The main assumptions of this study were: (i) that spectrally similar soils are similar according to SOC content; and (ii) that using spectral-based clustering might enhance the quality of the prediction model. A total of 939 sample's soil spectral data and SOC content were selected from the regional soil Vis-NIR database of Dalmatia, Croatia. The spectral dataset was partitioned into distinct clusters using unsupervised learning (UL) techniques: Principal Component Analysis (PCA) and Fuzzy C-means (FCM) method. The ellipsoidal shape of the soil spectral data set was best separated into three clusters, indicating a reasonable quality of clustering as seen by the Silhouette score of 0.57. The most important wavelengths for clustering were at the following ranges: 1980–2025 nm, 1900, 735–775, 490–530, 1200, 2100, 2200, 2130, 2400 485, and 440 nm. The identified clusters had mean SOC content values of 22.25, 13.36, and 17.29 g C kg−1. At a significance level of 0.05, these values exhibit a statistically significant difference. The FCM clustering enhanced PLSR model's precision as measured by the Prediction Interval (PI). However, it had little impact on accuracy for SOC predictions as assessed using the Residual prediction deviation (RPD). Our models are suitable for performing approximate or preliminary screenings for the prediction of SOC content. Therefore, we recommend using UL techniques and chemometrics combined with Vis-NIR spectroscopy to supplement conventional SOC content laboratory analyses.

The Barreiras Formation possesses soils with horizons and subsurface layers cemented by Si, Al and Fe and commonly enriched with organometallic compounds, which show current and past podzolization processes. The study of these horizons and cemented layers can assist in understanding pedogenesis and paleoenvironmental evolution. Three soil profiles were selected along a toposequence for which morphological and micromorphological descriptions were made and samples of organic matter from spodic horizons and cemented layers were dated using carbon isotopes (12C, 13C, 14C), with the aim of obtaining records of paleoenvironmental conditions and understanding the genetic chronology of the soils. The results were interpreted considering three premises: (i) podzols develop under predominantly humid climatic conditions; (ii) organic matter enclosed in cemented horizons is fossilized and provides data regarding the chronological record of cementation time; and (iii) analysis of fossil plant organic residues using the 13C/12C ratio (δ13C) provides an indication of paleo-vegetal coverage. The results indicate that there were two distinct podzolization events in the study area under humid climatic conditions because the area was dominated by tree vegetation according to δ13C, which ranged from −27.2 %o to −25.3 %o. The first, and oldest, podzolization event, related to the range of 17,530–14,970 years BP, reached all three soil profiles, while the second, younger, event started around 6430 years BP, and is registered only in the upper part of the cemented layer of the P-10 profile located at the top of the slope. Combining the results of organic matter dating with morphological and micromorphological analyses of the profiles leads to the conclusion that the P-10 profile is developing on a cemented bedrock and the P-13 and P-15 profiles are developing on two bedrocks — superficial horizons arising from colluviums coming from the top of the slope and subsurface horizons developing from cemented material.

In countries with extensive agricultural practices, there is a significant risk of soil degradation, making it essential to develop techniques for understanding and detecting these changes. In this study, we used an earth observation system to identify the temporal bare soil frequency and thus, relate it with soil tillage and its impact on soil carbon degradation. The work was performed in two important agricultural states of Brazil, São Paulo and Paraná. For that, historical field and Remote Sensing (RS) data were analyzed to identify the relation between bare soil areas and their degradation. The frequency of bare soil was detected by Landsat images, in the last 36 years using the Geospatial Soil Sensing System (GEOS3). Historical soil surface temperature data was produced using the same images. In addition, legacy pedological and crops (i.e., soil cover) maps were used. Finally, soil texture information was spatialized based on a synthetic soil image (SISY). A total of 28,000 sites with topsoil organic carbon (SOC) were used as the reference for degradation. The soils of the state of Paraná presented significantly lower bare soil areas when compared to the state of São Paulo, mainly due to the wide use of the No-Tillage system. The advancement of sugarcane harvesting technologies together with the "boom" of the commodities after 2000s was responsible for the considerable increases in soil cover conservation. It was noticed that the more exposed the soil remains, the less carbon it has, having a negative correlation (r≈ −0.5). Sandy soils in both states proved to be the ones that were subject to the highest exposure rates and thus, more degraded. This fact is of concern, given that sandy soils are more susceptible to degradation factors, such as erosion. We observed important historical public policies related to the temporal tillage systems adopted by agro-community, which had a significant impact on carbon dynamics. The remote technique was able to infer how the soil has been managed. This information is crucial as it provides a solid basis for developing future public policies aimed at sustainable production.

Improper management and disposal of waste from industries, agriculture, households and forests contribute to environmental and soil pollution, health risks and disease outbreaks, nutrients loss and greenhouse gases production. Traditionally, organic wastes have been managed through landfill, incineration, composting, vermicomposting, and biomethanization. Blatticomposting, an emerging method, is being recognized as an environmentally friendly, cost-effective technology with resilience to harsh conditions. In blatticomposting of organic waste, cockroaches, along with their gut microbes, play a crucial role in nutrient recovery and the mineralization of organic waste into blatticompost. Although research on cockroaches dates back far into history, their significance in waste management has recently gained recognition. Hence, this perspective substantiates the potential of cockroaches as an emerging technology in the bioconversion of organic wastes into insect frass known as blatticompost. Here, we discussed the attributes of cockroaches as omnivorous feeders, their merits in waste conversion, and the limitations. We demonstrate the agronomic and environmental benefits of blatticompost, as well as the biological and physiological properties that influence the waste conversion cycle, the potential to reduce greenhouse gas emissions from soils, and enhance nutrient cycling. We propose methods to enhance and expand the use of cockroaches in waste management on a large scale. Our analysis reveals that cockroaches are effective composters, and their frass is a valuable organic fertilizer that can contribute to soil health and environmental sustainability.

This study evaluated the use of waste materials to produce Technosol, a "tailor-made" soil consisting of construction and demolition waste (CDW), solid waste from stone mining (WSM), natural soil (NS), and compost from plant pruning (CPP), for improving soil quality in forest recovery projects. Samples of CDW were characterized using X-ray fluorescence and X-ray diffraction. The potential of the Technosol as a substrate was assessed using a mixture of "Class A" CDW, WSM, NS, and CPP in the following proportions: (a) 10 % CDW + 42.5 % WSM + 42.5 % NS + 5 % CPP, (b) 20 % CDW + 37.5 % WSM + 37.5 % NS + 5 % CPP, and (c) natural soil as a control. A randomized block design was used with nine treatments and three replications using 5.5 L pots. The experimental treatments consisted of two proportions of mixtures, natural soil, and three tree species: pioneer, Cecropia pachystachya, secondary, Handroanthus impetiginosus and climax, Copaifera langsdorffii. The activity of the enzymes β-glucosidase and arylsulfatase was determined in the Technosol and natural soil at the end of the experiment. During 180 days, the height of the plants and the diameter of the stem were determined at intervals of 30 days and, at the end of the experiment, the aerial part dry mass (leaves and trunk) and roots were evaluated. The Technosol constructed from the mixture (a) proved to be viable for improving soil quality, as indicated by a greater enzymatic activity compared to other soils, and for the growth of H. impetiginosus seedlings, showing the capacity to gain plant height over 180 days after planting.

Fertilizers influence biochemical interactions in the rhizosphere that can affect crop performance. This study evaluated the interaction of plantain (Musa × paradisiaca) growth with soil pH, acid phosphatase and urease activities under different fertilizer amendments in Buea with mono-modal and Akonolinga with bi-modal rainfall patterns in Cameroon. The two experiments were setup in June 2021 following a randomized complete block design with NPK (nitrogen, phosphorus, and potassium), bio-inoculant consortia (plant growth-promoting bacteria – PGPB, Beauveria, Trichoderma, PGPB + Trichoderma), and untreated control, with four replications each. Soil samples were collected on 30th September 2021 and 30th April 2022 for analyses of soil physico-chemical and biological properties. Higher plantain performance occurred in Buea than Akonolinga across samplings, while treatments modulated plantain performance. Significant correlations occurred between plantain height or stem girth with rhizosphere pH, acid phosphatase and urease activities. The soil in Akonolinga is clayey with 38 % higher clay content than Buea, while Buea was clay-loamy with two times more silt than Akonolinga. The pre- and post-planting soil pH in Buea were strongly acidic as compared to extremely acidic soil in Akonolinga, with significant variation of post-planting pH across treatments, sampling time, and field sites. The positive correlation of soil pH, acid phosphatase and urease activities with plantain growth strongly indicate functional relationships that highlight fertilizer effects, sampling time or site-specific variations, and their interactions on plantain performance. Thereby, highlighting the role of locally formulated bio-inoculants in improving crop performance. These findings open up avenues for further studies on the role of bio-inoculants on crop nutrient uptake, and control of crop pests and diseases, in order to promote a holistic management approach that integrates bio-inoculants, crop type, and site-specific factors.

Aluminum is one of the most abundant elements in earth’s crust and soils. Global soil acidification has occurred with industrialization and enhances Al solubility in acidic soils, resulting in Al phytoxicity and reducing crop production. Earthworms play an important role in nutrient recycling in soils and maintaining soil health. Rhizosphere microorganism excretes exopolysaccharides (EPS) into the rhizosphere. The objectives of this study is to examine effects of EPS from Rhizobium Tropici on aluminum uptake and ecotoxicity to earthworms in soils and litters. Overall this study provides the scientific understanding of the EPS in alleviation of Al toxicity to earthworms in soils. Results showed the clear mitigation of EPS in reducing earthworm mortality rate and increasing its reproductivity under Al stress. EPS significantly decreased Al uptake from soil and litters, and decreased Al in subcellular distribution (cell membrane, cytosol and organelle fractions) in earthworms from soils. Al in purges was found to be mainly present in the residual fraction, while EPS slightly increased Al in water soluble and exchangeable fractions in purges. Overall water soluble and organic matter bound Al in soils were correlated well with Al in earthworms, but Al in earthworms were controlled by total Al in purges. The current study concluded that earthworm Lumbricus Terrestre may be a potential bio-indicator of Al ecotoxicity in soils and EPS from Rhizobium Tropici effectively mitigated Al ecotoxicity in soils.

In this perspective, I focus on problems caused by plastics or microplastics in soil that are based on my knowledge. I point out that contacts that I have had from lawyers and policy makers show that plastics in soil are going to become important legal and regulatory issues. I describe an experiment that I did with the microplastic, polyethylene glycol, added to soil, which showed that it caused ponding of water on the soil surface and reduced infiltration, probably due to the participation of the polymers of the microplastic in a process called solvation. The large, hydrated molecules apparently clogged the soil pores, preventing aeration. I also showed in the same experiment that polyethylene glycol increased the uptake of the toxic heavy metal, cadmium, into wheat plants. I end the perspective by describing a recent experiment that indicates that the Casparian strip is a likely barrier for the uptake by lettuce of polystyrene microplastics that are 200 nm in diameter. However, smaller particles might penetrate it, and we need more studies to determine the size of nanoparticles that can move through the Casparian strip and up to the shoot.