Geoderma Regional最新文献

{"title":"Cover crop mixtures enhance belowground carbon input and suppression of spontaneous flora under Danish conditions","authors":"Juliana Trindade Martins ,&nbsp;Nadja Fuglkjær Bloch ,&nbsp;Kirsten Lønne Enggrob ,&nbsp;Zhi Liang ,&nbsp;Laura Sofie Harbo ,&nbsp;Jim Rasmussen ,&nbsp;Leanne Peixoto","doi":"10.1016/j.geodrs.2024.e00879","DOIUrl":"10.1016/j.geodrs.2024.e00879","url":null,"abstract":"<div><div>Cover crop (CC) mixtures offer a unique set of advantages that can enhance soil health and agricultural productivity when compared to pure stand CC. However, a quantitative understanding of the varying contributions of different carbon (C) input pathways in CC mixtures is lacking. To address these gaps, a field experiment with multiple-pulse labelling with ¹³CO₂ was used to quantify C-derived from CC mixtures via plant biomass, as well as via phyllo- and rhizodeposition. We assessed the impact of preceding main crops (barley, barley-pea, pea, and faba bean) on soil C input to 75 cm depth by two CC treatments (pure stand ryegrass versus a mixture of chicory, plantain, and ryegrass) and their effect on spontaneous flora (SF) biomass and diversity. In topsoil layers (0–25 cm), net C lost to soil via phyllo- and rhizodeposition was higher with mixed CC (30 g C m⁻²) than pure stand ryegrass (25 g C m⁻²). Between 25 and 75 cm, mixed CC and pure stand CC had similar C inputs via rhizodeposition despite larger root biomass in mixed CC. Cover crops reduced SF biomass and diversity, with mixed CC exerting the strongest suppressive effect, reducing biomass (individuals counted) by 57 % compared to the control. The improved efficiency of mixed CC was attributed to species complementarity in leaf and root patterns, resource utilization, and nutrient uptake. In conclusion, well-designed mixed CC had a greater positive impact on soil C inputs and suppression of SF compared to CC pure stand with ryegrass, resulting from complementary above and belowground traits.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00879"},"PeriodicalIF":3.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal variation-dependent biochar impacts on coastal acid-sulfate soil in paddy fields and the consequences on rice growth and yield","authors":"Hao Phu Dong ,&nbsp;Binh Thanh Nguyen ,&nbsp;Anh Hoang Le ,&nbsp;Gai Dai Dinh","doi":"10.1016/j.geodrs.2024.e00878","DOIUrl":"10.1016/j.geodrs.2024.e00878","url":null,"abstract":"<div><div>Utilizing eco-friendly and cost-effective amendments, like biochar produced from agricultural biomass wastes offers numerous benefits for ameliorating acid-sulfate soils in coastal regions. This study investigates seasonal variation and rice husk and longan biochar's impacts on soil properties, quality, and rice (<em>Oryza sativa</em> L.) growth and yield in acid-sulfate paddy fields during dry and rainy seasons. Five treatments (T) were tested: T1 (no biochar), T2 and T3 (10-tone and 20-tone rice-husk biochar ha⁻¹), and T4 and T5 (10-tone and 20-tone longan biochar ha⁻¹). Results showed that biochar improved soil properties with pH increasing by 3.2 % to 9.2 % and exchangeable Al decreasing by 7.7 % to 18.1 %, compared to T1, dependent on treatments and seasons. Soil quality index in biochar treatments increased by 30 %, 54 %, 26 %, and 16 % for T2, T3, T4, and T5, respectively, compared to T1 in the dry season. This season exhibited the highest grain weight (1.06 kg m⁻²) and total biomass (2.31 kg m⁻²) in T3, followed by T5, T2, T4, and T1. The rainy season benefits were less pronounced, likely due to leaching, suggesting more frequent applications may be necessary in high-rainfall regions. Liming effects and leaching in the rainy season were identified as primary mechanisms influencing soil quality and rice yield. Rice-husk biochar was more effective than longan biochar in mitigating soil constraints and enhancing rice yield. In short, biochar effectively ameliorates acid-sulfate soil constraints, improving rice yield and growth. However, rapidly diminishing effects during the rainy season necessitate further investigation for optimal application in high-rainfall regions.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00878"},"PeriodicalIF":3.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil carbon sequestration under N fertilized or mixed legume-grass pastures depends on soil type and prior land-use","authors":"Wesley dos Santos Souza ,&nbsp;Stallone da Costa Soares ,&nbsp;Bruno Grossi Costa Homem ,&nbsp;Ítalo Braz Gonçalves de Lima ,&nbsp;Lucas Peralta Carneiro Borges ,&nbsp;Daniel Rume Casagrande ,&nbsp;Claudia de Paula Rezende ,&nbsp;José Marques Pereira ,&nbsp;Erika Flávia Machado Pinheiro ,&nbsp;Marcos Gervasio Pereira ,&nbsp;Bruno José Rodrigues Alves ,&nbsp;Segundo Urquiaga ,&nbsp;Robert Michael Boddey","doi":"10.1016/j.geodrs.2024.e00876","DOIUrl":"10.1016/j.geodrs.2024.e00876","url":null,"abstract":"<div><div>Grass-fed beef operations with well-managed pastures mixed with stoloniferous forage legumes are an alternative to increase animal productivity and sequester carbon (C) in the soil. However, using the same system, differences in response time and C sequestration may occur when established in different regions. The objective of this study was to evaluate the impact on C and nitrogen (N) stocks in the soil due to the implementation in the same year, of pasture systems with and without N fertilization or mixed with stoloniferous forage legumes in two regions under different edaphoclimatic conditions. The two experiments were established at the same time and carried out in two areas contrasting in soil type and edaphoclimatic features. The first area was in a transition between the Cerrado and the Atlantic Forest biomes with a Ferralsol with a uniform clayey texture (Lavras site). The second area was in an Atlantic Forest biome with an Acrisol with low natural fertility and sandy texture (Itabela site). Marandu grass (<em>Urochloa brizantha</em> cv. Marandu) fertilized or not with N or mixed with forage legumes for a shorter and longer times were evaluated. Soil samples were taken at the start of the study and after 8 and 15–38 years of grazing and analyzed for total C and N, ¹³C abundance and fractionation of soil organic matter. After the first eight years at Lavras, the soil indicated that C and N stocks were starting to increase under this management after a long period of plough tillage for maize production. The longer-term pastures (after 15 and 20 years of establishment) mixed with forage legume or fertilized with N, respectively, showed that C stocks recovered to their original status under the native vegetation at the Lavras site. At Itabela, the soil C and N stocks were similar to the stocks under the native vegetation even after 35 or 38 years of mixed pasture, but the stocks were far lower than at Lavras, which can be attributed to the much coarser soil texture. Pasture systems of similar productivity may promote the accumulation of very different C stocks depending on the land use history prior to their installation and soil clay content.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00876"},"PeriodicalIF":3.1,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil sampling design matters - Enhancing the efficiency of digital soil mapping at the field scale","authors":"Daniel Žížala ,&nbsp;Tomáš Princ ,&nbsp;Jan Skála ,&nbsp;Anna Juřicová ,&nbsp;Vojtěch Lukas ,&nbsp;Roman Bohovic ,&nbsp;Tereza Zádorová ,&nbsp;Robert Minařík","doi":"10.1016/j.geodrs.2024.e00874","DOIUrl":"10.1016/j.geodrs.2024.e00874","url":null,"abstract":"<div><div>Optimisation of sampling design (methods chosen to select the samples) and sample size (number of samples) remains a key challenge in digital soil mapping, especially in the area of precision farming with the expected economic benefits from the introduction of new technologies. As the existing information is available in the form of relevant environmental covariates, its combination with non-parametric machine learning techniques requires careful planning from the initial field sampling to the final production of digital soil maps. The aim of this study is to compare widely used covariate-wise sampling designs combined with variable sample sizes for supervised prediction of common soil drivers of agricultural productivity (pH, soil organic carbon, soil macronutrients) in a real case study of a field (35 ha) with heterogeneous soil properties. From a total of 200 samples, we evaluated different sample sets where 10, 30 and 60 field samples were selected by conditioned Latin Hypercube Sampling (cLHS) and Feature Space Coverage Sampling (FSCS) to calibrate random forest (RF) models. The evaluation was performed on independently in-situ sampled test points. In addition to these datasets, we also compared the investigated methods with Simple Random Sampling (SRS) in a numerical benchmark experiment with increasing sample size, comparing the global accuracies of the predicted maps on the test points, but using interpolated maps as the artificial true population for each soil characteristic. The results of the study in both the field experiment and the numerical experiment showed slightly better results for the FSCS method, especially when the number of samples was small. At smaller training sample sizes, the risk of insufficiently accurate prediction models was slightly lower for FSCS and the difference decreased as the sample size increased. Nevertheless, sample size proved to be the most important factor in the accuracy of RF models, regardless of the sampling technique. The results suggest that a sample size between 18 and 30 training samples (0.6 to 1 sample ha⁻¹) seems plausible for covariate-wise predictions using RF at field scale in our case study. The relative importance of each auxiliary variable for each RF calibration was also assessed for the field experiment. The results showed that the additional introduction of spatial proxies overshadowed the importance of other covariates, but only significantly improved the model calibration at larger sample sizes. The calibrated models without spatial proxies showed the strongest effect of remotely sensed surface characteristics.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00874"},"PeriodicalIF":3.1,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of anthropogenic factors and soil properties on earthworm diversity in southern Mediterranean agroecosystems","authors":"Asma Bengrid ,&nbsp;Hana Bouzahouane ,&nbsp;Fouzia Trea ,&nbsp;Otmani Amira ,&nbsp;Ali Becheker ,&nbsp;Kheireddine Ouali","doi":"10.1016/j.geodrs.2024.e00877","DOIUrl":"10.1016/j.geodrs.2024.e00877","url":null,"abstract":"<div><div>This study examines the biodiversity of earthworms in agroecosystems in the Annaba region of northeastern Algeria, focusing on the impact of agricultural practices and soil environmental conditions on these species. Seven earthworm species from the Lumbricidae and Megascolecidae families have been identified, of which five are new records for this region. Areas with intensive human activity exhibited a decrease in earthworm abundance and diversity, whereas areas with less intensive agricultural practices showed higher levels of earthworm diversity. Variations in soil properties related to land use and plant diversity were notable. Intensive agricultural practices resulted in altered soil characteristics, such as higher pH, electrical conductivity (EC), and salinity, while organic amendments increased organic carbon and nutritional diversity. Essential nutrients, such as calcium and magnesium, are crucial for earthworm vitality, while high levels of pH, salinity, and EC can reduce their populations. Canonical Correspondence Analysis supports these findings. In summary, agricultural practices and soil environmental conditions significantly influence earthworm populations, underscoring the need for sustainable methods to preserve underground biodiversity and ecosystem services.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00877"},"PeriodicalIF":3.1,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New hydro-pedotransfer functions for Austrian soil mapping applications","authors":"Florian Darmann,&nbsp;Irene Schwaighofer,&nbsp;Monika Kumpan,&nbsp;Thomas Weninger,&nbsp;Peter Strauss","doi":"10.1016/j.geodrs.2024.e00875","DOIUrl":"10.1016/j.geodrs.2024.e00875","url":null,"abstract":"<div><div>Knowledge about the hydrological characteristics of soils is essential for modeling soil water dynamics, soil mapping, or civil engineering applications. Directly measuring soil hydraulic properties (SHPs) is time-consuming and expensive. Therefore, they are usually estimated from easily measurable parameters with pedotransfer functions (PTFs). Numerous PTFs have been developed for different scales, from a single watershed to continental applications. Global PTFs cover a broader spectrum of environmental conditions, whereas regional PTFs are designed for specific areas with distinctive soil types and landscapes. Our main hypothesis was that applying machine learning (ML) approaches representing state-of-the-art methodology, combined with a regionally focused database, would result in the most appropriate pedotransfer functions for national soil mapping applications. We developed point PTFs using a database of about 2300 samples from 520 agricultural sites. The data set encompassed a wide range of landscapes and soil types. The PTFs were utilized to predict soil field capacity (Θ₆₀ at pF = 1.8 and Θ₃₃₀ at pF = 2.5), permanent wilting point (Θ₁₅₀₀₀), and saturated hydraulic conductivity (Ks). The random forest (RF) method was employed for model development, while quantile regression was used to assess the prediction quality. The new PTFs obtained an R² between 0.56 for Ks and 0.85 for Θ₁₅₀₀₀ and were compared with established PTFs. Subsequently, we applied the newly generated PTF to official soil data from the Austrian soil survey to predict hydrological soil information for agricultural areas in Austria. The interquartile range between the 10 % - and the 90 % - quantile was visualized to identify regions with different prediction qualities. This will be helpful for future sampling campaigns. High uncertainties were particularly identified for areas where soils dominate that are underrepresented in the data set. This includes soils with a high clay or sand content, typically found at valley bottoms of the alpine foothills or the Bohemian massif in the North of Austria. For areas with a large number of available samples, the prediction showed promising results. Further sampling for future improvements may be planned efficiently based on these results. Moreover, this research sheds light on a path forward, emphasizing assessing soil functionality on a regional scale, providing crucial information for further modeling, and allowing an adjusted and appropriate land management approach.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00875"},"PeriodicalIF":3.1,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142437753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elemental trends and weathering indices to assess volcanic ash deposition on soil weathering status along Maui climosequences","authors":"Ryan C. Hodges ,&nbsp;Janis L. Boettinger ,&nbsp;Jonathan L. Deenik","doi":"10.1016/j.geodrs.2024.e00872","DOIUrl":"10.1016/j.geodrs.2024.e00872","url":null,"abstract":"<div><div>The western slopes of Haleakalā, Maui, are greatly affected by an orographic climate effect, creating a massive precipitation gradient and rain shadow with significant impact on pedogenic weathering and differentiation of soil formed in basalt. However, the presence of volcanic vents along East Maui's northwest rift have created irregularity in the deposition of volcanic ash across the landscape, making it difficult to determine a soil's relative age and degree of ash influence on its development. The objectives of this study were to 1) characterize and classify the basalt substrate of pedons sampled across a wide climatic gradient; 2) determine how elemental composition and soil chemical properties vary with precipitation and elevation; 3) identify pedogenic thresholds of western Haleakalā climosequences; and 4) determine if elemental trends and weathering indices can distinguish pedons and soil horizons that have been influenced by volcanic ash. We sampled 16 soils across elevational and precipitation gradients formed in Kula Volcanics on northwest-facing slopes &lt;5 %. Soils were sampled and described to 1-m depth. Total elemental analysis was determined on rock samples and soil horizons by x-ray fluorescence, and various soil physical and chemical properties were measured in the laboratory. We calculated a total of 22 weathering indices across coastal and elevational climosequences. Soil pedon rock samples were alkalic basalt and predominantly classified as tephrite basanite with four samples classifying as foidite. We identified pedogenic thresholds for SiO₂/TiO₂ at 500 mm and 1300 mm mean annual precipitation (MAP) for the coastal climosequence, showing that although the pedon in Kahului (AIR) had lower MAP than the two pedons in Paia (CEM, PAIA), it is more weathered. Crystalline Fe (CD-AO) was variable in pedons below 1500 mm MAP, increased sharply with increased MAP, then decreased in pedons OL and HAI-E likely due to the reduction and loss of iron. Crystalline Fe (CD-AO) was generally higher at lower elevation pedons likely due to the relatively older age of lowland soils. Values of SiO₂/TiO₂ generally decreased with soil depth, but whole pedon values of SiO₂/TiO₂ were highly variable with increasing precipitation due to the influence of volcanic ash before also dropping substantially in high rainfall pedons. Soil SiO₂/TiO₂ and MnO/TiO₂ normalized to the pedon rock fragments may be viable indicators for distinguishing ash-rejuvenated soil pedons and genetic horizons from those that are not.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00872"},"PeriodicalIF":3.1,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Agricultural terraces in Puebla, Mexico: An ethnopedological approach","authors":"Javier Leonardo Toxqui-Roldán ,&nbsp;Carlos Alberto Ortiz-Solorio ,&nbsp;Ma del Carmen Gutiérrez-Castorena ,&nbsp;Atenógenes Leobardo Licona-Vargas","doi":"10.1016/j.geodrs.2024.e00873","DOIUrl":"10.1016/j.geodrs.2024.e00873","url":null,"abstract":"<div><div>Terrace systems have been instrumental in the evolution of agriculture across various cultural contexts. This technology offers several benefits, including soil and water conservation, improved soil fertility, enhanced agricultural management, and increased crop yields. Several studies have been conducted on agricultural terraces in Mesoamerica. Nevertheless, there has been a lack of research on anthropogenic soils and ethnopedological studies in Mexico. This study aimed to ascertain the local soil knowledge and describe the ancestral terrace systems within a popoloca community in southern Puebla, Mexico. An ethnopedological survey was conducted on a 10,366 ha area to determine the land types and terrace systems present. Surface terraced soil samples were collected, and nine soil profiles within runoff terraces were described. The objectives were as follows: 1) to characterize and describe terrace systems in Santiago Acatepec, 2) to understand the indigenous land classification system and 3) to study the relation and impact of terraces systems on soil formation and WRB classification. The results indicate two types of terraces (hillside and runoff terraces), covering 2578 ha of land. Farmers recognize eight distinct land classes, with unique characteristics and agricultural uses. The land classes encompass both anthropogenic and natural soils. These land classes are classified as Terric Anthrosols, Eutric Regosols, Eutric Leptosols, and Pellic Vertisols. These results show farmers' detailed knowledge about their soils and the advantages and limitations of terraces. The modern and ancient terraces were classified according to seven diverse types of embankments or walls. The traditional embankment, designated as “cuaxustles,” is associated with runoff terraces and is known to have a lifespan exceeding one hundred years. Following the construction of a terrace, the land in question can be cultivated for agricultural purposes after a period of two years. The traditional knowledge of the soil has enabled the farmers of Acatepec to establish new agricultural areas, select crops that are well-suited to the soil conditions and climate of the region, and implement long-term modifications to the landscape. The findings indicate that it is feasible to implement environmental modifications that prioritize soil conservation and enhancement on a significant scale while also considering economic factors and the time frame involved.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00873"},"PeriodicalIF":3.1,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How magnetism-based fractional spinels contribute to the bioavailability of geogenic chromium in serpentine soils of Taiwan","authors":"Chia-Yu Yang ,&nbsp;Wei-Hao Lee ,&nbsp;Shan-Li Wang ,&nbsp;Zeng-Yei Hseu","doi":"10.1016/j.geodrs.2024.e00871","DOIUrl":"10.1016/j.geodrs.2024.e00871","url":null,"abstract":"<div><div>Serpentine soils are highly rich in geogenic chromium (Cr), typically associated with spinel minerals. The high resistance of these minerals to weathering has raised concerns regarding their contribution to Cr bioavailability in serpentine soils. This study collected soil horizon samples from two pedons (Entisol and Ultisol) in eastern Taiwan and applied a two-step magnetic separation method to divide the bulk soils into strongly magnetic (SM), weakly magnetic (WM), and nonmagnetic (NM) fractions. The basic characteristics of the bulk soils were examined. To characterize the mineralogy and geochemistry of the fractions and determine their quantitative contribution of bioavailable Cr in serpentine soils, we analyzed their mineral composition, magnetic properties, and elemental composition and valence by using various spectrometric techniques, such as X-ray diffraction, electron probe microanalysis, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy, as well as vibrating sample magnetometry. The results indicated the main Cr-bearing minerals were magnetite and chromite in the SM and WM fractions, with minor occurrences in layer silicates, such as serpentine and chlorite, in the NM fraction. The total Cr content decreased in the following order: SM &gt; WM &gt; NM. The SM fraction had the lowest weight proportion, and this proportion was lower for the Ultisol than the Entisol. This observation indicated that the weathering of Cr spinels is associated with the substantial cation substitution of Al, Ca, Mn, and Ni for Fe and Cr in broken mineral grains and increases in the Fe(III) and Cr(VI) concentrations in magnetite. The SM fraction, mainly consists of magnetite and chromite, exhibited the highest concentration of bioavailable Cr extracted by 0.1 M HCl. However, the Cr-bearing layer silicates represented the largest potential pool of bioavailable Cr in the bulk soils because the weight proportion of the NM fraction was higher than those of the other fractions and increased during pedogenesis.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00871"},"PeriodicalIF":3.1,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined inorganic and organic fertilizers improved soil microbial biomass and nitrogen dynamics in Upper Eastern region of Kenya","authors":"Erick O. Otieno ,&nbsp;Florence K. Lenga ,&nbsp;David M. Mburu ,&nbsp;Milka N. Kiboi ,&nbsp;Andreas Fliessbach ,&nbsp;Felix K. Ngetich","doi":"10.1016/j.geodrs.2024.e00869","DOIUrl":"10.1016/j.geodrs.2024.e00869","url":null,"abstract":"<div><div>Soil microbial biomass elements and mineralization processes are essential in replenishing soil nutrients. Yet, the effect of fertilization on the microbes is still not well-defined. This study aimed to determine the effect of integrated soil fertility inputs (inorganic and organic) on microbial biomass, carbon (MBC), nitrogen (MBN), phosphorus (MBP), nitrogen (N) mineralization, and N use efficiency in a field experiment. The treatments were: control (no fertility input), sole inorganic fertilizer, and different combinations of inorganic and organic inputs in a randomized block design. The results showed that Conventional tillage + maize residue + goat manure + <em>Dolichos lablab</em> intercrop (CT4); minimum tillage + maize residue + <em>Tithonia diversifolia</em> + goat manure (MT5); and minimum tillage + maize residue + goat manure + <em>Dolichos lablab</em> (MT4) intercrop increased microbial C, N, and P by 78 %, 48 %, and 41 %, respectively compared to control (CT0). Compared to CT0, N mineralization significantly varied (<em>p</em> &lt; 0.0001) among the treatments at planting and on the 15th, 30th, 45th, and 60th days after planting during the 2020 short rains season. It also differed significantly (<em>p</em> = 0.0018, 0.0028, &lt; 0.0001, and 0.0028,) on the 45th, 60th, 75th, 90th, and 105th days, respectively, relative to CT0 after planting during the 2021 long rains season. The CT4 had 5.11 and 52.80 kg N ha⁻¹ higher apparent nitrogen recovery and partial factor productivity N, respectively. Similarly, MT4 greatly enhanced N apparent recovery efficiency by 57.5 % relative to CT0. Integrating fertility inputs improved soil biological fertility and mineralized N. Therefore, technologies that integrate organic inputs, either solely or with inorganic fertilizers, should be harnessed and promoted as medium and long-term technologies to advance soil biological fertility, and mineral N and N use efficiency in smallholder farmers.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"39 ","pages":"Article e00869"},"PeriodicalIF":3.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2352009424001160/pdfft?md5=3341093979cf9741a12d4572af6034ba&pid=1-s2.0-S2352009424001160-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}