Green Synthesis of Different Nanoparticles and its Effect on Irrigation Water and Soil Properties and Origanum Majorana Productivity

The term of nanotechnology has emerged recently in several fields of interest that refers to the researches and innovations that are concerned with making materials on a very small size close to the scale of atoms and molecules. In the present work, the effects of green synthesis of different nanoparticles on the quality of irrigation water, the availability of some heavy metals content in soil and the plant, and the productivity of Marjoram were studied in detail. The obtained results showed that the addition of nanoparticles (NPs) materials has resulted in noticeable variations in the removal percentages of Cu and Fe from aqueous solution. The maximum values obtained for adsorption of Cu (II) on ZnO, MgO, and SiO2 NPs, within pH (3–5) were 89.9%, 83.3%, and 68.36%, respectively. Whereas, the maximum adsorption values of Fe (III) at pH 3.3 were 82%, 80%, and 65% for ZnO, MgO, and SiO2 NPs, respectively. It was clearly seen that the effective of NPs application on reduction of the available Cu in the studied soil samples. The order of sequence for the effects of NPs application was found to take the following order Zn2 > Zn1 > Mg2 > Si2 > Mg 1 > Si1 > C (control). The highest values of the available Cu were observed in the control treatment, whereas the lowest values were obtained when Zn2 was added, and the same tendency was observed with the substantial concentrations of Fe. The addition of NPs to the soil samples had positively affected the Cu uptake via plant. The effects of NPs and the additions of Cu and Fe on the availability of NPK in the soil system were very completed and osculated from one treatment to another. The same tendency was observed with the total concentration of NPK in the plant.

Carbon Materials Advancing Microorganisms in Driving Soil Organic Carbon Regulation

Carbon emission from soil is not only one of the major sources of greenhouse gases but also threatens biological diversity, agricultural productivity, and food security. Regulation and control of the soil carbon pool are political practices in many countries around the globe. Carbon pool management in engineering sense is much bigger and beyond laws and monitoring, as it has to contain proactive elements to restore active carbon. Biogeochemistry teaches us that soil microorganisms are crucial to manage the carbon content effectively. Adding carbon materials to soil is thereby not directly sequestration, as interaction of appropriately designed materials with the soil microbiome can result in both: metabolization and thereby nonsustainable use of the added carbon, or—more favorably—a biological amplification of human efforts and sequestration of extra CO2 by microbial growth. We review here potential approaches to govern soil carbon, with a special focus set on the emerging practice of adding manufactured carbon materials to control soil carbon and its biological dynamics. Notably, research on so-called “biochar” is already relatively mature, while the role of artificial humic substance (A-HS) in microbial carbon sequestration is still in the developing stage. However, it is shown that the preparation and application of A-HS are large biological levers, as they directly interact with the environment and community building of the biological soil system. We believe that A-HS can play a central role in stabilizing carbon pools in soil.

Rhizobium Inoculation Enhances the Resistance of Alfalfa and Microbial Characteristics in Copper-Contaminated Soil

Some studies have reported the importance of rhizobium in mitigating heavy metal toxicity, however, the regulatory mechanism of the alfalfa-rhizobium symbiosis to resist copper (Cu) stress in the plant-soil system through biochemical reactions is still unclear. This study assessed the effects of rhizobium (Sinorhizobium meliloti CCNWSX0020) inoculation on the growth of alfalfa and soil microbial characteristics under Cu-stress. Further, we determined the regulatory mechanism of rhizobium inoculation to alleviate Cu-stress in alfalfa through plant-soil system. The results showed that rhizobium inoculation markedly alleviated Cu-induced growth inhibition in alfalfa by increasing the chlorophyll content, height, and biomass, in addition to nitrogen and phosphorus contents. Furthermore, rhizobium application alleviated Cu-induced phytotoxicity by increasing the antioxidant enzyme activities and soluble protein content in tissues, and inhibiting the lipid peroxidation levels (i.e., malondialdehyde content). In addition, rhizobium inoculation improved soil nutrient cycling, which increased soil enzyme activities (i.e., β-glucosidase activity and alkaline phosphatase) and microbial biomass nitrogen. Both Pearson correlation coefficient analysis and partial least squares path modeling (PLS-PM) identified that the interactions between soil nutrient content, enzyme activity, microbial biomass, plant antioxidant enzymes, and oxidative damage could jointly regulate plant growth. This study provides comprehensive insights into the mechanism of action of the legume-rhizobium symbiotic system to mitigate Cu stress and provide an efficient strategy for phytoremediation of Cu-contaminated soils.

An overview of a land evaluation in the context of ecosystem services

The environment is changing quickly and it is ever more burdened in connection with the greater needs of human society. This fact has increased efforts to improve the management of land and natural resources and the necessity to evaluate them. Land valuations become more important as the land consumption increases. Soil needs to be evaluated in the whole context of how its quality is affected and the values it provides. The concept of ecosystem services offers this holistic view. This paper defines ecosystem services (ES), the various linkages between soil properties, their functions and benefits, the assessment of soil quality using indicators and then briefly mentions EU environmental assessment methods and terms used in the context of ES. The article also mentions frameworks with which to assess and evaluate the soil quality that can be divided into two groups. The first group is comprised of a framework of indicators that describe the current state of the soil system assessment for evaluating the quality of the agricultural land. This is based on a detailed measurement of the terrain, a statistical analysis of soil databases or processing the status of specific threats to the soil. The second group is comprised of a framework of indicators focused on changes in the soil quality and applied soil management. These frameworks deal with the productivity of the soil in various systems of farming, compare agricultural systems or discuss the advantages of soil biota as indicators of soil quality in detail. Many of the designs of the soil quality indicators focus on the soil management in the context of a single discipline such as agriculture or water pollution. There are concepts for considering the soil quality in regional planning.

Establishment of a transparent soil system to study Bacillus subtilis chemical ecology

Bacterial secondary metabolites are structurally diverse molecules that drive microbial interaction by altering growth, cell differentiation, and signaling. Bacillus subtilis, a Gram-positive soil-dwelling bacterium, produces a wealth of secondary metabolites, among them, lipopeptides have been vastly studied by their antimicrobial, antitumor, and surfactant activities. However, the natural functions of secondary metabolites in the lifestyles of the producing organism remain less explored under natural conditions, i.e. in soil. Here, we describe a hydrogel-based transparent soil system to investigate B. subtilis chemical ecology under controllable soil-like conditions. The transparent soil matrix allows the growth of B. subtilis and other isolates gnotobiotically and under nutrient-controlled conditions. Additionally, we show that transparent soil allows the detection of lipopeptides production and dynamics by HPLC-MS and MALDI-MS imaging, along with fluorescence imaging of 3-dimensional bacterial assemblages. We anticipate that this affordable and highly controllable system will promote bacterial chemical ecology research and help to elucidate microbial interactions driven by secondary metabolites.

Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection

Gas concentrations and isotopic signatures can unveil microbial metabolisms and their responses to environmental changes in soil. Currently, few methods measure in situ soil trace gases such as the products of nitrogen and carbon cycling or volatile organic compounds (VOCs) that constrain microbial biochemical processes like nitrification, methanogenesis, respiration, and microbial communication. Versatile trace gas sampling systems that integrate soil probes with sensitive trace gas analyzers could fill this gap with in situ soil gas measurements that resolve spatial (centimeters) and temporal (minutes) patterns. We developed a system that integrates new porous and hydrophobic sintered polytetrafluoroethylene (sPTFE) diffusive soil gas probes that non-disruptively collect soil gas samples with a transfer system to direct gas from multiple probes to one or more central gas analyzer(s) such as laser and mass spectrometers. Here, we demonstrate the feasibility and versatility of this automated multiprobe system for soil gas measurements of isotopic ratios of nitrous oxide (δ18O, δ15N, and the 15N site preference of N2O), methane, carbon dioxide (δ13C), and VOCs. First, we used an inert silica matrix to challenge probe measurements under controlled gas conditions. By changing and controlling system flow parameters, including the probe flow rate, we optimized recovery of representative soil gas samples while reducing sampling artifacts on subsurface concentrations. Second, we used this system to provide a real-time window into the impact of environmental manipulation of irrigation and soil redox conditions on in situ N2O and VOC concentrations. Moreover, to reveal the dynamics in the stable isotope ratios of N2O (i.e., 14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O), we developed a new high-precision laser spectrometer with a reduced sample volume demand. Our integrated system – a tunable infrared laser direct absorption spectrometry (TILDAS) in parallel with Vocus proton transfer reaction mass spectrometry (PTR-MS), in line with sPTFE soil gas probes – successfully quantified isotopic signatures for N2O, CO2, and VOCs in real time as responses to changes in the dry–wetting cycle and redox conditions. Broadening the collection of trace gases that can be monitored in the subsurface is critical for monitoring biogeochemical cycles, ecosystem health, and management practices at scales relevant to the soil system.