Hamada Abdelrahman, PhD

A pot experiment was conducted to examine the ability of Blue Panic grass (Panicum anti- dotale) to grow in slightly saline soils (2.40 dS m–1) under different levels of saline irrigation water in the presence or absence of compost. Eight treatments were set up in a randomized block design with five replicates as follows: T1 (Freshwater), T2 (Freshwater + compost at 20%), T3 (Saline water 5000 mg L–1), T4 (T3 + compost at 20%), T5 (Saline water 10000 mg L–1), T6 (T5 + compost at 20%), T7 (Saline water 15000 mg L–1) and T8 (T7 + compost at 20%). Growth parameters of Blue Panic Grass were evaluated at the end of the experimental period as plant and root length, shoot, and root fresh and dry weights, total chlorophyll, and total carbohy- drates. In general, tested Blue Panic Grass appeared to be tolerant to high salt concentrations in irrigation water, and slightly significant differences were found for all the measured para- meters. A remarkable growth increase occurred in plants grown in compost-amended soils, with respect to the unamended soils. The results demonstrate the possibility to stabilize the yield of blue panic grass, an important feed crop in Egypt, irrigated with saline water, which can secure animal feed resources without reducing the already limited freshwater availability.

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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.

Soils are among the key resources of sustainable development in Egypt. There would be no development, in any nation, without policies and implementation for soil protection, conservation, and sustainability. This is due to the role soils play in almost all fields, including agriculture and its subsectors (farming of animals and plants to produce food, feed, fiber, fuel, etc.), as well as the industrial sector. Egypt faces, currently, great and serious challenges related to the changes in land use, new challenges for soil sciences scientists. Other important future soil issues include the role of soils in global climate changes mitigation/adaptation, establishment of soil protection law, and enforcing it. To solve emerging soil-related problems in Egypt, potential contributions from soil scientists, policymakers, and society are expected. Therefore, this chapter is an attempt to focus on emerging concern on soil and to suggest suitable solutions under the Egyptian conditions.

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.

The changes in soil organic matter composition induced by anthropogenic factors is a topic of great interest for the soil scientists. The objective of this work was to identify possible structural changes in humic molecules caused by a 2-year rotation of durum wheat with faba bean, lasted for a decade, and conducted with different agricultural practices in a Mediterranean soil.
Humic acids (HA) were extracted at three depths (0-30, 30-60 and 60-90 cm) from a Mediterranean soil subjected to different tillage (no tillage, minimum tillage and conventional tillage), crops (faba bean and wheat), and fertilization. The changes in HA quality were assessed by several chemical (ash, yield and elemental analysis) and spectroscopic techniques (solid-state 13C nuclear magnetic resonance, Fourier transform infrared and fluorescence).
The results suggest that the different agronomic practices strongly affected the quality of HA. Smaller but more aromatic molecules were observed with depth, while the fertilization induced the formation of simpler and less aromatic molecules due to the enhanced decomposition processes. Under no tillage, more stable humic molecules were observed due to the less soil aeration, while under conventional tillage larger and more aromatic molecules were obtained. Compared to wheat, more aromatic and more oxidized but less complex molecules were observed after faba bean crop.
The inorganic fertilization accelerates the decomposition of organic substances rather than their stabilization. At the end of each crop cycle, humic matter of different quality was isolated and this confirms the importance of the rotation practice to guarantee a diversification of the soil organic matter with time. Finally, no tillage induces the formation of more stable humic matter.

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.

The objective of this work was to investigate the chemical composition and the quantitative changes in soil organic matter (SOM) fractions in response to multiple historical inputs of charcoal that ceased >60 years ago. The topsoil (0–5 cm) and subsoil (5–20 cm) samples of charcoal enriched soils and the unamended reference soils were assessed for C and N contents in bulk soil, particulate organic matter (POM) fractions and water extractable organic matter (WEOM). The SOM molecular characteristics were investigated in the solid phase by nuclear magnetic resonance (NMR) and in the WEOM by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Formerly added charcoal additions reduced the extracted amount of WEOM and altered POM pattern: an increased proportion of C and N stored in coarse, intermediate, and fine POM relative to corresponding total C and N was found in subsoils. In contrast, C and N stored in the residual fraction (<20 µm) decreased. NMR results revealed a higher aromaticity of SOM in charcoal enriched soils, while the FT-ICR-MS results indicated an increased presence of lignin- and tannin-like compounds in the WEOM of these soils. Former charcoal additions enhanced soils capacity to retain and stabilize C and N. Particularly, the presence of charcoal particles elevated C and N stored in large POM fractions >20m, which presumably increases soil porosity and thus the soils’ capacity to retain water.

The economic, political and geographic changes that occurred lately in Egypt depleted farmland in the valley and delta of the Nile river. The two main problems that causes farmland depletion are the urban sprawl and the expected shortage in Egypt water share of the Nile water due to the ongoing construction of the Ethiopian dam. Accordingly, it is the role of decision makers, supported by scientists, to introduce solutions to the farming system to optimize the use-efficiency of available land and water resources for sufficient food production. Several measures can be taken to ensure food security in Egypt including cultivation of strategic crops in neighboring countries as has been already done, e.g. Egypt-Zanzibar farm. However, it is necessary to take effective management measures for farming land in Egypt. The on-site solutions are limited to the use of precision farming tools to maximize the productivity per unit area and unite volume of land and water, respectively. The use of unmanned aerial vehicle (UAV) has proven successful in establishing sustainable intensification of cropping systems in other African countries, e.g. Ghana, which suggests the urgent need to implement it in Egypt.

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.

This work evaluated the response of organic tomato seedlings to locally produced compost-amended growing media and commonly used N liquid fertilizers. Green (GC) and mixed (MC) composts were used in growing media formulation with 70, 45, 20, and 0% (control based on peat) on volume basis for organic tomato seedling growth. Three locally available N liquid fertilizers, hydrolyzed-protein-based fertilizer (HP), blood-meal-based fertilizer (BM), and algae-extract-based fertilizer (AE), were tested. Seedlings were evaluated 34 days after sowing for plant height; stem diameter; shoot weights; sturdiness index; specific leaf area; and N, P, and K contents in the seedlings shoot. The statistical analysis showed that the substrate type, fertilizer, and their interaction significantly (p ≤ 0.05) affected, in most cases, the seedlings growth. The compost, especially with 20 or 45% amended substrate, produced longer seedlings with thicker diameter, greater fresh and dry weights, and greater leaves number compared to the control (compost-free) substrate. The use of the HP or the AE fertilizer generally contributed to better seedlings growth than did the BM-based fertilizer. The HP fertilizer clearly affected (p ≤ 0.01) the seedling diameter, fresh weight, and leave numbers while the AE fertilizer affected clearly seedling sturdiness index. The use of the GC or MC compost complemented with the HP or the AE fertilizer successfully reduced up to 45% of peat use in growing media and produced robust organic tomato seedlings.

Purpose

The study aimed to describe the carbohydrates and amino compounds content in soil, the light fraction (LF), the >53 μm particulate organic matter (POM), and the mobile humic acid (MHA) fraction and to find out whether the carbohydrates and amino compounds can be used to explain the origin of SOM fractions.

Materials and methods

Soil samples were collected from two agricultural fields managed under organic farming in southern Italy. The LF, the POM, and the MHA were sequentially extracted from each soil sample then characterized. Seven neutral sugars and 19 amino compounds (amino acids and amino sugars) were determined in each soil sample and its correspondent fractions.

Results and discussion

The MHA contained less carbohydrate than the LF or the POM but its carbohydrates, although dominated by arabinose, were relatively with larger microbial contribution as revealed by the mannose/xylose ratio. The amino compounds were generally less in the LF or the POM than in the MHA, while the fungal (aspartic and serine) and bacterial (alanine and glycine) amino acids were larger in the MHA than in the LF or the POM, underlining the microbial contribution to the MHA. Results from both sites indicated that total carbohydrates content decreased moving from the LF (younger fraction) to the MHA (older fraction), which seems to follow a decomposition continuum of organic matter in the soil-plant system.

Conclusions

The study showed that the MHA is a labile humified fraction of soil C due to its content of carbohydrates and concluded that the content of carbohydrates and amino compounds in the LF, the POM and the MHA can depict the nature of these fractions and their cycling pattern and response to land management.

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

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.

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.

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 field experiments, in the south of Italy, were established in 2009 to study and characterize SOM during transition to organic farming. Experiments included a cereal/leguminous rotation fertilized with permitted amendments with three field replicates. 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) and Ca-bound humic acid (CaHA). Isolated fractions were quantified and analyzed for their C and N content and carbohydrates and amino compounds composition. The masses of the isolated fractions increased during 2-year course, with noticeable increases in LF and POM. Moreover LF and POM were found more responsive than MHA to treatment and crop. The xylose/mannose ratio explained that MHA-carbohydrates were mainly of microbial origin while LF- and POM-carbohydrates were of plant origin. Amino compounds constituted up to 30% of total soil N and were found to be more responsive to seasonal variation than to agronomic practices.

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.

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.