Variability Of Soil Properties Research Articles

Hydrosedimentological monitoring in runoff plots of a degraded tropical area under restoration of the Brazilian Atlantic Forest

Rainfall erosion is a concerning process for landowners, government agencies and civil society as it involves soil loss, an indispensable natural resource for the production of food, fibers, and biofuels, as well as a means to support enterprises or even preservation of large conservation areas for sustainability and potential carbon sink. Specific Projects using runoff and soil loss plots have been adopted in different parts of the world, contributing to the understanding of erosion dynamics. This research is the result of extensive fieldwork carried out on a rural property undergoing forest restoration through a Payment for Environmental Service initiative. Four runoff plots with dimensions of 22m x 4m x 0.5m (length x width x depth) connected to sediment catchment tanks were implemented on a convex slope to analyze erosion in four different treatments: planting native seedlings, seedlings with green manure, natural regeneration with selective pruning, and exposed soil. The results of monitoring over approximately one year showed that 80.15% of all accumulated surface runoff occurred in the plot with exposed soil, as well as 99.15% of all soil loss. The treatment that presented the best conservation rates was natural regeneration, since there was no need to dig holes to introduce seedlings, causing less soil disturbance. Thus, it was concluded that land use and changes in land use are one of the main factors controlling erosion and surface runoff in the study area, however, in the long term, variations in soil properties due to vegetation may reflect more strongly this dynamic.

Influence of Cross-Correlation on the Modelled Uncertainty in Stress–Strain Behavior of Soft Clays

Reliability-based design is increasingly being applied to geotechnical problems because it allows the robust consideration of various sources of uncertainty, such as the inherent variability of soil properties. Some soil properties, however, are mutually dependent, and ignoring this cross-correlation may lead to biased estimates of the probability of unsatisfactory performance. Hence, in this study, the Gaussian copula was used to evaluate how the applied cross-correlation or independence between the compressibility properties affects the uncertainty in the stress–strain response of two marine soft clays. Two settlement calculation methods were considered: the compression index and Janbu tangential stiffness methods. The correlation coefficients were defined from the site-specific oedometer data at two extensively studied clay sites, and from a database. The simulated oedometer curves were compared to the observed variability in the site-specific data. The settlements in the clay sublayers were then computed, and different cases were compared by means of boxplots. It is concluded that the Janbu method leads to a significant overestimation of uncertainty in settlement if the cross-correlation between the compressibility parameters is ignored. On contrary, the compression index method seems less sensitive to the assumed correlation structure, and as such, the parameters can be treated as independent in most cases.

Remediation Efficiency and Soil Properties of TCE-Contaminated Soil Treated by Thermal Conduction Heating Coupled with Persulfate Oxidation

Less attention was paid to the remediation of volatile organic compounds (VOCs) contaminated soil treated by thermal conduction heating (TCH) coupled with chemical oxidization. In this study, the lab-scale remediation experiments of trichloroethylene (TCE)-contaminated soil by TCH and TCH coupled with persulfate (TCH + PS) were performed to explore the influences of PS usage, temperature, reaction time, and the variation of soil properties. TCE was removed from contaminated soils using TCH with a temperature lower than boiling point, and the removal ratio of TCE reached 78.21% with a reaction time of 6h at 60 °C. In the TCH + PS treatments, the removal ratio increased to 87.60~99.50% when the PS dosage was increased from 7.0 mmol/kg to 17.5 mmol/kg at 60 °C. However, the usage efficiency of PS had no positive relationship with oxidant usage and temperature. The treatment with 14 mmol/kg PS after 3h at 50 °C had the highest PS usage ratio of 3.05. In addition, soil pH and soil organic matter (SOM) did not decrease significantly in the TCH-only treatment, while the content of SOM declined by almost 50% after the TCH + PS treatment. Overall, it was concluded that TCH + PS achieved higher removal efficiency, whereas TCH had less disturbance on soil pH and SOM. As such, the applicability of TCH-only or TCH + PS treatments is site-specific.

Impact of humic acid on various properties of soil and crop productivity- A review

To raise the amount and quality of agricultural produce, numerous studies have been conducted in recent years. The development of agriculture is not just influenced by mechanization and new hybrid seeds; soil quality also plays a significant role. Lack of organic matter in soil frequently renders it unsuitable for plant growth. To address this problem and increase agricultural yields, humic compounds have started to be applied to soil in many parts of the world. Humic acid (HA) can now be applied to crops or soil using a variety of methods, including soil application, foliar application, seed treatment, root dipping, and drip irrigation, as HA is available in various forms viz., granule, powder, flakes, liquid and also in conjunction with inorganic fertilizers. However, soil application is the most effective in numerous studies. Numerous experiments on crops were carried out to determine the ideal dosage of humic acid, and it was found that character, yield, and soil characteristics all had a favourable impact on crop production. This review clarifies the significance of humic acid for various crops and the health of the soil, as well as how it increases agricultural output.

Investigation on wave-induced responses of heterogeneous seabed around a buried pipeline based on nonstationary random field model

The instability of the seabed poses a threat to the structural integrity and functionality of submarine pipelines. This numerical study investigates wave-induced responses in a heterogeneous seabed around a buried pipeline, considering spatial variability in soil properties through nonstationary random field models. Three scenarios of spatial variability for soil parameters changing with depth are simulated using both stationary and nonstationary random field models via the Karhunen-Loève expansion method. The discrete random fields are validated in terms of correlation structures and statistical characteristics. The stochastic finite element method, incorporating random fields and a poroelastic seabed model through a LiveLink code, is employed to examine probabilistic outcomes of dynamic soil responses and liquefaction zone distributions within a probabilistic framework. Contrastive analyses are conducted for seabed models with different random field scenarios, in addition to deterministic analyses. The results of the stochastic analysis show that the increasing trend of soil strength with depth has significant effects on the seabed responses and transient liquefaction characteristics around a pipeline.

Spatial and temporal variation of soil properties and soil organic carbon in semi-arid areas of Sub-Sahara Africa

Land cover land use (LCLU) patterns play a crucial role in shaping the biosphere and global climate. This influence is especially pronounced in arid and semi-arid regions, where environmental vulnerabilities are heightened. Studies have shown that LCLU Change is a key concern in the scientific community, particularly regarding its influence on soil health. This study focuses on the Gaborone area in Botswana, which has experienced rapid population growth and LCLU changes from 2002 to 2022.Landsat 7 (2002) and Sentinel-2A (2022) from USGS datasets were used to detect LCLU changes and assess their impacts on soil properties, namely: soil organic carbon (SOC) content, bulk density, soil pH, and texture. Image classification was done using a supervised classification method based on a Maximum Likelihood classifier and accuracy assessment done via a contingency matrix. LCLU change detection was achieved using the post classification comparison approach. Moreover, soil properties analysis was done using the Walkley and Black method, core method, Bouyoucos hydrometric method, and a pH meter, respectively. The effects of LCLU on soil properties and SOC were studied using a Random Forest regression analysis.Water bodies, tree cover, cropland, shrubland, bare land, and build-up were identified as major LCLU classes in the study area, with shrubland being the dominant class during the study period. A significant variation in soil properties was found across the different LCLU types. SOC content, a key determinant of soil fertility and moisture retention, was found to be higher in the tree cover and shrubland classes compared to cropland and built-up areas. A Random Forest regression analysis showed a substantial influence of LCLU on soil properties, particularly SOC dynamics. The study concludes by highlighting the interconnectedness of LCLU changes and soil properties, advocating for integrated land management strategies to balance development and environmental preservation in this climate-vulnerable landscape.

Delineation of Soil Management Zones and Validation through the Vigour of a Fodder Crop

In Mediterranean farming systems, the semi-arid conditions and agricultural ecosystems have made site-specific management an important approach. This method aims to understand and handle the variability of soil properties and crop management, particularly through the utilization of geospatial information and accessible technology. Over three years in a 30 ha experimental field located in the Alentejo region (Portugal), crop establishment was monitored using data from soil apparent electrical conductivity (ECa), remote sensing (Sentinel-2), and in situ soil sampling. The procedure began with Step 1, involving the acquisition of soil spatial information and spatial interpolation. Subsequently, in Step 2, management zones (MZs) for soil characteristics were delineated using a combination of ECa measurements and soil analysis, and Step 3 spanned over three years of gathering meteorological data and crop remote sensing measurements. In Step 4, site-specific crop MZs were delineated by vegetation indexes (VIs). This article aims to increase the importance of in situ and remote assessments to more accurately identify areas with different productive potential. Results showed three MZs based on the percentage of sand, ECa, altimetry, exchangeable calcium, and exchangeable calcium properties, validated by crop VIs (Normalized Difference Vegetation Index (NDVI), Normalized Difference Red-Edge Index (NDRE), and Normalized Difference Moisture Index (NDMI)) over time. Although there are many sensorial techniques available for site-specific management, this paper emphasizes a methodology for the farmer to identify different MZs combining remote and in situ evaluations, supporting new opportunities for a more rational use of natural resources. Based on soil parameters, three site-specific management areas could be selected. NDMI was the index that best explained the MZs created according to soil properties.

Understanding the impact of within-field Olsen P variation on common wheat production in Olsen P deficient soils

This study investigates the influence of Olsen phosphorus (Ps) within-field variability on common wheat production in Ps-deficient soil. It covers a comprehensive investigation conducted over two growing seasons in Tuscany, Italy, aiming to evaluate the impact of within-field Ps variation on common wheat production and crop responses to different agronomic treatments. Field experiments were undertaken, employing 24 treatments, including 4 wheat varieties, 2 seeding densities, and 3 nitrogen fertilization levels. Soil samples were collected to determine within field variability of main soil properties. At harvesting, aboveground biomass was collected to determine grain yield, straw, and total protein content. Firstly, an ANOVA was performed to account for the effect of the agronomical treatments on crop parameters, namely the Agronomical Input Model (AIM). Then, soil total nitrogen (Ns) and Ps, were added as covariates in a new model, namely the Agronomical and Soil Input Model (ASIM). Results showed a significant spatial variability of Ps within the fields, ranging between 13.7 and 17.4 mg kg-1. Despite this minimal variation in Ps, we observed a linear increase in GY of about 1430 kg ha-1 for each increase of 1 mg kg-1 in Ps. Further studies should be conducted to account for non-linear responses at both lower and higher Ps levels. The ASIM model outperformed AIM, indicating a notable increase in predictive accuracy for both grain yield and protein concentration due to its incorporation of soil parameters. The variance explained by ASIM in predicting the grain yield and protein concentration in grain increased by about 11.0 % and 17.3 %, respectively, with respect to AIM. The study emphasizes the necessity of managing within-field Ps variability through targeted fertilization strategies to enhance wheat production in Ps-deficient soils. By addressing soil nutrient variability, this research aims to contribute to more precise and efficient common wheat production systems.

Geospatial Variability of Soil Properties of the Different Villages in Arajiline Block of Varanasi District of Uttar Pradesh

The current study was conducted at the different villages of the Arajiline block of Varanasi district, Uttar Pradesh, India during November, 2022–June, 2023 to evaluate the variability of soil properties and nutrient indexof soils. The random sampling technique was used to collect 40 soil samples at different locations with the help of GPS at 0–15 cm depth. The collected soil samples were air-dried in shade at room temperature, passed through a 2 mm filter paper, and analyzed for different physico-chemical properties. The result revealed that the TS (range 8.2–81.3%), VFS (range 4.2–35.5%), Silt (range 10.1–54.2%), Clay (range 7.7–38.8%), BD (range 1.08–1.45 g cm-3), PD (range 2.04–2.33), Porosity (range 30.24–51.56%) pH (range 6.4-7.8), EC (range 0.1-0.3 dS m-1), OC (0.2-0.6%), and available N, P, K, S, Ca, and Mg varied from 130.12–260.30 kg ha-1, 14.2-23.2 kg ha-1, 145.0–240.0 kg ha-1, 7.5–17.6 kg ha-1, 3.8–8.2 cmol(P+)/kg, and 2.1-4.1 cmol(P+)/kg, respectively. The findings indicated that the studied soils were slightly acidic to moderately acidic and free from salinity hazards; 70% of the soil samples were low in organic carbon, 30% were medium in organic carbon, and 100% of the soil samples were low in available N and medium in available P, K, and S. 100% of soil samples were found to be sufficient in exchangeable Ca and Mg. The findings of this research could help in crop nutrient management, fertilizer recommendation, and decision-making for increasing agricultural production and farmer profitability.

Evaluating Intra-Field Spatial Variability for Nutrient Management Zone Delineation through Geospatial Techniques and Multivariate Analysis

This research study underscores the importance of effectively managing soil nutrients in a site-specific manner to enhance crop productivity while considering the spatial variability of the soil. The objective is to identify subfields with similar soil characteristics, referred to as management zones (MZs), to promote sustainable land utilization. This study was conducted in two central pivot fields located in Southern Idaho, USA, where barley and sugar beets were grown. Soil samples were collected from each field in a grid pattern and analyzed for various chemical properties. These properties included soil pH, organic matter, cation exchange capacity, excess lime, electrical conductivity, total inorganic nitrogen, phosphorus, potassium, calcium, magnesium, zinc, iron, manganese, copper, and boron. Descriptive statistics and normality assessments were performed, and the coefficient of variation was calculated to assess the heterogeneity of soil properties, revealing significant variability. To determine the spatial variability of soil properties, ordinary kriging was used revealing diverse spatial patterns for each location and soil variable examined with moderate to strong spatial dependence. To develop the MZs, a combination of principal component analysis and fuzzy k-means clustering was utilized, and specific parameters that represented the overall variability of soil properties in each field were identified. Based on the identified parameters, two clusters were created in each field. The first management zone (MZ1) exhibited lower values of soil pH, excess lime content, and electrical conductivity compared to the MZ2. Consequently, higher crop productivity was observed in MZ1 in both fields. The biomass yields of barley and sugar beets in MZ1 surpassed those in MZ2. This study highlights the effectiveness of the methodology employed to delineate MZs, which can be instrumental in precise soil nutrient management and maximizing crop productivity.

SEISMIC MITIGATION EFFECT FOR LARGE-SPACE UNDERGROUND STRUCTURES CONSIDERING SPATIALLY VARYING SOIL PROPERTIES

The seismic response of the large-space underground structure (LSUS) is significantly influenced by the physical properties of the surrounding soil media, while the soil owns a strong spatial variability. This study proposes a seismic response analysis process of the soil-LSUS interaction system is proposed, which can consider the characteristic of the spatially distributed soil properties. The proposed process begins with establishing the spatially random field model of the soil properties using the improved latent space method. Then, the model is calibrated based on the real data and Bayesian approach, and the realization of the random field is accomplished. Further, the soil-LSUS interaction finite element (FE) model is established, which incorporating the soil physical properties generated from the random field. Finally, the nonlinear time-history analysis of the soil-LSUS interaction FE model is conducted. As an illustration of the proposed process, a typical LSUS located in Guangzhou is selected as an example, and the seismic mitigation measure which the lead-filled steel tube damper (LFSTD) is installed between the intermediate column and the top beam is adopted for the LSUS. The influence of the spatial variability of soil properties on the seismic mitigation effect of the LSUS is investigated. Results indicate that the spatial variability of the soil properties can cause a minor influence on the force and deformation of the intermediate column and the energy dissipation ratio between the LFSTD and structure, while it can bring a significant influence on the maximum deformation and force and the shape of the hysteresis loop of the LFSTD.

A mathematical approach to calculating slope stability under physical triggering forces. Application to landscape mechanics

In the field of land management, the limit equilibrium calculation method is a mathematical method that harmonizes the complex interplay of diverse factors determining the slope stability. Rooted in mechanical and mathematical principles, this method has paramount significance for guiding the course of safe land management in mountainous regions, especially in the case of infrastructure development projects. Conventional limit equilibrium techniques, while provid- ing preliminary stability assessments, often neglect key factors that can trigger slope failure. These approaches traditionally ignore the spatial variations in soil properties, the temporal dy- namics of phenomena, the kinetic responses to external loads, the complexities of geological formations, and the influences of the hydrological and climatic conditions on slope stability. Our innovative method adopts an enriched mathematical framework that redefines the landscape of force equilibrium techniques. We meticulously tailor this framework by adapting the founda- tional relationships derived from the Mohr-Coulomb shear strength criterion to accommodate the spatially variable geomechanical parameters. This adaptation allows us to capture the nu- anced shifts in mechanical properties over the extent of the slope. Furthermore, we introduce supplementary equations that seamlessly integrate the influences of traffic-induced loads and hydraulic pressures, while also statistically quantifying the contributions of stabilizing struc- tures. To determine the efficacy of this geomatic and landscape-centric numerical tool, we have subjected it to rigorous testing on a test slope. The outcomes derived from our mathematical model reveal the primacy of traffic-related forces as the main destabilizing agents, contrasted with the strengthening effects of reinforcements in maintaining slope stability.

Evaluating Growth Patterns and Soil Dynamics of the Endangered African Rosewood (Pterocarpus erinaceus Poir.) in Contrasting Ecological Regions in Ghana

Pterocarpus erinaceus (Poir.) is an endemic and endangered species of the Guinea‐Sudano‐Sahelian​ zones currently overexploited for timber, fodder, and medicinal purposes. Therefore, plantations are critical to meeting the high demand in the international market while reducing pressure on natural stands, but its growth performance across different ecological zones is not well documented. Thus, we assessed the influence of ecological zones and soil properties on the survival and growth performance of P. erinaceus. Data were collected from 12 subplots of P. erinaceus stands in the Dry Semi‐Deciduous Fire Zone (DSFZ) and 16 subplots in the Moist Semi‐Deciduous North West Zone (MSNW). We assessed the survival and growth performance of P. erinaceus using one‐way ANOVA, variation in soil properties using the Generalized Linear Model, and the influence of soil properties on P. erinaceus growth characteristics via correlation analysis. We found that the percentage survival of P. erinaceus was similar in both ecological zones. However, P. erinaceus demonstrated a high level of variation in growth attributes, growing taller with deeper canopies in wetter conditions and larger crown spread in drier conditions. The aboveground biomass carbon stocks of P. erinaceus stands were similar in both ecological zones, highlighting the potential role of the species as a carbon sink in the ecological zones. Soil organic matter, nitrogen, and calcium contents were higher in soils of the MSNW stands than those of the DSFZ stands. However, potassium, magnesium, sodium, and phosphorus contents were stable across the ecological zones. We concluded that wetter conditions enhance the growth performance of P. erinaceus as a timber species.

Biomass Storage Potential and Improvement in Soil Properties under Different Bamboo Plantations in the Terai Region of Central Himalaya

This study evaluates six bamboo species, i.e., Dendrocalamus hamiltonii, Bambusa nutans, Dendrocalamus asper, Bambusa bambos, Bambusa balcooa, and Dendrocalamus strictus, regarding their growth behavior, nutrient uptake, and effect on the soil properties of the Terai region. Various aboveground growth parameters exhibited significant variations with the maximum clump girth (8.60 m) and internodal length (35.37 cm) of B. nutans, which was also reported by the culm diameter (5.70 cm) of D. hamiltonii and the number of culms per clump (65) of D. strictus. The total aboveground biomass ranged from 51.14 Mg.ha-1 in D. asper to 362.56 Mg.ha-1 in D. hamiltonii. The most significant variation in soil properties was observed in the 0-40 cm soil layer. Under D. hamiltonii, the lowest soil bulk density (1.07 g.cm3; 1.21 g.cm3) and the maximum soil porosity (59.00%; 56.40%), soil organic carbon (1.54%; 0.72%), and available soil nitrogen (228.29 kg.ha-1; 173.73 kg.ha-1) were found the 0-40 and 40-80 cm soil layers. Furthermore, significant enhancements in soil microbial population were recorded. Thus, bamboo plantations have great potential to enhance the biomass generation and fertility quotient of fallow lands.

Variability in the Physical Properties of an Eroded Cultivated Steep Land Under Farmers’ Practice and Vetiver Technology (Bio-Engineering Structure).

Variability in soil properties is evident in the variability in crop performance in a field and failure of engineering structures. During erosion particles are detached, transported and deposited at different locations down the slope. An experiment was conducted on 20 and 30% slopes within the Cross River University of Technology to assess variability in soil physical properties as induced by water erosion on erosion plots constructed and planted to maize/cassava mixture. No vetiver [farmer’s practice] and vetiver grass strips at 5m, 15m and 25m [bioengineering structure] constituted the treatments. Core samples (0 – 15cm) were collected at 5m intervals down the slope in all the treatments for determination of some soil physical properties. Infiltration was measured using double ring infiltrometer. Coefficient of variability (CV%) values ranged from 2 – 4% [bulk density], 2 – 4% [porosity], 16 – 33% [gravimetric moisture], 3 – 8% [void ratio], 16 – 33% [volume wetness], 15 – 32% [degree of saturation], 16 – 37% [water volume ratio], 2 – 7% [air-filled porosity], 16 – 33% [available moisture holding capacity] for the two slopes. Initial infiltration ranged between 1.87 – 2.90cm per minute and 82.63 – 127.80cm after 260 minutes for cumulative infiltration. Coefficient of variability were 19.5% [initial infiltration] 6.18% [cumulative infiltration] for 20 and 30% slopes respectively. CV% values of <15%, 15 – 35% and >35% are considered low, moderate and high respectively. Understanding field variability of soil properties could be a veritable tool for precision soil management to optimize and increase profitability.

Evaluation of soil properties variability along a toposequence in Wasinmi, Southwest Nigeria

Abstract Topography significantly influences soil development and characteristics within an uneven agricultural field. Therefore, a comprehensive understanding of soil attributes and processes through detailed pedological knowledge is crucial for effective soil management. This research was carried out in Wasinmi, southwestern Nigeria, to delineate and categorise the soils across different slopes for agricultural insights. Three soil profiles were excavated across the topographical sequence, specifically designated as upper, middle, and lower slope positions. The prevailing soil texture was sandy loam with a discernible trend of lighter soil colour as the slope descended and soil depth increased. The pH of the soil ranged from moderately acidic to slightly acidic. The saturated hydraulic conductivity and soil organic matter content were lowest on the lower slope. Available phosphorus distribution varied inconsistently with higher concentrations of heavy minerals observed at the upper slope. The study underscored the influential role of topography in soil property variations and the need for tailored management practices. The classification of the soils revealed Typic Plintustults in the upper and middle slope positions, while the soils in the lower slope were identified as Typic Kandiaquults. This study demonstrated that topography significantly influenced soil properties, thereby emphasising the need for informed practices to better support the long-term sustainability of land use and agricultural outputs in topographically diverse landscapes.

The influence of spatial heterogeneity of the properties of agricultural fields on productivity

The use of differentiated technologies in crop production ensures high yields while minimizing environmental impacts and significant resource savings. To optimize technological impacts, it is necessary to know the distribution of soil properties and their changes in space and time. The purpose of the work is to assess the variability of soil characteristics and the impact on crop yields. The article presents studies of the variability of soil properties, the unevenness of soil moisture during the operation of wide-range sprinkler equipment and the influence of spatial heterogeneity of properties and the use of differentiated technologies on crop yields.

Assessing the Spatial Variability of Soil Physical Properties of the Lesser Himalayas in India

Understanding the spatial variability of soil properties is crucial for assessing the impact of measures taken to address land surface processes such as soil erosion and water pollution. It is also vital for recommending effective land management strategies. The present study was conducted to assess the spatial variations in soil textural fractions (sand, silt, and clay), bulk density and porosity. Soil samples were collected from 115 randomly selected locations using the Global Positioning System (GPS). The samples were taken at an average depth of 0-20 cm. A thorough examination was carried out in the laboratory to assess the physical properties of the soil. Afterwards, there was an analysis conducted to characterise the physical properties of soil and understand how they vary across different locations. The measured soil properties showed low to very high variability (6.26- 37.2%) for the Coefficient of variation (CV). The spatial dependence of soil properties was observed through the weak to strong nugget-to-sill ratios. Mapping the spatial variability of soil parameters involved using the Ordinary Kriging (OK) approach of Geostatistical analysis. This method helped identify the best-fit models for different soil parameters, such as Spherical for Silt, bulk density and porosity. Exponential for clay; and Gaussian for sand these spatial interpolation maps can be a valuable tool for pinpointing areas of land degradation in the study region and recommending specific land management strategies.

Potato tuber yield and quality under potassium and magnesium addition on top of the nitrogen and phosphorus fertilization

The aim of the study to investigate the effect of individual or combined K and Mg addition on potato tuber yield and quality along the gradient of soil and environmental conditions, which was formed by the five experimental plots in the forest-steppe one of West Siberia. Location and time of the study. Microplot field experiment with moderately early potato cultivar Jelly with three fertilization treatments (N100P60, N100P60+K100 and N100P60+K100+Mg100) was setup in five replicates on five experimental plots with agricultural grey soils in the Novosibirsk Region in 2023. Geographical coordinates of the experimental sites varied from 55°15'40" to 54°47'09" NL and from 83°31'42" to 82º37' 56" EL. Methods. Instead of traditional temporal gradient (3–4 years of the experiment at a site) to account for weather variation, with the same purpose we used a spatial gradient, which in addition allowed to assess the effect of soil properties variation among the sites. Soil samples, collected prior to the experiment, were analyzed for organic carbon content, nitrate and ammonium nitrogen, exchangeable phosphorous, potassium and magnesium, as well as soil pH and electrical conductivity. In the course of the experiment air and soil (at 5 and 15 cm depth) temperatures was automatically recorded. At the end of the experiment potato tuber mass and number, as well as the aboveground phytomass, were measured at each microplot. After five months of tuber storage sensory properties (flavour, aroma, colour, mealiness and friability) of boiled tubers were assessed using a Hedonic scale. Analysis of variance, principal components extraction and multiple regression by partial least squares method were performed using Statistica v. 13.1. software. Results. Addition of K at the background NP fertilization (N100P60+K100 treatment) increased tuber yield by 30% and the aboveground phytomass by 40%. Addition of Mg (N100P60+K100+Mg100) did not affect yield properties, but markedly improved potato culinary quality. More than half of the variance of the potato yield properties was accounted for by the variation in soil and environmental conditions of the experimental fields location. Exchangeable Mg, ammonium N and soil pH were the main soil properties, allowing to forecast the current year tuber yield. The contribution of soil and environmental conditions of the experimental fields into the variance of the sensory properties, albeit small, was statistically significant (p≤0,05) for aroma and colour, with the similar trend for flavour and friability (0,05≤p≤0,10). Agrochemical properties, i.e. soil organic carbon, readily exchangeable P and nitrate N contents, as well as soil pH, were the main variables, determining tuber quality for consumers. Conclusions. The study performed on the agricultural grey soil in the forest-steppe zone of West Siberia confirmed the importance of optimizing potato mineral nutrition. Addition of NPK at the balanced rates significantly increased potato yield as compared with NP. Although addition of MG together with NPK did not increase the yield, it markedly improved sensory properties of potato. Some soil properties and temperature conditions, found to determine the yield (effective soil fertility), can be used in prognostic models for potato tuber yields and quality.

Correlations between soil properties and spectral index (healthy vegetation) in soybean crops

Precision agricultural technologies, such as the use of spatial variability of soil properties, have been extensively studied for soybean cultivation. The objective of this study was to analyze the spatial variability of soil properties cultivated with soybean and to correlate the healthy vegetation (HV) spectral index with the bands B8A (classifying vegetation - 865 nm), B11 (measuring the moisture content of soil and vegetation - 1610 nm), B02 blue (useful for soil and vegetation discrimination - 490 nm). A sampling grid was installed for data collection in an area of 2,126.02 ha, with 270 regular points and 98 random points, totaling 368 points. For the soil, the contents of P (resin), K+, Ca2+, Mg2+, H+, Al3+, pH values, sum of bases (SB), cation exchange capacity (CEC), and base saturation were determined at a depth of 0.0 to 0.20 m. Most of the soil properties had exponential and spherical dependence. Clay percentages and Ca, Mg, and P contents had positive spatial correlation with the healthy vegetation spectral index (HV) while no spatial correlation was observed for pH, B, K, silt, sand, S, H+Al, Al, SB, and CEC. The sensor image used in this study in relation to HV showed good application for observing the spatial variability of the soil properties and soybean yield.