Evaluation of Particleboards Made from Giant Reed (Arundo donax L.) Bonded with Cement and Potato Starch

There is a general concern about the rationalization of resources and the management of waste. Plant residues can contribute to the development of new non-polluting construction materials. The objective of this study was to valorize a plant residue such as the giant reed and obtain a particleboard with cement using potato starch as a plasticizer in a manufacturing process involving compression and heat. The influence of cement and starch in different proportions and its stability over time were analyzed. Finally, their physical and mechanical properties were evaluated and compared to European Standards. High-quality sustainable particleboards (boards with high structural performance) were obtained and can be classified as P6 according to European Standards. Mechanical properties were improved by increasing the starch content and pressing time, whereas greater resistance to water was obtained by increasing the cement content. Giant reed particles seem to tolerate the alkalinity of the cement since there was no sign of degradation of its fibers. The use of these residues in the manufacture of construction materials offers a very attractive alternative in terms of price, technology and sustainability.

Physicochemical Characterization of Cardoon “Cynara cardunculus” Wastes (Leaves and Stems): A Comparative Study

The disposal of vegetable wastes in nature is harmful for marine habitats and biota. These types of waste are frequently used as fuel, generating polluting products, with undesired side effects on the environment. Therefore, it is essential to find better alternatives for the capitalisation of these waste products. Their diversified chemical composition can become a potential resource of high added value raw materials. The knowledge of the physicochemical properties of these wastes is therefore essential. The present work aimed for characterising the physicochemical properties of a plant residue belonging to the Asteraceae Family, collected from a vegetable market in Fez city, Morocco. The vegetal tissues were analysed by Scanning Electron Microscopy coupled with EDX, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Inductively Coupled Plasma Atomic Emission Spectroscopy, and by Thermogravimetric/Differential thermal analyses. Other additional parameters were also measured, such as moisture, volatile matter, ash, and fixed carbon contents. Acidic and basic surface functions were evaluated by Boehm’s method, and pH points at zero charge were equally calculated. The results revealed a strong congruence between the morphological and structural properties of this plant. These vegetal wastes comprise a homogeneous fibrous and porous aspect both in surface and in profile, with a crystalline structure characteristic of cellulose I. A mass loss of 86.49% for leaves and 87.91% for stems in the temperature range of 100 °C to 700 °C, and pHpzc of 8.39 for leaves and 7.35 for stems were found. This study clarifies the similarities and differences between the chemical composition and morphological structure of these vegetal wastes, paving the way for future value-added applications in appropriate fields.

Decomposition of carbon adsorbed on iron (III)-treated clays and their effect on the stability of soil organic carbon and external carbon inputs

The interaction of organic carbon (OC) with clay and metals stabilizes soil carbon (C), but the influence of specific clay-metal-OC assemblages (flocs) needs further evaluation. This study aimed to investigate the stability of flocs in soil as affected by external C inputs. Flocs representing OC-mineral soil fractions were synthesized using dissolved organic C (DOC) combined with kaolinite (1:1 layer structure) or montmorillonite (2:1 layer structure) clays in the absence or presence of two levels of Fe (III) (named low or high Fe). Flocs were mixed with soil (classified as Luvisol) and incubated with or without 13C labelled plant residue (i.e., ryegrass) for 30 days. The CO2 emissions and DOC concentrations as well as their 13C signatures from all treatments were examined. Total C mineralization from flocs was approximately 70% lower than non-flocced DOC. The flocs made with montmorillonite had 16–43% lower C mineralization rate than those made with kaolinite with no Fe or low Fe. However, when flocs were made with high Fe, clay mineralogy did not significantly affect total C mineralization. A positive priming effect (PE) of flocs on native soil OC was observed in all treatments, with a stronger PE found in lower Fe treatments. The high-Fe clay flocs inhibited ryegrass decomposition, while the flocs made without clay had no impact on it. Interestingly, flocs significantly decreased the PE of ryegrass on native soil OC decomposition. These results indicate that the adsorption of DOC onto clay minerals in the presence of Fe (III) stabilizes it against decomposition processes and its stability increases as Fe in flocs increases. Flocs also protect soil OC from the PE of external degradable plant C input. This study showed that Fe level and clay mineralogy play an important role in controlling soil C stability.

Suppression of Banana Fusarium Wilt Disease With Soil Microbial Mechanisms Via Pineapple Rotation and Residue Amendment

Aims The large outbreak of banana Fusarium wilt has become a bottleneck limiting the industry’s development, and crop rotation is a cost-effective and essential measure to overcome the obstacles of banana crop monoculture. The present work was carried out to explore the mechanisms of how changes in physicochemical properties and the reestablishment of soil microorganisms in high-incidence soils are affected by crop rotation and plant residue. Methods In this study, pineapple-banana crop rotation and pineapple residue amendment were used to alleviate banana Fusarium wilt, and their effects on bacterial and fungal communities were studied using the MiSeq Illumina sequencing platform. Results Both pineapple-banana rotation and residue addition significantly reduced disease incidence. Moreover, pineapple rotation and residue amendment altered the bacterial and fungal community composition. The taxonomic and phylogenetic alpha diversity of bacteria and fungi significantly increased against disease suppression and nutrition competition. The relative abundances of the Burkholderia, Pseudomonas, Elaphocordyceps, Penicillium, and Talaromyces genera were higher, and the number of Fusarium was significantly lower in rotational soil than in banana monoculture soil. Finally, linear models (LM) was used to show that the Burkholderia and Talaromyces in crop rotation, and Aspergillus in residue amendment have significant negative relationship to disease incidence, which plays a key role in Fusarium reduction. Conclusions To consider the economic benefits and protect the vitality of the soil, this study suggested that pineapple-banana rotation and pineapple residue amendment both could be considered for the sustainable management of banana wilt.

Effect of Repeated Plant Debris Reutilization as Organic Amendment on Greenhouse Soil Fertility

Greenhouse agriculture typically generates large amounts of waste with plant residue (agricultural biomass) being the most abundant. This residue is generated on a seasonal basis, which complicates the external management of the material. Recently, the European Union (EU) has been implementing a policy based on sustainability through the circular economy that seeks to minimize waste generation. The effect of reusing 3.5 kg·m−2 tomato plants from the previous season as the only fertilizer versus no fertilization and inorganic fertilization in 215-day tomato cycles after transplanting was studied in this trial. The study was carried out during three seasons in greenhouse agriculture in Almeria (Spain) with the repeated use of the solarization technique. The plant debris had similar production results during two of the three seasons and fruit quality parameters were similar to inorganic fertilization. In addition, some physicochemical variables improved and the biological depressive effect of solarization was mitigated. The results suggest that the reuse of the tomato plant debris as the only fertilizer could be an alternative to conventional fertilization under the conditions tested.

The spatial degradation of Riceland and farmers perception of its causal factors and strategic adaptations

Deli Serdang District is among the highest rice producer districts in North Sumatera Province. Unfortunately, climate change and improper cultivation management practices degrade riceland fertility and affect stagnant rice productivity over the years. This study aims to identify the spatial pattern of the limited-factors for riceland suitability and determine land degradation factors and the strategic actions to increase rice production. This study was conducted in 2019 in six districts and interviewed sixty farmers for getting information about riceland degradation issue. The field survey, soil analysis and household-based survey are some methods implemented in this study. The two tools, ArcGIS and SPSS, were used to gain the purposes of the research. The results show that the low status of nutrient availability, root condition and nutrient retention are the main factors of riceland degradation. Besides, this study found that climate change, lack of organic fertilizer implementation, water scarcity and excessive chemical fertilization implementation were significant factors of land degradation based on farmers perception. In addition, some of the strategic actions were frequently implemented to minimize the degradation rate are implementing the minimum tillage, using certified seed, giving a fallow season for riceland and recycling plant residue as organic fertilizer. The study suggests implementing the proper cultivation management practices like Integrated Crop Management (ICM) and Climate Smart Agriculture (CSA) to achieve the sustainability of rice production.

The Diversity and Ecology of Macromycetes on Soils of Adjara, Georgia

The publication is devoted to the study of the diversity of the species composition of macromycetes on different soils of Adjara, Georgia. The aim of the study was to identify and determine the composition of on different macroscopic fungi in different soils; establishment of the scale of development and spread of macromycetes in adverse and favorable conditions. Morphological features of collected fruiting bodies, such as shape, size, colour, odor, hymenophore and velum types, etc., were analysed. Spore slides were prepared in glycerin and fuchsin acid and observed under a light microscope. Some samples were isolated on a Malt agar medium, and macroscopic and microscopic characteristics of isolates were observed for precise identification. Identifications were done using relevant literature. At locations in the outdoor area and in the greenhouse, a total of 165 macrofungal species were recorded fruiting on soil, between them 35 species are considered edible, 14 poisonous, while 106 species are inedible Most of the species belong to the division Basidiomycota (151) and only 14 to the division Ascomycota. Identified species distributed in 5 Classes, 13 Orders, 36 families and 68 Genuse. The highest number of soil-inhabiting basidiomycetous macrofungal species was in the forest soil plot (116), followed by the Pasture soil (29). The on families with the highest number of species was Russulaceae (17%), Agaricaceae (15%), Boletaceae (12%), Cortinariaceae (9%) and Psathyrellaceae - 8%, The remaining 31 families-39%. Lactarius, Cortinarius, Russula, Amanita and et al., were the richest genus. All 6 substrates studied, it observed that the species that had a higher frequency were Agaricus subrufescens, Calvatia cyathiformis and Leucocoprinus cretaceus, occurring in soil, soil/litter and pasture. On the other hand, Agaricus campestris, A. rufoaurantiacus, Chlorophyllum hortense and Volvopluteus earlier among others, were collected only from two substrates (soil/and plant residue). The other genera (most of it) occurred in only one substrate. Peaks macromycetes was in May and October, when the average temperature remained between 22 - 26°C and relative humidity between 78% and 92%. The occurrence of macromycetes was higher in May, when the temperature was milder and stable on average 24°C. Found that Adjara support a large and diverse community of macrofungi fruiting on soil, many species of which are previously undiscovered and undescribed. On this basis, works of longer duration and more intensive sampling are needed to obtain data regarding fungal communities, with more attention to specific variables such as microclimate, soil moisture, soil type, soil pH and vegetation types.

Development of fungal-mediated soil suppressiveness against Fusarium wilt disease via plant residue manipulation

Background The development of suppressive soils is a promising strategy to protect plants against soil-borne diseases in a sustainable and viable manner. The use of crop rotation and the incorporation of plant residues into the soil are known to alleviate the stress imposed by soil pathogens through dynamics changes in soil biological and physicochemical properties. However, relatively little is known about the extent to which specific soil amendments of plant residues trigger the development of plant-protective microbiomes. Here, we investigated how the incorporation of pineapple residues in soils highly infested with the banana Fusarium wilt disease alleviates the pathogen pressure via changes in soil microbiomes. Results The addition of above- and below-ground pineapple residues in highly infested soils significantly reduced the number of pathogens in the soil, thus resulting in a lower disease incidence. The development of suppressive soils was mostly related to trackable changes in specific fungal taxa affiliated with Aspergillus fumigatus and Fusarium solani, both of which displayed inhibitory effects against the pathogen. These antagonistic effects were further validated using an in vitro assay in which the pathogen control was related to growth inhibition via directly secreted antimicrobial substances and indirect interspecific competition for nutrients. The disease suppressive potential of these fungal strains was later validated using microbial inoculation in a well-controlled pot experiment. Conclusions These results mechanistically demonstrated how the incorporation of specific plant residues into the soil induces trackable changes in the soil microbiome with direct implications for disease suppression. The incorporation of pineapple residues in the soil alleviated the pathogen pressure by increasing the relative abundance of antagonistic fungal taxa causing a negative effect on pathogen growth and disease incidence. Taken together, this study provides a successful example of how specific agricultural management strategies can be used to manipulate the soil microbiome towards the development of suppressive soils against economically important soil-borne diseases.

Comprehensive Study on the Mechanism of Sulfating Roasting of Zinc Plant Residue with Iron Sulfates

Zinc plant residue (ZPR) is a secondary material generated during hydrometallurgical zinc production that contains considerable contents of valuable elements such as Zn, Cu, Fe, Pb, Cd, Ag, In, Ga, Tl. Zinc, copper and accompanying elements in ZPR are in different minerals, mainly in the ferrites. A promising approach for recycling ZPR is the sulfating roasting using iron sulfates followed by water leaching. In this study, the composition of ZPR and the obtained products were thoroughly investigated by various methods including X-ray diffraction analysis (XRD), chemical phase analysis and Mössbauer spectroscopy. The effect of temperature, amount of iron sulfates and roasting time on the conversion of valuable metals into a water-soluble form was thermodynamically and experimentally studied both using pure ferrites and ZPR. Based on the results of time-resolved XRD analysis and synchronous thermal analysis (STA), a mechanism of the sulfation roasting was elucidated. The rate-controlling step of zinc and copper sulfation process during the ZPR roasting was estimated. The sulfating roasting at 600 °C during 180 min with the optimal Fe2(SO4)3∙9H2O addition followed by water leaching enables to recover 99% Zn and 80.3% Cu, while Fe, Pb, Ag, In, Ga retained almost fully in the residue.