Effect Of Soil Moisture Content Research Articles

Feature Variable Selection Based on VIS-NIR Spectra and Soil Moisture Content Prediction Model Construction

The hydrological cycle, surface energy balance, and the management of water resources are all significantly impacted by soil moisture. Because it governs the physical processes of evapotranspiration and rainfall penetration, surface soil moisture is a significant climatic variable. In this work, visible-near infrared (VIS-NIR) bands were used to compare and analyze the spectra of loess samples with varying moisture concentrations. The investigation looked at how changes in the soil moisture content impacted the response of the soil spectra. The researchers used a genetic algorithm (GA), interval combination optimization (ICO), and competitive adaptive reweighted sampling (CARS) to filter feature variables from full-band spectral data. To forecast the moisture content of loess on the soil surface, models like partial least squares regression (PLSR), support vector machine (SVM), and random forest (RF) were created. The findings indicate that: (1) the most reliable spectrum preprocessing technique is the first derivative (FD), which can significantly enhance the model’s prediction power and spectral characteristic information. (2) The feature band selection method’s prediction effect of soil moisture content is typically superior to that of full-spectrum data. (3) The random forest (RF) prediction model for soil moisture content with the highest accuracy was built by combining the genetic algorithm (GA) with the FD preprocessed spectra. The results may provide a new understanding on how to use VIS-NIR to measure soil moisture content.

The effect of soil moisture content and soil texture on fast in situ pH measurements with two types of robust ion-selective electrodes

Abstract. In situ soil pH measurements with ion-selective electrodes (ISEs) are receiving increasing attention in soil mapping for precision agriculture as they can avoid time-consuming sampling and off-site laboratory work. However, unlike the standard laboratory protocol, in situ pH measurements are carried out at lower and varying soil moisture contents (SMCs), which can have a pronounced effect on the sensor readings. In addition, as the contact with the soil during in situ measurements should be relatively short, effects of soil texture could be expected because texture controls the migration of protons to the electrode interface. This may be exacerbated by the fact that the electrodes used for in situ measurements are made of less sensitive but more robust materials as compared to the standard glass electrode. Therefore, the aim of the present study was to investigate the effect of soil moisture and soil texture on pH measurements using robust antimony and epoxy-body ISEs pressed directly into the soil for 30 s. The SMC was gradually increased from dry conditions to field capacity. A wide range of soil texture classes were included, with sand, silt, and clay contents ranging from 16 % to 91 %, 5 % to 44 %, and 4 % to 65 %, respectively. An exponential model was fitted to the data to quantify the relationship between SMC and pH. The results show that an increase in SMC causes a maximum increase in pH of approximately 1.5 pH units, regardless of the type of pH ISE used. Furthermore, for sandy soil textures, a rather linear relationship between pH and SMC was observed, whereas, with decreasing mean particle diameter (MPD), the model had a pronounced exponential shape, i.e., a greater pH increase at low SMC and a plateau effect at high SMC. With increasing SMC, the pH values asymptotically approached the standard pH measured with a glass electrode in 0.01 M CaCl2 (soil : solution ratio of 1:2.5). Thus, at high SMC, subsequent calibration of the sensor pH values to the standard pH value is negligible, which may be relevant for using the sensor pH data for lime requirement estimates. The pH measurement error decreases exponentially with increasing soil moisture and increases with decreasing MPD. Using a knee point detection, reliable pH values were obtained for SMC > 11 %, irrespective of the pH ISE used. An analysis of the regression coefficients of the fitted exponential model showed that the maximum pH increase also depends on soil texture; i.e., the influence of soil moisture variation on the pH value increases with decreasing MPD. Moreover, the concavity of the exponential curve increases with decreasing MPD.

Effect of Soil Moisture Content on the Shear Strength of Dicranopteris Linearis-Rooted Soil in Different Soil Layers of Collapsing Wall

The occurrence and development of Benggang is closely related to the decreased shear strength of collapsing walls. Plant roots can improve the soil shear resistance, and their soil reinforcing effect is restricted by soil moisture content (SMC). However, the effect and mechanism of SMC on the shear properties of rooted soil with different soil properties remain unknown. Therefore, the dominant soil erosion-resistant plant Dicranopteris linearis was selected as the research object, and shear tests were conducted to determine the shear strength response of rooted soil to SMC in the lateritic layer (LL), sandy layer (SL) and detritus layer (DL) with SMCs from 15% to 30%. The results showed that, compared with 15% SMC, the average decrease in shear strength of 30% SMC in the LL, SL and DL rooted soil were 17.37%, 21.96% and 23.36%, respectively. The rooted soil cohesion changed with increasing SMC in a binomial function, and the optimal SMC in the LL was 22.78%, which was higher than that of the SL (19.67%) and DL (18.39%). The cohesion increment of rooted soil weakened with increasing SMC, and the decrease was greatest in the SL. When the SMC increased from 15% to 30%, the internal friction angle of the rooted soil decreased by 34%, 11% and 12% in the LL, SL and DL, respectively. The Wu and Waldron’s model (WWM) correction parameters k′¯ of the LL, SL and DL were 0.59, 0.14 and 0.05, respectively. With the modified WWM, a new prediction model for the shear strength of rooted soil based on SMC was established. In short, a high SMC weakened the mechanical effect of Dicranopteris linearis-rooted soil, especially in the SL and DL of the collapsing wall, and attention should be given to drainage facilities when treating Benggang erosion.

Effects of the soil moisture content and leaf memory effect on pesticide droplet absorption

Most pesticide spraying studies focus on increasing droplet deposition on target surfaces, with little consideration of post-deposition pesticide droplet absorption mechanisms. The pesticide droplet absorption efficiency of leaves is related to environmental factors and plant growth status during pesticide application. In field environments, irrigation-based soil moisture content regulation is a key plant growth status adjustment method. A theoretical pesticide droplet leaf absorption model was established to study the effects of soil moisture content on droplet absorption. Controlled environment experiments were carried out to investigate the absorption of pesticide droplets, and a chi-square test was used to verify the model reliability. The results showed that pesticide droplet leaf absorption flux first increased and then decreased with increasing soil water content. The diurnal leaf water potential and stomatal conductance variationsindicated a memory effect, resulting in diurnal variationsin the pesticide droplet leaf absorption flux. Under the same soil water conditions, the absorption flux first increased and then decreased from 8 am to 6 pm (Beijing Time). Effective application of pesticides can be significantly enhanced by controlling soil moisture content and selecting the appropriate spraying time. The best spraying combination improved the application effectiveness nearly threefold overthat of the worst combination. The results are crucial for rational pesticide use, crop spraying optimization, and water savings.

Load-Settlement Analysis of Axially Loaded Piles in Unsaturated Soils

Unsaturated soil covers a significant part of the world, and studying the behavior of deep foundations in this medium is an important step in increasing accuracy and economic efficiency in geotechnical studies. This paper presents an analytical solution to investigate the load-carrying characteristics of single piles embedded in unsaturated soils, accounting for the effect of groundwater level on the pile’s response. For this purpose, relationships for shear modulus and Poisson’s ratio for unsaturated soils were collected from the literature to consider their effects as key parameters on pile performance. A parametric study was conducted to evaluate the effect of soil moisture content on the behavior of the pile-soil system for different soil types, and the effect of pile slenderness on its load-settlement behavior was studied for varying soil moisture contents. The results indicate that the pile stiffness increases as the soil suction increases while below a critical slenderness value, hence increasing the pile load capacity. However, this improvement occurs within a limited range of soil suction that is narrower for coarse-grained soils. The pile settlement corresponding to soil failure was also evaluated by modifying the existing solutions for unsaturated soils. The developed solutions were verified against the predictions of published solutions as well as the results of finite element analysis and pile load tests. It was found that the system stiffness decreases by 50% when the water table rises from the pile toe level to the ground surface in the studied soil.

Response of soil aggregate disintegration to antecedent moisture during splash erosion

Soil aggregate breakdown is the initial stage of splash erosion. Preventing aggregate disintegration can effectively control the material source for sediment transport. The impact factors of aggregate disintegration have been partially studied, but the effect of soil moisture content on slaking and physico-chemical dispersion remains unclear. In this study, simulation tests of splash erosion were carried out on three sandy clay loam soils with different years of vegetation restoration (S1, S2 and S3 were 55, 80 and 100 years of reforestation and land restoration, respectively). Three rainfall heights (1.5 m, 2 m and 2.5 m) were used to simulate aggregate disintegration caused by different rainfall kinetic energies. Soil aggregates with five antecedent moisture contents (air drying, 5 %, 10 %, 15 %, and 20 %) were subjected to three different pretreatments: fast wetting (FW), slow wetting (SW) and shaking after prewetting (WS). It was found that the mean weight diameter in the fast wetting (MWDFW) treatment increased and then decreased with increasing moisture content. Aggregate sensitivity to slaking decreased with increasing moisture content. After rainfall, the macroaggregates content (>0.25 mm) increased and then decreased with increasing moisture content. In the S1 sample, the contribution of physico-chemical dispersion to splash erosion was dominant for increasing splash erosion rate at the moisture content of 15–20 %. The slaking contributed more to decreasing splash erosion rate with increasing moisture content in the S2 and S3 samples. This study clarifies the response of slaking and physico-chemical dispersion to moisture content, which is helpful for thoroughly understanding the disintegration mechanisms of soil aggregates.

Effect of soil moisture content on thermal performance of ground source heat exchangers: An electromagnetism topology-based analysis

Ground source heat pump (GSHP) technology has gained significant attention as a viable solution for the heating, ventilation, and air conditioning (HVAC) of buildings. One of the factors that can impact the performance of GSHP systems is the soil moisture content. In this study, an innovative approach, referred to as soil impedance topology, is introduced as an alternative to traditional methods for measuring soil moisture content in geothermal heat pump systems. This method is inspired by pipeline grid utilizes impedance measurement, which provides a direct measurement of soil moisture content without the need for sensors. The study also proposes a changing rule of impedance with varying moisture content, where capacitance increases and resistance decreases when the soil moisture content is less than 20% but stabilizes beyond a water content of 20%. The accuracy of the topological mechanism prediction method is high, as demonstrated through the verification of the Smith circle and measured data. However, it is noted that the performance may be insufficient in the high frequency band and high soil moisture content. The use of impedance topology provides a more accurate and reliable method for measuring soil moisture content as well as for modeling and predicting heat transfer rates and system performance. This technology has strong potential to improve efficiency, reduce energy costs, and enhance the environmental sustainability of geothermal heat pump systems.

Development and Performance Evaluation of a Pressure-Adjustable Waterjet Stubble-Cutting Device with Thickness Detection for No-Till Sowing

No-till maize (Zea mays L.) sowing is often affected by stubble. The high-pressure waterjet at a constant rate is powerless to precision applications of stubble cutting and causes water waste. In this study, a pressure-adjustable stubble-cutting device with a stubble-thickness detection device was designed. Through experiments, the quantitative analysis of the moisture content and electrical conductivity (EC) of the field soil and stubble during the spring sowing period was conducted, and the effect of soil moisture content (SMC), soil compaction (SC) and machine forward speed (V) on the stubble-thickness detection error (STDE) was explored. On this basis, the optimal parameters of the device were analyzed and evaluated, and a verification experiment was applied. The results showed that STDE decreased with the increase of SMC and SC and increased with the increase of V. The response time of the pressure adjustment system is 0.12 s. The stubble-cutting device with thickness detection for two-level pressure regulation reduced the water consumption (WC) by 13.22% under the condition that the stubble-cutting rate (SCR) remained unchanged. The WC increased with the increase of waterjet pressure (P) and decreased with the increase of V. The SCR increased first and then decreased with the increase of cutting angle (α). The response surface optimization analysis showed that when P was 26 MPa, α 90.45° and V was 3.36 km/h, the performance was optimal with a 3.03% STDE, a 95.49% stubble SCR and a 49.98 L/ha WC. The measured value of the field verification experiment had a 4.11% relative error existing in STDE, a 4.06% relative error existing in the SCR and a 1.81% relative error existing in WC compared with the predicted value of the regression model. In contrast to the constant rate waterjet cutting device, the application of this device can save WC by 13.22%. This study can provide a reference for the application of waterjet technology and conductivity detection technology in the agricultural field.

Construction of a soil clod recognition bench-scale experiment for discrete element method modeling of tilling phenomena

Rotary claws are used to break soil into small pieces and plow the soil flat. In this study, rotary claw development in tiller machines was evaluated using both equipment and the discrete element method (DEM). However, evaluation through equipment is imprecise and time consuming. Although DEM is an effective method for modeling the movement of granular materials, it requires numerous parameters to ensure accuracy, which must be determined through experimental evaluation and comparison. To resolve this concern, an image processing method was developed that leverages point cloud data obtained from a depth camera to capture changes in soil shape, distribution, and soil clod size before and after tilling. The effect of soil moisture content and claw rotation speed on soil clod formation and decomposition was evaluated. The experimental results show that the location, number, and soil clod size vary with soil moisture content and claw rotation speed. The results were compared with the DEM simulation to reconcile differences and confirm the feasibility of the proposed method. The model experiment system for soil clods and the image processing method facilitates a quantitative comparison between experimental and DEM simulated soil dispersal, which accelerates the search for DEM parameters to reproduce the tilling.

Effects of moisture content on strength and compression properties of foundation soils of cultural relics in areas flooded by the Yellow River

This study investigated the effects of soil moisture content on the strength and deformation properties of the foundation soils of cultural relics. Our goal is to inform the formulation and implementation of the repair scheme for cultural relics above the foundation soils and help protect cultural relics. Soil samples with five different moisture contents were prepared and used in unconfined compression, triaxial, and consolidation tests. Several mechanical parameters were determined under different soil moisture contents: failure morphology, compressive strength, compressive modulus, and compressibility coefficient. Based on the test results, the soil cohesion and angle of internal friction were obtained using Mohr’s circle. Regions where the mechanical parameters were particularly sensitive to moisture content were located during the consolidation test. These were also the regions where the soil’s compressive modulus declined rapidly, which was detrimental to the overall stability and safety of overlying structures. The internal structure and particle size distribution of the foundation soils supporting cultural relics were determined by scanning electron microscopy. Constitutive parameters of soils were determined by the triaxial test and consolidation test. It was also found that when the soil moisture content exceeded the optimal level, the foundation soils were very likely to pose a risk to the safety of the overlying cultural relics. The moisture content of foundation soils supporting cultural relics deserves special attention in engineering practice.

Experimental Study on the Effect of Soil Moisture Content on Critical Temperature Rise for Typical Cable Backfill Materials

The increased utilization of power grid requires operating power cables close to their thermal limit. Buried power cables in such condition experience thermal instability where thermal resistance increases as the moisture migrates away from the proximity of the cable forming a dry-out zone. While it is common to use a two-zone model to account for the dry-out zone in ampacity calculations, there is a limited number of studies on characterizing backfill materials for their critical temperature rise ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> ), especially for crushed rock sands. In addition, dependency of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> on moisture content is sometimes not acknowledged. This study measures the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> for three typical backfill materials and investigates the relationship between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> and moisture content. The results show that crushed rock sand has higher <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> compared to natural sand. Overall, large range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> was measured depending on moisture content and type of soil. Ampacity calculations with the established <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> show that at low moisture content, the thermal resistivity of the soil has a higher influence on ampacity than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> . At relatively high moisture content, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \theta_{x}$</tex-math></inline-formula> becomes the predominant factor governing the overall ampacity.

Effects of Water Stress, Nitrogen, Magnesium and their Interactions on Some Growth Characteristics and Essential Oil content of Rosemary (Rosmarinus officinalis L.)

A factorial experiment was applied with four replicates on rosemary plants (Rosmarinus officinalis L.) grown in pots inside the glasshouse of the Department of Biology, College of Science, Salahaddin University, Erbil, Iraq, during April, 2019 to July, 2020, to determine the effects of soil moisture content ( SM1: 100% and SM2: 60% field capacity), nitrogen fertilizer (N1: 100, N2: 200 and N3: 300kg/hectare), and magnesium fertilizer (Mg1: 0.0, Mg2: 30 and Mg3: 60kg/hectare) and their interactions on some growth characteristics and essential oil content of rosemary plants. Two cuttings were taken from rosemary shoots (on March, 2020 and July, 2020) after 12 and 15 months of planting respectively. Results showed that cutting 1: SM2 decreased plant height, number of branches, Shoot fresh weight (FW), shoot dry weight (DW), leaves DW &amp; stem DW. N3 increased plant height, number of branches, Shoot FW, shoot DW, leaves DW, stems FW &amp; stem DW. Interaction treatment SM1N3Mg3 increased plant height, Shoot FW, shoot DW, leaves DW, stems FW and stem DW, while in cutting 2: SM2 decreased shoot DW, stems FW and stem DW. N3 increased Shoot FW and stem DW. Mg3 increased Root FW, but decreased stems FW. SM1N3Mg1 increased stem DW. In cutting 1+ cutting 2, SM2 decreased accumulative stem DW and biological yield FW. N3 increased accumulative Shoot FW; Accumulative leaves DW, accumulative stem FW, accumulative yield FW and biological yield DW. Mg3 increased biological yield FW, while SM1N3Mg3 treatment increased accumulative shoot DW, accumulative leaves DW, biological yield FW, and biological yield DW. In the second harvest, SM2 and Mg2 decreased rosemary essential oil %, N3 and SM1N3Mg2increased EO% and concrete content, while SM1Mg2 increased EO.

RESEARCH ON SOIL FRAGMENTATION CHARACTERISTICS BASED ON FRACTAL DIMENSION AND IMAGE PROCESSING

To improve the complex process of judging the degree of soil fragmentation during potato-soil separation and to establish a fast and effective judging method. Soil drop experiments were performed using sandy soil from the potato growing region of Hohhot, Inner Mongolia Autonomous Region, China. The effects of soil moisture content, hardness, volume, drop height, inclination of the separating sieve and composition of the separating sieve rod on soil fragmentation were investigated. The fractal dimension and image processing used to quantify soil fragmentation and scattering and obtain quantitative indicators of soil fragmentation. The results showed that the following factors influenced soil fragmentation in descending order of statistical significance: soil hardness, fall height and soil volume. The softer the soil was, the greater the fall height; the larger the soil volume was, the greater the fragmentation. Meanwhile the correlation between the two indicators is extremely high, simplifying assessment of the degree of soil fragmentation. This study clearly shows the influence of the intrinsic physical properties of soil and the external physical parameters of potato excavators on the characteristics of crushed soil. The results can provide a basis for improving the efficiency of potato-soil separation and designing more efficient devices for harvesting potatoes.

Studies on Controlling Variables of the Conveying Unit of a Power Tiller Operated Groundnut Digger

A power tiller operated groundnut digger was designed and developed in the Dept. of Farm Machinery and Power Engineering, CAET, OUAT, Bhubaneswar during 2021–22. The objective of this project was to optimize the operational parameters of the digger's conveying unit using the RSM technique. The study analysed the effects of soil moisture content and conveyor speed, on the conveying efficiency and soil separation efficiency with two different types of peg geometries. The central composite rotatable design (CCRD) method with a quadratic model was utilized to correlate the independent parameters with the conveying and soil separation efficiencies. The results indicated that variations in soil moisture content and conveyor speed had a significant impact on the conveying and soil separation efficiencies. The optimum parameters for the conveying unit of a power tiller operated groundnut digger were found to be a soil moisture range of 9.0-12.0%, a conveyor speed of 1.0 m/s and straight shank with bending tip pegs, resulting in a conveying efficiency and soil separation efficiency of 89.45% and 71.45%, respectively.

Response of quizalofop-resistant rice to sequential quizalofop applications under differential environmental conditions

AbstractQuizalofop-resistant rice allows for over-the-top applications of quizalofop, a herbicide that inhibits acetyl-coenzyme A carboxylase. However, previous reports have indicated that quizalofop applied postemergence may cause significant injury to quizalofop-resistant rice. Therefore, field experiments were conducted to evaluate the response of quizalofop-resistant rice cultivars to quizalofop applications across different planting dates. Under controlled conditions, the effects of soil moisture content, air temperature, and light intensity on quizalofop-resistant rice sensitivity to quizalofop were investigated. In the planting date experiment, injury of more than 11 percentage points was observed on early-planted rice compared with late-planted rice at the 5-leaf stage, with higher injury observed under saturated soil conditions. However, quizalofop applications at the labeled rate caused ≤16% reduction in yield regardless of planting environment. Quizalofop-resistant cultivars exhibited more injury by at least 25 percentage points when soil was maintained at 90% or 100% of field capacity because rice cultivars ‘PVL01’, ‘PVL02’, and ‘RTv7231 MA’ exhibited ≥42%, 30%, and ≥54% injury, respectively, compared with ≤10%, ≤5%, and ≤22% injury, respectively, at 40% or 50% of field capacity, pooled over rating timing. Greater injury ranging from 18% to 31% was observed on quizalofop-resistant rice grown under low light intensity (600 µmol m−2s−1) compared with 5% to 14% injury under high light intensity (1,150 µmol m−2s−1). The injury persisted from 7 to 28 d after 5-leaf stage application (DAFT), averaged over quizalofop-resistant cultivars and air temperatures (20/15 C and 30/25 C day/night, respectively). At 7 DAFT, greater injury (by 5 to 21 percentage points) was observed on quizalofop-resistant cultivars; PVL01, PVL02, and RTv7231 MA exhibited 33%, 9%, and 58% injury, respectively, under 20/15 C temperature conditions compared with 13%, 4%, and 37% injury, respectively, under 30/25 C day/night conditions averaged over light intensities. Overall, quizalofop is likely to cause a greater risk for injury to quizalofop-resistant rice if it is applied under cool, cloudy, and moist soil conditions.

Spectra transfer based learning for predicting and classifying soil texture with short-ranged Vis-NIRS sensor

Classifying soil texture is critical to investigate soil processes and functions influencing agronomic decisions and environmental stewardship. Despite the multiple benefits together with accurate estimation potential of visible and near-infrared reflectance spectroscopy (Vis-NIRS) over the traditional method of texture analysis, the prediction accuracy of the Vis-NIRS decreases due to the negative effect of soil moisture content (MC) on soil spectra. This study evaluated the performance of piecewise direct standardization (PDS) and direct standardization (DS) for eliminating the soil MC influence from fresh (non-processed wet) soil spectra to improve the accuracy of soil texture classification using a short-ranged (305–1700 nm) Vis-NIRS (Tec5 Technology, Germany). A set of 96 composite soil samples was collected from 18 fields, and the second set of 294 non-composite samples was collected from 10 of these 18 fields. All soil samples were scanned using a Vis-NIRS sensor after drying, grinding, and sieving, while the non-composite samples were additionally scanned in wet conditions. After analysing the composite samples for percent sand, silt, and clay, partial least squares regression (PLSR) models were calibrated (72 samples in calibration set) and validated (23 samples in validation set). Then, the PLSR model was used to predict the textural fractions for the wet, air-dried, DS and PDS transferred spectra of non-composite soil samples followed by their texture classification. Validation results indicated that the Vis-NIRS sensor predicted sand, silt, and clay fractions with excellent accuracies [coefficient of determination (R2) = 0.88–0.93; residual prediction deviation (RPD) = 2.91–3.74; ratio of the performance to interquartile range (RPIQ) = 2.12–5.02; root means square error (RMSE) = 3.62–8.06 %). Spectra transferred by the PDS and DS improved the texture classification accuracy up to 70 % and 90 %, respectively, while the wet soil spectra misclassified most fields (accuracy = 20 %). Unlike PDS, the DS predicted particles’ distribution seemed approximately similar to laboratory observations. Therefore, it was concluded that transferring the wet Vis-NIRS spectra by the DS algorithm can provide a rapid and accurate prediction of particle fractions and classification of soil texture classes with minimized effort, time, and cost.

Two decades of monitoring earthworms in translocated grasslands at Manchester Airport

Construction of a second runway at Manchester Airport included a mitigation package of habitat restoration with relocation of earthworms as prey items for protected vertebrates. Translocation of turf in blocks was the standard method used for four of five monitored sites with loose soil moved at the other. To assess earthworm communities at these translocated grassland sites, monitoring was undertaken each October (1998–2019) by digging and hand sorting of soil, followed by vermifuge application. Fourteen earthworm species were recorded, representing all ecological groups, but the majority were endogeic species, dominated by Aporrectodea caliginosa. Total earthworm numbers fluctuated during the monitoring period, with lowest density at 4 m−2 and highest more than a hundred times larger. The overall mean from all sites across the monitoring period was 151 ind. m−2. The differences between sites such as total earthworm numbers and species richness were clearly influenced by the translocation method and specific site topography. Created Hummocks to 3 m for hibernating amphibians proved successful with grassland soil establishing well. Lumbricus terrestris failed to establish due to translocation technique. Using non-metric multidimensional scaling, integration of environmental data with earthworm records showed effects of soil moisture content, pH and rainfall on abundance of ecological groupings and particular species. In general, earthworm community composition was dynamic over the monitoring period suggesting that this and population size needs to be appraised over realistic timescales, which may be best monitored in decades.

Экологические особенности накопления радионуклидов компонентами наземных экосистем зоны отчуждения

The studies were carried out 30 years after the Chernobyl accident on the lands of the former land use subject to natural successional changes. The patterns of the lateral distribution of 137Cs, 90Sr, 241Am in the upper 20-cm soil layer of various biogeocenoses, including those depending on the height fluctuations of the relief, have been studied. The values of the coefficient of variation (V) of the content of radionuclides in the upper soil layer decrease with the time that has passed since the accident. The highest value of the coefficient of variation (75.2 %) was obtained for 90Sr in the soil in the pine forest. The influence of various soil conditions on the entry of radionuclides into birch sap, cap mushrooms, and meadow grasses was studied. Despite the significant excess of the density of soil contamination with 137Cs of all the studied communities (up to 9.1 times), its volumetric activity in the juice is significantly lower than 90Sr, which indicates a lower availability of 137Cs compared to 90Sr. Dynamic processes of accumulation of radionuclides during the entire period of the movement of sap are studied. With increase in extent of moistening of the soil, accumulation of radionuclides in mushrooms tends to decrease. At the same time differences between types is established that connected with feeding habits of mushroom and variability of microclimatic conditions. The effect of soil moisture content, the ratio of 137Cs mobility forms in the soil on the biological availability of the radionuclide by meadow grasses was studied. A decrease in the specific activity of radionuclides in the plant components of ecosystems was found as the phytocenoses moved away from the epicenter of the accident at an identical density of soil contamination. A relationship has been established between the accumulation of radionuclides and the agrochemical parameters of the soil: maintenance of humus, absorption capacity, cation exchange capacity, hydrolytic acidity, content of exchange phosphorus, concentration of mobile calcium, magnesium and potassium on post-agrogenic lands. The analysis of the soil-to-plant transfer factors (Cf) and aggregated transfer factors (Tag), the discrimination coefficient (DF) of 137Cs by a chemical analog element (potassium) was carried out. Species features of plants associated with the transport of K+ - Cs+ cations make significant adjustments to the mechanisms of 137Cs accumulation. Attention is drawn to the significant increase in the concentration of 90Sr in all components in recent years.

A closer look at underground natural gas pipeline leaks across the United States

Underground natural gas (NG) pipeline leakage can result in methane (CH4) buildup and migration through the soil. What is not well understood in such scenarios is how the soil conditions affect the gas migration behavior, particularly in regard to the relative contributions of specific soil properties such as soil moisture content. The objective of this study was to investigate the effects of soil properties on CH4 concentration and migration from leaking underground NG pipelines. Site characteristics such as surface cover and spatial dimensions, soil samples, and gas concentration data were collected from over 70 gas leakage sites across the United States using a standardized sampling method. Soil samples were collected from excavation sites that were 1.5′–5′ in depth. The collected soil samples were analyzed in the laboratory to measure the soil texture, permeability, and moisture. Statistical analysis was performed to evaluate the effects of soil properties on CH4 migration distance and concentration. Soil texture was consistent across geographic locations due to standardized pipeline backfill protocols, allowing for the analysis of gas concentration and transport data with respect to soil conditions. Soil moisture content was the dominant influence on the gas concentration and spreading distance. High soil moisture content was associated with reduced lateral diffusion and elevated concentrations near the leak point, whereas dry conditions were associated with reduced concentrations and greater spreading distance. Increasing soil moisture content reduced the lateral diffusion of CH4 into the soil due to water-induced tortuosity, resulting in elevated concentrations close to the leak point. Lateral migration of CH4 was suspected to be by diffusion, starting at 5 m from the leaks, while transport within the immediate vicinity of the leak was controlled by advection. These findings demonstrate a pronounced effect of soil moisture content and permeability on CH4 migration distance and concentration, providing key insight into the effects of soil conditions on NG migration and how to account for such effects in leak detection surveys.

Interactive effect of soil moisture content and phosphorus fertilizer form on chickpea growth, photosynthesis, and nutrient uptake

Water shortage and soil nutrient depletion are considered the main factors limiting crops productivity in the Mediterranean region characterized by longer and frequent drought episodes. In this study, we investigated the interactive effects of P fertilizer form and soil moisture conditions on chickpea photosynthetic activity, water and nutrient uptake, and their consequent effects on biomass accumulation and nutrient use efficiency. Two P fertilizer formulas based on orthophosphates (Ortho-P) and polyphosphates (Poly-P) were evaluated under three irrigation regimes (I1: 75% of field capacity, I2: 50% FC and I3: 25% FC), simulating three probable scenarios of soil water content in the Mediterranean climate (adequate water supply, medium, and severe drought stress), and compared to an unfertilized treatment. The experiment was conducted in a spilt-plot design under a drip fertigation system. The results showed significant changes in chickpea phenotypic and physiological traits in response to different P and water supply regimes. Compared with the unfertilized treatment, the stomata density and conductance, chlorophyll content, photosynthesis efficiency, biomass accumulation, and plant nutrient uptake were significantly improved under P drip fertigation. The obtained results suggested that the P fertilizer form and irrigation regime providing chickpea plants with enough P and water, at the early growth stage, increased the stomatal density and conductance, which significantly improved the photosynthetic performance index (PIABS) and P use efficiency (PUE), and consequently biomass accumulation and nutrient uptake. The significant correlations established between leaf stomatal density, PIABS, and PUE supported the above hypothesis. We concluded that the Poly-P fertilizers applied in well-watered conditions (I1) performed the best in terms of chickpea growth improvement, nutrient uptake and use efficiency. However, their effectiveness was greatly reduced under water stress conditions, unlike the Ortho-P form which kept stable positive effects on the studied parameters.