Similar Soil Research Articles

Grassland extensification enhances nest densities of ground‐nesting wild bees

Abstract Ground‐nesting wild bees provide essential pollination services in agroecosystems, but they are jeopardized by intensive agricultural management. To mitigate such negative impacts, agri‐environment schemes have been implemented. While the success of enhancing floral food resources is relatively well studied, the role of agri‐environmental schemes in providing suitable nesting habitat remains underexplored. We studied the effectiveness of meadow extensification according to the Swiss agri‐environment scheme in promoting nesting of ground‐nesting bees. Using a paired design, we quantified their nests during four rounds (March–June) in pairs of nine randomly selected extensively (i.e. no fertilizer input, postponed first mowing) and nine intensively managed meadows with similar soil properties, slope, exposure and landscape context. Nest numbers and vegetation characteristics were surveyed in areas of 250 m2. Vegetation properties were also assessed in 0.5 × 0.5 m plots around nest locations and randomly selected locations without nests within each meadow to assess their role as drivers of nesting incidence (nest presence/absence) at this plot scale. We found substantially higher nest numbers of ground‐nesting bees in extensively (mean ± SE per sampling round = 46.8 ± 14.2) compared to intensively managed meadows (0.8 ± 0.3; no nests in three of nine intensively managed meadows). Extensively managed meadows harboured nests of several dominant crop pollinator species, including aggregations of, for example, Lasioglossum malachurum contributing to high nest densities in some of them. Number of nests was negatively related to grass cover and vegetation height, which were lower in extensively compared to intensively managed meadows. Plot‐level nesting incidence increased with bare ground and moss cover, and decreased with grass cover. Synthesis and applications. Our study shows that extensively managed meadows are better nesting habitats for ground‐nesting bees than intensively managed meadows, if reduced management intensity is associated with altered vegetation characteristics such as reduced grass cover and vegetation height, and small‐scale availability of bare ground, driving these effects. This highlights that maintaining and promoting extensive management of meadows can promote ground‐nesting wild bees, including dominant crop pollinators, not only by enhancing floral resources but also by improving nesting opportunities in agroecosystems.

Numerical Study on Optimization of Piled Raft Foundation on Stratified Soil under Static Load

Piled raft foundation (PRF) is a combination of pile and raft that provides adequate bearing capacity under the allowable settlement. This research aims to optimize the PRF design for a 48-story Commercial Bank headquarters building in Addis Ababa, Ethiopia, by conducting parametric study on various pile configuration using FLAC3D (Fast Lagrangian Analysis of Continua in three Dimensions) software. We analyzed 28 piled raft configurations and found that increasing the distance between piles increases the raft load sharing distribution by 11.5% while reducing settlement. Despite variations in pile length and diameter, a close load sharing between the pile and raft is accomplished at a separation of seven times the pile diameter (7D). The largest settlement decrease achieved was 9% for a 2-m pile diameter by doubling the pile length from 10 to 20 m, indicating that increasing pile length is ineffective for settlement reduction. We also proposed two new pile configurations that share load equally among pile and raft, and slightly increase total settlement below 10-cm limit. The results show that the first configuration exceeds differential settlement limit, but the second configuration reduces it by 95% and saves 40% of piles. This study provides a useful reference for designing PRF for high-rise buildings in similar soil conditions.

Soil toposequences, soil erosion, and ancient Maya land use adaptations to pedodiversity in the tropical karstic landscapes of southern Mexico

The soil mantle of the tropical karst landscapes of southern Mexico was a key resource for ancient Maya agriculture and experienced deep transformation due to long-term human impacts under changing environmental conditions. We conducted a comparative analysis of three compound soil toposequences in mountainous (Sierra de Chiapas/Middle Usumacinta Valley, Busiljá, and Chinikihá archaeological sites) and platform (NE Yucatán Peninsula, Yalahau region) karst landscapes to reconstruct general tendencies and regional variations in pedodiversity development and soil–human interactions since the Early Preclassic Period. Toposequence characterization is based on macro- and micromorphological observations, accompanied by a suite of laboratory data. Calcareous upland geoforms of all toposequences have similar soil combinations consisting of shallow Rendzina and deep red clayey Terra Rossa types of profiles. We argue that Rendzinas, now dominant in the upland soil cover, in most cases, are not a product of incipient pedogenesis on limestone; they have developed from the residues of Terra Rossa soils after their advanced erosion. Pedosediments generated by ancient soil erosion have been found in the piedmont and depression positions in the mountainous landscapes of Chiapas, as a result of lateral downslope soil removal, and in the subsurface karstic cavities in the platform of NE Yucatán, indicating vertical “soil piping.” The soils of the lowland domains show contrasting differences between the toposequences: gleyic clay–rich soils and humic alluvial soils prevail in Chinikihá and Busiljá, whereas hydromorphic carbonate soils have formed in Yalahau karstic depressions. These differences in the lowland soil properties led to divergent ancient Maya land use strategies; in Chinikihá and Busiljá, the major agricultural domain was developed in the lowlands, implying largescale artificial drainage. On the contrary, in Yalahau, mostly upland Rendzinas were cultivated, implying “precision agriculture” and “container gardening.”

Spatial Variability of Soil Macronutrients and Chemical Properties in Ujjain Tehsil of Ujjain District of Madhya Pradesh, India

Understanding the characteristics of soil and how it may be utilised sustainably makes soil property mapping a crucial process. To improve crop yield and preserve healthy soil, it is essential to understand the heterogeneity of the soil in each location in order to establish site-specific nutrient management strategies for that area. The current research was carried out in the Ujjain tehsil (Ujjain) district of Madhya Pradesh state, India, with the aim of measuring the spatial variability of several soil macronutrients and soil chemical characteristics. Throughout the research region, 150 geo-coded surface soil samples with a depth of 0 to 15 cm were collected. The soil characteristics, namely pH, electrical conductivity (EC), soil organic carbon (SOC), available nitrogen (Av-N), available phosphorous (Av-P), available potassium (Av-K), and available sulphur (Av-S), were assessed in these samples using standard methods. The research region's ranges for soil pH, EC, SOC, Av-N, Av-P, and Av-K were 7.01 to 8.15, 0.10 to 0.79 dSm-1, 0.30-0.60%, 139.00 – 235.00 kg ha-1, 8.00 – 25.60 kg ha-1, and 301.00 – 463.00 kg ha-1, in that order. The data were analysed using classic statistics and geo--statistics by constructing semi-variograms and mapping by ordinary kriging techniques. Semi-variograms were calculated for soil characteristics and their spatial distributions were mapped. Best-fit models for measured soil properties were Exponential, Circular, Gaussian and Hole effect with Nugget/Sill (Co/Co+C) ratio for modelled variables indicated strong and moderate spatial dependences. The distribution maps of soil attributes could be utilized as a guide for site-specific crop management in similar soils. Further, this study demonstrates the usefulness of GIS- application in soil variability studies.

Comparative study of efficiencies of purification of cadmium contaminated irrigation water by different purification systems

Cadmium (Cd) contamination in rice threats food safety and human health. Control of Cd pollution has become an urgent need. Most existing studies on heavy metal pollution control have focused on industrial wastewater and few on irrigation water. Some researchers have found ecological ditches, plant ponds and constructed wetlands have the potential of treating heavy metal contaminated irrigation water, but they examined only one of the methods and the validity needs to be verified by field studies. Our study has filled the gap by combining the methods and using field experiments. We examined efficiencies of removal of Cadmium from irrigation water by 14 different combinations of ecological ditches, plant ponds, and constructed wetlands using field experiments. The effects of the purification on Cd concentration in paddy soil and rice grains were also examined. Results showed that there were significant differences among efficiencies of purification of Cd contaminated irrigation water using different systems and that pH, chemical form of Cd in irrigation water, vegetation coverage and biomass of aquatic plants significantly affect the efficiency. Of the 14 purification systems, seven resulted in the concentration of Cd in the effluent water meeting the National Standard for Irrigation Water Quality (GB5084–2021) for all days of the experiment period. The highest amount and rate of Cd removal were achieved by the combination of two-stage ecological ditch, two-stage plant pond, and one-stage constructed wetland, while the highest removal amount and rate per 100 m2 was achieved by the combination of one-stage plant pond and one-stage constructed wetland. Considering purification efficiency, area of coverage, and cost of construction and maintenance, we suggest that combination of plant pond and constructed wetland be a priority choice for purification of Cd pollution in irrigation water. Compared to the control data collected from rice grain and paddy soil irrigated by unpurified water, Cd concentration in rice grain and paddy soil irrigated by purified water declined by 5.08–19.42 % and 30.93–77.15 % respectively. All results showed that removal of Cd contamination from irrigation water effectively controlled cadmium pollution in rice grain and paddy soil. Our study not only contributes to pollution control practice, but also warrants further investigation of the mechanisms of how the treatment systems work. The most efficient method we identified could be applied locally, regionally and in areas of similar topography, climate, soil, vegetation, agriculture, and heavy metal pollution.

A maximum entropy approach to defining geographic bounds on growth and yield model usage

Growth and yield models are essential tools in modern forestry, especially for intensively managed loblolly pine plantations in the southeastern United States. While model developers often have a good idea of where these models should be used with respect to geographic location, determining geographic bounds for model usage can be daunting. Such bounds provide suitable areas where model predictions are likely to behave as expected or identify areas where models may do a poor job of characterizing the growth of a resource. In this research, we adapted a niche model methodology, commonly used to identify suitable spots for species occurrence (maximum entropy), to identify areas for using growth and yield models built from plots established in the Lower Coastal Plain and Piedmont/Upper Coastal Plain in the southeastern United States. The results from this analysis identify areas with similar climatic envelopes and soil properties to the areas where data was collected to fit these growth and yield models. These areas show notable overlap with the areas prescribed for use by the evaluated growth and yield models and support practitioners use of these models throughout these regions. Furthermore, this methodology can be applied to different forest models built using large regional extents as long as climatic and soil values are available for each site.

Effects of ploughing depth variations on maize (Zea mays) growth: a study at Nyankpala in the Northern Region of Ghana

This study evaluated the effect of different ploughing depths on maize (Zea mays) growth at Nyankpala in the Northern Region of Ghana. Plant height, leaf count, and stem girth were measured at no-plough (NT), 10-20 cm (PD20), and 20-30 cm (PD30) depths. Soil bulk density and texture were also determined for NT, PD20, and PD30. Plant data were evaluated using one-way analysis of variance in GENSTAT statistical program, and the means were separated with the least significant difference (LSD) at p<0.05. The results revealed significant differences between the various depths of ploughing, with the best maize growth characteristics recorded under PD30, followed by PD20 and finally, NT. The PD30 had nitrogen, phosphorus and potassium (NPK) contents of 0.24 %, 6.08 mg/kg, and 58 mg/kg, respectively, followed by NT with NPK contents of 0.13 %, 5.23 mg/kg, and 46 mg/kg, respectively. The bulk density of the soil decreased with increasing ploughing depth. From the results, the study recommends a plough depth of about 20-30 cm for maize production in the study area and other regions with similar physical soil properties and agronomic practices.

Soil pH Variability in Mangu, Bokkos and Pankshin Local Government Areas of Plateau State

This paper investigates soil pH variability in three local government areas (LGAs) in Plateau State, Nigeria: Bokkos, Mangu, and Pankshin. Soil pH is a crucial factor influencing soil biogeochemical properties, which in turn affect crop yield, soil nutrient levels, and microbial activity. The study utilized Stratified Random Sampling to collect soil samples, and employed IDW (Inverse Distance Weighted) interpolation for analysis. The results revealed a pH range of 4.5 to 7.07, categorized into five classes: very strongly acidic (4.5 - 5.05), strongly acidic (5.05 - 5.35), moderately acidic (5.35 - 5.58), slightly acidic (5.58 - 5.83), and neutral (5.83 - 7.07). Slightly acidic and moderately acidic soils were predominant across the entire study area, covering 1643.96 Km² and 1444.41 Km² respectively. Noteworthy variations in pH were observed between the LGAs, with Bokkos and Mangu exhibiting more acidic soils, while Pankshin had soils tending towards neutrality. These variations were attributed to the local topography and geology. The pH variations also play a significant role in determining suitable crops for cultivation. Bokkos and Mangu are conducive for extensive farming of maize and Irish potatoes, while Pankshin is better suited for millet and sorghum cultivation. Given the global implications of events like the Russia-Ukrainian war on food supply, the study recommends that relevant government agencies identify areas with similar soil characteristics and invest in extensive cultivation of crops well-suited to those soils. This could contribute significantly to enhancing food security on a global scale]

Comparative characteristics of the meadow soils of the Crimean mountain plateaus

The results of studies of mountain-meadow soils of the Crimean Mountain plateaus (yailas) within the range of heights from 580 to 1,493 m a.s.l. are presented. The aim of the research is a comparative analysis of the full-profile soils of the mountain meadows distributed on the western and eastern parts of the Main Ridge of the Crimean Mountains and their correspondence to similar soils of nearby mountain ranges. According to the results obtained, the soils of the western yailas are classified as Phaeozems and Umbrisols, while the eastern ones are mostly classified as Chernic Phaeozems. Chernic Phaeozems differ from Phaeozems and Umbrisols by higher values of the humification rate and the optical density of humic acids. In the humus horizons of Phaeozems and Umbrisols, the average values of the of humification rate varied from 21 to 31 percent, and Chernic Phaeozems from 27 to 34 percent. The optical density varied from 12.7 to 18.7 in Phaeozems and Umbrisols, and from 22.2 to 24.2 in Chernic Phaeozems. The climatic feature of the western yailas is the predominance of winter precipitation, or their relatively uniform distribution between warm and cold seasons, while at the eastern yailas the precipitation of the warm season prevails which may be responsible for the revealed differences in soil properties.

Biocrusts Indicators of Livestock Grazing Effects on Soil Stability in Sagebrush Steppe: A Case Study from a Long-Term Experiment in the Northern Great Basin

Biocrusts are sensitive to changes in livestock grazing intensity in arid rangelands and may be useful indicators of ecosystem functions, particularly soil properties like soil stability, which may suggest the potential for soil erosion. We compared biocrust community composition and surface soil stability in a big sagebrush (Artemisia tridentata) steppe rangeland in the northwestern Great Basin in several paired sites, with or without long-term cattle grazing exclusion, and similar soils (mostly sandy loams), climate, and vegetation composition. We found that livestock grazing was associated with both lower surface soil stability and cover of several biocrust morphogroups, especially lichens, compared with sites with long-term livestock exclusion. Surface soil stability did not modify the effects of grazing on most biocrust components via interactive effects. Livestock grazing effects on total biocrust cover were partially mediated by changes in surface soil stability. Though lichens were more sensitive to grazing disturbance, our results suggest that moss (mostly Tortula ruralis in this site) might be a more readily observable indicator of grazing-related soil stability change in this area due to their relatively higher abundance compared with lichens (moss: mean, 8.5% cover, maximum, 96.1%, lichens: mean, 1.0% cover, maximum, 14.1%). These results highlight the potential for biocrust components as sensitive indicators of change in soil-related ecosystem functions in sagebrush steppe rangelands. However, further research is needed to identify relevant indicator groups across the wide range of biocrust community composition associated with site environmental characteristics, variable grazing systems, other rangeland health metrics, and other disturbance types such as wildfire.

Diffuse Reflectance Spectroscopy for Mapping Soil Carbon Stock in the Gilbués Desertification Region at Brazilian Cerrado

The carbon stock (C Stock) is a key soil attribute, especially in areas under degradation. The objective of this study was to map the C Stock and other physical and chemical attributes on the soil surface of a micro-watershed located in the Gilbués Desertification Nucleus and to calibrate pedometric functions to map them, applying spectra obtained by Diffuse Reflectance Spectroscopy (DRS) in the near-infrared (NIR) region. This study was developed in the Piripiri Stream Micro-watershed (PSMW), which presents different levels of degradation. A total of 214 composite soil samples were collected from the 0–0.10 m depth layer. Spectral and laboratory analyses were performed following traditional methods. The results from 100 samples were subjected to descriptive analysis, pedometric modeling, and geostatistics, while the remainder were used exclusively for the prediction and modeling of the predicted attribute maps. C Stock ranged from 0.3 to 11%, with the highest values associated with the least sandy sites. We assert that stakeholders, including government agencies, could utilize DRS for mapping main soil attributes, such as C Stocks, soil granulometry, or total organic carbon, in regions characterized by similar parent material and soil properties. This application can support informed decision-making regarding land management in extensive areas facing soil threats.

Sustainable use of End-of-Life-Tires (ELTs) in a vibration isolation system

Huge stockpiles of End-of-Life Tires (ELTs) are of major global concern. This paper investigates and helps to demonstrate the beneficial utilization of ELTs to provide geotechnical seismic isolation (GSI) of machine foundations located on a rubber-soil mixture (RSM). A series of laboratory tests is conducted to extend the understanding of RSM behavior beyond that previously elaborated, particularly by demonstrating the efficiency of the GSI-RSM system and by defining its optimal parametric values. The results indicate that increasing the thickness of the RSM layer and soil cap, along with the addition of rubber content, up to the optimum values lead to enhanced performance. Beyond these optimum values, the benefits start to decrease. For the determined optimum rubber content (8%), RSM layer thickness (0.1B), and soil cap thickness (0.15B) at a vibration moment level of 0.17 N.m, the GSI-RSM system achieves maximum reductions of 36%, 43%, and 77% in resonant frequency, resonant displacement, and resonant acceleration, respectively, compared to untreated beds. Moreover, the GSI-RSM system effectively reduces the developed peak particle velocity (PPV) and kinetic energy, independent of the excitation frequency. The increased damping and significant energy dissipation demonstrates the system’s effectiveness in mitigating vibrations. This environmentally-friendly technique presents a low-cost alternative for improving the vibration behavior of soil beds. It provides the basis for the wider adoption of ELTs for GSI, for machine foundations and for other infrastructure projects with similar soil vibration concerns, including building foundations, transportation infrastructure and industrial facilities. In this way the research contributes to the growing body of sustainable practices in the construction industry.

Root rot of spring wheat in field crop rotations in the forest-steppe of the Irkutsk region

The paper presents the results of the studies to assess the prevalence of root rots and yields of spring wheat in the forest-steppe zone of the Irkutsk region in field crop rotations on different back-grounds of fertilization and tillage practices. The experiment scheme: forecrops – fallow in crop rotation (fallow – wheat – oats), pea-oat mixture and corn in crop rotation (pea-oat mixture – wheat – corn – wheat); tillage methods – plowing with PLN-5-35 plow to a depth of 20-22 cm, BDT-3 disking to a depth of 12-14 cm; fertilization - no fertilizer, complete mineral fertilizer N45P45K45. The prevalence of root rot decreased on average for 3 years in the crop rotation with 33 % saturation of wheat and its sowing on a fallow forecrop in comparison with 50 % saturation in pea-oats by 6.1 %, in corn by 0.9 %; disc tillage compared to plowing in fallow forecrop by 11.8 %, in pea oats by 4.7 %, in corn by 9.2 %; on fertilized background in three-field crop rotation in fallow by 4 %, in pea oats by 1.9 %, in corn by 4.8 %. Statistically reliable highest yield of spring wheat was observed in three-field crop rotation with 33 % saturation of wheat on fallow at soil plowing, which is higher than similar soil treatment in crop rotation with 50 % saturation of wheat at sowing on pea and oat mixture by 31.3 %, on corn by 23.8 %. Application of mineral fertilizers N45P45K45 increased the yield, while tillage with discing and the forecrops such as pea and oat mixture and corn decreased the yield. Over the rotation, root rot incidence decreased from baseline with a concomitant increase in yield – with 33 % wheat saturated in the rotations by 9.0 % and 35.0 %, and with 50 % wheat saturated in the rotations by 6.6 % and 45.7 %.

Persistence of pathogens and bacterial community dynamics in tropical soil after application of raw sewage

The objective of this work was to evaluate the persistence of faecal indicators and pathogenic organisms (Salmonella spp., Escherichia coli and viable helminth eggs) and the structure/diversity of bacterial communities in soil receiving raw sewage (RS) for an extended period of application (3 uninterrupted years). In the experimental design, three treatments were defined: (1) Control soil, characterized by the analysis of a composite sample collected in an area of similar soil, but not a recipient of RS (TSC); (2) Soil receiving conventional mineral fertilization, and furrow irrigation with supply water (TW); and (3) Fertirrigated soil with RS applied by furrows (TF). The results of persistence of pathogenic organisms and indicators in TF indicated a sanitary quality similar to the control soil (TSC), thus potentially bringing low risks of contamination with pathogens present in the soil. The presence of viable helminth eggs was not identified in any treatment studied, because of its low concentration in the raw sewage of the studied system. The TW, TF and TSC treatments had 34.8% of bacterial diversity in common. The bacterial composition of the soil showed a predominance of the Proteobacteria phylum in all treatments studied; however, TF was the one with the highest relative abundance of this phylum (44.8%).

Simulation of the Impact of Rangeland Management Strategies on Soil Health, Environmental Footprint, Economic Impact, and Human-Edible Nutrient Conversion from Grasslands in the Central and Northern Great Plains of the United States

The objective of this study was to determine the impact of combinations of management practices on the sustainability of rangelands in different ecoregions across the Great Plains. Six study sites were selected in Kansas, Nebraska, Wyoming, Montana, and South Dakota, encompassing the Flint Hills, High Plains, and Sandhills ecoregions. Twelve rangeland management scenarios were developed from combinations of stocking density (light, moderate, heavy), grazing management (continuous, rotational), and fire regime (no burn, spring burn) along with a no-management scenario. Each scenario was simulated at each site using established computer models: Agricultural Policy/Environmental eXtender model, Integrated Farm System Model, and Impact Analysis for Planning. Additionally, human-edible nutrient conversion was computed. A sustainability index was developed to encompass the three sustainability pillars (i.e., environmental, economic, and social) into a single value. Unmanaged rangelands generally had less soil (20%), nitrogen (30%), and phosphorus (50%) losses, although this was not consistent across ecoregions, and similar or greater soil carbon deposition than grazed rangelands. There was an interaction among stocking density, grazing management, fire regime, and ecoregion for many indicators of soil health, greenhouse gas emissions, economic activity, and human-edible nutrient conversion. The scenarios with the greatest overall sustainability index value had moderate to high index values for each of the three pillars (people, planet, profit). In conclusion, the ranking of rangeland management practices based on sustainability indicators was inconsistent across ecoregions, indicating that the optimal management system to improve sustainability of rangelands is not the same for all ecoregions.

A pedo‐climatic approach towards soil health assessment: Soil texture‐specific scoring curves on arable land in Norway

AbstractSoil health assessments that integrate physical, chemical and biological indicators help the evaluation of soil functioning, provide a framework for monitoring soil degradation, guide land management activities and secure the delivery of soil ecosystem services. In this study, we assessed soil health by soil texture class on arable land in Southeast Norway and mid‐Norway and between grassland and arable land in mid‐Norway. We used descriptive statistics and the Welch t‐test with unequal variance and Bonferroni corrections to compare a physical soil indicator (bulk density) and chemical indicators (organic matter, P‐AL, K‐AL, Ca‐AL, Mg‐AL, Na‐AL and pH). We developed scoring curves from cumulative normal distribution functions on regional soil data for various soil indicators where climate, soil texture class and land use were considered. Our results show that for certain soil texture classes, average soil indicator values differed between pedo‐climatic zones on arable land, but for others the difference was not significant. The variability between the pedo‐climatic zones for these can be neglected, but for the ones that differ, the variability is important to consider when assessing soil health. Similarly, this was the case when comparing land use (grassland and arable land) for most soil indicators in mid‐Norway. This finding illustrates the importance of addressing unique local conditions in soil health assessments. We propose aggregating similar soil texture classes where no differences are apparent when developing scoring curves. The sub‐optimal levels of plant available nutrients (P‐AL and K‐AL) found in the soil in both pedo‐climatic zones highlights the importance of suitable threshold values for targeted soil ecosystem services to ensure soil health and sustainable agricultural production. We also recommend prioritizing the most relevant soil ecosystem services to limit the number of soil indicators that need monitoring.

Canopy structure and understorey light availability in Nothofagus and podocarp-broadleaf stands in a New Zealand forest

ABSTRACT The ability of some ectomycorrhizal fungi to access organic sources of nitrogen is known to influence decomposition, nitrogen mineralisation and soil carbon storage. The consequences for aboveground ecosystem structure and processes are less well-documented. We used the LAI-2200C Plant Canopy Analyzer to compare leaf area index and understorey light availability of ectomycorrhizal Nothofagus stands and arbuscular mycorrhizal podocarp-broadleaf stands growing on similar soils at a dry forest site in the Wairarapa district of New Zealand’s North Island. N. solandri was the sole overstorey tree in the three Nothofagus stands, and the ericaceous shrub Leucopogon fasciculatus was prominent in the understorey. The three podocarp-broadleaf stands were more diverse and more varied, the major contributors to basal area being Elaeocarpus dentatus, Hedycarya arborea, Cyathea dealbata, Carpodetus serratus and Dacrydium cupressinum. Leaf area index of Nothofagus stands averaged one unit lower (4.04) than that of neighbouring podocarp-broadleaf stands (5.11). Average light availability under Nothofagus stands (3.6–4.9%) was twice that beneath podocarp-broadleaf stands (1.6–2.1%). The lower leaf area index, greater light transmittance, and monodominance of Nothofagus stands probably reflects suppression of arbuscular mycorrhizal species by ectomycorrhizal short-circuiting of the nitrogen cycle. This study expands the evidence of positive feedback mechanisms stabilising ectomycorrhizal dominance in some forests.

Use of Genus Cistus in Phytotechnologies: Application in a Closed Mercury Mine

The Almadén mining district is known to be one of the richest mercury areas in the world. Despite the high concentrations of this metal, this territory has well-established vegetation that provides a wide range of mercury-tolerant plants that can be used as ecosystem services. This is the case of some species of Cistus that grow wild and spontaneously as part of the natural flora of Almadén. The objective of this study was to evaluate if there were differences between the absorption and distribution of Hg of five species of the genus Cistus in spontaneous growth and to evaluate their potential application in phytotechnologies. The work has been carried out with plant samples collected under field conditions in the “Fuente del Jardinillo” located in the old mining area of Almadén (Ciudad Real). The experimental plot was divided into three previously characterised subplots to ensure that all the sampled plants had grown in similar soil conditions (pH, organic matter content, EC, CEC, total Hg and available Hg). Additionally, the experiment was carried out in triplicate. The results showed that despite the homogeneity of the soil, the absorption of Hg in the aerial part of the plants showed significant differences related to Cistus species. The values in the bioaccumulation of mercury in the aerial part were also different. Based on the uptake of mercury by the plants sampled in this study, its potential use in phytotechnologies was established, classifying them as phytoextractors (Cistus albidus, C. ladanifer and C. monspeliensis) and phytostabilisers (C. crispus and C. salviifolius).

Organic farming systems affect carbon stocks but not soil structure and associated physical properties in a long-term farming trial on Chernozem

An asset of organic farming systems with diversified crop rotations, next to a cut in pesticide and mineral fertilizer application, is the built-up of organic carbon stocks in the long-term. In addition, the inclusion of deep-rooting legumes like alfalfa is known to improve soil structure and increase particulate organic matter contents in the subsoil. These views have been challenged recently ascribing limited potential for legume-based crop rotations to increase carbon stocks in Chernozems (Mollisols) due to limited accrual of mineral-associated organic carbon. Likewise, the direct impact of these legumes on soil structure and associated soil properties like water retention and transport has been questioned and linked to indirect effects instead.The objective of this study was to investigate the impact of legume-based crop rotations on carbon stocks and soil structure properties in the Flurweg II long-term farming systems trial (26 years) established on a Chernozem soil in Germany. We compared one conventional (INT) and two organic farming systems, with (O + M) and without (O - M) integrated livestock management. The three farming systems differ in biomass return via plant residues or farmyard manure as well as share and type of legumes in the eight-year crop rotation (INT: pea, O - M: faba bean and pea, O + M: biannual alfalfa). The comparison included yields, carbon stocks, soil physical properties and microstructure properties based on X-ray computed tomography of soil within and beneath the plow horizon. All farming systems underwent conventional plowing. In addition, we compared carbon stocks and microstructure properties with those from the nearby Westerfeld tillage trial with conventional and reduced tillage in a legume-free crop rotation.The carbon stocks in the plowed topsoil of the Flurweg II systems trial increased significantly with organic farming including livestock (INT: 53 ± 2 vs. O + M: 61 ± 2 t ha−1), but not without (O - M: 53 ± 4 t ha−1), likely because of farmyard manure application in the O + M system. This increase in topsoil carbon stocks is only moderate compared to the increase in topsoil carbon stocks in the Westerfeld tillage trial by switching from conventional to reduced tillage (53 vs. 70 t ha−1). The carbon stocks of the whole soil profile (down to 48 cm) in the Flurweg II systems trial tended to increase with organic farming irrespective of livestock integration (INT: 72 ± 5 t ha−1 vs. O ± M: 82–83 ± 7 t ha−1). Particulate organic matter (POM) contents and biopore diameter below the plow layer tended to increase with alfalfa in the crop rotation of the O + M farming system. However, the legacy effect four years after the presence or absence of alfalfa was only in the range of natural, spatial variability. As a result of similar soil microstructure there was also hardly any difference in hydraulic conductivity and no difference in soil mechanical properties between farming systems.This study shows that Chernozems in this region still have the capacity to increase POM contents and carbon stocks with climate-smart, regenerative agricultural management, but also demonstrate that this has limited effects on structural properties.

Modelling of the effects of working width, tillage depth and operational speed on draft and power requirements of disc plough in sandy-clay soil in South-East Nigeria

Discrepancies amongst ecological soil situations necessitate records of the performance of machines under diverse soil categories for choice of tools to lessen cost, minimize energy loss, and increase agricultural production. This research sought to investigate to what extent the working width, operational speed and cutting depth influence the draft force and power requirements of disc plough in sandy-clay soil in South-East Nigeria, and to obtain model equations that could predict the draft and power necessities of the implement, which would be a guide to selecting apposite ploughing implements based on soil type/conditions in South-East Nigeria and other areas globally with similar soil type/condition.. Results specified that the highest draft force of 3.051 kN/m was obtained when the plough was operated at working width of 60 cm, depth of 20 cm and speed of 7 km/hr. While the highest drawbar power of 5.42 kW was achieved when the plough was engaged at full width of 180 cm, tillage depth of 15 cm and speed of 6 km/hr. Statistical analyses showed that tillage depth and operational speed has significant effect (p˂ 0.05) on the draft force and drawbar power of the disc plough as compared to the working width. Quadratic model was statistically significant for the responses (P ˂ 0.05). Results pointed out that the coefficient of determination; R2 was 0.9993 for draft force and 0.9759 for drawbar power, which indicated high correlations amidst the factors. The Predicted R² of 0.9888 for draft force was reliable with the Adjusted R² of 0.9984. While the Predicted R² of 0.6140 for drawbar power was reliable with the Adjusted R² of 0.9449. The adequacy Precision (100.383 for draft force and 19.912 for the drawbar power) obtained indicated decorous indicator and that the models could navigate the design space. The optimum draft force and drawbar power of 1.95 kN/m and 4.95 kW were respectively achieved with the desirability of 1.000 at optimal working width of 119.06 cm, ploughing depth of 13.71 cm and operational speed of 7.74kmh−1. Farmers can hereafter, appraise and select the disc plough with the models.