Soil Research最新文献

The optimum gypsum form and rate required to ameliorate soil sodicity constraints caused by supplementary irrigation with water containing sodium bicarbonate in humid regions are unknown.

Evaluate the short-term effect of different gypsum forms and rates on (i) soil physicochemical properties and (ii) grain yield in a barley (Hordeum vulgare L.)/maize (Zea mays L.) sequence.

We conducted two field experiments in the southeastern Argentinean Pampas on soils with low electrical conductivity (0.2 dS m⁻¹), assessing three forms of gypsum (granulated, pelletised, and powdered) applied a month before barley sowing at 2000 kg ha⁻¹. In one experiment, 3000 kg ha⁻¹ was also tested. Soil properties and grain yield were determined at barley and maize harvests (i.e. 7 and 13 months after the gypsum application, respectively).

(i) Gypsum did not significantly affect soil physical properties; (ii) powdered gypsum at 3000 kg ha⁻¹ enhanced soil chemical properties at barley harvest, decreasing pH by 7% and exchangeable sodium percentage by 35%, while increasing the exchangeable Ca²⁺/Na⁺ ratio by 70% (0.0–0.1 m depth); (iii) powdered gypsum improved soil chemical conditions at deeper soil depths (0.1–0.2 m) at maize harvest; (iv) barley grain yield increased with gypsum application; and (v) maize yield was negatively correlated with soil pH and positively correlated with the Ca²⁺/Na⁺ ratio.

Powdered gypsum can rapidly improve soil chemical properties and increase crop yields.

Powdered gypsum, especially at 3000 kg ha⁻¹, could be used to alleviate soil sodicity issues in the short-term.

The conservation of soil and water has become an important foundational project of worldwide social and economic development in the 21st century, especially for the protection and development of critical ecological function areas in Western China.

To clarify the current status of soil erosion and its drivers in the alpine temperate forest-grass subregion of Qilian Mountains in Qingdong (ATFSQMQ).

Based on GIS technology, the Universal Soil Loss Model (RUSLE) and Geographical detector were used to simulate the extent of soil erosion and assess the drivers of soil erosion in the ATFSQMQ from 2001 to 2020, and the Patch-generating Land Use Simulation (PLUS) model and Coupled Model Intercomparison Project Phase 6 (CMIP6) model were used to predict the future soil erosion in the study area.

(1) The soil erosion modulus of the ATFSQMQ decreased going from northwest to southeast, and soil erosion increased during the 2001–2020 period, and the average soil erosion modulus increasingly fluctuated. (2) Micro-erosion is the main form of soil erosion; from 2001 to 2020, regions with micro-erosion and mild erosion decreased, while those with moderate, strong, solid, and severe erosion increased slightly. (3) Vegetation cover is the dominant factor affecting soil erosion, and the synergistic effect of vegetation cover and precipitation has the highest explanatory power.

The soil erosion modulus fluctuated and increased from 2001 to 2020, but will gradually improve in the future.

The analyses in this paper can shed light on the current state of soil erosion and the drivers behind it, enabling the government to target soil erosion area management.

Deep-banded nutrient rich amendments can overcome crop productivity constraints of Australian dense clay subsoils. However, knowledge on essential microbial community in field trials is limited.

We examined subsoils that had been deep-ripped 2 years earlier with various types of amendments (organic, a blend of organic and inorganic, and purely inorganic). Subsoil samples (15–25 cm) were collected encompassing the amendment band (0 cm), as well as at increasing distances from it (14 and 28 cm). Bacterial 16S rRNA, fungal ITS amplicon sequencing, and SOM/TOC measurements on amendment band samples were done to assess microbial communities.

While no variations were detected in bacterial communities across treatments, soils enriched with organic substrates diverged significantly in fungal diversity compared to the control, concentrated primarily within the amendment bands. Fungal response to these organic amendments was primarily dominated by an enrichment of filamentous saprotrophic fungi.

Changes in fungal diversity and the enrichment of saprotrophic fungi is primarily attributed to the introduction of organic substrates into the subsoil. However, despite the absence of SOM/TOC differences between treatments, SOM/TOC levels were initially expected to rise in response to organic amendments. Consequently, variations in fungal communities may have initially arisen from heightened SOM/TOC levels but persisted even as these levels returned to baseline, suggesting a lasting legacy effect.

A single application of deep-banded organic amendments was effective in enriching agriculturally significant fungi within dense clay subsoils after 2 years. This can further aid crop productivity by fostering soil structural improvements and optimising nutrient cycling, even after the organic amendments are undetectable.

Plant roots can increase soil shear strength and reinforce soil. However, wetting and drying alternation (WD) could lead to soil structure destruction, soil erosion and slope instability.

This study tried to explore the effects of wetting and drying alternation on shear mechanical properties of loess reinforced with root system.

Direct shear testing was conducted on alfalfa (Medicago sativa L.) root system-loess composites with three soil bulk densities (1.2 g·cm⁻³, 1.3 g·cm⁻³ and 1.4 g·cm⁻³) under 0, 1, 2 and 3 cycles of wetting and drying alternation (WD0, WD1, WD2 and WD3).

The morphological integrity of the root-loess composites was obviously better than the non-rooted loess after WD. Under the three soil bulk densities, negative power-law relationships were observed between the shear strength, cohesion and internal friction angle and the cycles of WD. WD deteriorated the soil shear strength. The most obvious decrease in soil shear strength occurred under WD1, which was 13.00–22.86% for the non-rooted loess and 17.33–25.09% for the root-loess composites. The cohesion was decreased more than the internal friction angle by WD.

The most obvious damage to the soil was under WD1. The roots inhibited the deterioration effect of WD on the shear property of loess, and the inhibition by the roots decreased with the cycles of WD.

The results could provide new insights into the mechanical relationship between plant roots and loess under WD, and provide a scientific basis for the ecological construction in the loess areas.

Analysing freeze-thaw erosion is of great significance to ecological environment protection and land resource utilisation in high altitude areas.

We used seven indicators (temperature, precipitation, vegetation cover, elevation, slope, slope orientation, and sand content) to calculate the freeze-thaw erosion intensity index for different seasons from 2000 to 2019.

We used a graded weighted evaluation model and a geographical detector method to analyse spatiotemporal pattern and driving factors of freeze-thaw erosion intensity in Qiangtang grasslands.

(1) From 2000 to 2019, the total area of freeze-thaw erosion was higher in the non-growing season than in the growing season. The area of moderate and above-average freeze-thaw erosion increased over time in the non-growing season but decreased in the growing season. The spatial distribution of freeze-thaw erosion was mainly determined by the annual range of precipitation and temperature, which reflect the intensity and frequency of freezing and thawing cycles. (2) Vegetation cover was an indirect factor that influenced the soil moisture and stability. The slope was another important factor that affected the spatial distribution of freeze-thaw erosion in different regions.

The results show that in 2000–2019 the area of freeze-thaw erosion showed a downward trend. The erosion degree in the non-growing season is on the rise.

Our study provides new insights into the dynamics and mechanisms of freeze-thaw erosion in Qiangtang grasslands and contributes to the understanding and management of water and climate change impacts on this region.

The ability of soils to contribute to greenhouse gas mitigation requires the stock of carbon to be increased in the long term. Studies have demonstrated the potential of soils to increase in carbon at global to regional scales, with soil mineral surface area a key factor to this potential. However, there is limited knowledge on the distribution of mineral surface area and whether the distribution of soil carbon sequestration potential varies at the farm scale.

The aim of this study was to evaluate the spatial variability in mineral surface area and sequestration potential of SOC at a farm scale.

We used a case study farm to apply existing published methodology and assess the spatial distribution of the mineral surface area, the maximum amount of stable carbon that a soil could hold, and the subsequent potential for soil carbon sequestration at the farm scale. A total of 200 samples were collected across the farm using a balance accepted sampling design prior to analysis for total carbon, mineral surface area, and sequestration potential.

Despite being in a localised area, the farm demonstrated that the distributions of mineral surface area and total carbon were related to variation in the underlying soil type. When data were examined spatially, there were areas within the farm that had greater potential to stabilise more carbon and also regions where there were greater carbon stocks.

The spatial distribution of SOC, mineral surface area, and potential to increase MAOC was well represented by the spatial distribution of soil type within a farm. This case study demonstrated areas within the farm that had potential to increase the MAOC fraction.

This case study offers an approach that would give farmers and land managers knowledge to improve the understanding of the carbon dynamics across their farm and to identify areas that have greater potential to contribute to greenhouse gas mitigation and the areas that would be more susceptible to soil carbon loss. Using this approach could allow targeted management practices to be applied to specific regions on-farm to either increase soil carbon or protect existing stocks.

The research explores the benefits of real time tracking of soil moisture for various land management contexts and the importance of spatio-temporal modelling and mapping to gain clear and visual understanding of soil moisture fluxes across a farm.

This research aims to outline the key processes required for building an operational on-farm soil moisture monitoring system where the product is highly granular daily soil moisture maps depicting variations temporally, spatially and vertically.

We describe processes of capacitance soil moisture probe installation, data collection infrastructure, sensor calibration, spatio-temporal modelling, and mapping.

An out-of-bag soil moisture evaluation modelling system was tested for nearly 2 years. We found a model accuracy (RMSE) estimate of 0.002 cm⁻³ cm⁻³ and concordance of 0.96 were found. This result is averaged over this period but fluctuated daily, and related to rainfall patterns across the target farm, which were not directly incorporated into the modelling framework. As expected, incorporating prior estimates of soil moisture into the modelling framework contributed to very accurate estimates of real time available soil moisture.

This research promotes the importance of iterative improvements to the soil moisture monitoring system, particularly in areas of sensor recalibration and spatio-temporal modelling. We stress the need for a longer-term view and plan for ongoing maintenance and improvement of such systems in the emerging digital farming ecosystem.

The results of this research will be useful for researchers and practitioners involved in the design and implementation of on-farm soil monitoring systems.

Cultivating forage crops is crucial to improve feed production, and grazing is an important utilisation method to improve soil fertility.

Improving soil organic carbon (SOC) content and reducing carbon dioxide (CO₂) emission through grazing management from a spring wheat field.

We compared sheep rotational grazing and control, and studied their effects on SOC and CO₂ emission from a spring wheat field.

Sheep rotational grazing improved SOC content (by 23.5%) and soil easily oxidised organic carbon (EOC) content (by 7.7%) and reduces soil microbial biomass carbon (MBC) content (by 35.8%) compared with the control. Sheep rotational grazing reduced CO₂ emission compared with the control. Sheep grazing reduced cumulative CO₂ emission by 28.9% and 33.0% in May and June compared with the control.

Sheep grazing improved SOC content and reduce CO₂ emission from a spring wheat field.

Based on our short-term study, sheep rotational grazing has a significant effect on SOC, EOC and MBC contents and CO₂ emission from spring wheat fields in arid regions. For a large-scale assessment of sheep grazing on soil fertility and CO₂ emission, more investigation for different soils and climates is necessary. Furthermore, a long-term study is also necessary to better understand the effect of sheep rotational grazing on soil fertility and CO₂ emission from spring wheat fields in arid regions.

There is limited information on how catena features can be used to refine fertiliser recommendations in the undulating landscapes of the east African highlands.

(1) Determine the effects of landscape positions and soil types on crop-nutrient responses, and rainwater productivity (RWP); and (2) identify wheat yield-limiting nutrients across landscape positions.

Two sets of on-farm nutrient management experiments with wheat were conducted on foot slope, mid-slope, and hillslope positions over 71 sites in 2016 and 2019. The first experiment were on Vertisols, Nitisols, Regosols, and Cambisols with different levels of N/P₂O₅, K₂O, and SO₄. The second experiment were on Vertisols, Nitisols, and Cambisols with different levels of N/P₂O₅ and Zn.

NP increased yield across landscape positions. NP × K and NP × S interactions increased total biomass by 5–76%. Zinc × soil type interaction increased total biomass on Vertisols (6%) and Cambisols (9%), but increasing Zn did not improve yield on Nitisols. Zinc × landscape position interaction increased total biomass at foot slope (2%) and mid-slope (13%) positions. Zinc × NP interaction increased biomass yield on Cambisols, Nitisols, and Vertisols. N₁₃₈P₆₉ significantly increased RWP at foot slope, mid-slope, and hillslope positions. Soil nutrient and water contents decreased with increasing slope regardless of nutrient source and application rate.

Landscape position may be an indicator for targeting site-specific fertiliser recommendations. Farms on hillslopes could be better ameliorated by applying organic amendments with sustainable land management practices.

Taking into account landscape position can help better manage fertiliser use on undulating land in the east African highlands.

Soil organic matter (SOM) is largely composed of carbon (C) and nitrogen (N), the proportions of which often change with soil depth. The relationships between SOM, C, and N in forest soils can be greatly altered in degraded landscapes and understanding these relationships is integral for successful forest restoration planning.

The current study investigated SOM, C, and N relationships in highly degraded forest soils by depth following regreening (one-time application of soil amendments and afforestation). Additionally, the use of standard C:OM ratios (which are commonly used to estimate soil C) were assessed.

The SOM, C, and N were measured at five different depths, at nine sites, ranging in time since regreening treatment applications across one of the world’s largest regreening programmes in the City of Greater Sudbury, Canada.

The C:OM and C:N ratios decreased with soil depth while N:OM increased. The C and N were significantly correlated with SOM at all depths (excluding the L horizon). The C:OM ratio was lower than standard values and did not change between 16 and 41 years since the application of 10 Mg ha⁻¹ of dolomitic limestone.

Despite massive soil degradation, SOM, C, and N relationships over soil depth at the regreening sites are consistent with unimpacted forest soils. Applying commonly used C:OM ratios drastically overestimated soil C pools, especially at lower depths.

Even in the most degraded landscapes, restoration can improve soil properties. Standard C:OM ratios should be used with caution.