This study evaluates the effect of planting three cover crops (CCs) (barley, Hordeum vulgare L.; vetch, Vicia villosa L.; rape, Brassica napus L.) on the direct emission of N₂O, CO₂ and CH₄ in the intercrop period and the impact of incorporating these CCs on the emission of greenhouse gas (GHG) from the forthcoming irrigated maize (Zea mays L.) crop. Vetch and barley were the CCs with the highest N₂O and CO₂ losses (75 and 47% increase compared with the control, respectively) in the fallow period. In all cases, fluxes of N₂O were increased through N fertilization and the incorporation of barley and rape residues (40 and 17% increase, respectively). The combination of a high C:N ratio with the addition of an external source of mineral N increased the fluxes of N₂O compared with -Ba and -Rp. The direct emissions of N₂O were lower than expected for a fertilized crop (0.10% emission factor, EF) compared with other studies and the IPCC EF. These results are believed to be associated with a decreased NO₃(-) pool due to highly denitrifying conditions and increased drainage. The fluxes of CO₂ were in the range of other fertilized crops (i.e., 1118.71-1736.52 kg CO₂-Cha(-1)). The incorporation of CC residues enhanced soil respiration in the range of 21-28% for barley and rape although no significant differences between treatments were detected. Negative CH₄ fluxes were measured and displayed an overall sink effect for all incorporated CC (mean values of -0.12 and -0.10 kg CH₄-Cha(-1) for plots with and without incorporated CCs, respectively).

A pot experiment was conducted to determine the influence of commercial nanoparticles (ZnO-NPs) at different doses for use as nanofertilizer on nutrient uptake and its distribution in cherry tomato (Solanum lycopersicum L var. cerasiforme) plants in an acidic (soil pH 5.5) and calcareous soil (soil pH 8.5) from the Mediterranean area. We determined crop yield; macro- (N, P, K, Mg, S and Ca) and micro-nutrient (B, Cu, Fe, Mn, Na and Zn) concentrations in the different parts of the crop (root, stem, leaves and tomato fruits) and the extent of nutrient translocation to the aerial part of the plant. The concentrations of macronutrients N, P, K and Mg in tomato fruits grown in both soils can be considered adequate in terms of nutritional requirements. However, the Ca concentration in tomato fruits grown in the calcareous soil did not reach the required concentration to be considered sufficient. This effect was related to the characteristics of this calcareous soil. Although different concentrations of ZnO-NPs did not affect Fe and Na concentrations in tomato fruit, B concentration in tomato fruits increased with the application of ZnO-NPs. In addition, Cu concentration decreased with the application of ZnO-NPs compared to treatments without any Zn application (Nil-ZnO NP) in the calcareous soil. Manganese concentrations decreased with ZnO-NPs application in both soils. The effect of the application of ZnO-NPs depends on soil characteristics. Zinc applied as a nanofertilizer in the form of ZnO-NPs can be used to increase the crop yield and to obtain an adequate Zn biofortification in cherry tomato crop. The Zn concentrations in tomato fruits reached ranges of 4.5–4.8 mg Zn kg⁻¹ in the acidic soil and 2.5–3,5 mg Zn kg⁻¹ in the calcareous soil. Nutrient concentrations in these fruits following biofortification are adequate for human consumption.

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Soil salinity and salt leaching are a risk for sustainable agricultural production in many irrigated areas. This study was conducted over 3.5 years to determine how replacing the usual winter fallow with a cover crop (CC) affects soil salt accumulation and salt leaching in irrigated systems. Treatments studied during the period between summer crops were: barley (Hordeum vulgare L.), vetch (Vicia villosa L.) and fallow. Soil water content was monitored daily to a depth of 1.3 m and used with the numerical model WAVE to calculate drainage. Electrical conductivity (EC) was measured in soil solutions periodically, and in the soil saturated paste extracts before sowing CC and maize. Salt leaching was calculated multiplying drainage by total dissolved salts in the soil solution, and use to obtain a salt balance. Total salt leaching over the four winter fallow periods was 26 Mg ha−1, whereas less than 18 Mg ha−1 in the presence of a CC. Periods of salt gain occurred more often in the CC than in the fallow. By the end of the experiment, net salt losses occurred in all treatments, owing to occasional periods of heavy rainfall. The CC were more prone than the fallow to reduce soil salt accumulation during the early growth stages of the subsequent cash crop