JWSS - Journal of Water and Soil Science

Because of the undesirable effects of lead on soil properties and human health, evaluation of its remediation methods seems to be essential. In order to evaluate the effect of humic acid (HA) on the  decontamination of lead (Pb) spiked-soils in the presence of wormwood plant (Artemicia absantium), an experiment was carried out in a completely randomized  block design with three replications. Experiment factors including different concentrations of Pb (Pb(NO₃)₂ in the  solid form) (0, 250, 500 and 1000 mg kg^-1) and levels of HA (0, 100 and 200 mg kg^-1) were considered. At the end of the growing period of plants, some soil and plant properties were measured. According to the results, BR, MBC, root and shoot dry weights, RWC and Fe and Zn concentrations in the shoot were decreased by increasing the soil Pb concentration. So, the mean values of BR and MBC in Pb₁₀₀₀ treatment was 60 and 51.1 percent lower than those of Pb₀, respectively. Pb accumulation in the root and shoot was enhanced as a result of the increase in the soil Pb concentration. The maximum Pb concentration of shoot (37.10 mg kg^-1) and root (38.1 mg kg^-1) was seen in the Pb₁₀₀₀ treatment. Also, the results suggested that humic acid had a positive effect on the shoot of Fe, Zn and Pb concentrations. So, the concentration of these elements in HA₂₀₀ treatment showed an increase 1.25, 1.64 and 1.66 times more than that of HA₀, respectively. Leaf proline amount was increased significantly by elevating the soil Pb concentration; however, application of 200 mg kg^-1 humic acid decreased leaf proline by 54.5 percent, as compared to the control (HA₀). Therefore, humic acid effect on increasing the plant Pb uptake, improving soil biological properties, and increasing availability and dissolution of Pb showed its ability in promoting the phytoremediation efficiency. According to the obtained results of this study, woodwarm plant (Artemicia absantium) is a non-accumulator that could not be used for phytoremediation purposes.

The pyrolysis of fruit trees Pruning waste to be converted to biochar with microbial inoculation is a strategy improving the biological properties in calcareous soils. In order to investigate the biochar effect on some soil biological properties of the soil in the presence of microorganisms, a factorial experiment was carried out in a completely randomized design in the rhizobox under greenhouse condition. The factors included organic matter (pruning waste biochar and control), microbial inoculation (arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria) and soil (rhizosphere and non-rhizosphere). After the end of the wheat plant growth period, microbial respiration (BR), Substrate-induced respiration (SIR), microbial biomass carbon (MBC), microbial biomass phosphorus (MBP), acid phosphatase (ACP) and alkaline phosphatase (ALP) enzymes in the rhizosphere soil and non-rhizosphere soil were determined. The results showed that the biochar and microbial inoculation application increased BR, SIR, MBC, MBP and ALP and decreased ACP, as compared to the control. So, the highest increase in the value of BR, SIR and MBC was related to mycorrhizal inoculation with biochar. An increase of 2.67 fold of ACP activity was observed in the treatment of bacterial inoculation with Biochar, as compared to the control treatment. Also, pruning waste biochar increased the amounts of MBC, MBP and ALP by 45.62%, 56.22% and 62.6% in the rhizosphere soil rather than non-rhizosphere soil, respectively. Microbial inoculation led to the increase of 1.31 and 1.41 folds by MBP and ACP in the rhizosphere soil, as compared with non-rhizosphere soil. Bacterial inoculation in the rhizosphere soil increased the ACP enzyme activity (28.31%), as compared with non-rhizosphere soil. It could be concluded that application of biochar in the conditions of microbial inoculation improved the soil biological properties.

Synergistic relationships between mycorrhizal fungi (AMF) and organic compounds affect the mobility of the micronutrient elements in the rhizosphere and improve their bioavailability. In order to evaluate the effect of biochar and pruning waste compost of apple and grape trees, as well as AMF, on micronutrient bioavailability in calcareous soil at the wheat rhizosphere, an experiment was carried out in a completely randomized design under greenhouse conditions in a rhizobox study. Some factors including the organic sourses (pruning waste biochar, pruning waste compost and control), microbial inoculation (AMF and no inoculation) were considered. At the end of the growth period, Organic matter (OM) content and bioavailability of micronutrients including iron (Fe), Zinc (Zn), Copper (Cu) and Manganese (Mn) in the rhizosphere and their uptake by wheat plant were determined. The results indicated that OM, Fe, Zn, Mn and Cu were significantly increased in the rhizosphere soil under the influence of organic sources and mycorrhizal inoculation. Furthermore, biochar application in the mycorrhizal tratment resulted in 74.73% and 19.28% increase in Fe and Mn, as compared to non-inoculated conditions, in rhizosphere. The presence of mycorrhizal fungi increased the bioavailability of 94.66% and 29.54% Zn and Cu in the compost treatment, as compared to non-inoculated ones. Application of organic sources and mycorrhizal inoculation increased the micronutrient uptake and plant dry weight.

In order to investigate P acquisition efficiency (PACE) and P utilization efficiency (PUTE) of the corn in the presence of phosphate-solubilizing microorganisms (PSMs), a factorial experiment was carried out in a completely randomized design in the greenhouse. The factors were including P sources (tricalcium phosphate (TCP) and rock phosphate (RP)) and microbial inoculation (control, soluble P as KH₂PO₄ (Ps), inoculation with bacteria (PSB), inoculation with fungi (PSF), co-inoculation of PSB + PSF). At the end of growth period, plant dry weight and P content in plant and soil available-P were measured and then PACE, PUTE and phosphorus efficiency (PE) indices were calculated. The results showed that, the interaction of phosphate source and microbial inoculation was significant with respect to shoot P content, soil P, PUTE and PE. PSF-TCP treatment increased 7 times shoot phosphorus content compared to cont-RP treatment.  PUTE in Cont-TCP treatment was 2.35 times higher than the TCP-P_S. The inoculation of PSF increased the PACE 1.61 times compared to co-inoculation of PSB + PSF tretment. Also, the highest PE index (99%) was obtained from SF-TCP treatment. In general, in calcareous soils with low P availability, inoculation of PSM with insoluble phosphorus sources can meet the phosphate needs of the plant.

can provide useful information about P adsorption and the factors affecting it. A batch experiment was performed with phosphorus concentrations (0 to 35 mg/L) in two soils with different electrical conductivity (EC) (2 and 15 dSm^-1) by a variety of biochar treatments including simple apple-grape biochar (BC), rock phosphate- biochar (BC-RP), enriched-biochar (BC-H₃PO₄-RP), enriched-biochar (BC-HCl-RP), triple superphosphate (TSP), and control (Cont). The results indicated that phosphorus sorption capacity varied between the soils. Biochar treatments were effective in reducing the phosphorus adsorption of both soils. Due to BC-H₃PO₄-RP and BC-HCl-RP treatments, the maximum phosphorus adsorption of soils decreased in S1 soil by 14 and 23 % and in S2 soil by 26 and 19%, respectively. Also, the use of these treatments decreased the parameters of Langmuir absorption intensity (K_L) of S1 soil to 0.085 and 0.066, respectively and S2 soil to 0.11 and 0.15, L/mg respectively, and Freundlich absorption capacity (K_F) of S1 soil decreased to 19.2 and 22.5 and S2 soil to 28.2 and 28.1 L/kg, respectively. Enriched biochars significantly reduced the buffering indices of both soils indicating phosphorus adsorption decreased and increased the availability of phosphorus for the plant. The standard phosphorus requirement of S2 soil was lower than S1 soil by both equations. Therefore, enriched biochar can be an effective strategy to increase phosphorus availability and reduce the use of chemical fertilizers in saline and non-saline conditions; however, more field studies are needed for a clear understanding of the potential of P-enriched biochar as a fertilizer alternative.