To test an assumption that organic soil can ameliorate nutritional disorders associated with metal and salinity stresses, we exposed salt-sensitive strawberry and lettuce to four salinity (0–60 mM NaCl) and three contamination (0.3–5 mg Cd/kg) rates in peat (pHH2O = 5.5). The results showed that, even at 20 mM NaCl, salinity stress exerted a dominant effect on rhizosphere biogeochemistry and physiological processes, inducing leaf-edge burns, chlorosis/necrosis, reducing vegetative growth in crops; at ≥40 mM, NaCl mortality was induced in strawberry. Signifiacntly decreased K/Na, Ca/Na and Mg/Na concentration ratios with raising salinity were confirmed in all tissues. The combined CdxNaCl stresses (vs. control) increased leaf Cd accumulation (up to 42-fold in lettuce and 23-fold in strawberry), whereas NaCl salinity increased the accumulation of Zn (>1.5-fold) and Cu (up to 1.2-fold) in leaves. Lettuce accumulated the toxic Cd concentration (up to 12.6 mg/kg) in leaves, suggesting the strong root-to-shoot transport of Cd. In strawberry Cd, concentration was similar (and sub-toxic) in fruits and leaves, 2.28 and 1.86 mg/kg, respectively, suggesting lower Cd root-to-shoot translocation, and similar Cd mobility in the xylem and phloem. Additionally, the accumulation of Cd in strawberry fruits was exacerbated at high NaCl exposure (60 mM) compared with lower NaCl concentrations. Thus, in salinized, slightly acidic and organically rich rhizosphere, pronounced organo- and/or chloro-complexation likely shifted metal biogeochemistry toward increased mobility and phytoavailability (with metal adsorption restricted due to Na+ oversaturation of the caton exchange complex in the substrate), confirming the importance of quality water and soils in avoiding abiotic stresses and producing non-contaminated food.

This research was conducted in order to determine a potential use of waste sludge of animal origin as soil amendment in the relation to the content of macroelements N, P and S and to determine effect of sludge application on the quantity and quality of lettuce (Lactuca sativa L.). The experiment was set up in 3 treatments with 3 replications. Treatments included control and two different amounts of animal waste sludge which was used as soil amendment (fertilization) for lettuce. The study investigated crystal green salad sort Posavka because of good accumulation ability to N (nitrophilic plant). Results showed that content of total N in waste animal sludge was 7.48%, total P was 1% and content of total S was 1.55%. Statistical analysis showed no significant difference in yield between the treatments. The content of NO3 -in lettuce was not statistically significant between the treatments and the values were less than those prescribed by the legislation, which lead us to conclusion of safety use of sludge regarding the nitrates. According to the results of test parameters it can be cocluded that the animal waste sludge is well provided with macroelements (N, P and S) and suitable for use in agriculture as an amendment for improving soil quality. Certainly, for crops that are not used for human consumption, with additional obligated control of other chemical and microbiological parameter before the use.

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