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Land use has a great impact on soil dynamics. The soils of various land use systems in Central Karakoram have been under immense pressure in the recent past due to certain anthropogenic activities such as land use practices and land use cover changes. These influences have an impact on the spatial distribution of metallic elements (MEs) in the soils of various land uses. Herein, we investigated the occurrence of the MEs, copper (Cu), zinc (Zn), and nickel (Ni), in soils of various land uses such as the permafrost, pasture, forest, and agricultural lands of the Central Karakorum region. The MEs were extracted in exchangeable, adsorbed, organically bound, carbonated, precipitated, and residual forms. The concentrations of MEs showed a significant dependence on the extraction method used, and the extraction trend followed the order of EDTA > HNO3 > KNO3 > NaOH > H2O. Zn showed the highest concentration compared to Ni and Cu in all extractions, whereas the land uses' ME concentration followed the order of agricultural land > permafrost > forest > pasturelands. The highest values of total Zn, Ni, and Cu were 712 ± 01 mg/kg, 656 ± 02 mg/kg, and 163 ± 02 mg/kg, respectively, in agricultural soil. The ME concentration showed significant variations between different land uses, and the highest concentration was noted in agricultural soil. Zn was found to be a dominant ME compared to Ni and Cu. We believe this effort will provide opportunities for scholars to investigate MEs around the globe. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs), a new solid-state electron transfer material was anchored to nitrogen-doped TiO2 via sol gel method. The introduction of GQDs effectively extended light absorption of TiO2 from UV to visible region. GQD-N-TiO2 demonstrated lower PL intensity at excitation wavelengths of 320 to 450 nm confirming enhanced exciton lifespan. GQD-N-TiO2-300 revealed higher surface area (191.91m2 g−1), pore diameter (1.94 nm), TEM particle size distribution (4.88 ± 1.26 nm) with lattice spacing of 0.45 nm and bandgap (2.91 eV). In addition, GQDs incorporation shifted XPS spectrum of Ti 2p to lower binding energy level (458.36 eV), while substitution of oxygen sites in TiO2 lattice by carbon were confirmed through deconvolution of C 1 s spectrum. Photocatalytic reaction followed the pseudo first order reaction and continuous reductions in apparent rate constant (Kapp) with incremental increase in RB5 concentration. Langmuir–Hinshelwood model showed surface reaction rate constants KC = 1.95 mg L−1 min−1 and KLH = 0.76 L mg−1. The active species trapping, and mechanism studies indicated the photocatalytic decolorization of RB5 through GQD-N-TiO2 was governed by type II heterojunction. Overall, the photodecolorization reactions were triggered by the formation of holes and reactive oxygen species. The presence of •OH, 1O2, and O2• during the photocatalytic process were confirmed through EPR analysis. The excellent photocatalytic decolorization of the synthesized nanocomposite against RB5 can be ascribed to the presence of GQDs in the TiO2 lattice that acted as excellent electron transporter and photosensitizer. This study provides a basis for using nonmetal, abundant, and benign materials like graphene quantum dots to enhance the TiO2 photocatalytic efficiency, opening new possibilities for environmental applications. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an essential element for soil quality and plant growth. But little is known about P fractions consequent to microbial inoculation in soils amended with inorganic phosphorus. In this regard, the overall soil P fractions after microbial treatments varied as hydrochloric acid – P (HCl-P) > Sodium hydroxide – P (NaOH-P) > Sodium bicarbonate – P (NaHCO3-P) > Water – P (H2O-P) determined through sequential fractionation. Inorganic P amendment of soil increased residual P fractions indicating non-availability of chemical P fertilizers added in soil. Bacterial–fungal co-inoculation, significantly increased NaHCO3-P and H2O-P fractions, as compared to mono inoculations and un-inoculated controls. Inoculated microbial populations increased in numbers contributing to the modification of the soil pH. In soil without TriCalcium Phosphate (TCP), microbial treatments showed a reduced pH compared to the control, with a maximum pH decrease in mono bacterial inoculations. In conclusion, tested bacterial and fungal strains exhibited efficient P solubilization in soil, and thus, have potential to be used as biofertilizers, subject to other necessary trials. [ABSTRACT FROM AUTHOR]

Both salinity and cadmium (Cd) contamination of soils are the most critical issues of global food security. Soil application of biochar could decrease toxic metal and sodium (Na) uptake by plants in the season, but its long-term residual effects on metal uptake in latter crops need evaluation. A pot experiment with rice was conducted under ambient conditions in a Cdcontaminated soil which was used in an earlier experiment on wheat where soil was treated with different rates of biochar (0, 3, and 5% w/w) and irrigated with water having different salinity levels (0, 25, and 50 mM). Further treatments were not applied in the current study. The results revealed that plant growth and photosynthesis reduced while Cd and Na concentrations and oxidative stress were increased in plants under combined Cd and salinity. Biochar application reduced the Cd and Na concentrations and increased the potassium (K) concentrations in plants while diminished the oxidative stress in salt-stressed rice. Biochar positively affected the plant growth and physiology in a soil treated with 0, and 25 mM salt stress. However, plant growth and photosynthesis were reduced with biochar amendments under 50 mM NaCl stress. Soil AB-DTPA extractable Cd was higher in salinized soil without biochar addition, while biochar reduced the Cd extractability. It can be concluded that all biochar amendments had a significant residual effect on decreasing Cd and Na uptake while plant growth was negatively affected at higher biochar and salinity levels. [ABSTRACT FROM AUTHOR]

The sensitivity of crop genotypes determines the level of growth reduction by salinity. Effect of salinity levels (7.5 and 15 dihydrate m−1) using completely randomized design (CRD) with four replications per treatment were compared on germination, chlorophyll content, water potential, ionic sodium and potassium (Na+, K+) balance, and other growth-related parameters of six wheat genotypes for varietal differences under long-term salinity stress. Chlorophyll contents at flowering stage and yield aspects at maturity of all the wheat genotypes decreased with increasing salinity. The maximum Na+concentration was observed at 7.5 and 15 dS m−1in Bhakhar and Saher-2000, respectively, while minimum Na+concentration was observed for 9476. However, the maximum K+concentration and water potential was noticed in 9476 at 7.5 dS m−1. Careful selection of salt-tolerant genotypes for field crops is an important perspective especially in the developing countries facing salinity problem. Our results revealed that the wheat genotype 9476 performed best regarding growth and physiological parameters compared to other wheat genotypes. [ABSTRACT FROM AUTHOR]

Land use has a greater influence on the contamination of soils. The current research is conducted to study the effect of different land-use patterns and soil depth on heavy metal fractions in the soil. Significant differences among heavy metals (Cd, Cu, Fe, Ni, Pb, and Zn) in soils under various land use systems were observed. Variations in the soil heavy metals concentration were found dependent on land use patterns. Irrespective of the type of metal, Land uses differed for heavy metals concentrations in the order of fallow>pasture>crop>forest soils. Extracting reagents considerably varied for the concentrations of metals: HNO3>Na2EDTA>NaOH>KNO3>H2O. However, Ni concentration was found higher with NaOH than Na2EDTA. Surface soil indicated a higher magnitude of heavy metals than sub-surface soil. This study will provide valuable information on heavy metal fractions associated with land use in the Abbottabad region of lesser Himalayas, Pakistan. [ABSTRACT FROM AUTHOR]

Studies on the availability of plant nutrients in soils treated with manure co-composted feed-stocks are very rare. The present investigation aimed at studying the nutrient release pattern from three soils amended with maple tree leaves co-composted with cow manure. Soils were mixed with the compost at the rate of 20 t/hm² and incubated at room temperature. Prior to incubation, plants residue samples were analyzed for total elemental concentrations (NO3, NH4, P, K, Ca, Mg, Na, Zn, Mn, Fe, Cu, Ni and Cd). Water extractability of nutrients from soils was affected by the type of soil and ratio of composted manure applied. Extractable NH4, P, K, Ca and Mg concentrations varied in the descending order of sandy clay, sandy loam and silt loam except NO3. The concentrations of P, K, Ca and Mg in the amended soils increased with the ratio of manure co-composted with leaf litter while those of NO3, NH4 and trace elements decreased. The residual nutrients in soil varied directly with their contents in the compost amendments. Co-composting improved the availability of nutrients in soils and this should be an ideal approach to managing the enormous waste generated from the livestock sector for restoring soil fertility. [ABSTRACT FROM AUTHOR]