Soil Development Research Articles

Growth and protein response of rice plant with plant growth-promoting rhizobacteria inoculations under salt stress conditions.

Soil salinity has been one of the significant barriers to improving rice production and quality. According to reports, Bacillus spp. can be utilized to boost plant development in saline soil, although the molecular mechanisms behind the interaction of microbes towards salt stress are not fully known. Variations in rice plant protein expression in response to salt stress and plant growth-promoting rhizobacteria (PGPR) inoculations were investigated using a proteomic method and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Findings revealed that 54 salt-responsive proteins were identified by mass spectrometry analysis (LC-MS/MS) with the Bacillus spp. interaction, and the proteins were functionally classified as gene ontology. The initial study showed that all proteins were labeled by mass spectrometry analysis (LC-MS/MS) with Bacillus spp. interaction; the proteins were functionally classified into six groups. Approximately 18 identified proteins (up-regulated, 13; down-regulated, 5) were involved in the photosynthetic process. An increase in the expression of eight up-regulated and two down-regulated proteins in protein synthesis known as chaperones, such as the 60kDa chaperonin, the 70kDa heat shock protein BIP, and calreticulin, was involved in rice plant stress tolerance. Several proteins involved in protein metabolism and signaling pathways also experienced significant changes in their expression. The results revealed that phytohormones regulated the manifestation of various chaperones and protein abundance and that protein synthesis played a significant role in regulating salt stress. This study also described how chaperones regulate rice salt stress, their different subcellular localizations, and the activity of chaperones.

Contribution by Giant petrels and Brown skuas to soil phosphatization in Harmony Point - Maritime Antarctica.

This research was conducted for the purpose to evaluate the contribution Giant petrels and Brown skuas nestings in the formation of ornithogenic soils by the phosphatization process in Harmony Point, Maritime Antarctic. Ten nests were selected to collect topsoil samples (0-20 cm), from 0 m up to 20 m away, with regular spacing of 2 m. The analysis of the samples included the physical, chemical, mineralogical and geochemical analyzes. Phosphate minerals were identified. The presence of high content of some trace elements, such as Zn, Cu and Sr is associated with the bird's excrements. Total-P and bioavailable-P recorded higher levels. This result demonstrates the importance of the time factor in the bird's nesting, as well as in the development of the soil in these soil-forming environment. Phosphatization in these areas is not restricted to the specific location of the nest, since high values of P have been identified at distances between 8 and 12 m, from de nest's top. This suggests the transport of P rich solutions and phosphatized material along fractures by the freeze-thaw cycles, contributing to increase the geographical expression of this phenomenon in this ice-free area, consequently the development of soils and the establishment of vegetation.

Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon

AbstractIn a database of lunar fractured boulders (Rüsch & Bickel, 2023, https://doi.org/10.3847/psj/acd1ef), we found boulders with reflectance features dissimilar to previously known morphologies. We performed a photo‐geologic investigation and determined that the features correspond to a dust mantling on top of boulders with a unique photometric behavior. We next performed a photometric model inversion on the dust mantling using Bayesian inference sampling. Modeling indicates that the dust photometric anomaly is most likely due to a reduced opposition effect, whereas the single scattering albedo is not significantly different from that of the nearby background regolith. This implies a different structure of the dust mantling relative to the normal regolith. We identified and discussed several potential processes to explain the development of such soil. None of these mechanisms can entirely explain the multitude of observational constraints unless evoking anomalous boulder properties. Further study of these boulders can shed light on the workings of a natural dust sorting process potentially involving dust dynamics, a magnetic field, and electrostatic dust transport. The presence of these boulders appears to be limited to the Reiner K crater near the Reiner Gamma magnetic and photometric anomaly. This close spatial relationship further highlights that poorly understood processes occur in this specific region of the Moon.

On the study of the wheat nematode Anguina tritici chitwood, 1935 and their importance in wheat cultivation in Uzbekistan conditions

In our study, the wheat nematode Anguina tritici Chitwood, 1935 was registered in wheat ears in surveyed grain-growing farms in 5 regions of Uzbekistan. Larval stages of two- and three-year-old nematodes were observed at different stages of development in plant organs and root soil. The population density, depending on the living conditions, ranged from 8 to 60 larvae per 100 cm3 of soil and roots, and in stems and leaves from 12 to 25 larvae per 20 g. In heavily infected ears of wheat, the number of galls ranged from 9 to 50 copies. For the effectiveness of agrotechnical measures, such as crop rotation in the fight against wheat nematode, experiments were conducted to assess the viability of wheat nematode larvae. One-year-old, two-year-old and three-year-old galls were selected and the number of larvae was counted. It turned out that the number of viable larvae in annual galls is higher than in two-year and three-year-old galls.This is due to the fact that after a period of time, the accumulated food reserves in the body were used up for the viability of the larvae.

An integrated UAV growth monitoring model of Cinnamomum camphora based on whale optimization algorithm.

To explore an effective analysis model and method for estimating Cinnamomum camphora's (C. camphora's) growth using unmanned aerial vehicle (UAV) multispectral technology, we obtained C. camphora's canopy spectral reflectance using a UAV-mounted multispectral camera and simultaneously measured four single-growth indicators: Soil and Plant Analyzer Development (SPAD)value, aboveground biomass (AGB), plant height (PH), and leaf area index (LAI). The coefficient of variation and equal weighting methods were used to construct the comprehensive growth monitoring indicators (CGMI) for C. camphora. A multispectral inversion model of integrated C. camphora growth was established using the multiple linear regression (MLR), partial least squares (PLS), support vector regression (SVR), random forest (RF), radial basis function neural network (RBFNN), back propagation neural network (BPNN), and whale optimization algorithm (WOA)-optimized BPNN models. The optimal model was selected based on the coefficient of determination (R2), normalized root mean square error (NRMSE) and mean absolute percentage error (MAPE). Our findings indicate that apparent differences in the accuracy with different model, and the WOA-BPNN model is the best model to invert the growth potential of C. camphora, the R2 of the model test set was 0.9020, the RMSE was 0.0722, and the MAPE was 7%. The R2 of the WOA-BPNN model improved by 18%, the NRMSE decreased by 33%, and the MAPE decreased by 9% compared with the BPNN model. This study provides technical support for the modern field management of C. camphora essential oil and other dwarf forestry industries.

Prediction of wheat SPAD using integrated multispectral and support vector machines.

Rapidly obtaining the chlorophyll content of crop leaves is of great significance for timely diagnosis of crop health and effective field management. Multispectral imagery obtained from unmanned aerial vehicles (UAV) is being used to remotely sense the SPAD (Soil and Plant Analyzer Development) values of wheat crops. However, existing research has not yet fully considered the impact of different growth stages and crop populations on the accuracy of SPAD estimation. In this study, 300 materials from winter wheat natural populations in Xinjiang, collected between 2020 to 2022, were analyzed. UAV multispectral images were obtained in the experimental area, and vegetation indices were extracted to analyze the correlation between the selected vegetation indices and SPAD values. The input variables for the model were screened, and a support vector machine (SVM) model was constructed to estimate SPAD values during the heading, flowering, and filling stages under different water stresses. The aim was to provide a method for the rapid acquisition of winter wheat SPAD values. The results showed that the SPAD values under normal irrigation were higher than those under water restriction. Multiple vegetation indices were significantly correlated with SPAD values. In the prediction model construction of SPAD, the different models had high estimation accuracy under both normal irrigation and water limitation treatments, with correlation coefficients of predicted and measured values under normal irrigation in different environments the value of r from 0.59 to 0.81 and RMSE from 2.15 to 11.64, compared to RE from 0.10% to 1.00%; and under drought stress in different environments, correlation coefficients of predicted and measured values of r was 0.69-0.79, RMSE was 2.30-12.94, and RE was 0.10%-1.30%. This study demonstrated that the optimal combination of feature selection methods and machine learning algorithms can lead to a more accurate estimation of winter wheat SPAD values. In summary, the SVM model based on UAV multispectral images can rapidly and accurately estimate winter wheat SPAD value.

Biologization of oilseed fertilization systems in the conditions of the Rostov region

The article reflects the results of studies conducted in the dry steppe zone of the Russian Federation to evaluate fertilizer systems for oilseeds with the widespread use of biological preparations. The practical aspects of managing soil fertility and agrocenosis productivity in the form of an alternative fertilization system - without the use of mineral fertilizers and their limited use - are covered. The influence of biologized fertilizer systems on the elements of soil fertility, growth and development of oilseeds has been established. Data on recording biometric indicators when using the studied agricultural techniques are presented. Indicators of crop productivity were determined, and the obtained data on economic and energy assessment of the effectiveness of the studied elements of the oilseed biologization system were analyzed. A comprehensive positive effect of the studied agricultural practices on productivity has been established.

Land management of formerly subtropical Atlantic Forest reduces soil carbon stocks and alters microbial community structure and function

Soil carbon (C) sequestration has been proposed as one means to mitigate the effects of climate change and to guarantee food safety. However, forest conversion to managed land uses can deplete soil C stocks and affect soil microbial communities, potentially impacting a wide range of ecosystem services. Our objective was to investigate the effect of forest conversion to intensive land uses on soil C dynamics and soil microbial community structure and function in the subtropical portion of the Atlantic Forest biome. We evaluated four land uses - forest fragment, grassland, and agriculture with five or fifty years of cultivation. We analyzed soil C pools, edaphic variables, and soil bacterial/archaeal (16S) and fungal (ITS) communities. Forest conversion to managed land uses reduced soil C stocks and altered soil microbial community structure, with implications for soil C dynamics. Bacterial/archaeal and fungal community composition were strongly correlated with pH, base saturation, and calcium (Ca) and magnesium (Mg) content. However, soil C pools were not associated with potential extracellular enzyme activity or microbial diversity. Finally, the fungal species Mortierella minutissima ASV_1 and several bacterial groups were positively correlated with soil C stocks, potentially representing indicators of soil C storage. Our study indicates that land use change affects the interplay between soil microbial communities and soil C pools, with consequences to soil C storage. Our findings may support the development of soil C enhancement programs within the Atlantic Forest biome.

Impacts of forest age on soil characteristics and fertility quality of Populus simonii shelter forest at the southern edge of the Horqin Sandy Land, China.

The sand fixing shelter forests in the Horqin Sandy Land are a key area in the "3-North" Shelter Forest Program in China, which has a history of over 50 years of artificial afforestation. Populus simonii Carr is one of the most dominant silvicultural species in the region. The aim of this study is to understand the soil characteristics and soil fertility of Populus simonii shelter forests at different growth stages and to establish a scientific basis for soil nutrient regulation and sustainable management of Populus simonii shelter forests at the southern edge of the Horqin Sandy Land. Sample plots were selected for young (≤15 a), middle-aged (16-25 a), near-mature (26-30 a), mature (31-40 a), and over-mature (≥41 a) forests. Each forest studied was in a state of natural restoration with uniform stand conditions and no artificial fertilizer was applied. These sites were selected to study changes in the soil characteristics in soil depths of 0-20, 20-40, and 40-60 cm. In order to avoid the problem of multicollinearity between soil variables and to reduce redundancy, principal component analysis (PCA), Pearson's correlation analysis, and Norm value calculation were used to select the least correlated indicators with the highest factor loadings. This was used to establish the minimum data set. The soil fertility quality of these shelterbelts in different forest ages was quantified using the soil quality index (SQI). In the growth stage from young to nearly mature forests, the soil bulk weight and pH decreased with increasing forest age. Soil capillary porosity, noncapillary porosity, total porosity, water content, field water holding capacity, and organic carbon content increased with increasing forest age and soil nutrient content gradually improved. At the stage of near-mature to over-mature forests, the effect of forest age on soil bulk density was not significant and all other soil characteristics decreased to varying degrees as the forest age increased. The soil also developed from alkaline to neutral. The SQI of the total data set and the SQI of the minimum data set consistently showed that near-mature forests (NMF) > middle-aged forests (MAF) > mature forests (MF) > over-mature forests (OMF) > young forests (YF). The results of the two evaluation systems showed a significant positive correlation (P < 0.05, R 2 = 0.8263) indicating that it is feasible to use the minimum data set to evaluate the soil fertility of shelter forests of different forest ages. The age of the forest has an obvious effect on the soil characteristics and overall soil fertility of shelter forests. The Populus simonii shelter forests on the southern edge of the Horqin Sandy Land have great soil development at the early stage of afforestation and the soil nutrient content gradually increases. The soil fertility reaches a peak when the forest is nearly mature and the soil fertility declines after the age of the forest reaches 30 years.

Experimental studies of the control process of the working body of a single-bucket excavator

The operator's actions are studied when controlling a single-bucket excavator when digging a trench for underground pipeline laying. The angular parameters of the working body of a single-bucket excavator are obtained. The time of the full cycle of soil development and the main elements of the software and hardware complex for collecting and processing data are determined. The dependence of the time of a technological operation on the angular parameter of the working body of the excavator is obtained. Keywords single-bucket excavator, trench, working body, operator, hardware and software complex

Modelling of soil destruction process by bulldozer using a spatially oriented working unit

The article uses approaches to creating a model for calculating soil cutting forces by spatially oriented working units of construction machines used on construction sites. The use of such a model is due to the need for continuous improvement of existing equipment and the creation of new ones, taking into account the existing needs. Today, there is a need for efficient performance of construction works related to the operation of construction equipment with dumping equipment. This, in turn, poses the task of determining the performance of mechanised earthworks in various working environments, one of the most common in Ukraine being marl clay, loam and argillaceous clay.&#x0D; The main method of mechanical soil development is cutting. The main geometric conditions are the position of the cutting wedge edge relative to the cutting direction and the surface of the massif, the outline of the cutting edge, the outline and number of working surfaces of the cutting wedge, the number of so-called side cut surfaces and the so-called blocked cut surfaces. The peculiarity of the digging process is that its power and energy indicators depend on the kinematic conditions and geometric parameters – thickness, width and area of the cut, as well as on the angles of orientation of the working unit in space.&#x0D; The computational model was created in accordance with the working hypothesis, where the movement of spatially oriented knives moves perpendicular to the blade equipment, at different ratios of the blade movement speed and knife movement, which creates spatial interaction with the working environment, and the deviation of the application of the full cutting force by an angle α.&#x0D; In accordance with the working hypothesis, we obtained five plans for the movement of the spatially oriented blade of the blade. Depending on the plan of movement of the spatially oriented knife, its geometric interaction with the working environment changes and the cutting force changes accordingly.&#x0D; The need to create more productive and efficient earthmoving equipment requires the use of modern design solutions. In the course of the study, a model for calculating the cutting of soils by spatially oriented earthmoving tools in the form of a dihedral knife of dump equipment was created. A comparison of soil cutting forces at different depths during the operation of a spatially oriented working body is also proposed. The results are summarised in the form of tabular data and graphs.

STUDY SOIL DEVELOPMENT AND CLASSIFICATION IN ERBIL PROVINCE, KURDISTAN, IRAQ USING MATHEMATICAL INDICES

The study area located at Erbil province, Kurdistan, Iraq, seven pedons were elected. Twenty-one soil samples were collected in the study area. Different physiochemical and fertility indices have been used to determine the soils development, despite of generating interpolated maps for them. The results indicated that the low values of clay were found in the less pedon developed and argillic horizon existed in development pedons. Study soils were non-saline, slightly to moderately alkaline, and had relatively high bulk density values. Organic matter is concentrated at the soil surface. Considerable total carbonates are found in studied soils and have irregular distribution manner, as well as have high CEC values. Low C/N ratio due to highly decomposed organic matter. The active CaCO3/total CaCO3 increases with depth in all pedons, while, slightly fluctuated in one pedon. The ratio of total clay in BH /AH was found just in some pedons and more than (1) therefore these soils are considered development, and are more developed depending on the ratio of fine clay/total clay. Soils are classified into three groups the first was the least developed soils, the second group has the most development. Third group are intermediate in their development. Pedogenic processes included leaching, illuviation, eluviation, alkalization, humification, lessivage, desalinization, calcification, decomposition, and littering. Studied soils classified as Inceptisols and Mollisols.

Study of a Tailings Dam Failure Pattern and Post-Failure Effects under Flooding Conditions

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam’s failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam’s fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams.

Effects of topography, climate, mineralogy and physicochemical properties on potassium forms in various soils of Fars province, southern Iran

The relationship between potassium (K) and soil physicochemical properties can be used to understand the K cycling. Topography, as a soil forming factor, has an important effect on the soil characteristics of every region. This study was conducted to investigate K and its relationship with climate, mineralogy, and physicochemical properties in toposequences of two regions (Sepidan and Darab) in southern Iran. XRD analysing patterns showed montmorillonite, illite, chlorite, and kaolinite as diagnostic minerals of these regions. Due to being located in arid regions of Iran and lack of good rainfall, the results did not show any significant difference between the selected areas. So, climate could not be considered as an effective factor in supplying K for plants. In both regions, topography affected soil development as a soil forming factor, so that anywhere the more developed soil was observed, the more extracted K forms were found. In different physiographic units of Sepidan region, topography, by affecting soil properties through microclimate, drainage and sunshine quality, caused differences in distribution of K forms. The correlation between different K forms and soil properties in both regions because of weathering and releasing K from K-bearing minerals like illite, showed a relationship with soils finer section.

Estimating the SPAD of Litchi in the Growth Period and Autumn Shoot Period Based on UAV Multi-Spectrum

The relative content of chlorophyll, assessed through the soil and plant analyzer development (SPAD), serves as a reliable indicator reflecting crop photosynthesis and the nutritional status during crop growth and development. In this study, we employed machine learning methods utilizing unmanned aerial vehicle (UAV) multi-spectrum remote sensing to predict the SPAD value of litchi fruit. Input features consisted of various vegetation indices and texture features during distinct growth periods, and to streamline the feature set, the full subset regression algorithm was applied for dimensionality reduction. Our findings revealed the superiority of stacking models over individual models. During the litchi fruit development period, the stacking model, incorporating vegetation indices and texture features, demonstrated a validation set coefficient of determination (R2) of 0.94, a root mean square error (RMSE) of 2.4, and a relative percent deviation (RPD) of 3.0. Similarly, in the combined litchi growing period and autumn shoot period, the optimal model for estimating litchi SPAD was the stacking model based on vegetation indices and texture features, yielding a validation set R2, RMSE, and RPD of 0.84, 3.9, and 1.9, respectively. This study furnishes data support for the precise estimation of litchi SPAD across different periods through varied combinations of independent variables.

ACHIEVEMENTS AND PERSPECTIVES OF DEVELOPMENT IN SOIL MICROBIOLOGY AT MOSCOW UNIVERSITY

The article summarizes the results of recent research by the staff of Soil Biology Department Faculty of Soil Science of Lomonosov Moscow State University in the field of assessing the genetic potential of microbial communities of soils and their application in the development of fundamental soil and environmental technologies. Promising areas of further work related to the use of the microbial potential of soils for the purpose of bioremediation territories from ecotoxicants, the development of technologies for selfpurification of soils based on the stimulation of natural communities of microorganisms, as well as the use of microbial cultures for biodegradation of petroleum products, pesticides and synthetic polymers. Another important direction is related to the development of scientific basis for the indication of biological objects in the environment and space objects. Within the framework of this direction, genomic analysis of uncultivated microorganisms from the Arctic, Antarctic and other extreme habitats is carried out, and the knowledge gained apply as a model of alien life. Another relevant direction for the Department of Soil Biology is the development of agrobiotechnologies based on the management of the natural soil microbiome, the creation of microbial preparationsstimulators of plant growth and development, microbiological ways to increase the proportion of biological nitrogen in plant nutrition, application of microbial plant endosymbionts and bioinsecticides. An equally important aspect is the search of producers of biologically active substances, such as phytohormones, antibiotics, enzymes, probiotics, hydrolytics of natural and artificial polymers. The considered areas of research in the field of soil biology are important for improving land management, environmental protection and the development of environmental technologies.

Soil organic matter and biogenic-abiogenic interactions in soils of Larsemann Hills and Bunger Hills, East Antarctica

Although Antarctic soils are usually described as weakly developed, recent studies indicated the significant variability in soil forming conditions across the sixth continent as well as considerable diversity of soils. The identification of pedogenetic processes in Antarctica is crucial for understanding not only the current state of its environment, but also for better understanding of soil development on Earth through time. Our study provides a detailed investigation of micromorphological features and molecular composition of organic matter of soil and soil-like bodies of remote areas of East Antarctica - Larsemann Hills and Bunger Hills, which are characterized by harsh environmental conditions. Studied soils showed predominantly coarse structure and low organic carbon content, alkaline to almost neutral pH range. Thin sections of studied soils were characterized by predominance of grains of quartz, feldspars, and other primary minerals with angular shapes indicating relatively weak degree of their alteration. All studied humic substances are characterized by the predominance of aliphatic structures. Moreover, it was observed that studied humic acids contains significant amounts of carbohydrates, polysaccharides, esters and amino acids and hydrophilic fragments predominate. Organo-mineral interactions were mostly connected with development of biofilms in the topsoil horizons with the maximal biological activity among studied soils.

Enhancement of nitrogencycling and functional microbial flora by artificial inoculation of biological soil crusts in sandy soils of highway slopes.

Biological soil crusts (BSCs) are common in arid and semi-arid ecosystems and enhance soil stability and fertility. Highway slopes severely deplete the soil ecological structure and soil nutrients, hindering plant survival. The construction of highway slope BSCs under human intervention is critical to ensure the long-term stable operation of the slope ecosystem. This study investigated the variation rules and interaction mechanisms between soil nutrients and microbial communities in the subsoil BSCs on highway slopes. Bacterial 16S rRNA high-throughput sequencing was employed to investigate the dynamic compositional changes in the microbial community and perform critical metabolic predictive analyses of functional bacteria. This study revealed that the total soil nitrogen increased significantly from 0.557 to 0.864g/kg after artificial inoculation with desert Phormidium tenue and Scytonema javanicum. Actinobacteria (44-48%) and Proteobacteria (28-31%) were the dominant phyla in all samples. The abundance of Cyanobacteria, Cytophagaceae, and Chitinophagaceae increased significantly after inoculation. PICRUST analysis showed that the main metabolic pathways of soil microorganisms on highway slopes included cofactor and vitamin, nucleotide, and amino acid metabolisms. These findings suggest that the artificial inoculation with Phormidium tenue and Scytonema javanicum could alter soil microbial distribution to promote soil development on highway slopes toward nutrient accumulation.

Enhancing sugar beet yield and quality in Northeast China: Investigating the synergistic impact of sugar mill filter mud and biochar on black soil

In this study, different ratios of sugar beet sugar factory filter mud and biochar in different proportions were used to assess the effect of incorporating filter mud into the field on soil quality and its influence on two distinct sugar beet (Beta vulgaris) varieties: high-yielding KWS9147 and high-sugar KWS1176. The experiment was conducted in 2022 at the Hulan Campus of Heilongjiang University in Harbin City, Heilongjiang Province, China. Eight treatments were employed, including CK1 (no filter mud or biochar application), CK2 (20 t/ha biochar), T1 (16.67kg/ha filter mud), T2 (16.67 t/ha filter mud + 20 t/ha biochar), T3 (33.33 t/ha filter mud), T4 (33.33 t/ha filter mud + 20 t/ha biochar), and T5 (50kg/ha filter mud). For sugar beets, parameters such as the SPAD value(Soil and Plant Analyzer Development, represents the relative content of chlorophyll), disease resistance (root rot and brown spot), tuber yield, and sugar content were evaluated. Soil analysis included nitrogen content, available potassium content, available phosphorus content, and soil sucrase, urease, and phosphatase activities. Results indicated that the combined application of 16.67 t/ha filter mud and 20 t/ha biochar had a positive impact on the growth indices, tuber yield, sugar content, effective phosphorus, and quick-acting potassium content in KWS1176. In contrast, for KWS9147, the most favorable effect was achieved with the application of 16.67 t/ha filter mud. This treatment improved plant leaf growth, increased tuber yield and sugar content, reduced root rot incidence, elevated alkaline dissolved nitrogen content in the inter-root soil, and enhanced soil phosphatase activity. Biochar application did not contribute significantly to these improvements. Therefore, returning sugar mill sludge to the field demonstrated its potential to enhance soil quality, promote the yield of sugar beet varieties, and improve resistance to root rot while also providing an eco-friendly solution for managing environmental issues related to sludge accumulation.

Microbial carbon use efficiency and soil organic carbon stocks across an elevational gradient in the Peruvian Andes

Soils of mountain ecosystems are one of the most vulnerable ecosystems to climate change, while the ecosystem services they produce are significant and currently at risk. High altitude soils contain high C stocks, but due to difficult access to sites these areas are understudied. Moreover, how the C and N cycling is changing in response to climate change in these ecosystems, is still unclear. Microbial carbon use efficiency (CUE) and its dependency on the environmental constraints along the altitudinal gradients is one important unknown factor. Here we present results from an altitudinal gradient study (3500 to 4500 m a.s.l.) from a Polylepis forest in the Peruvian Andes. We measured the soil organic carbon (SOC) stocks and microbial metabolic CUE by 13C glucose tracing and microbial resource use efficiency (CUEC:N) based on enzyme activity measurements. We expected to find an increase in SOC stock, microbial nutrient limitations, and lower CUE with elevation. SOC stocks depended on soil development and followed a unimodal curve that peaks at 4000 m in two of the three studied valleys. Neither 13CUE nor CUEC:N changed significantly with altitude. Soil C:N ratio, β-glucosidase, chitinase, and phosphatase enzyme activities increased with elevation, but peroxidase activity decreased with elevation. We suggest that more labile organic matter left at high elevation could compensate for the increasing nutrient limitation at high elevation, resulting in no noticeable change in CUE with elevation.