Soil Compaction Research Articles

Barriers of adopting sustainable soil management practices for organic and conventional farming systems

There is a general consensus among stakeholders about the benefits of sustainable soil management practices for soil health, yet their implementation lags behind expectations. The aim of this paper is to analyse factors supporting or hindering the implementation of sustainable soil management practices in conventional and organic farming systems. This is achieved using a Logit model, based on penalized maximum likelihood estimation on survey data by 76 farmers from 10 federal states in Germany. Affected factors were categorized in two main groups: agricultural soil management practices, and barriers to their implementation. The measures for soil improving agricultural management included (I) structural landscape elements, (II) organic fertilization, (III) diversified crop rotation, (IV) permanent soil cover (V) conservation tillage, (VI) reduced weight pressure, and (VII) optimized timing of wheeling. Results show differences in preferences between conventional and organic farmers for key sustainable soil management practices, including conservation tillage, optimized wheeling timing, reduced weight pressure, and diversified crop rotation. Economic constraints decrease crop rotation diversification in conventional systems by 14%. Conservation tillage raises the chance of a farm being conventional by 16%, while optimizing wheeling timing reduces it by 60%, highlighting soil compaction concerns among organic farmers. Marginal effects confirm that economic factors, not knowledge, are the main barriers to sustainable soil management. Inconsistent policies, lack of support, and insufficient financial incentives from government institutions can hinder the willingness of farmers to adopt these practices, further exacerbating the barriers to adoption.

Deep learning-based inversion of soil and rock compaction density utilizing Falling Weight Deflectometer (FWD) and Surface Waves

Methods relying on a single dynamic parameter to estimate the material density for the compaction quality testing of earth-rock dams and roadbed projects, present certain limitations in terms of applicability, testing accuracy, and work efficiency. The theory of elastic wave propagation reveals that the compaction density of the medium results from the combined interaction of multiple material properties. This study proposes a method that utilizes the transient surface wave method and a vehicle-mounted Falling Weight Deflectometer (FWD) to jointly enhance the accuracy of soil and rock material compaction detection. The transient surface wave method is employed to extract surface wave velocity and compressional wave velocity. The analysis of the FWD signal involves extracting dynamic parameters closely related to material density, including stiffness coefficients, central frequencies, and stiffness impedances, from time-domain, frequency-domain, and mechanical impedance analyses. A fully connected deep neural network is introduced to intelligently estimate the compaction density. The deep learning model is optimized by selecting the optimal activation function and optimization algorithm, as well as additional tuning. Extensive testing shows that deep learning model produce results closely approximating the true compaction density values. The average relative errors for the wet density and the dry density are 2.9% and 2.85%, respectively, meeting the quality control requirements for density testing. The proposed approach enables rapid detection and control of the compaction quality of soil and rock materials, providing a new method for the in-situ rapid detection of compaction quality.

Sustaining Soil Health in High Tunnels: A Paradigm Shift toward Soil-centered Management

This review was conducted to synthesize current knowledge, learn producer and Extension specialist perspectives, and identify gaps in understanding of the role of soil health in sustaining production in high tunnel (HT) systems. This synthesis includes findings from scholarly resources related to soil health in HTs, including research and Extension-based literature, perspectives from experienced HT producers and technical assistance providers, and the direct observations of a broad network of university research and Extension personnel working with HTs. Findings are intended to identify knowledge gaps and additional research and Extension resource needs of greatest priority to the HT producer community and technical assistance providers that support them at the time of publication. A review of 68 research articles and 58 Extension resources was conducted. Focus group interviews were conducted with small groups of experienced HT farmers in four regions of the eastern half of the United States, with in-depth farm case studies conducted in individual farmers in three of these regions. Growers across regions identified soil fertility management, soilborne diseases, soil compaction, and lack of consistency of soil analyses specific to HTs as the greatest soil-related challenges to HT production. Research and resources for technical assistance providers on mitigation strategies to remediate yield-limiting HT soil conditions, such as excessive soil salinity and high pathogen populations, were also lacking. As such, process-based research on techniques such as leaching, soil steaming, solarization, and anaerobic soil disinfestation in tunnels that consider short- and long-term costs, benefits, and effects on soil and plant productivity should be prioritized in the future when considering the impact of HT production on soil health. Interviews also indicated a need for networking opportunities for technical assistance providers across agencies (e.g., Natural Resources Conservation Service, Extension, nongovernmental organizations). Despite a high and increasing rate of adoption, there is currently a lack of information about maintaining HT systems. Given that HTs play a critical and growing economic role for specialty crop growers throughout the eastern United States, comprehensive intervention across the research–Extension spectrum to sustain productivity in HT systems is recommended.

Resilience underground: Understanding earthworm biomass responses to land use changes in the tropics

Soil biodiversity, like terrestrial biodiversity, is currently under threat by changes in land use. Intensively managed farming activities with agrochemicals have degraded both soil biodiversity and health. However, little is known about how these changes in land use affect the distribution of earthworm biomass in Southeast Asia. We conducted earthworm sampling across multiple habitats, including lowland forests, exotic monoculture plantations (e.g., oil palm and rubber tree), and agroforestry orchards. To survey earthworm populations, we excavated the top 30 cm of soil at 18 sites encompassing 399 plots distributed across natural and human-modified ecosystems in Selangor and Negeri Sembilan, Peninsular Malaysia. We found that earthworm abundance was negatively related to increasing soil compaction, leaf litter weight, soil pH, and undergrowth height, whereas it was positively associated with increasing undergrowth and canopy cover. Our findings demonstrated that agroforestry orchards, rubber tree plantations, and mature oil palm plantations had higher earthworm abundance than those in logged lowland forests. Earthworm abundance in unlogged lowland forests and young oil palm plantations, on the other hand, was lower than in logged lowland forests. Overall earthworm weight was greater in rubber tree plantations, agroforestry orchards, mature oil palm plantations, and unlogged lowland forests than those in logged lowland forests, while young oil palm plantations exhibited lower earthworm weight than logged lowland forests. Our data indicate that increases in soil compaction and leaf litter weight were associated with decreased earthworm weight. These results demonstrate the importance of site-level habitat management for maintaining healthy earthworm populations and soil biodiversity.

Segmental retention models for representing the hydraulic properties of evolving structured soils

AbstractCommon parametrizations of soil hydraulic properties rely on unimodal curves, which cannot accurately represent the properties of many macroporous, aggregated, mixed, or compacted soils. Multimodal hydraulic curves are increasingly used to represent these structured soils in eco‐hydrological models, but the dynamics of the processes that shape soil structure—and the resulting dynamics of soil hydraulic properties—are often neglected. In cases such as compaction recovery, where the structure‐shaping process can be modeled, coupling the evolving pore volumes to soil hydraulic properties in a physically based way remains challenging. Here, we show how modeled or estimated soil structure evolution, when expressed as a time series of porosities in a few pore size classes, can be assimilated into established models of soil hydraulic properties. Our method relies on the division of retention models into smooth segments, whose water contents can be independently adjusted. We apply the approach to examples of modeled soil structure evolution from the published literature: one describing soil structure recovery after compaction and one describing structure formation as a result of organic amendment. In the cases considered, the estimated soil hydraulic conductivity varies more strongly than the modeled porosity which drives it. This shows that transport‐related soil functions can be impacted longer (after compaction) or sooner (after amendment) than suggested by the evolution of structural metrics such as porosity. In general, modeling the evolution of soil hydraulic properties in cases such as these paves the way for holistic, process‐based modeling of land management practices and their impact on soil functioning.

RESULTS OF COMPARISON TESTS FOR CHOOSING THE TYPE OF ROLLER

The article presents the results of the experimental studies on determining the optimal values of the roller of the plowed land and selecting its type on the basis of this. In experimental studies, the provision of complete processing of the field surface is ensured mainly by the selection of the type of roller and the planer for installation on the roller, in order to obtain the required level of moisture for seed germination according to agrotechnical requirements. it is noted that there are gear-plate, rod working parts. In order to verify these obtained results, we made plate, gear-plate, and rod coils, which have a constant diameter, and conducted experimental studies using them. In experimental studies, after using different rollers with a constant diameter, the influence of soil compaction, density and tensile strength was studied. In order to reduce the influence of various variable factors on the obtained results, the experiments were carried out on a specially prepared agro background, that is, it was first plowed and then leveled. In order to test the theoretically based parameters of the roller selected for conducting experimental studies in field conditions, the bases of the roller with a coverage width of 1.5 m and fixed-diameter bases with slats, toothed-slats, and wire plates to be installed on them were developed. released and prepared. Based on the results of experimental studies, the following can be noted: in order to ensure that the compaction quality and density of the soil meet the agrotechnical requirements, and to ensure that the rolling resistance is minimal, it is necessary to have a gear-plate roller.

Stormwater retention performance of tree integrated infiltration trenches designed for suburban streetscapes

The volume of stormwater generated by streetscapes in cities is a primary driver of urban stream degradation. Large infiltration trenches can be integrated into streetscapes to potentially retain large volumes of runoff and increase growth rates of nearby trees. To test this, a field study was conducted where three structural soil infiltration trenches receiving runoff (12 m long, 0.6 m wide and 0.6 deep) were installed alongside a carpark in Melbourne, Australia, with sizing determined by space constraints in a typical streetscape. The three structural soil trenches had raised outflow drainage, which created internal water storage for runoff received from a carpark. To separate the effects on tree growth of i) the presence of structural soil from ii) passive irrigation into the structural soil, three structural soil trenches (6 m long, 0.6 m wide and 0.6 deep) not receiving runoff and without outflow drainage were also installed. Runoff capture, exfiltration, outflow and tree growth was monitored over 19 months. Only one system performed close to the design intent and retained 18 % of runoff, due to slow soil exfiltration rates (<0.1 mm h−1). Compacted soil generated pervious-area runoff that filled the structural soil trenches not receiving impervious-area runoff from the carpark. Tree growth near these structural soil trenches was poor (59 % relative growth) compared with trees receiving runoff from the carpark (112 % relative growth), due to a lack of drainage, emphasising the need for drainage of stormwater systems in heavy textured soils to promote tree growth. This study highlights that options for creating storage for stormwater in streetscapes have the potential to meet local runoff infiltration targets. However, meeting local runoff volume reduction targets will require alternative ways to reduce surface runoff.

Mineralogical Impact on the Compaction of Residual Gabbro Soils in the Construction of Platinum Tailings Storage Facilities

AbstractOver the past decade, there have been 45 tailings storage facility (TSF) disasters worldwide resulting in fatalities, serious environmental damage, and the destruction of entire ecosystems. These failures often stem from substandard design or operational practices. Many TSFs are constructed in regions associated with intrusive mafic rocks such as gabbro, norite, pyroxenite, and anorthosite, which are commonly found alongside platinum group metals in areas like the Bushveld Igneous Complex in South Africa and the Great Dyke in Zimbabwe. The stability of these structures can be significantly influenced by the residual soils present at the construction sites. Residual soils, both cohesive and non-cohesive, contain varying quantities of different minerals, which can impact the compaction characteristics and, consequently, the stability of the TSF foundations. Cohesive soils rich in clay minerals, such as kaolinite and smectite, exhibit properties that can hinder effective soil compaction. The expansive nature of smectite due to its ability to absorb large amounts of water and host free exchangeable cations counteracts the compaction process, reducing soil stability. Soil compaction is a complex process influenced by several factors, including compaction effort, method, water content, particle size distribution, and mineralogy. This study aimed to analyse these factors using a series of laboratory tests, including foundation indicators, MOD AASHTO compaction testing, and X-ray diffraction analysis, on residual soils from two TSF construction sites. The findings revealed that soils with high clay content tend to retain more water and have a higher optimum water content, adversely affecting their compaction properties. This study highlights the critical need to consider the mineralogical composition and weathering effects of residual soils in the design and construction of TSFs. By improving our understanding of these factors, we can enhance the stability of TSF foundations, reducing the likelihood of future failures. The insights gained from this research highlight the importance of thorough geotechnical assessments in the successful design and maintenance of TSFs.

Natural Recovery Dynamics of Alfalfa Field Soils under Different Degrees of Mechanical Compaction

Soil compaction in alfalfa fields has become increasingly severe due to the mechanization of animal husbandry and the increased use of heavy agricultural machinery. Perennial alfalfa land undergoes mechanical compaction several times during the planting period without mechanical tillage. The compacted soil structure may recover through moisture changes, freezing and thawing cycles, and plant growth, but the extent and rate of this recovery remain unknown. In this study, alfalfa plots with two different soil types (medium loam and sandy) in Gansu, China, were selected to address these issues. The areas of the plots were 120 m × 25 m and 80 m × 40 m, respectively. In the third year after sowing, three types of agricultural machinery with grounding pressures of 88 kPa, 69 kPa, and 48 kPa were used to compact the soil one, three, five, and seven times. The interval between replicates was 1 h. Each treatment had one plot of 10 m × 5 m, and the experiment was repeated 4 times, totaling 44 plots. Changes in soil bulk density, soil cone index, and saturated hydraulic conductivity were measured after 1, 4, 8, and 17 weeks, respectively. The results showed that the post-compaction soil bulk density and soil cone index largely influenced the recovery of the compacted soil. Recovery became problematic once the soil bulk density exceeded 1.5 g/cm3. The soil bulk density recovery rate varied across different soil layers, with the top layer recovering faster than more profound layers. The initial state could be restored when the change in post-compaction soil bulk density was minimal. Sandy soil recovered faster than medium-loam soil. The recovery of the soil cone index in each layer of medium-loam soil under lower compaction was more noticeable than that under severe compaction. However, with undergrounding pressures of 88 kPa and 69 kPa, the soil cone index could not fully recover after multiple compactions. The recovery of soil-saturated hydraulic conductivity in both soil types was slower and less pronounced. The recovery of soil-saturated hydraulic conductivity in medium-loam soil was slower than that in sandy loam. After 7 compactions and 17 weeks under a grounding pressure of 88 kPa, the saturated hydraulic conductivity remained below 20% of its initial value of 20 mm/h. In contrast, sandy soils recovered faster, reaching 60 mm/h within a week of each compaction event. This research is crucial for ensuring high and stable alfalfa yields and supporting sustainable agricultural practices.

Impact of Crude Oil Pollution on some Geotechnical Characteristics of North Rumaila Soils in the Southern Iraqi Province of Basrah Governorate

Background: Pollution affects the soil and results in a change in its natural, chemical, or organic characteristics and properties, which directly or indirectly affect the geotechnical properties of the soil and make it unsuitable for engineering use. The aim of the study is to determine how adding various amounts of crude oil to the study area's soil affects the soil's geotechnical characteristics, including soil shear resistance, compaction coefficients, and California bearing capacity. Materials and Methods: The North Rumaila site was chosen for the study. At a depth of one meter, natural, pollution-free soil was extracted, and weight percentages of 2%, 4%, 6%, 8%, and 10% of crude oil were added. Grain size analysis, moisture content, direct shear, compaction, and Californian bearing tests were conducted. Results: The findings indicate that the soil at the North Rumaila site has a moisture content of 6.45% and is mostly silty sand with small amounts of clay and gravel. Crude oil was added to the soil, which caused the Californian to lose some of its bearing capacity, the optimal moisture content to raise, the angle of internal friction to decrease, and the bearing capacity of the soil to decrease. Conclusion: Pollution by crude oil effects negatively impacted the soil's geotechnical qualities.

Composite Sand–Clay Infrastructural Soil Fills: Characteristic Consolidation and Hydraulic Properties

In the design construction of infrastructural projects comprised of geotechnical applications, including composite soil fill layers, compacted sand-clay soil fills are widely preferred as barrier layers, particularly in solid waste landfills, to minimize leakage, to prevent leachate from entering into groundwater. When bentonite clay with high water absorption capacity and low hydraulic conductivity is mixed with sand possessing relatively enhanced frictional properties, greater shear strength capacity, an effective fill material exhibiting low sensitivity to frost, and low volume change in case of wetting, drying can be obtained. On the other hand, when montmorillonite clay is loaded, due to highly critical volumetric contraction or dilation characteristics (high compressibility nature of clay), the soil fill composed of sand-clay will significantly consolidate. This situation may cause differential settlement problems of infrastructural fills employed in geotechnical applications. In this regard, the load conditions (mechanical effects) and the environmental conditions (physicochemical effects) in the field control compressibility characteristics and consolidation properties of sand-bentonite clay mixtures. This will ultimately impact the desired stability conditions of sand-clay soil layers built for constructed infrastructural fill, resulting in a deviation from anticipated performance conditions. To this end, in this study, the specimens of sand-bentonite clay mixtures prepared with different contents of sand-bentonite clay were subjected to one-dimensional consolidation tests to investigate the effect of bentonite content used in the mixture on consolidation behavior, hydraulic properties, and effect of sand amount on rate of consolidation and on resulting compressive strength behavior.

Mechanical mowing of semi‐natural grasslands compromises soil quality and survival of a conservation target plant species

Mowing is a crucial management strategy for conservation and restoration of semi‐natural grasslands. In the past decades, dominant mowing methods have changed from manual to mechanical, using heavy machines causing soil compaction. Whereas the negative effects of compaction are well understood in agriculture and forestry, they have received little attention so far in nature management. This study aims to investigate the effects of compaction on soil quality, arbuscular mycorrhizal fungal communities, and survival of a target plant species. We subjected seven grasslands to three contrasting mowing types: manual mowing with a brush cutter, softtrack mowing—designed to minimize soil compaction—and tractor mowing. We compared compaction, soil properties, and arbuscular mycorrhizal communities among the types. Additionally, we experimentally subjected intact grassland sods containing Devil's bit scabious (Succisa pratensis Moench), a target species of grassland conservation, to compaction levels corresponding to the three mowing types. Subsequently, we assessed plant survival. We found that soil compaction, soil nutrient availability, and toxic soil elements were significantly higher in the softtrack‐ and tractor‐mown parts of grassland sites compared to the manually mown parts. Also, the arbuscular mycorrhizal community composition differed significantly among mowing types, with the largest differences between “manual” and “tractor.” Succisa pratensis survival significantly decreased by 43 and 71% on the short term and by 71 and 86% on the longer term with increasing compaction. Consequently, mowing‐associated soil compaction compromises nature management targets via at least four mechanisms: nutrient enrichment, soil toxicity, changes in arbuscular mycorrhizal communities, and decreased survival of the target plant species.

Regulatory mechanism of soil and water conservation measures on understorey erosion in a subtropical hilly region

Vegetation restoration affects soil erosion by altering near soil-surface characteristics and hydrodynamic mechanisms. However, the regulatory mechanisms of vegetation restoration in reducing soil erosion under forests are not fully clear. Five soil and water conservation measures (SWCM) with different vegetation structures and characteristics were used in the pure forest of Pinus massoniana which included the grass and shrub, grass, grass and shrub + level furrow, grass, shrub and trees and grass + fish-scale pits, to analyze the impact of vegetation restoration on near soil-surface characteristics and soil erosion. The data were analyzed using Structural Equation Modeling (SEM) to find the key indicators affecting soil erosion under forest. The findings revealed that, as opposed to the control plots (CK), there were significant alterations in the near soil-surface attribute following the application of SWCM. These changes were characterized by an increase in soil porosity, soil water content, soil nutrient content, root biomass, litter, and vegetation cover, and a decrease in soil compaction, disintegration coefficient, and bulk density, with the most significant improvement occurring in 0–10 cm soil layer. The SWCM significantly reduced soil erosion, with runoff and soil loss reduction ranging from 60.46 % to 74.09 % and 67.62 % to 79.99 %, respectively. Structural equation models revealed the influence of SWCM on soil erosion. Specifically, soil water content and litter had a favourable influence on reducing soil erosion, root biomass had a direct positive impact on soil erosion, and vegetation cover directly leads to a reduction in soil erosion. Soil physical properties primarily influenced soil erosion through their effect on vegetation cover. Combining bioengineering and vegetation measures is superior at enhancing soil structure, improving nutrient content, and decreasing soil erosion compared to single vegetation measures. It is recommended to combine bioengineering with vegetation strategies to effectively curb understory forest erosion and enhance soil quality in pine forests.

3775-year-old wood burial supports "wood vaulting" as a durable carbon removal method.

Six-times more carbon dioxide (CO2) is removed each year by terrestrial photosynthesis than fossil fuel emissions. However, the carbon is mostly returned to the atmosphere by decomposition. We found a 3775-year-old ancient wood log buried 2 meters belowground that was preserved far beyond its expected lifetime. The wood had near-perfect preservation, with carbon loss less than 5% compared to a modern sample. The lack of decay is likely due to the low permeability of the compact clay soil at the burial site. Our observation suggests a hybrid nature-engineering approach for carbon removal by burying woody biomass in similar anoxic environments. We estimate a global sequestration potential of up to 10 gigatonnes CO2 per year with existing technology at a low cost of $30 to $100 per tonne after optimization.

Soil compaction in a crop-livestock system with maize (Zea mays L.) cultivation in the northeastern region of Brazil

Soil compaction in a crop-livestock system with maize (Zea mays L.) cultivation in the northeastern region of Brazil

Estimating the compacted dry density of gravelly soil with oversized particles

The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio P of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, X, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as P increases from zero up to approximately 0.75. The slope of the X-P relation, (X − 1.0) / P, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by X obtained from the substitution of P into the relevant X-P relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.

Computing the pressure of agricultural tractors on soil and mapping its compaction

Manufacturers of agricultural machines, when designing, pay a little attention to its impact on soil, thus producing models with high compression loads on the soil or with a small contact area between the tyres/tracks and the soil surface. Therefore, the aim of this study is to evaluate the negative impact of both wheeled and tracked agricultural tractors on the soil, in terms of soil compaction, and its causes (i. e. design features of tractor tyres/tracks), during the last six decades (i. e. from 1961 to 2021). Soil compaction is caused by the pressure applied by agricultural machines on the soil through the contact area of their tyres/tracks with the soil surface. So, the main indicator of the negative impact on the soil by the tractors manufactured during the last 60 years, i. e. the average pressure applied by the tyres or tracks of tractors manufactured in EU and in the post-Soviet cuntries from 1961 to 2021 to the soil, was computed. A general decrease of the average pressure of the tyres/tracks on the soil can be observed in 1980s and 1990s, followed by its general increase since 2000, above all for the tractors having power higher than 140 kW. Thus, there is an urgent need to assess spatial and temporal changes in soil vulnerability to compaction, that depends on weather conditions and soil properties, as well as agricultural management practices, and can only be fully assessed by means of a combination of traditional techniques (i. e. use of soil cone penetrometer followed by 2D mapping using GIS or 3D mapping through geostatistics) and mechanical approaches (i. e. computation of agricultural machine parameters – soil contact area). The results show that tractor manufacturers did not take care of reducing soil compaction during the considered period.

A review on tillage system and no-till agriculture and its impact on soil health

Soil tillage is a fundamental agriculture practice aimed at preparing the soil for planting, managing crop residues, controlling weeds, preparing the ground for the next crop, integrating leftover crops and nutrients into the soil, and enhancing soil structure. However, tillage practice significantly influences activities like soil moisture, temperature, aeration, and mixing the crop residues within the soil. This article explores the impacts of traditional tillage methods and alternative approaches to reduce production costs, environmental consequences, and safeguard soil for sustainable crop production through the secondary source of results as published research papers, documents, government official and institution reports. Traditional tillage method involves the mechanical disruption of soil, which affects critical factors such as moisture retention, temperature regulation, and aeration. While use of such heavy machines can improve short-term productivity, its long-term impacts include soil compaction, erosion, and loss of organic matter, leading to environmental degradation and declining soil health. In contrast, No-till and reduced tillage practices offers a promising solution to contemporary challenges such as global climate change, water conservation, rapid soil degradation, and desertification. Under this system, wide range of crops can be grown effectively in low production cost by reducing fuel and labor requirements. No-tillage and minimal tillage is being adopted across a wide range of farm sizes, from small plots of land to vast expanses, in various countries around the world with promising sustainability.

Change in Land Use Affects Soil Organic Carbon Dynamics and Distribution in Tropical Systems

Anthropogenic land cover change is directly responsible for the deforestation and degradation of tropical forests. In this context, assessing soil organic carbon (SOC) stocks is key to understanding the impact of anthropogenic activities on SOC so that we can implement management practices that effectively reduce emissions or promote carbon sequestration. Our objective was to assess the effect of land-use change on the dynamics and distribution of SOC in three systems (agriculture, pasture and agroforestry) after 40 years of deforestation in a tropical dry forest in the central–eastern region of Honduras. For this purpose, the bulk density, percentage of coarse fragments (&gt;2 mm) and soil organic carbon content were determined at three depths (0.00–0.10 m, 0.10–0.20 m and 0.20–0.30 m). The results showed an increase in bulk density for all new uses, although soil compaction had not yet occurred. In terms of total soil organic carbon (TOC) stocks, deforestation caused a decrease from 17% to 48% in agricultural and agroforestry soils, respectively; on the other hand, grasslands did not show significant differences compared to tropical dry forest, suggesting that they have a high potential as carbon sinks in deforested tropical areas. However, this did not imply a better state of the system, as the greatest increases in bulk density were found in pastures.

Spatio-Temporal Dynamics of Soil Penetration Resistance Depending on Different Conservation Tillage Systems

As conservation tillage becomes one of the foundations of sustainable crop production, important questions arise about its value, which needs to be defined and evaluated. One of the most important indicators of soil compaction is penetration resistance (PR), which comes as a short-term response to the state of soil physics. The objective of this work is to compare different tillage treatments (TT) on soil compaction on silty clay loam Stagnosol and silt Gleysol in the continental part of Croatia. The research included three tillage treatments: ST—conventional tillage, CTD—deep conservation tillage, and CTS—shallow conservation tillage. PR was determined on each soil depth of 5 cm up to 80 cm, and measuring was provided on two measuring dates. The obtained results showed a higher influence of the year factor than TT. In the upper layers (up to 35 cm), PR values between TT were with significant differences, but in most cases below root-limiting critical values, while in deeper soil layers (35–80 cm), we found that penetration values on each tillage treatment begin to stabilize and smooth out in most cases, with similar dynamics on both soil types and measurement dates. In most of the cases, the highest PR was measured for conservation treatments in wetter soil conditions.