Valley Soils Research Articles

Trapnell's Upper Valley soils of Zambia: the production of an integrated understanding of geomorphology, pedology, ecology, and land use

Abstract. The Ecological Survey of Northern Rhodesia (now Zambia), undertaken in the 1930s under the leadership of Colin G. Trapnell, was a seminal exercise to relate soil, vegetation, and agricultural practices through intensive field observation. In this article, we examine early activities of the survey in the Upper Valley region around the Kafue Flats and the neighbouring plateau, where Trapnell recognized how geomorphological processes of normal erosion gave rise to distinctive soils with associated vegetation communities and considerable potential for crop production. We consider how Trapnell's approach to fieldwork gave him a particular insight into how soil conditions constrained agriculture in the Zambian environment; the adaptive value of traditional practices; and how these were developed as communities moved and responded to social, economic, and environmental change. We argue that Trapnell's work was innovative and that distinctions must be drawn between his understanding and what has been called the ecological theory of development. Close attention to Trapnell's experience could inform modern efforts to understand indigenous knowledge of African soils and their agricultural potential.

Benefits of Crotalaria juncea L. as Green Manure in Fertility and Soil Microorganisms on the Peruvian Coast.

The soils of the Barranca valley are among the best soils in Peru, but with so many years of application of agrochemicals and other agricultural practices, they are losing their productive capacity. Consequently, it was suggested to assess the impact of Crotalaria juncea L. as a green manure on soil fertility and the populations of bacteria and fungi present in the soil. Crotalaria was cultivated for 75 days and incorporated as green manure. After 90 days, the presence of bacteria and fungi was evaluated. Metabarcoding was employed, and the 16S rRNA and ITS2 amplicons were sequenced using the Illumina MiSeq platform. The sequences were processed using various bioinformatics tools. The results indicate that soils have a high diversity of bacteria and fungi. Likewise, in plots where the presence and action of natural biocontrol is suppressed (C0 and P0), pathogenic fungi increase their population in the fallow period (C1), while in P1, the addition of Crotalaria as a green manure promotes an increase in the population of bacteria and fungi, and at the same time it suppresses pathogenic fungi. The genera (bacterial and/or fungal) that increase due to the effect of Crotalaria are beneficial because they are involved as degraders of organic matter, promotion of plant growth and biological control of pathogens. Crotalaria is an alternative to improve soil fertility, increase the beneficial bacterial population, and reduce pathogenic fungi.

Geochemical and Documentary Topography of a Medieval Silver Valley: Detection of Workshops and Identification of Their Function

ABSTRACTThis paper presents the interdisciplinary investigation (archaeology, geochemistry, history) of a medieval silver and lead production site located in southern France, in the Minier valley (Occitanie, Aveyron, Le‐Viala‐du‐Tarn). In order to identify the production sites, in situ geochemical surveys were carried out using a portable X‐ray fluorescence spectrometer and differential GPS, guided on the analysis of medieval archival sources. The cartographic representation of the metal concentrations in the surface horizons shows significant enrichment of zinc and lead in the vicinity of the mines. This first type of enrichment makes it possible to highlight the activities of separation of sphalerite and silver‐bearing galena. The galena thus isolated on the hillsides is then transported to the vicinity of watercourses, where it is crushed, washed, and smelted. These secondary activities result in a last type of enrichment in which only lead is found in large quantities. The cross‐referencing of the information made it possible to overcome the challenges related to the location of the mineral processing workshops, which were often invisible on the surface. The medieval workshops have been located and a function suggested, outlining the first trends in the spatial and social division of labour and providing a solid corpus for future archaeological excavations. Finally, this study highlights the persistence of significant metal contamination in the soils of a rural valley and encourages the consideration of former mining areas when examining the environmental impact of metal production.

Natural and anthropogenic factors influence flowering synchrony and reproduction of a dominant plant in an inter-Andean scrub.

Agriculture expansion, livestock, and global change have transformed biological communities and altered, through aerosols and direct deposition, N:P balance in soils of inter-Andean valleys, potentially affecting flowering phenology of many species and thereby flowering synchrony and plant reproduction. We evaluated the influence of variation in temperature and moisture along the local elevational gradient and treatments with the addition of N and P and grazing on flowering synchrony and reproduction of Croton, a dominant shrub of the inter-Andean dry scrub. Along the elevational gradient (300 m difference between the lowest and highest site), we set up plots with and without grazing nested with four nutrient treatments: control and addition of N or P alone or combined N + P. We recorded the number of female and male flowers in bloom monthly from September 2017 to August 2019 to calculate flowering synchrony. We assessed fruiting, seed mass, and pre-dispersal seed predation. Higher growing-season soil temperatures, which were negatively associated with local elevation and higher nitrogen availability promoted flowering synchrony of Croton, particularly among larger plants. Greater flowering synchrony, high soil temperatures, and addition of N + P resulted in production of more fruits of Croton, but also intensified pre-dispersal seed predation. Temperature, availability of moisture throughout the elevational gradient, and nutrient manipulation affected flowering synchrony, which subsequently affected production of fruits in Croton. These results emphasize the critical role of current anthropogenic changes in climate and nutrient availability on flowering synchrony and reproduction of Croton, a dominant plant of the inter-Andean scrub.

Surface Flux Patterns of Nutrient Concentrations and Total Suspended Solids in Western Carpathian Stream within Agricultural, Forest, and Grassland Landscapes

The intricate processes of surface water erosion are vital for ecological systems and river-scale management; yet, understanding them comprehensively remains a challenge. Forested agricultural catchments, especially in the Carpathian region, face significant degradation, potentially leading to inorganic nutrient leaching and total suspended solid (TSS) flux. Continuous rainwater inundation of soils in river valleys exacerbates this issue. Utilizing innovative tools like SWAT+, studies have revealed higher concentrations of inorganic nutrients in main watercourses from flysch catchments, with agricultural use linked to N-NO3− concentrations and pasture use linked to anion P-PO43−. Maintaining detailed records is crucial for researchers comparing data. SWAT+ proves valuable for studying TSS washing out and inorganic nutrient leaching, informing collaborative watershed management policies involving stakeholders from agriculture, conservation, and water management sectors. The insights on nutrient leaching, particularly phosphorus (P) and nitrogen (N), are instrumental for shaping policies targeting nutrient pollution within pasture land use for EU agriculture. These findings can guide policy frameworks focused on sustainable practices, especially for eco-schemes, and encourage collaborative watershed management efforts.

Impact of deforestation on the hydrogen, oxygen and iron isotope compositions of Amazonian streams

We examined the consequences of deforestation and pasture establishment on H, O and Fe isotope cycling in the hydrosphere, with focus on small watersheds from the central and eastern part of Brazilian Amazonia. The δ18O- δD relationships in stream water samples show that the evaporation effect is greater in pasture than in forest, thereby highlighting the impact of deforestation on atmospheric water circulation and rainfall.A clear effect of deforestation was also found on the dissolved load of these streams. Water temperature, pH, conductivity, major cations and dissolved carbon organic content are lower in forest streams compared to those from deforested areas. Dissolved (i.e., filtrate <0.45 μm) iron concentrations are typically higher in these tropical forest streams. They also show δ57Fe signatures commonly higher than that of the continental crust (i.e., > 0.1‰). In these black waters enriched in organic matter, the heavier iron isotope composition in the forested areas is related to the oxidized Fe strongly bound to colloidal organic matter. On the other hand, dissolved iron from streams draining older deforested areas shows isotopic compositions usually lighter than the continental crust (δ57Fe < 0.1‰). The negative δ57Fe signatures of these areas are likely caused by deforestation involving erosion and rejuvenation of soils in valleys, which leads to the occurrence of a partial iron reduction in the soils. These modifications increased the proportion of isotopically light, dissolved and more reduced Fe in the streams.Those effects are less obvious on more recent pastures since they display more chemical and isotopic scatter along the sampling months. In a stream flowing through an area undergoing slash and burned deforestation within the year, dissolved iron concentrations and isotopic compositions are much more scattered, with δ57Fe values varying by >10 ‰ as a result of fire or heavy rain events. This likely depicts the disruption of the iron cycling in the water-soil-plant system with strong changes in the soil mineralogy, organic matter characteristics and biomass activity resulting from the forest fire. Our results suggest that more than a decade is needed to reach a new dynamic steady state of the Fe biogeochemical cycle in pastures.Hence, the contrasted Fe isotopic compositions between the streams draining pristine tropical forests and those from deforested areas indicate that, like H and O isotopes, Fe isotopes are a sensitive indicator of the transformations affecting the biogeochemical cycling of tropical environment in response to deforestation. However, in contrast to hydrogen and oxygen isotopes that reveal the exchanges between surface waters and atmosphere, iron isotopes rather highlight the physical-chemical reactions occurring between surface waters and the soils, but with the biomass mediation for all three isotopic tracers.

Does the State of Scientific Knowledge and Legal Regulations Sufficiently Protect the Environment of River Valleys?

The pressure of human activity in river valley environments has always been high. Even today, despite the increasing awareness of societies around the world regarding the need to protect water and biodiversity, there are concerns that the current river valley management systems are insufficient. Therefore, the aim of this study was to assess the state of knowledge about the soils and forest ecosystems of river valleys in terms of the possibility of protecting river valley environments. This study used data obtained from the Forest Data Bank (FDB) database, which focuses on forests in Poland. After analyzing 17,820 forest sections where the soils were described as fluvisols, it was found that forest areas associated with fluvisols (typical, fertile soils of river valleys) are quite well recognized and protected in Poland. Most (55%) forested fluvisols are located in Natura 2000 sites (an important European network of biodiversity hotspots), 4% in nature reserves, and 1% in national parks. Additionally, the main forest habitat type associated with fluvisols is riparian forest, composed mainly of Quercus, Ulmus, and Fraxinus, which is protected as Natura 2000 habitat type 91F0. Preserving the sustainability of the forest is also a form of soil protection. Despite the identification of soils and forests in river valleys, as well as appropriate legal tools, their protection may be ineffective due to the fragmentation of forms of protection and the lack of a coherent system for managing river valleys. Because the conservation status of the river valleys is also influenced by the management of areas located outside the river valleys, in order to protect river valley ecosystems, integrated conservation plans for entire catchments should be implemented. Due to potential conflicts related to the management of areas with diverse expectations of local communities, it would be advisable for such plans to be created by local experts but under the supervision of a specialist/specialists from outside the area covered by a given river basin.

Bioremediation of Saline Soils with the Consortium of Halophilic Bacteria

88 strains of bacteria were isolated and purified from the naturally saline soils of Kumisi, Sagarejo and Alazani valley (Eastern Georgia). Based on the initial identification all strains belong to the genus Bacillus. Two strains – Bacillus spp. 8(3)1) and Bacillus spp. 7(5)4, resistant to chloride, sulfate and mixed (chloride-sulfate) salinity, as well as possessing high cellulase and amylase activities were selected as a result of successive screenings among the isolated bacteria. After the antagonism between potential members of the consortium has been excluded, the consortium of halophilic bacteria was created. Compost was made and applied to moderately saline soils using the halophilic consortium. The bioremediation of saline soils of Alazani was especially successful: the halophilic consortium has reduced the salt content in the soil by 41% during the 21 days of composting.

Sustainable water management in rice cultivation reduces arsenic contamination, increases productivity, microbial molecular response, and profitability

Arsenic (As) and silicon (Si) are two structurally competitive natural elements where Si minimises As accumulation in rice plants, and based on this two-year field trial, the study proposes adopting alternating wetting and drying (AWD) irrigation as a sustainable water management strategy allowing greater Si availability. This field-based project is the first report on AWD's impact on As-Si distribution in fluvio-alluvial soils of the entire Ganga valley (24 study sites, six divisions), seasonal variance (pre-monsoon and monsoon), rice plant anatomy and productivity, soil microbial diversity, microbial gene ontology profiling and associated metabolic pathways. Under AWD to flooded and pre-monsoon to monsoon cultivations, respectively, greater Si availability was achieved and As-bioavailability was reduced by 8.7 ± 0.01–9.2 ± 0.02% and 25.7 ± 0.09–26.1 ± 0.01%. In the pre-monsoon and monsoon seasons, the physiological betterment of rice plants led to the high rice grain yield under AWD improved by 8.4 ± 0.07% and 10.0 ± 0.07%, proving the economic profitability. Compared to waterlogging, AWD evidences as an optimal soil condition for supporting soil microbial communities in rice fields, allowing diverse metabolic activities, including As-resistance, and active expression of As-responsive genes and gene products. Greater expressions of gene ontological terms and complex biochemical networking related to As metabolism under AWD proved better cellular, genetic and environmental responsiveness in microbial communities. Finally, by implementing AWD, groundwater usage can be reduced, lowering the cost of pumping and field management and generating an economic profit for farmers. These combined assessments prove the acceptability of AWD for the establishment of multiple sustainable development goals (SDGs).

Особенности микроэлементного состава горных аллювиальных почв Западного Кавказа

The object of the study is the microelement composition of mountain alluvial soils, the formation of which occurs quite intensively due to the activity of processes that determine the development of soil cover in mountainous relief conditions. The study is based on the analysis of features forming the system of soil compounds of microelements in alluvial soils of river valleys of the Western Caucasus using the example of the Bolshoy Zelenchuk River valley. The study specified that alluvial soils are characterized by a constant supply of microelements in the composition of suspensions and dissolved substances in river waters, which during flood spills flood the flood-plain part of river valleys. In addition, microelements are supplied mechanically from the mountain slopes directly adjacent to the river valley. A certain role is played by the processes of aerial transfer of dust particles with air flows, including those of a transboundary nature. Rising groundwater also causes the movement of dissolved forms of trace elements in mountain alluvial soils in both radial and lateral directions. Based on the results of the study, we can conclude that mountain alluvial soils are characterized by a strong connection with soil-forming rocks, which are the most important source of microelements. Features of the development of the system of soil compounds of microelements in mountain alluvial soils are determined by the specific conditions for the occurrence of soil-forming processes in them. Their study is necessary due to the important environment-forming significance of mountain alluvial soils in modern landscapes of river valleys, which are the most developed areas of mountainous countries.

Changes in humus content on the territory of agricultural lands in the Issyk-Kul basin of Kyrgyzstan

The Issyk-Kul valley of Kyrgyzstan has very large diversity of soil types which is developed by complex of abiotic and biotic factors including mountain-valley landscapes and different climatic conditions. We found that there is a process of significant loss of humus content in almost all studied areas of the Issyk-Kul region, both in the upper and lower layers of the soil. The humus content has been significantly decreased in the upper layer of valley soils during the past four decades. Among them, mountain-valley chestnut and dark chestnut soils, represented in the Issyk-Kul region, showed themselves to be the most depleted. Here, the difference in humus content between the top arable and non-arable layers is 40%. More stable humus content is shown in the mountain light chestnut and mountain-valley light brown soils, presented in certain areas of the Ton, Ak-Suu and Tyup districts. Apparently significant decrease in the humus content in chestnut soils is associated with intensive long-term anthropogenic use, including non-compliance with agrotechnical standards.

Estimation of Nitrite (NO2−), Phosphate (PO34−) and Sulfate (SO24−) in Soil Samples of Kathmandu Valley and Western Nepal

Title: Estimation of Nitrite (NO2−), Phosphate ( PO34− ) and Sulfate ( SO24− ) in Soil Samplesof Kathmandu Valley and Western Nepal Soil is a dynamic resource that interacts with the ecosystems such as water, air, flora and fauna that influence plant, life on earth. Soil fertility largely affects agriculture, plant and animal productivity. It requires to preserve water and air quality to sustain human health and habitation. Nitrite, phosphate, and sulfate of soil samples from 10 different places were estimated. Nitrite was analyzed by the addition of benzidine, hydrochloric acid solution, dimethylaniline followed by the addition of NaOH, a pink red colored azo dye was formed and was measured spectrophotometrically in the range of 0.068 to 0.213 mg/L. At a pH of 8.5 the available phosphates were extracted with sodium bicarbonate solution and acidified with H2SO4. In the presence of ammonium molybdate and hydrazine hydrate, a light blue colored ammonium phosphomolybdate complex was formed and was measured by spectrophotometer in the range of 0.158 to 0.279 mg/L. In presence of excess of BaCl2, sulfate ion was then determined by turbidimetry method in the range of 0.130 to 0.271 mg/L.

Effect of Sedimentary Environment in Iron and Manganese Crystallization Index of some Soil of Anbar Government

This study was conducted to elucidate the impact of depositional conditions on different sedimentary and desert environments on the crystallization index of iron and manganese. The study area is located within the administrative boundaries of Anbar Governorate. Eight desert valleys were selected, including Al-Qaim Valley, Al-Mohammadi Valley, Al-Damamah Valley, Hauran Valley, Al-Baghdadi Valley, Zaghdan Valley, Al-Sahliyah Valley, and Al-Sheikh Hadeed Valley, with two pedons per site, one in the sedimentary deposits and one in the desert deposits. The samples were prepared for laboratory analysis. Total iron and manganese, non-crystalline iron and manganese oxides, crystalline iron and manganese oxides. Then, the crystallization index was calculated for both iron and manganese elements in both sedimentary and desert soils alike. The results showed that the values of the soil pH in sedimentary soils ranged from 7.12-8.06, while they were recorded in the desert soils with a range of 7.31-8.03. In general, they fell within the limits of basic to highly basic degrees. Electrical conductivity (Ec) was recorded in a range of 0.76-11.80 ds.m-1, which were classified as low salinity to saline soils, as their values decreased with increasing depth in both desert and sedimentary soils are the result of climatic conditions of high temperatures in as well as water and wind additions that helped the accumulation of salts in the surface horizons. The cation exchangeable capacity (CEC) varied between 10.06 and 40.58 cmolc.kg-1, consistently corresponding to the clay content present in the soil. Notably, desert soils exhibited superior crystallization indices for iron and manganese compared to sedimentary soils. However, there was a decline in the crystallization index of iron relative to manganese across all study soils, attributed to the high content of total iron in the parent material, with the presence of a certain pattern in the distribution in the desert soils, where it took a regular distribution with the depth. On another hand, in the sedimentary soils it took a random distribution with the depth due to influence of the sedimentary soils with the movement and transmission of the separate clay through the soil horizons. The ratio of iron to manganese crystallization varied from 0.140 to 14.142 Generally, it increased with depth in desert and sedimentary soils, except for Hauran valley and Al-Baghdadi valley soils, where it decreased due to high total iron content in their parent material.

The Natural Consequences of Land Use Change on Transformation and Vegetation Development in the Upper Odra Floodplain

River channels are regulated in various ways and the fertile soils of valleys are occupied for agricultural purposes, accompanied by human settlements. In many places on the floodplains, gravel or sand is mined and former pits fill with water. The consequences are changes in water relations, changes in land use and land cover. Natural riparian ecosystems gradually disappear. In addition, river valleys are susceptible places for the spread of invasive plant species. In the section of the Upper Odra Valley discussed in this article, all of the aforementioned factors have played roles in shaping modern habitats. The present study shows the impact of human-induced changes on the transformation of the plant cover of the Upper Odra Floodplain. In designated transects, we studied land use changes from 1910 to the present day and examined plant species diversity. The results show that the more heavily transformed floodplain adjacent to the channelized channel has a higher level of species diversity than agricultural areas located along a section of the river with a natural channel course. Most of the river valleys are colonized by geographically invasive alien species, such as Reynoutria japonica, Reynoutria sachalenesis and Impatiens glandulifera, which have contributed to the fact that all of the species typical of the ash, poplar and willow riparian forests characteristic of this habitat type have retreated, which is the main reason for the very low biodiversity.

Salinization and Solonetsization of Soils in River Valleys of the Kulunda Plain

The surface of the Kulunda Plain is dissected by a system of ancient wide valleys, former runoff hollows, which have a very small slope (less than 1°). Rivers flow along these weakly expressed valleys, redistributing readily soluble salts throughout the territory. The regime of these rivers is characterized by a sharp and high flood wave and low (up to complete drying) runoff in the summer. The purpose of this work is to study the ion-salt system of soils of ancient runoff troughs of the Kulunda Plain, groundwater and river waters in order to identify modern processes of soil salinization. During floods, river water feeds close-lying groundwater, influencing its chemical composition. Studies of three key sites in the valleys of the Bagan (Novosibirsk region), Burla and Kulunda (Altai Territory) rivers took place in 2021–2022. Ground waters of varying degrees of mineralization (from 3.4 to 63.0 g/l) and lie close to the surface (2–5 m), which causes a wide distribution of saline hydromorphic soils in the study area. Differences in the salt state of soils in different valleys, groundwater and river waters are discussed. The degree of salinization of soils depended on their granulometric composition. The high content of physical clay contributed to the rise of salts with groundwater and their accumulation in the soil profile. A large amount of exchangeable sodium in the soil absorbing complex of the studied soils (more than 3–5 cm (eq)/kg), the predominance of easily soluble sodium salts in the soil solution with its low mineralization, as well as the alkaline reaction of the soil medium indicates the manifestation of the process of soil salinization.

Zonal Concept: Landscape Level Parameters and Application

Abstract Zonal concept is a traditional approach in land assessment. Although its principles have been known for over a hundred years, they have not yet been thoroughly evaluated using modern analytical approaches. Assessing the empirically established parameters for characterising a zonal site, establishing threshold values of significant environmental factors, along with assessing the applicability of the zonal concept, were the goals of this study. The data analysed were obtained from the robust and objective Czech National Forest Inventory database. Regression, indirect ordination, hierarchical clustering and spatial analyses of geo-information systems were used. The study revealed seven crucial environmental factors: Slope, Slope Height, Terrain Surface Texture, Negative Openness, Multi-Resolution Index of Valley Bottom Flatness, Soil Type and Soil Subtype. A graphical model of zonal/azonal sites was constructed based on calculated threshold values of the factors. This methodic approach introduces significant geomorphological information that are otherwise problematically detectable in field mapping. We suggest it is possible to use the zonal concept as a base layer for general landscape assessment. Zonal site classification can become a part of a precise land management practice, consisting of valuable empiricism of traditional landscape ecological classifications enriched by modelling in disturbance ecology and prediction of climate change effects.

Microbial diversity in Antarctic Dry Valley soils across an altitudinal gradient.

The Antarctic McMurdo Dry Valleys are geologically diverse, encompassing a wide variety of soil habitats. These environments are largely dominated by microorganisms, which drive the ecosystem services of the region. While altitude is a well-established driver of eukaryotic biodiversity in these Antarctic ice-free areas (and many non-Antarctic environments), little is known of the relationship between altitude and microbial community structure and functionality in continental Antarctica. We analysed prokaryotic and lower eukaryotic diversity from soil samples across a 684 m altitudinal transect in the lower Taylor Valley, Antarctica and performed a phylogenic characterization of soil microbial communities using short-read sequencing of the 16S rRNA and ITS marker gene amplicons. Phylogenetic analysis showed clear altitudinal trends in soil microbial composition and structure. Cyanobacteria were more prevalent in higher altitude samples, while the highly stress resistant Chloroflexota and Deinococcota were more prevalent in lower altitude samples. We also detected a shift from Basidiomycota to Chytridiomycota with increasing altitude. Several genera associated with trace gas chemotrophy, including Rubrobacter and Ornithinicoccus, were widely distributed across the entire transect, suggesting that trace-gas chemotrophy may be an important trophic strategy for microbial survival in oligotrophic environments. The ratio of trace-gas chemotrophs to photoautotrophs was significantly higher in lower altitude samples. Co-occurrence network analysis of prokaryotic communities showed some significant differences in connectivity within the communities from different altitudinal zones, with cyanobacterial and trace-gas chemotrophy-associated taxa being identified as potential keystone taxa for soil communities at higher altitudes. By contrast, the prokaryotic network at low altitudes was dominated by heterotrophic keystone taxa, thus suggesting a clear trophic distinction between soil prokaryotic communities at different altitudes. Based on these results, we conclude that altitude is an important driver of microbial ecology in Antarctic ice-free soil habitats.

Effect of long-term influx of tertiary treated wastewater on native bacterial communities in a dry valley topsoil: 16S rRNA gene-based metagenomic analysis of composition and functional profile.

Although dumping treated wastewater into soil might provide nutrients and organic matter, it can also expose the ecosystem to biological and chemical risks. A vital indication of soil health and quality is the soil microbial community. The current work used next-generation 16S rRNA gene amplicon sequencing to evaluate the effects of the long-term influx of tertiary treated wastewater (TWW) into Wadi Uranah, a dry valley in Makkah city, Saudi Arabia, on native topsoil bacterial community composition and predicted functions. The findings demonstrated that neither the compositions of microbial communities nor their predicted functions using PICRUSt2 differed significantly (p>0.05) between polluted valley soil (PolVS) and unpolluted valley soil (UPVS). Alpha and beta diversity, however, showed that the PolVS samples had a considerably higher level of diversity and variability. Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes were the most prevalent phyla in both groups. Noticeable relative variations existed in some metabolic pathways such as cofactor, prosthetic group, electron carrier degradation, aldehyde degradation, and Entner-Doudoroff (ED) pathways. Overall, our findings suggest that because both groups have very similar core microbiomes and functions, the long-term disposal of tertiary TWW into Wadi Uranah may have little to no influence on the composition and function of soil bacterial communities. In addition, the long-term discharge of tertiary TWW after partially treated wastewater's initial disposal may have helped the native soil microbial community recover.

Environmental aspects of mineral fertilizing of perennial grass mixtures on drained organic soils

Environmental protection and effective use of floodplain organic soils of river valleys in the humid zone is associated with the development of sustainable agrosystems, in which 65–75% of the sown area is allocated to perennial grasses. The main measure in the technology of growing perennial grass mixtures is the introduction of mineral fertilizers. The conducted studies show that the highest yield of perennial grass mixtures on average for 2016–2019 was obtained with the introduction of recommended doses of fertilizers obtained on the basis of perennial studies (N45P45K120) — 8.9 t/ha, and with the addition of 2 l/ha Organic Balance — 9.4 t/ha of dry mass; for the yield of 8.5 t/ha for the calculated dose of fertilizers to increase the yield of herbs N45P84K150 and 8.3 t/ha for the calculated dose for the planned yield taking into account the content of nutrients in the soil N45P138K293. Therefore, the most economically profitable and scientifically justified application of mineral fertilizers to crops of perennial grasses obtained on the basis of long-term scientific data, taking into account soil, climatic and weather conditions. In addition, the introduction of different doses of mineral fertilizers led to their corresponding leaching into the drainage waters, the leaching of NO3 during the growing season in the version with the recommended dose of fertilizers was 12.3 mg/l, and in the version with the introduction of mineral fertilizers for crop growth (N45P84K150) increased leaching into groundwater up to 17.2 mg/l of water. Thus, the economic and ecological evaluation of determination of doses of mineral fertilizers calculated by various methods showed that it is most expedient to determine calculations based on data obtained in long-term studies on crops of perennial grasses.

Chemical Properties of Some Alkaline Sandy Soils and Their Effects on Phosphorus Dynamics with Bone Char Application as a Renewable Resource of Phosphate Fertilizer

Several chemical properties of alkaline soils play an important role in dissolving phosphate minerals, which greatly affect the phosphorous availability to plants. The current study was carried out to assess bone char application on the availability and distribution of phosphorus in some alkaline sandy soils. This incubation experiment was performed by selecting some alkaline soils from different locations in Upper Egypt: Arab El-Awamer (Assiut Governorate), West El-Minia (El-Minia governorate), and New Valley Governorate. Bone char was applied at a dose of 4 g kg−1 soil. The incubation periods lasted for 7, 16, 35, 65, and 84 days. Phosphorus availability in Arab El-Awamer soil increased significantly with applying bone char and was greatly influenced by soil chemical properties and incubation periods. Bone char addition caused a relative increase of available phosphorous in the sequence as follows: Arab El-Awamer soil ˃ New Valley soil ˃ West El-Minia soil. Available phosphorous showed a negative correlation with electrical conductivity, soluble calcium, and soluble sulfate. A significant increase of NH4Cl-Pi, NaHCO3-Pi, NaOH-Pi, HCl-Pi, and residual P fractions occurred in some soils with bone char application. Phosphorus fractions distribution in all soils followed: HCl-P ˃ residual P ˃ NaHCO3-P ˃ NaOH-P ˃ NH4Cl-P. The correlation between phosphorus availability and phosphorus fractions was positive. Our results focus on the importance of using bone char as an amendment in P-poor alkaline soils for improving phosphorus availability. So, bone char is an effective technique for sustainable agriculture because it is a clean and renewable resource of phosphate fertilizers.