had a similar effect compared to mineral fertilization.

Indirect Measurement of Electrical Conductivity and Exchangeable Cations on Soil Water Extracts: Assessing the Precision of the Estimates

Abstract The electrical conductivity of saturated soil paste extracts with respect to the electrical conductivity of extracts obtained applying different soil-water dilution ratios (from 1:1 to 1:5) was estimated considering 194 soil samples of different texture, salinity, and pH. A smaller data set composed by 50 samples was used to estimate exchangeable sodium percentage (ESP) values from the concentration of soluble cations determined on 1:2 water extracts. Both estimation procedures were carried out applying a linear multivariate model, according to a “stepwise” approach. The dilution ratio 1:2 provided the best estimates, although all the dilution ratios gave reasonable results. The ESP prediction model included the concentration of soluble sodium; the addition of electrical conductivity and pH values of the 1:2 soil-water extracts improved precision.

Yield response of fennel (Foeniculum vulgare Mill.) to irrigation with saline water

Salinity causes yield reductions if threshold levels are exceeded, while it can cause the deterioration of some qualitative parameters and/or the improvement of others. Two years (2000–2001, 2006–2007) research was carried out to evaluate the effect of water quality on yield and quality of fennel, a vegetable very common in Apulia region. We compared two types of soil and two sodium absorption ratio of irrigation water obtained by dissolving in distilled water NaCl + CaCl2 (1:1) or only NaCl, and four electrical conductivity of water of 0.7 (control), 4, 8 and 12 dS m−1. The soil type does not show any noticeable effect on the tested parameters. The salt type influenced the plant development and the total soluble solids contained in the bulbs. The plant height, the leaf and the bulb weight were, respectively, 6, 11 and 21% higher in NaCl + CaCl2 treatment as compared to NaCl one. The plant height, the leaf and the bulb weight dropped, respectively, by 33, 49 and 71%, shifting from 0.7 to 12 dS m−1 salinity treatments. The dry matter content and total soluble solids increased with rising salinity. In fact, shifting from the control to the more saline treatment, the leaves and the bulbs dry matter increased, respectively, by 15 and 13%, and total soluble solids increased by 17%. Moreover, the increase in salinity favoured the production of flattened bulbs. The application of the Maas and Hoffman model to salinity response confirms the ranking of this species among moderately salt sensitive species, even though the critical threshold was the same for NaCl and NaCl + CaCl2 treatments (1.26 dS m−1), while the slope was higher in NaCl treatment (14.24% m dS−1) than NaCl + CaCl2 (10.39% m dS−1).

Spatial distribution of roots and cracks in soils cultivated with sunflower

ABSTRACT The 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.