Hamada Abdelrahman, PhD

Mitigation of greenhouse gas (GHGs) emissions and improving soil health using biochar (BC) shall help achieving the UN-Sustainable Development Goals. The impacts of walnut shells biochar (WSB) pyrolyzed at different temperatures on CO2 and N2O emission and soil health have not been yet sufficiently explored. We investigated the effects of addition of WSB pyrolyzed at either 300 °C (WSB-300), 450 °C (WSB-450), or at 600 °C (WSB-600) to alkaline soil on CO2 and N2O emissions, nutrients availability, and soil enzymes activities in a 120-day incubation experiment. Cumulative N2O emissions were reduced significantly as compared to the control, by 64.9%, 50.6%, and 36.4% after WSB-600, WSB-450 and WSB-300, respectively. However, the cumulative CO2 emissions increased, over the control, as follows: WSB-600 (50.7%), WSB-450 (68.6%), and WSB-300 (73.4%). Biochar addition, particularly WSB-600 significantly increased soil pH (from 8.1 to 8.34), soil organic C (SOC; from 8.6 to 22.3 g kg−1), available P (from 21.0 to 60.5 mg kg−1), and K (181.0–480.5 mg kg−1), and activities of urease, alkaline phosphatase, and invertase. However, an opposite pattern was observed with NH4+, NO3−, total N and β-glucosidase activity after WSB application. The WBS produced from high temperature pyrolysis can be used for N2O emissions mitigation and improvement of soil pH, SOC, available P and K, and activities of urease, alkaline, phosphatase. However, WBS produced from low temperature pyrolysis can be used to promote N availability and β-glucosidase; however, these findings should be verified under different field and climatic conditions.

Sustainable and safe management of aquaculture sediments is of great concern. Biochar (BC) and fishpond sediments (FPS) are rich in organic carbon and nutrients and thus can be used as soil amendments; however, it is not fully explored how the biochar amended fishpond sediments can affect soil properties/fertility and modulate plant physiological and biochemical changes, particularly under contamination stress. Therefore, a comprehensive investigation was carried out to explore the effects of FPS and BC-treated FPS (BFPS) on soil and on spinach (Spinacia oleracea L.) grown in chromium (Cr) contaminated soils. Addition of FPS and BFPS to soil caused an increase in nutrients content and reduced Cr levels in soil, which consequently resulted in a significant increase in plant biomass, chlorophyll pigments, and photosynthesis, over the control treatment. The most beneficial effect was observed with the BFPS applied at 35 %, which further increased the antioxidant enzymes (by 2.75-fold, at minimum), soluble sugars by 24.9 %, and upregulated the gene expression activities. However, the same treatment significantly decreased proline content by 74.9 %, Malondialdehyde by 65.6 %, H2O2 by 65.1 %, and Cr concentration in spinach root and shoot tissues. Moreover, the average daily intake analysis showed that BFPS (at 35 %) could effectively reduce human health risks associated with Cr consumption of leafy vegetables. In conclusion, these findings are necessary to provide guidelines for the reutilization of aquaculture sediments as an organic fertilizer and a soil amendment for polluted soils. However, more future field studies are necessary to provide guidelines and codes on aquaculture sediments reutilization as organic fertilizer and soil amendment for polluted soils, aiming for a more sustainable food system in China and globally, with extended benefits to the ecosystem and human.

Isolation and drying soil microaggregates and their building units are of crucial importance when studying their structure and function within different soil management systems. Our aim was to evaluate how different drying techniques preserve small aggregate building units after different disintegration steps. After applying fast wetting, slaking, or ultrasonic dispersion at 440 J mL− 1 to Cambisol topsoils under either long-term forest, grassland, or arable soil management, aggregate-size distributions were assessed using fast image analyses after optical particle-size assessment prior and after air- and freeze-drying. Microaggregates isolated by dry-sieving served as control. While ultrasonic dispersion significantly disintegrated soil aggregates into smaller units, slaking in water did not. Intriguingly, freeze-drying preserved the aggregate size distribution fairly well, with a reaggregation ranging between 1.2 and 10.1%. In contrast, air-drying led to substantial reaggregation of particles ranging between 20.4 and 44.9%. However, freeze-drying also led to slight deformation of particles and also to a redistribution of elements between size-fractions, the extent of which being different for the samples under different land-use. We conclude that ultrasonic treatment followed by freeze-drying is suitable to preserve the correct aggregate size of at least Cambisols, but the properties of the secondary particles may still not reflect true geometric forms and chemical properties.

Reusing by-products such as cow bones in agriculture can be achieved thorough pyrolysis. The potential of bone-derived biochar as a promising material for metals immobilization in contaminated mining soils has not yet been sufficiently explored. Therefore, cow bones were used as biochar feedstock were pyrolyzed at 500 °C (CBL) and 800 °C (CBH) and. The two biochars were applied to a mine contaminated soil at 0 (control), 2.5, 5 and 10%, w/w, dosages; then, the soils were incubated and cultivated by maize in the greenhouse. Cadmium (Cd) and zinc (Zn) bioavailability and their sequentially extracted fractions (acid soluble, reducible, oxidizable, and residual fraction), soil microbial function, and plant health attributes were analyzed after maize harvesting. Bone-derived biochar enhanced the content of dissolved organic carbon (up to 74%), total nitrogen (up to 26%), and total phosphorus (up to 27%) in the soil and improved the plant growth up to 55%, as compared to the control. The addition of CBL altered the acid soluble fraction of both metals to the residual fraction and, thus, reduced the content of Zn (55 and 40%) and Cd (57 and 67%) in the maize roots and shoots, respectively as compared to the control. The CBL enhanced the β-glucosidase (51%) and alkaline phosphatase activities (71%) at the lower doses (2.5–5%) as compared to control, while the activities of these enzymes decreased with the higher application doses. Also, CBL improved the antioxidants activity and maize growth at the 2.5–5% application rate. However, the activity of the dehydrogenase significantly decreased (77%), particularly with CBH. We conclude that CBL, applied at 2.5–5% dose, can be utilized as a potential low cost and environmental friendly amendment for stabilization of toxic metals in contaminated mining soils and producing food/feed/biofuel crops with lower metal content.

The objective of this work was to evaluate the suitability of carbohydrates and amino compounds in soil and soil organic matter (SOM) fractions to depict the management‐induced changes in soil over short‐term course. Soil samples were collected from two experimental fields managed according to organic farming regulations and a sequential fractionation procedure was applied to separate the light fraction (LF), particulate organic matter (POM), and mobile humic acid (MHA). Contents of carbohydrates and amino compounds were determined in soil and correspondent SOM fractions. Over a 2‐year course, carbohydrate contents decreased in the LF fraction while it increased noticeably in the POM and slightly in the MHA fractions leading into questioning whether decomposing materials get incorporated into older fractions. Amino N content constituted up to 30% of total soil N, with a major contribution of the humic fraction (MHA). Although the LF, POM, and MHA fractions showed the greatest amino N content after the compost‐legumes combinations, the carbohydrate and amino N contents in the POM and MHA fractions of the unamended soil increased as large as the corresponding fertilized plots, underlining that conservative soil management results in accumulation of labile forms of soil C and N that consequently might build up soil fertility. The changes after different treatments suggest the suitability of carbohydrates and amino compounds as short‐term indicators for soil management.

Amino acids (AAs) and peptides are thought to be part of humic acids (HAs) but debate whether they are an integral part of the HAs is still going. Humic acids sequentially extracted from peat and sod-podzolic soil were analyzed for their AAs content, elemental composition and by FTIR spectroscopy. Extracted HAs were hydrolyzed in 6 M HCl for 16 h for AAs release, which was detected by capillary electrophoresis system. Alanine, arginine, sum of aspartic acid and asparagine, sum of cysteic acid and cysteine, sum of glutamic acid and glutamine, glycine, histidine, leucine and isoleucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, valine were identified. The total content of hydrolysable AAs in sod-podzol HAs increased by 6.2–8.2% with increasing the extraction cycles while an inverse tendency was observed for AAs released from peat HAs. Moreover, individual AAs expressed as percentages of total AAs were constant values with coefficients of variation lower than 20% for the studied HAs.

Organic farming can overcome the environmental consequences of intensive conventional farming. The objective of the work was to investigate the changes in labile soil organic matter (SOM) fractions during the conversion from conventional to organic farming in two Italian sites, namely Foggia (FG) and Metaponto (MT), that differed mainly in initial soil organic carbon (SOC) content. Fields were cultivated with lentil and wheat in rotation and treated with either: i) compost or ii) nitrogen or phosphorus (N/P) fertilizers in three field replicates. The SOM was sequentially fractionated into light fraction (LF), particulate organic matter (POM) and mobile humic acid (MHA) fraction. Isolated fractions were quantified and analyzed for C and N contents. Although total SOC responded to the fertilization treatments, the LF and POM fractions were yet more responsive. The MHA represented on average 15% of SOC at both sites, however, the LF represented only 5–6% of total SOC but was the most responsive to changes in soil management. Compost application contributed significantly greater quantities of LF, POM and MHA than did the N/P fertilizers application. The initial SOC content can play an important role in determining the impacts of introducing organic farming practices on SOM fractions. Although both sites had an initial low SOC content, the MT site, with a lower SOC content, showed a substantial fractional C increments as compared to the FG site.

Lead and Zn contaminated soils, after sewage sludge (SS) or industrial wastes (IW) applications, were incubated with 5 and 10 mmol kg–1 soil of diethylene triamine penta acetic acid (DTPA) and ethylene diamine tetraacetic acid (EDTA) or with 10 and 20 mmol kg–1 soil of citric acid for up to 60 days. Consequently, Amaranthus retroflexus L. and Chenopodium album L. were tested in a chelate-assisted Pb and Zn phytoextraction greenhouse trial. In both incubated soils, the organic (Org) bound Pb increased over the incubation period, simultaneously, with a decrease in the oxide bound (Oxid) and carbonate bound (Carb) Pb fractions. Similar observations was found for Zn fractions during the incubation course of both contaminated soils. The EDTA was more effective in increasing the exchangeable Pb at 40 days of incubation in both soils whereas the DTPA was more effective in increasing the exchangeable Zn at 40 days of incubation. The pot experiment showed that Amaranthus retroflexus L. was more effective than Chenopodium album L. in the phytoextraction of Pb and Zn. The maximum amount of Pb and Zn Amaranthus phytoextracted in a 70-d growth period was 6.5 and 8.2 mg kg–1 soil, respectively, whereas the maximum phytoextracted amounts of Pb and Zn by Chenopodium were 3.9 and 3.5 mg kg–1 soil, respectively. Although EDTA and DTPA was more effective in redistributing metals among their fractions during incubation, higher removal of Pb and Zn was achieved after citric acid by Amaranthus. After environmental and economic evaluation, studied weed species can be used in chelate-assisted phytoremediation to decontaminate Pb- and Zn-contaminated soils.

Agricultural practices need to be adapted to variable field conditions to increase farmers' profitability and environmental protection, so contributing to sustainability of farm management. This study proposes a combined approach of multivariate geostatistics and non-parametric clustering to delineate homogeneous zones that could be potentially managed with the same strategy. In a durum wheat field of Southern Italy, in organic farming, some soil physical and chemical properties (electrical conductivity; pH; exchangeable bases; total nitrogen; total organic carbon; available phosphorous), elevation and the Normalized Difference Vegetation Index were determined and interpolated by using geostatistics.
The clustering approach, applied to the (co)kriged estimates of the variables, produced the delineation of four sub-field zones. A significant relation between soil fertility and yield was not found in such zones. Despite this, the proposed approach has the potential to be used in future applications of precision agriculture. Further work could focus on site-specific nitrogen fertilization with suited machinery.

Two types of compost were produced at the experimental compost facility of
the Mediterranean Agronomic Institute of Bari (IAMB). The green waste compost (GWC) was composed of olive pruning and broccoli residues, and mixed waste compost (MWC) was composed of olive pruning and bovine manure. Both composts have alkaline pH, acceptable salinity content and low C/N ratio. They were evaluated as components of growing media in partial substitution of Sphagnum peat for organic melon seedlings production. A greenhouse trial was carried out to evaluate the composts as a peat substitute for melon seedlings’ growth. Treatments, differentiated on the basis of the volume percentage of both composts, were compared to the control (a mixture of peat, coconut fiber and perlite). Compost-based substrates were analyzed for physical, physicochemical and chemical parameters (bulk density, porosity, pH, EC, nutrients content, etc.). In accordance with the guidelines of organic production, all treatments were fertilized, at the beginning of the trial, with guano. At transplant stage of nursery trial, biometric parameters and nutrient contents of shoots were measured. Compost addition has affected the chemical and physical characteristics of the media. Even though significant differences were observed, recorded values were in the range of acceptability for growing media. In terms of performance, seedling growth in treatments containing 30 and 50% of composts was significantly higher than in control. In terms of peat substitution, good results were obtained even though 10% of peat was used in the tested media.

One of the most cost-effective approaches in precision farming is the managing of relatively contiguous homogeneous zones in the field. Soil samples were collected in a 3 ha field of the CRA-Cereal Research Centre’s experimental farm located in Foggia (southern Italy). Soil carbon mineralization indices and physical-chemical properties were interpolated by using the geostatistical techniques of kriging and co-kriging. The application of a clustering algorithm, based on a non-parametric density estimate, to the (co)kriged surface variables produced the subdivision of the field into four distinct classes. This information can be useful for the site-specific supply of nutrient inputs, in order to match crop requirements with intrinsic patterns of soil fertility.

Global concerns towards potentially toxic elements (PTEs) are steadily increasing due to the significant threats that PTEs pose to human health and environmental quality. This calls for immediate, effective and efficient remediation solutions. Earthworms, the 'ecosystem engineers', can modify and improve soil health and enhance plant productivity. Recently, considerable attention has been paid to the potential of earthworms, alone or combined with other soil organisms and/or soil amendments, to remediate PTEs contaminated soils. However, the use of earthworms in the remediation of PTEs contaminated soil (i.e., vermiremediation) has not been thoroughly reviewed to date. Therefore, this review discusses and provides comprehensive insights into the suitability of earthworms as potential candidates for bioremediation of PTEs contaminated soils and mitigating environmental and human health risks. Specifically, we reviewed and discussed: i) the occurrence and abundance of earthworms in PTEs contaminated soils; ii) the influence of PTEs on earthworm communities in contaminated soils; iii) factors affecting earthworm PTEs accumulation and elimination, and iv) the dynamics and fate of PTEs in earthworm amended soils. The technical feasibility, knowledge gaps, and practical challenges have been worked out and critically discussed. Therefore, this review could provide a reference and guidance for bio-restoration of PTEs contaminated soils and shall also help developing innovative and applicable solutions for controlling PTEs bioavailability for the remediation of contaminated soils and the mitigation of the environment and human risks.

In   organic   agriculture   fertilizers   are   permitted   in   organic   forms,   as defined   by   regulation.   Mineralization   of   organic   fertilizers   is   a   biological   decomposition   that   release   plants’   available   nutrients;;   hence   soil   microbial   communities are   vital   in   the   organic   cropping   systems.   Composting   microorganisms   can   work   for   the   farmer’s   benefit   recycling   agricultural   organic   wastes   into   materials   that   contribute   to   healthy   and   biologically   active   soil.   Composting   process   has   been   deeply  described  to  highlight  the  link  among  starting  mixture,  process  factors  and  final  resulting  compost.  Composting  and  crop  residues  incorporation  are  fundamental  to  recycle  resources  at  farm  level  to  improve  the  nutrients  use  efficiency  and  to decrease  the  off-­farm  input  needs.  In  the  organic  farming  a  balanced  combination  of compost  application  and  crop  residues  incorporation  increases  the  microbial  carbon use   efficiency,   which   regulates   the   soil   organic   matter   decomposition   and   nutrients  mineralization  resulting  both  to  increase  the  yield  and  to  decrease  the  negative impact  on  the  environment.

Biochar prepared from various feedstock materials has been utilized in recent years as a potential stabilizing agent for heavy metals in smelter-contaminated soils. However, the effectiveness of animal bone-derived biochar and its potential for the stabilization of contaminants remains unclear. In the present study, sheep bone-derived biochar (SB) was prepared at low (500 °C; SBL) and high temperatures (800 °C; SBH) and amended a smelter-contaminated soil at 2, 5, and 10% (w/w). The effects of SB on soil properties, bioavailable Zn and Cd and their geochemical fractions, bacterial community composition and activity, and the response of plant attributes (pigments and antioxidant activity) were assessed. Results showed that the SBH added at 10% (SBH10) increased soil organic carbon, total nitrogen, and phosphorus, and also increased the oxidizable and residual Zn and Cd fractions at the expense of the bioavailable fractions. The SBH10 lowered the Zn and Cd contents in maize roots (by 57 and 60%) and shoot (by 42 and 61%), respectively, compared to unamended control. Additionally, SBH10 enhanced urease (98%) and phosphates (107%) activities, but reduced dehydrogenase (58%) and β-glucosidase (30%) activities. Regarding the effect of the pyrolysis temperature, SBH enhanced the activity of Acidobacteria, Bacteroidetes, Firmicutes, Nitrospirae, Verrucomicrobia, Chlorobi, and Microgenomates, but reduced Actinobacteria and Parcubacteria in comparison to SBL. However, only the SBL10 reduced the Proteobacteria community (by 9%). In conclusion, SB immobilized Zn and Cd in smelter-affected soils, enhanced the bacterial abundance and microbial function (urease, phosphates), and improved plant growth. However, validation of the results, obtained from the pot experiment, under field conditions is suggested.

Abstract: Wild edible plants (WEP) represent a nutritious and important food source in many countries. In this study the content of 13 elements (Na, K, Ca, Mg, Fe, Mn, Cu, Zn, Cr, Co, Cd, Ni and Pb) in 11 different genotypes of WEP was determined by inductively coupled plasma-optical emission spectroscopy. Each genotype was collected from the inner countryside and from fields near the highways of the metropolitan area of Bari (Apulia region). The elements intake by the consumption of potential serving sizes of WEP was also evaluated and discussed.Independently from the harvesting area, Borago officinalis and Papaver rhoeas could be considered good sources of Mn and Fe, respectively. Amaranthus retroflexus and Sinapis arvensis may contribute to an adequate intake for Ca, while Portulaca. oleracea may be a good source of Mg. In contrast, the Pb content in Plantago lagopus (1.40 mg kg-1 FW) and A. retroflexus (0.33 mg kg-1 FW) - both harvested from the inner part of the countryside (IPC) areas - was over the maximum level fixed by the in EC regulation 1881/2006. The Cd content of A. retrof

Biodegradation of microplastics (MPs) in contaminated biowastes has received big scientific attention during the past few years. The aim here is to study the impacts of livestock manure biochar (LMBC) on the biodegradation of polyhydroxyalkanoate microplastics (PHA-MPs) during composting, which have not yet been verified. LMBC (10% wt/wt) and PHA-MPs (0.5% wt/wt) were added to a mixture of pristine cow manure and sawdust for composting, whereas a mixture without LMBC served as the control (CK). The maximum degradation rate of PHA-MPs (22–31%) was observed in the thermophilic composting stage in both mixtures. LMBC addition significantly (P < 0.05) promoted PHA-MPs degradation and increased the carbon loss and oxygen loading of PHA-MPs compared to CK. Adding LMBC accelerated the cleavage of C–H bonds and oxidation of PHA-MPs, and increased the O–H, CO and C–O functional groups on MPs. Also, LMBC addition increased the relative abundance of dominant microorganisms (Firmicutes, Proteobacteria, Deinococcus-Thermus, Bacteroidetes, Ascomycota and Basidiomycota) and promoted the enrichment of MP-degrading microbial biomarkers (e.g., Bacillus, Thermobacillus, Luteimonas, Chryseolinea, Aspergillus and Mycothermus). LMBC addition further increased the complexity and connectivity between dominant microbial biomarkers and PHA-MPs degradation characteristics, strengthened their positive relationship, thereby accelerated PHA-MPs biodegradation, and mitigated the potential environmental and human health risk. These findings provide a reference point for reducing PHA-MPs in compost and safe recycling of MPs contaminated organic wastes. However, these results should be validated with other composting matrices and conditions.

Two types of compost were produced: green waste compost (GWC) and mixed waste compost (MWC). GWC was composed of green wastes while MWC was composed of green wastes and animal manure. Both composts have alkaline pH, acceptable salinity content, low C/N ratio. Humification indices and IsoElectroFocusing (IEF) were used to describe the evolution of organic matter during composting. Humified carbon has increased for both compost but with a higher percentage for GWC. IEF profiles for both composts were similar and they did not provide further interpretation. A greenhouse trial was carried out to evaluate peat substitutability at 30, 50 and 70% compost on melon seedlings growth. Compost addition has affected chemical and physical properties of the mixes. Biometric parameters and shoot content of nutrients were measured. The results obtained showed that peat could be substituted with 30% of both composts. Moreover MWC could successfully replace peat with a percentage up to 70%.

Management of industrial hazardous waste is of great concern. Recently, aluminum rich drinking water treatment residuals (Al-WTR) received considerable attention as a low-cost immobilizing agent for toxic elements in soils. However, the suitability and effectiveness of modified Al-WTR as stabilizing agent for toxic metals such as Cu and Pb in mining soil is not assessed yet. We examined the impact of different doses (0, 0.5, 1.5, and 2.5%) of raw and Fe/Mn- and P- modified Al-WTR on the bioavailability and uptake of Cu and Pb by ryegrass in Cu and Pb contaminated mining soil. The addition of Fe/Mn-and P- modified Al-WTR to the soil reduced significantly the concentrations of Pb (up to 60% by Fe/Mn-Al-WTR and 32% by P-Al-WTR) and Cu (up to 45% by Fe/Mn-Al-WTR and 18% by P-Al-WTR) in the shoots and roots of ryegrass as compared to raw Al-WTRs and untreated soil. Our results demonstrate that modification of the raw Al-WTR increased its pH, CEC, specific surface area, active functional groups (Fe-O and Mn-O), and thus increased its immobilization efficiency. Our results highlight the potential of the modified Al-WTR, particularly the Fe/Mn-Al-WTR, for the remediation of Cu and Pb contaminated soils and recommend field scale verification.

The transition from conventional to organic farming is the most difficult period facingorganic growers. Total soil organic carbon (SOC) might not be a suitable tool to track the changes in organically based soil fertility within a 2- to 3-year transition period. Labile fractions that are important for nutrient cycling and supply are likely to be controlled by management to a much greater extent than is total soil organic matter (SOM).!Isolation and characterization of labile fractions are likely to better show the effects of management on SOM and better provide more information on fertility status. Two field experiments were established in 2009 in the south of Italy, at Foggia and Metaponto, to study the changes in SOM pools during the transition to organic farming. Experiments were a cereal/leguminous crop rotation under treatments of amendments (compost and fertilizers) permitted in organic farming performed in triplicate replication. Soils were sampled at the beginning of the project and after each crop harvest in 2010 and 2011. A sequential fractionation procedure was used to separate different SOM-fractions: light fraction (LF), two size classes of particulate organic matter (POM), mobile humic acid (MHA) fraction and Ca-bound humic acid (CaHA) fraction. Isolated fractions were quantified and analyzed for their contents of C and N. Soil, LF, POM and MHA were characterized for their contents of seven carbohydrates and amino compounds, namely 19 amino acids (AAs) and two amino sugars. Masses of the fractions increased during the 2-year course with noticeable increases in the LF and POM. Compost application contributed to significantly greater quantities of LF, POM and MHA than did fertilizer application. Carbohydrate contents, over the 2-year scale, decreased in LF while it increased noticeably in POM and slightly in the MHA fraction. Amino compounds constituted up to 30% of total soil N with a major contribution of the humified fractions, MHA and CaHA. The obtained results recommend inclusion of leguminous crops in crop rotation and application of compost for building up soil fertility during the transition to organic farming. The introduced fractionation procedure is recommended for studying SOM in short-term studies.

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