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An inadequate replacement of organic matter in agricultural lands progressively leads to soil fertility reduction and therefore, soil application of organic fertilizers and amendments should be promoted. The objectives of this 3-year research project on organic lettuce were to investigate the agronomic performance of experimental organic amendments obtained by using agro-industrial wastes in comparison with a commercial organic fertilizer, and to evaluate their short-term effects on soil mineral-N and soil organic carbon changes. Two types of olive pomace mixtures, with different initial C/N ratios, were composted and either stopped at the active phase (A1 and B1) or processed until maturation (A2 and B2). Also an anaerobic digestate (DA) and the B2 in combination with mineral fertilizer (B2-MIN) were studied. The four composts, DA and B2-MIN were compared with a commercial organic fertilizer (Org), and an unfertilized control (N0). Results suggested that the best compromise for organic lettuce yield and soil fertility could be obtained with the B2 compost, thus highlighting the need for choosing a good stage of maturity of the compost, along with an appropriate C/N ratio of composting mixture, to improve the fertilizing efficiency of agro-food residues in organic farming. Furthermore, the application of immature amendments did not increase (B1) or significantly reduce (A1) marketable lettuce yield, indicating that the choice of organic fertilizer is an important concern in sustainable agriculture, especially in organic vegetable production.

A field experiment was carried out in southern Italy to investigate the effects of irrigation and salinity on a maize crop and soil properties. The experiment was laid out comparing different irrigation rates (I1, I2, I3—re‐establishing 50, 75 and 100% of the calculated maximum evapotranspiration) and water quality (FW, fresh water and SW, saline water). Grain yield was significantly greater by 60% in 2008 than in 2010. No significant difference was shown for grain yield between the irrigation treatments, whereas water productivity decreased significantly with increasing irrigation rates. Irrigation with saline water did not significantly reduce grain yield compared with fresh water, but it improved grain quality with higher protein content (9.1%) and lower grain moisture percentage (13.3%). Saline water determined a significant increase of saturated soil paste extract Na, ECe, SAR, some exchangeable cations and ESP compared with FW in both years. Furthermore, at the end of the experiment these parameters were lower than those at the end of the first maize crop. Lastly, in the saline treatment, at the end of the trial, the ECe and ESP values were below the critical threshold for soil salinization and/or sodification. Copyright © 2016 John Wiley & Sons, Ltd.

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A field experiment was conducted in Mediterranean conditions to evaluate the effects of different irrigation volumes and water quality on yield performance of tomato crop. The tomato crop was irrigated re-establishing 50 (I1), 75 (I2) and 100% (I3) of the crop evapotranspiration (ETc) with two water quality: fresh water with EC 0.9 dS m-1 (FW) and saline water with EC 6 dSm-1 (SW). At harvest, total and marketable yield, weight, number, , total soluble solids (TSS) and dry matter of fruit were calculated, The results showed no statistical differences among the three different irrigation volumes on tomato yield and quality. The salinity treatment did not affect yield, probably because the soil salinity in the root zone on average remained below the threshold of tomato salt tolerance. Instead, salinity improved fruit quality parameters as dry matter and TSS by 13 and 8 %, respectively. After the first field application of saline water, soil saturated extract cations (SSEC), electrical conductivity of soil paste extract (ECe), sodium absorption ratio (SAR) and exchangeable sodium percentage (ESP) cations increased; the largest increase of cations, in particular of Na, occurred in the top layer. At the end of the experiment, the absolute value of SSEC, ECe and SAR, for all the effects studied, were lower than those recorded in 2007. This behavior was suitable to the reduced volumes of treatments administered in 2009 in respect to the 2007. Furthermore, the higher total rainfall recorded in 2009 increased the leaching and downward movement of salts out of the sampling depth

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The objective of this study was to compare the results of calcimetric and dry combustion methods for quantitative estimation of soil total inorganic carbon (TIC). To this aim, 117 soil samples from three localities in the Mediterranean area (one in Spain and two in Southern Italy), representing a wide range of total inorganic carbon contents (ranging from 1.9 to 54 g 100g−1), were collected. TIC (expressed as CaCO3) was quantified using the volumetric calcimeter method, as reference, and dry combustion in order to find an accurate and rapid method, suitable for different types of soils. The results revealed a concordance between the two methods compared, as shown by the recovery values close to one, for the whole data set and for data grouped per experimental site. Specifically, the dry combustion method showed slightly greater values of TIC compared to volumetric method, probably due to soil acid pretreatments, in dry combustion, and to an incomplete decomposition of carbonates that would require more time for removal, in a calcimeter method. Linear regression equations between the two methods were not affected by different soil types. Overall, our study demonstrated that the dry combustion was a reliable method and could provide accurate estimates of TIC in soils with different calcium carbonate content.