Clay Soil Research Articles

Thermal desorption remediation effects on soil biogeochemical properties and plant performance: Global Meta-analysis

Soil contamination remains a global problem, and numerous studies have been published for investigating soil remediation. Thermal desorption remediation (TDR) can significantly reduce the contaminants in the soil within a short time and consequently has been used worldwide. However, the soil properties respond to TDR differently and are dependent on the experimental set-up. The causative mechanisms of these differences are yet to be fully elucidated. A statistical meta-analysis was thus undertaken to evaluate the TDR treatment effects on soil properties and plant performance. This review pointed out that soil clay was reduced by 54.2%, while soil sand content was enhanced by 15.2% after TDR. This might be due to the release of cementing agents from clay minerals that resulted in the formation of soil aggregates. Soil electrical conductivity enhanced by 69.5% after TDR, which might be due to the heating-induced loss of structural hydroxyl groups and the consequent liberation of ions. The treatment of TDR leads to the reduction of plant germination rate, length, and biomass by 19.4%, 44.8%, and 20.2%, respectively, compared to that of control soil. This might be due to the residue of contaminants and the loss of soil fertility during the thermal process that inhibited plant germination and growth. Soil pH and sulfate content increased with heating temperature increased, while soil enzyme activities decreased with thermal temperature increased. Overall, the results suggested that TDR treatment has inhibited plant growth as well as ecological restoration.

Monitoring of Architectural Monuments

The article presents the main provisions that it is advisable to follow when organizing and conducting monitoring during the operation of cultural heritage sites. It is noted that the existing regulatory documents do not take into account the specifics of monitoring during operation, but are mainly aimed at protecting the monument from neighboring construction.Criteria are proposed to control the technical condition of historical buildings. Among them is the rate of development of long-term precipitation, which is considered as an indicator of the intensity of natural and man-made impacts on the building.Among them is the rate of development of long-term precipitation, which is considered as an indicator of the intensity of natural and man-made impacts on the building. It is noted that for stone structures, critical masonry stretching deformations serve as an effective criterion for the preservation of historical buildings, since in calculating the interaction of structures and foundations they are the primary criterion for calculating the second group of limiting states. In relation to it, the criterion of absolute precipitation and relative difference of precipitation is secondary. It is shown that over time, for buildings built on weak water-saturated clay soils, an increase in the unevenness of precipitation occurs. Special attention is paid to taking into account the accumulated uneven precipitation of buildings of historical development. The article presents the most characteristic types of deformations of buildings, among which in St. Petersburg the bend is most common, which is due to the regularity of building and rebuilding sections of urban neighborhoods.Monitoring is also considered as a reliable means of diagnosing the technical condition of the monument. The monitoring function is considered as a means of controlling the limitations of the monument’s operability, which continues to be operated in conditions of limited operational technical condition.

Improving the performance of evidential belief function model using five machine learning models in earth fissure susceptibility mapping

The frequency and occurrence of earth fissures threaten human settlements, infrastructure, and agricultural lands in many parts of the globe. This natural hazard has particularly posed great challenge in the North, Central, and Eastern parts of the Najaf Abad Basin of Iran. This paper presents a comparative analysis of machine learning algorithms for earth fissure susceptibility assessment, and involves the creation of an earth fissure database by selecting and validating 200 fissure locations. To improve the accuracy of the fissure locations, various geographic data sources, such as Google Earth images, field surveys, and GPS measurements, were employed. The locations were divided into training and validation sets based on sixteen conditioning factors for finding the earth fissure susceptible zones using EBF (Evidential belief function), EBF – Multilayer Perceptron (MLP), EBF – Function Tree (FT), EBF – Alternating decision tree (ADtree), EBF – Adaptive Boosting (AdaBoost), EBF – Random SubSpace (RSS), EBF – Naive Bayes Tree (NBTree) models. The results show that earth fissures occur in greater concentrations where groundwater levels are lowest, and their prevalence is closely associated to both agricultural activities and the presence of clay, clayey sand, and silty clay soils. Susceptibility analysis results revealed that 15–21 % agricultural dependent population falls under the very high susceptibility risk zone in and around the major cities of the Najaf Abad region. The receiver operating characteristic (ROC) curve analysis showed that the EBF-RSS algorithm has higher accuracy (>99 %) compared to other algorithms (>85 %) in training and validation phases for earth fissure susceptibility prediction. Our findings emphasise the need to prioritise these susceptible areas for sustainable land and water management strategies and implement effective measures to mitigate the impact of earth fissures. Our study also advances our knowledge on geospatial analysis and earth fissures-related hazard assessment by applying five machine learning algorithms that shows spatial similarity in susceptibility categories with splendid accuracy performance.

Nomenclature notes on vegetation of the Salicetea purpureae Moor 1958 class in Ukraine

A brief history of the syntaxonomic studies of floodplain vegetation of the Salicetea purpureae class in Ukraine is presented and the tasks of further research are established. Our study has shown that the vegetation of the class includes more than 30 associations, which belong to 6 alliances and 2 orders. According to the ecological peculiarities, they are divided into willow shrubs on the gravel banks of streams in the montane and subalpine belts of the temperate and boreal zones of Europe and the Caucasus (Salicion eleagno-daphnoidis), willow and poplar forests of lowland and foothill rivers formed on alluvium in the nemoral zone of Europe and at high altitudes in the Mediterranean region (Salicion albae), willow shrubs on the sandy-loamy soils of the river banks of lowlands and foothills of the nemoral zone of Europe (Salicion triandrae), willow shrubs on riverine dunes in central Ukraine (Artemisio dniproicae-Salicion acutifoliae), shrubs on temporarily flooded clay soils in central Ukraine (Rubo caesi-Amorphion fruticosae). The problems of using the phytosociological nomenclature during the analysis of the Salicetea purpureae vegetation on the territory of Ukraine are highlighted. It was found that half of the syntaxa listed in Ukrainian geobotanical literature are synonyms, published invalidly, or need typification. Every syntaxon is accompanied by explanations of its non-validity with citations of the relevant articles published in the 4th edition of the International Code of Phytosociological Nomenclature. In addition to the incorrectly cited associations, two of the six alliances (Artemisio dniproicae-Salicion acutifoliae, Rubo caesii-Amorphion fruticosae) also require correction because their description was based on the invalid nomenclatural types formed by the selection of species which are invalid according to The Euro+Med PlantBase. In this paper, we aimed to analyze the studies on the vegetation of the Salicetea purpureae class on the territory of Ukraine using the Braun–Blanquet approach, determine the issues that require more detailed research in the future, and make some notes on nomenclature discordances. Such review makes it possible to determine all mismatches in phytosociological nomenclature.

A Comparative Study of Real-World vs. Small-Scale Mat Foundations on Expansive Clay Soils for Low-Cost Housing

A Comparative Study of Real-World vs. Small-Scale Mat Foundations on Expansive Clay Soils for Low-Cost Housing

Effect of soil type on tipping point hydrological requirements for Axonopus compressus grass under extreme drought stress

Critical soil suctions (threshold, tipping point, and permanent wilting) corresponding to initial drought response, near-death stage, and complete mortality, respectively; is essential for formulating irrigation schemes of vegetation grown in compacted soil under drought conditions. The effect of soil types on these critical soil suctions are unexplored and is crucial in understanding the soil-specific plant water functions. This study aims to establish the drought response of Axonopus compressus (grass), based on stomatal conductance (gs) and chlorophyll fluorescence parameters (CI) grown in different soil types. A. compressus were grown in six soil types (2 coarse-grained and 4 fine-grained soils) for 8 weeks, followed by continued drought condition. The gs and CI were monitored along with soil suction and moisture content. Both leaf and root growth were observed to be higher in coarse-grained soils than fine-grained soils, even though the water retention of the coarse-grained soils were comparatively less. Drought stress initiation in plants was captured by ψthreshold from the CI (especially in fine-grained soils) before the gs response. The three critical soil suctions estimated from the correlation between CI and ψ were found to be increasing with higher soil clay fraction. Corresponding plant available water contents (based on v/v volumetric water content) with each of three critical soil suctions were found to be dependent on the relative growth of canopy to root growth that occurred in different soil medias. Especially, plant available water in ‘tipping suction’ was dependent on the soil clay fraction (i.e., higher fraction could restrict root water uptake) and is presented with a simple empirical correlation for A. compressus.

English

The current study was conducted in growth chamber with the aims to examine the effect of different soil types and temperature regimes on quantitative and qualitative traits of saffron and to assess the agro-climatic suitability of selected sites of Poonch Division of Azad Jammu & Kashmir for field scale saffron cultivation. Soil from 07 sites was collected and processed for pot filling. A total of 63 plastic pots (21 for each temperature level i.e., 19, 26 and 32 oC), were filled with soils of each site and incubated separately in growth chambers. The pots were arranged under completely randomized design (CRD) replicated thrice. Results indicated that maximum number of flowers (1.35 per plant), flower fresh weight (29.03 mg per plant), stigma length (1.21 cm), stigma fresh weight (8.97 mg per plant) and stigma yield (8.60 mg per pot) was recorded for Khaigala site (loam textured soil) at 26 oC followed by Trarkhel (sandy loam textured soil) and Abbaspur (loam textured soil) sites. On an average, maximum 58.30 days were taken to initiate flowering in soil of Alisojal site (clay loam textured soil) with flowering period of 17.06 days. The maximum number of daughter corms (2.92 per plant), corm diameter (9.61 mm), corm weight (15.76 g per plant), corm yield (47.28 g per pot), picrocrocin (11.32%) and safranal (0.22%) content was again recorded for Khaigala site (at 26 oC). However, maximum crocin content (14.33%) was noted for Alisojal site (1831 m altitude). The Cluster and PC analyses revealed that Khaigala, Trarkhel and Abbaspur sites produced saffron of better quality and agro-climatically suitable for establishment of saffron. Further, the saffron grown on loam and sandy loam textured soils showed better performance compared to that of clay textured soils.

Irrigation and oil palm empty fruit bunch mulch enhance eggplant growth, radiation interception and dry matter yield

Organic mulching is a well-known management practice that conserves soil water and nutrients as well as increases crop yield. Nonetheless, research on combined organic mulching using oil palm empty fruit bunch (EFB) and irrigation is limited. Field-based experiments were conducted over three seasons to test the sole and combined effects of EFB as organic mulch and irrigation on the growth, total dry matter yield (TDMY), accumulated intercepted photosynthetically active radiation (AIPAR), and radiation use efficiency (RUE) of African eggplant (Solanum aethiopicum L.) in a low fertile tropical sandy clay loam soil. Air-dried EFB was used as an organic mulch by spreading it on the soil surface at rates of 0 (EFB0), 20 (EFB20), and 40 t ha−1 (EFB40), and either fully-irrigated (I100), deficit-irrigated (I40), or non-irrigated (I0). The I100 plots were irrigated to field capacity (FC) every 3–4 days based on PR2 Profile Probe measurements and the resultant irrigation volume supplied to the plants via drip irrigation tubes. The I40 plots received 40 % of the water given to the I100 plots, and the I0 plots were solely rain-fed. At the end of the third season, the 40 t ha−1 EFB-mulch increased soil pH, electrical conductivity (EC), soil organic carbon, potassium, cation exchange capacity, and the soil’s specific surface area. In the first season, all the measured eggplant growth and yield parameters were neither responsive to irrigation only, EFB-mulch only, or both. In the second and third seasons, the EFB20 and EFB40 treatments significantly (p < 0.05) increased leaf chlorophyll content index (LCCI), photosystem II (Fv/Fm ratio), absolute performance index (PIabs), TDMY, AIPAR, and RUE compared to the non-mulched control treatment. Soil pH was high in the EFB-mulched plots and correlated positively with TDMY and AIPAR. The I100 significantly improved LCCI, Fv/Fm, PIabs, and TDMY during the second season. In the third season, a highly significant interaction between irrigation and mulching was detected on TDMY, AIPAR, RUE, LCCI, Fv/Fm ratio, and pH (H2O). This indicated a positive effect on soil nutrient availability especially phosphorus as TDMY and AIPAR correlated with soil pH. The I100 and I40 significantly increased AIPAR by 48.1 % and 37.2 %, and RUE by 26.7 % and 11.0 %, respectively, compared to I0 during the third season. The total dry matter yield of the African eggplant was enhanced by EFB-mulch, with the effect increasing over up to three growing seasons, especially when combined with irrigation during dry periods.

Phosphorus Adsorption as Affected by Concretionary Nodules of Oxic Rhodustalf in Southern Guinea Savannah Agroecological Zone of Nigeria

Hard, rounded masses of mineral matter, known as concretionary nodules, can be found in soil or sedimentary rock. These nodules are typically made up of minerals like iron oxides, hydroxides, and carbonates that have been deposited in groundwater. Their sizes can range from small pebbles to large boulders, and they often differ in composition or hardness compared to the surrounding rock or soil. Nodules act as a highly effective storage space for extra P, leading to a significant increase in overall P requirements. Phosphorus, although an essential element for all living organisms, including plants and animals, is scarce. Despite its importance, only a small fraction of the total phosphorus available can be readily absorbed by plants. Given the worldwide demand for phosphorus in food production, it is crucial to devise techniques for extracting it from different sources. However, there has been limited research on the understanding of phosphorus availability and adsorption mechanisms in these areas. Therefore, the study focused on exploring the impact of concretionary nodules on phosphorus sorption and the characteristics of low-activity clay soil in the Guinea savannah of Nigeria. Soil samples collected from the study area were used to investigate the soil’s ability to absorb phosphorus at depths ranging from 0 to 30-60-90-120-150 cm in different soil and concretion locations. Various soil and concretion types demonstrated distinct capacities for phosphorus adsorption, as indicated by the adsorption isotherm. The maximum monolayer adsorption capacities (Qmax values) were 161.0, 154.5, 149.6, 141.7, 139.8, and 139.3 mg/g for OBC, OBS, OC, OIS, OS, and OIC, respectively. At equilibrium with a 50-ppm solution, the pseudo-second-order rate constants for P sorption were 1.180 x 10&lt;sup&gt;–4&lt;/sup&gt;, 9.740 x 10&lt;sup&gt;–5&lt;/sup&gt;, 1.120 x 10&lt;sup&gt;–4&lt;/sup&gt;, 1.140 x 10&lt;sup&gt;–4&lt;/sup&gt;, 1.000 x 10&lt;sup&gt;–4&lt;/sup&gt;, and 8.010 x 10&lt;sup&gt;–5&lt;/sup&gt; g mg&lt;sup&gt;–1&lt;/sup&gt; min&lt;sup&gt;–1&lt;/sup&gt; for OIS, OIC, OBS, OBC, OS, and OC, in that order. In the 300-ppm equilibrium solution, the OIS, OIC, OBS, OBC, OS, and OC pseudo-second-order rate constants were 1.250 x 10&lt;sup&gt;–4&lt;/sup&gt;, 1.130 x 10&lt;sup&gt;–4&lt;/sup&gt;, 9.550 x 10&lt;sup&gt;–5&lt;/sup&gt;, 1.040 x 10&lt;sup&gt;–4&lt;/sup&gt;, 2.750 x 10&lt;sup&gt;–4&lt;/sup&gt;, and 1.420 x 10&lt;sup&gt;–4&lt;/sup&gt; g mg&lt;sup&gt;–1&lt;/sup&gt; min&lt;sup&gt;–1&lt;/sup&gt;, respectively. At the 500-ppm equilibrium, the pseudo-second-order rate constants for OIS, OIC, OBS, OBC, OS, and OC were 1.240 x 10&lt;sup&gt;–4&lt;/sup&gt;, 1.090 x 10&lt;sup&gt;–4&lt;/sup&gt;, 1.020 x 10&lt;sup&gt;–5&lt;/sup&gt;, 1.100 x 10&lt;sup&gt;–4&lt;/sup&gt;, 2.730 x 10&lt;sup&gt;–4&lt;/sup&gt;, and 1.180 x 10&lt;sup&gt;–4&lt;/sup&gt; g mg&lt;sup&gt;–1&lt;/sup&gt; min&lt;sup&gt;–1&lt;/sup&gt;, respectively. Consequently, the soil adsorption capacity increased with higher pseudo-second-order rate constants.

Treatment of clay soil contaminated with lead by in-situ immobilization process using animal bones

In this work, the application of bone wastes –Cow Bone, Pig Bone, and Horse Bone for the treatment of Lead (Pb) in Clay Soil by in-situ immobilization process, was investigated. The bone wastes were carbonized at a temperature of 700 OC for five hours. The Cow Bone Ash (CBA), Pig Bone Ash (PBA), and Horse Bone Ash (HBA) obtained were characterized with X-Ray Fluorescence (XRF). The physicochemical analysis of the soil sample was also performed. Batch experiments were done to investigate the effects of amendment dosage, time, and pH on immobilization efficiency. The physicochemical characterization of the amendments showed that they contain principally calcium phosphate. The XRF revealed that CBA contains 49.25 % CaO and 42.406 % P2O5, PBA contains 46.6 % CaO and 40.488 % P2O5 and HBA contains 45.664 % CaO and 33.857 % P2O5. The batch immobilization experiment revealed that CBA performed better than other sorbents in the removal of Pb. The removal efficiency is in the order CBA &gt; PBA &gt; HBA. The maximum removal of Pb in 100 g of soil was 71.2 %. This investigation has shown that animal bones can successfully remediate lead by immobilization process in a Pb contaminated Clay soil.

Characterization and Making Techniques of Calcareous Construction Materials for Phaya Thon Zu Temple in Bagan Historical Area, Myanmar.

The calcareous materials used in constructing the Phaya Thon Zu temple at the Bagan historical sites in Myanmar are mortars, plasters, and stuccos. Among them, the mortars and plasters are a mixture of original and new materials used for recent conservation treatments. In this study, the making techniques were examined through analysis of calcareous materials by production period. All calcareous materials have a mineral composition similar to soil, except calcite. Stuccos have the most refined aggregates, homogeneous particle size, and the highest lime and organic contents. They were designed to improve ease of carving and weathering resistance, considering the unique characteristics of the stuccos. Because all calcareous materials were mixed with soil, the origin of the clay materials was analyzed. It was concluded that the mortars were produced by mixing clay and sandy soil, and the original mortars showed characteristics similar to soil. It is highly possible that sandy soil from around the Htillominlo temple was used to produce new plasters, and it is estimated that a mixture of clay soil was used for the original plasters and stuccos. A clear provenance interpretation of the original and raw materials used for each construction and the mixing ratio of clay materials need to be discussed through experiments, along with the estimated provenance area of the raw calcareous materials.

Evaluation of Geotechnical Properties of Soil at Selected Sites in Al-Nasiriya City

Soil index properties are used to calculate and determine the geotechnical properties of soils and then determine soil suitability for the construction of engineering projects. Most of the geotechnical properties of soil affect each other directly or indirectly, and these properties can be utilized as indicators to calculate other properties. In the present study, some soil index properties were used to identify the geotechnical properties of soil. According to the unified classification system for soil, most soils were classified as low and high plasticity hilt. In addition, the soils showed a medium to a high degree of expansion according to the values of the Atterberg limit and were generally considered inactive clay soil. Based on the Standard Penetration Test values, consistency index, and compression index, the soil was stiff to extremely stiff and had high to extremely high compressibility. Finally, the results showed the need for soil for some engineering works, such as stabilization and modification, before the construction of engineering projects.

Treatment of Marine Clay Strength Behavior by Demolished Tile Materials and Cement

Known as a problematic soil in the civil engineering field, a sustainable solution to marine clay soil strength behaviour is needed. Another major concern in the engineering field is the solid waste management. Demolished Tile Material (DTM) is one of the largest contributors to construction waste. By utilizing DTM as a stabilizer product to treat marine clay soil, both problems can be minimized. The primary objective of this study is to assess the improvement in marine clay soil's strength characteristics through the addition of DTM and cement. Various proportions of DTM (4%, 8%, 12%, 16%, and 20%) were incorporated into the soil, with a constant 10% cement content. Unconfined Compressive Strength (UCS) measurements were taken at different curing times (0, 7, 14, 28, and 60 days). Results indicate a significant increase in UCS after treating marine clay with DTM and cement, with the most substantial improvement observed at 16% DTM content. The study also emphasizes the role of curing time in enhancing soil strength. The research findings shows that the potential of repurposing DTM for soil stabilization, reducing construction waste, and promoting environmentally responsible construction practices. This study also contributes to the sustainable development of marine clay areas in Malaysia and offers valuable insights for soil engineering and waste management in construction projects.

Diversity patterns of herbaceous community in environmental gradients of dehesa ecosystems

Dehesa is a unique ecosystem associated with high biodiversity, that integrates trees, livestock, and pasture, making agro-pastoral production compatible with sustainability. However, in the last few decades, a manifold of factors have caused a decline in tree vitality, density, and coverage, leading to long-term changes in species composition and ecosystem structure. This study aims to determine changes in the diversity of the herbaceous plant community in relation to environmental characteristics, the phytosanitary state of the holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.), and possible interactions with biotic agents, including Phytophthora cinnamomi. For this purpose, the floristic composition and alpha diversity of the understory were assessed in two dehesa stands in Southern Spain. Additionally, the spatial heterogeneity (beta diversity) patterns of herbaceous plants were evaluated in relation to a climatic gradient and subplot orientation at the regional, plot, tree, and subplot scales. Our findings show that microsite features and climate substantially impact the herbaceous plant community in dehesa stands. Annual precipitation is a crucial factor affecting the diversity and biomass of herbaceous plants on a broader, regional scale, consistent with its role as a limiting factor in the Mediterranean climate. However, site-level differences, such as soil clay content and plot slope angle, positively correlate with plant biodiversity, growth, and richness, varying with the Biodiversity Index considered. Moreover, microsites resulting from the combined effects of plot and tree are the main drivers of dissimilarities between samples, as expressed by beta diversity. Contrary to our initial hypothesis, our results reveal no significant association between tree health and herbaceous biodiversity decline.

Potential of Limestone Calcined Clay Cement (LC3) in soil stabilization for application in roads and pavements construction

Clay soil is associated with geotechnical problems of swelling and shrinkage, which causes deformations on structures. Ordinary Portland Cement (OPC) which is the most common stabilizing agent for clay soils, remains unaffordable in most developing countries, and its production also contributes about 8 % of global anthropogenic CO2 emissions. The present study aimed to investigate the effect of Limestone Calcined Clay Cement (LC3) on the stabilization of clay soils for applications in road construction. Clay soil was mixed with quarry dust to reduce the clay content and save cement. The mixture was stabilized using LC3 and OPC separately in proportions of 1 %, 3 % and 5 %. The effect of stabilizer dosage on the performance of clay soil was studied by monitoring the changes in Atterberg limits, Proctor test and soaked California Bearing Ratio (CBR). The mineralogical and microstructural investigation was carried out using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). Plasticity index (PI), linear shrinkage (LS), and optimal moisture content (OMC) of stabilized soil was found to decrease with increase in the dosage of LC3 and OPC. The Maximum Dry Density (MDD) and soaked CBR increased with addition of both LC3 and OPC. Formation of calcium silicate hydrate (C-S-H) in both LC3 and OPC stabilized clay soil, as well as formation of Hemi-carboaluminate in LC3 stabilized clay soil was responsible for improved properties of the stabilized soil. The performance of LC3 was found to be comparable to that of OPC, at optimum cement ratio of 5 %.

Circularity of potassium in a grassland-based dairy farm on a clay loam soil

A proportion of potassium (K) exits grassland-based dairy farms in tradeable products. Potassium imports are typically needed to offset depletion of soil reserves. The objectives of this study were to (i) quantify K entering and exiting a grassland-based dairy farm including K lost to water, (ii) to relate the balance between K entering and existing the farm to soil K fertility status in order to (iii) design a better K fertilisation strategy for grassland under temperate climatic conditions. The quantities of K entering and exiting a grassland-based dairy farm (Solohead Research Farm; 52⁰51’N, 08⁰21’W) were determined each year between 2005 and 2022. Potassium losses to groundwater were measured during the winters of 2020/21, 2021/22 and 2022/23. Averaged over 18 years, K entering (kg ha−1 ± standard error) was 82 ± 11 and exiting was 41 ± 4. The annual average farm K balance was 41 ± 12 kg ha−1 and ranged between −36 and 136 kg ha−1. Annual K loss to groundwater (mean ± SE kg ha−1) ranged between 6.9 ± 6.13 and 59 ± 7.4. Annual average soil test K (STK; following extraction using Morgan's solution (Na acetate + acetic acid, pH 4.8)) concentrations in paddocks across the farm ranged from 85 to 253 mg L−1. The yearly change in average STK concentrations correlated with annual farm K balance in the preceding year (R2=0.59; P<0.001). Annual farm-scale K budgets were useful in quantifying K flows in products and losses. Potassium leaching to groundwater represented the majority (55 %) of K exiting the farm; exceeding export of K in milk and other products. Maintaining overall farm STK status required annual fertiliser K inputs of 22.5 kg ha−1 between 2016 and 2022. This study elucidates the challenges in managing soil K fertility on grassland based dairy farms.

Integrated management to achieve synergy in sugarcane production and quality in China

ContextSugar production in China is struggling to keep up with the increasing demand driven by rapid growth in sugar consumption. However, knowledge gap persists in terms of how to locate and concentrate the sugarcane production in advantageous areas to secure the production of high-quality sugarcane characterized by high sugar content, while also optimizing resource utilization. ObjectiveThe objective of the study was to explore the effects of environmental and management factors on sugarcane yield and quality (characterized by sugar content). Moreover, it sought to determine how China's future sugarcane needs could be met with fewer resource inputs through production optimization. MethodsThis study conducted a comprehensive search and compiled 411 groups of measured data from 64 peer-reviewed publications on sugarcane production in China. Additionally, a Random Forest model was developed based on trial data and farmer survey data to predict county-level sugarcane yield and quality in China. Taking into consideration China's projected sugarcane demand in 2030, this study proposed three sugarcane planting scenarios to explore potential pathways for future sugarcane production. These scenarios included: S0, where all sugarcane acreages maintain their current level of production; S1, where medium- and low-yield (or quality) fields transition into high- and medium-yield (or quality) fields; and S2, where all sugarcane acreages strive for both high yield and high quality. ResultsResults showed that overall field management could improve yield by 37.1 % and quality by 5.26 %. Soil organic matter (SOM), available phosphorus (AP), mean annual precipitation (MAP), and soil clay are the most important drivers of yield. pH, AP, total nitrogen (TN), and SOM are the most important drivers of quality. S2 scenario reduced land inputs by 11 %, nutrient inputs by 5 %, and irrigation inputs by 13 %, based on meeting future sugarcane demand in 2030. ConclusionsBy identifying and focusing on dominant planting areas, we can enhance the quality and efficiency of sugarcane cultivation as a response to China's future demand for sugarcane. This approach will not only meet future demands for sugarcane but also alleviate the dual pressures of limited resources and environmental concerns. SignificanceOur research provides a conceptual framework to enable China to meet its future sugar demand and consumption more efficiently and in an environmentally friendly manner, thereby conserving resources and reducing environmental impact.

Characteristics of clay dispersion and its influencing factors in saline-sodic soils of Songnen Plain, China

Under the influence of salinity-sodicity stress, soil salinization and sodification tend to be severe and the dispersion of clay particles increases, which threatens agricultural production and food security. To explore the characteristics of clay dispersion in saline-sodic soils and their influencing factors, the quantitative relationship between clay dispersion indices and soil physicochemical parameters in saline-sodic soils of the Songnen Plain in China was investigated, to provide theoretical and data support for clay dispersion control in saline-sodic soils. Forty-two natural soil samples (0–0.2 m) were collected from saline-sodic soils in Songnen Plain, northeast China, and their physicochemical parameters and clay dispersion indices were determined. Correlation analysis, random forest analysis, and multivariate linear regression analysis were used in this study. The results showed that water-dispersible clay (WDC) ranged from 0.60 % to 18.38 % and total clay (TC) ranged from 4.70 % to 20.68 %. The maximum value of the clay dispersion ratio (CDR) is nine times the minimum value. In terms of turbidity, mechanical dispersion turbidity (MDT) ranged from 39.60 to 59,433 NTU, while spontaneous dispersion turbidity (SDT) ranged from 1.11 to 154.67 NTU. In terms of zeta potential, the minimum value of mechanical dispersion ZETA potential (MDZP) was −46.42 mV, and the maximum value was close to 0 mV. There was a significant correlation between soil physicochemical parameters and clay dispersion indices. Exchangeable sodium percentage (ESP) was the most important explanatory variable for CDR, followed by pH, Na+ex, HCO3-, Na+, CEC, CO32-, SAR, CROSS, and SOC, which could help construct the following multiple linear regression model: CDR=0.143+0.015*ESP −0.036*CO32- −0.006*Na+. Exchangeable sodium percentage has the strongest effects on clay dispersion among the soil parameters. Clay dispersion indices vary with soil physicochemical parameters. Compared to MDT, SDT, MDZP, and SDZP, CDR is more suitable for evaluating and predicting the clay dispersion condition in saline-sodic soils.

An Assessment of Biodegradability and Phytotoxicity of Natural Rubber in a Simulated Soil Condition via CO2 Evolution Measurement.

In this study, the biodegradation of various natural rubber (NR) samples, i.e., neat NR and NR filled with two different curative contents was investigated under a long-term simulated soil condition at a temperature of 25 ± 2 °C in accordance with ISO 17556. Natural clay loam soil, with a pH of 7.2 and a water holding capacity of 57.6%, was employed. Under controlled test condition both unvulcanized and vulcanized NR samples having low curative content, respectively designated as UNRL and VNRL, exhibited similar biodegradation behaviors to the neat NR. They showed fast biodegradation at the early stage, and their biodegradation rate did not significantly change throughout the test period (365 days). However, for the NR samples having high curative content, respectively called UNRH and VNRH for the unvulcanized and vulcanized samples, a biodegradation delay was observed within the first 130 days. Surprisingly, the UNRH showed a relatively high biodegradation rate after the induction period. At the end of the test, most of the rubber samples (the neat NR, UNRL, VNRL, and UNRH) showed a comparable degree of biodegradation, with a value ranging from 54-59%. The VNRH, on the other hand, showed the lowest degree of biodegradation (ca. 28%). The results indicate that the number of curatives does not significantly affect the biodegradability of unvulcanized NR in the long term, despite the fact that a high curative content might retard microorganism activity at the beginning of the biodegradation process. Apparently, crosslink density is one of the key factors governing the biodegradability of NR. The phytotoxicity of the soils after the biodegradation test was also assessed and represented in terms of seedling emergence, survival rate, and plant biomass for Sorghum bicolor. The values of seedling emergence (≥80%), survival rate (100%), and plant biomass of all soil samples were not statistically different from those of the blank soil, indicating the low phytotoxicity of the tested soils subjected to the biodegradation of the rubber samples. Taken as a whole, it can be concluded that the CO2 measurement technique is one of the most effective methods to assess the biodegradability of rubbers. The knowledge obtained from this study can also be applied to formulate more environmentally friendly rubber products.

Use of Lignin, Waste Tire Rubber, and Waste Glass for Soil Stabilization

The complex interactions between soil and additives such as lignin, glass powder, and rubber tires were investigated using principles of material and soil mechanics. Previous research has mainly focused on individual additives in clay soils. In contrast, this study investigates soil improvement with two different types of waste materials simultaneously. The improvement of soil properties by hybrid waste materials was evaluated using several laboratory tests, including the standard Proctor test, the unconfined compressive strength test, the California Bearing Ratio (CBR) test, and cyclic triaxial tests. The aim of this research is to identify key parameters for the design and construction of road pavements and to demonstrate that improving the subgrade with hybrid waste materials contributes significantly to the sustainability of road construction. The mechanical and physical properties were evaluated in detail to determine the optimal mixtures. The results show that the most effective mixture for the combination of waste glass powder and rubber tires contains 20% glass powder and 3% rubber tires, based on the dry weight of the soil. For the combination of waste glass powder and lignin, the optimum mixture consists of 15% glass powder and 15% lignin, based on the dry weight of the soil. These results provide valuable insights into the sustainable use of waste materials for soil stabilization in road construction projects.