Giuseppina Crescimanno

Structure alteration of a sandy-clay soil by biochar amendments

PurposeThe aim of the present study was to investigate structure alterations of a sandy-clay soil upon addition of different amounts of biochar (fbc).Materials and methodsAll the fbc samples were analyzed by high energy moisture characteristic (HEMC) technique and 1H nuclear magnetic resonance (NMR) relaxometry. HEMC was applied in order to evaluate aggregate stability of biochar-amended soil samples. 1H NMR relaxometry experiments were conducted for the evaluation of the pore distributions through the investigation of water dynamics of the same samples.Results and discussionThe HEMC technique revealed improvement in aggregate stability through measurements of the amount of drainable pores and the stability ratio. The latter increased as the amount of biochar was raised up. The 1H NMR relaxometry revealed a unimodal T1 distribution for both the sole sandy-clay soil and the biochar. Conversely, a bimodal T1 distribution was acquired for all the different fbc samples.ConclusionsImprovement in aggregate stability was obtained as biochar was progressively added to the sandy-clay soil. A dual mechanism of water retention has been hypothesized. In particular, intra-aggregate porosity was indicated as the main responsible for molecular water diffusion when fbc comprised between 0 and 0.33. Conversely, inter-aggregate porosity resulted predominant, through swelling processes, when fbc overcame 0.33.

Parameter estimation by inverse method based on one-step and multi-step outflow experiments

Abstract The applicability of the inverse method for determining the soil water characteristic θ(h) and the hydraulic conductivity/water content K(θ) functions was investigated on two Typic Haploxererts characteristic of the Sicilian environment. Shrinkage behaviour of the two soils was analysed in order to verify if significant changes in soil volume occurred during the outflow process. One-step outflow experiments were performed, with comparisons between different procedures analysed not only in terms of estimated average functions, but also from the point of view of the uncertainty in the predictions, evaluated by a first-order analysis. Multi-step outflow experiments were then performed and compared to results obtained by the one-step method. The results showed that the θ(h) and K(θ) functions deduced by performing optimization on the outflow volume V vs. time t obtained from multi-step experiments supplemented with three equilibrium θ(h) values were more reliable than the θ(h) and K(θ) functions determined by performing optimization on the V(t) obtained from one-step experiments supplemented with independently determined θ(h) values.

Plant Response to Saline-Water Irrigation in a Sicilian Vineyard

This chapter presents results of a 3-year field investigation in a vineyard located in Sicily (Mazara del Vallo, Trapani) within the framework of the Project “Evolution of cropping systems as affected by climate change” (CLIMESCO). Soil-plant responses to two saline irrigation waters were determined by measuring soil hydrological characteristics, soil salinity, crop transpiration and stomatal conductance in field plots of a Sicilian vineyard. The results proved that crop transpiration (T r) and stomatal conductance (G s) were significantly affected by soil salinity conditions, expressed by electrical conductivity of soil saturation extract (ECe). Significant reductions in T r and G s were found in plants irrigated with water of ECw = 1.6 dS m−1 (L) compared to T r and G s values in plots irrigated with water ECw = 0.6 dS m−1 (R). Significantly higher crop water stress index (CWSI) values, indicating stronger stress conditions, were measured in the L treatment, relative to the R treatment. Validity of the linear relationship between relative yield and relative transpiration was confirmed. A value of 0.7 for the yield response factor (Ky) provided accurate prediction of yield reduction in years 2008 and 2009. Reductions due to soil salinity, calculated according to Maas and Hoffman equation, showed that under conditions of water and salinity stress, yield reduction due to salinity represented a percentage of the total yield reduction of up to 11% in the L plots and up to 3.5% in the R plots. The investigation also indicated that ECe (1.5 dS m−1) discriminated a different plant response to salinity, indirectly confirming the Maas threshold value for grapes. Under the irrigation conditions in the Sicilian vineyard, it is suggested to implement management strategies aimed at keeping soil salinity below this threshold value. This can be realized by using low-salinity irrigation water only or by alternating the two irrigation sources.

Monitoring Soil Salinisation as a Strategy for Preventing Land Degradation: A Case Study in Sicily, Italy

Water demand is increasing worldwide. In regions affected by water scarcity such as those located in the Mediterranean basin, water supplies are already degraded, or subjected to degradation processes, which worsen the water shortage. In Sicily, the increasing scarcity of good quality water is expanding irrigation with saline-sodic waters, thus enhancing the risk of secondary salinization and sodification. Adequate management practices are urgently needed for sustainable use of saline/sodic waters. This chapter illustrates how the Geonics EM-38 probe was used for monitoring salinization in a Sicilian area where irrigation with saline water is increasingly practiced, and the risk of salinisation and desertification is envisaged. Electrical conductivity of bulk soil (ECa) measurement grids were taken with the EM-38 in a Sicilian vineyard at several dates, both prior to, and following irrigations, with two distinct irrigation treatments of different salinities (0.6 and 1.6 dS m–1 respectively). Though both water sources contributed to field salinity, high salinity source had a more adverse effect. This investigation proved the usefulness of EM-38 for efficient, rapid monitoring of the progressive effects of different irrigation strategies on soil salinization.