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We carried out mesocosm experiments using either the anecic earthworm Lumbricus terrestris or the endogeic earthworm Allolobophora chlorotica and loam, silt loam and sandy loam soils to investigate the differing impact of these earthworm of different ecotypes on aggregate formation (percentage water stable aggregates, %WSA) and soil water holding capacity (WHC), two soil properties that underpin many of the ecosystem services provided by soils. Earthworms significantly increased %WSA (by 16–56% and 19–63% relative to earthworm-free controls for L. terrestris and A. chlorotica, respectively). For L. terrestris, this increase was significantly greater in the upper 6.5 cm of the soil where their casts were more obviously present. Allobophora chlorotica treatments significantly increased WHC by 7–16%. L. terrestris only caused a significant increase in WHC (of 11%) in the upper 6.5 cm of the sandy loam soil. Linear regression indicated a consistent relationship between increases in %WSA and WHC for both earthworm species. However, for a given %WSA, WHC was higher for A. chlorotica than L. terrestris likely due to the known differences in their burrow structure. Overall, earthworms increased soil %WSA and WHC but the significant species/ecotype differences need to be considered in discussions of the beneficial impacts of earthworms to soil properties.

Incorporation of crop residues into the soil has been widely recommended as an effective method to sustain soil fertility and improve soil carbon sequestration in arable lands. However, it may lead to an increase in the emission of nitrous oxide (N 2 O) and leaching of nitrate (NO 3 − ) to groundwater due to higher nitrogen (N) availability after crop residue incorporation. Here, we conducted a meta-analysis based on 345 observations from 90 peer-reviewed studies to evaluate the effects of crop residue return on soil N 2 O emissions and NO 3 − leaching for different locations, climatic and soil conditions, and agricultural management strategies. On average, crop residue incorporation significantly stimulated N 2 O emissions by 29.7%, but decreased NO 3 − leaching by 14.4%. The increase in N 2 O emissions was negatively and significantly correlated with mean annual temperature and mean annual precipitation, and with the most significant changes occurring in the temperate climate zone. Crop residues stimulated N 2 O emission mainly in soils with pH ranging between 5.5 and 6.5, or above 7.5 in soils with low clay content. In addition, crop residue application decreased NO 3 − leaching significantly in soils with sandy loam, silty clay loam, and silt loam textures. Our analysis reveals that an appropriate crop residue management adapted to the site-specific soil and environmental conditions is critical for increasing soil organic carbon stocks and decreasing nitrogen losses. The most important novel finding is that residue return, despite stimulation of N 2 O emissions, is particularly effective in reducing NO 3 − leaching in soils with loamy texture, which are generally among the most productive arable soils.

Agriculture faces several challenges to use the available resources in a more environmentally sustainable manner. One of the most significant is to develop sustainable water management. The modern Internet of Things (IoT) techniques with real-time data collection and visualisation can play an important role in monitoring the readily available moisture in the soil. An automated Arduino-based low-cost capacitive soil moisture sensor has been calibrated and developed for data acquisition. A sensor- and soil-specific calibration was performed for the soil moisture sensors (SKU:SEN0193 - DFROBOT, Shanghai, China). A Repeatability and Reproducibility study was conducted by range of mean methods on clay loam, sandy loam and silt loam soil textures. The calibration process was based on the data provided by the capacitive sensors and the continuously and parallelly measured soil moisture content by the thermogravimetric method. It can be stated that the response of the sensors to changes in soil moisture differs from each other, which was also greatly influenced by different soil textures. Therefore, the calibration according to soil texture was required to ensure adequate measurement accuracy. After the calibration, it was found that a polynomial calibration function (R ≥ 0.89) was the most appropriate way for modelling the behaviour of the sensors at different soil textures.

It is not clear how the number of 15 N-injection needles affects the estimated results of gross N transformation rates in the presence of plants. To evaluate this, a 15 N tracing study of sandy loam soil and a silty loam soil in the presence of maize (Zea mays L., cv. “Zhengdan 958”) was conducted and the Ntraceplant tool was used to quantify gross N transformation rates. Our results showed that the number of 15 N-injection needles could significantly influence the estimated results of gross N transformation rates in the studied soil–plant systems. There was no discernible difference in the gross rates of N mineralization (Min), the oxidation of NH4+ to NO3− (ONH4), the oxidation of recalcitrant organic-N to NO3− (ONrec), the NH4+ and NO3− plant uptake between 4-needle and 6-needle injections for both studied soils. However, for the 1-needle and 2-needle injections in the silty loam soil, Min was significantly lower than the 4-needle and 6-needle injections. While, in sandy loam soil, Min measured with 1-needle injection was significantly higher than the 4-needle and 6-needle injections. The ONH4 and ONrec also varied for the 1-needle and 2-needle injections, compared to the 4-needle and 6-needle injections. The total plant N uptake rate declined with the increase in the number of injection needles. Based on these results and considering the simplicity of the experimental procedure, we suggest that the 4-needle injection could be used in the 15 N tracing studies conducted in pot (diameter = 6.4 cm in this study) experiments with plants, i.e., one needle for about 8 cm2.

To control outdoor exposure to natural radiation, assessment of activity concentrations of the radionuclides in soils is substantial. In this paper, the activity concentration of natural radionuclides (226Ra, 232Th, 40K) was estimated for 174 agriculture soil samples using a sodium iodide detector (NaI) of (3” × 3”). Soil samples were collected from seven regions (56 locations) in EL-Minya governorate, Upper Egypt. The variability of natural activity concentration with soil’s textures was checked. The texture types of soil samples were silt clay loam, clay loam, sandy clay loam, and sandy silt loam. The obtained results indicate that the mean values of specific activity ranged from 11.3 ± 0.5 (sandy silt loam) to 21 ± 1(silt clay loam), 6.8 ± 0.3 (sandy silt loam) to 13.7 ± 0.7 (sandy clay loam), and 112 ± 5 (sandy silt loam) to 272 ± 13.6 (sandy clay loam) Bq kg−1 for 226Ra, 232Th, and 40 K, respectively. The obtained results were compared with the global average and tolerable limits as recommended in UNSCEAR 2008. On the other side, the radiological hazard resulting from the total natural radioactivity in the studied soil samples was estimated by different approaches. The obtained values were within the recommended safety limit and do not pose significant radiation hazards.

Flooding and salinization triggered by storm surges threaten the survival of coastal forests. After a storm surge event, soil salinity can increase by evapotranspiration or decrease by rainfall dilution. Here we used a 1D hydrological model to study the combined effect of evapotranspiration and rainfall on coastal vegetated areas. Our results shed light on tree root uptake and salinity infiltration feedback as a function of soil characteristics. As evaporation increases from 0 to 2.5 mm/day, soil salinity reaches 80 ppt in both sandy and clay loam soils in the first 5 cm of soil depth. Transpiration instead involves the root zone located in the first 40 cm of depth, affecting salinization in a complex way. In sandy loam soils, storm surge events homogeneously salinize the root zone, while in clay loam soils salinization is stratified, partially affecting tree roots. Soil salinity stratification combined with low permeability maintain root uptakes in clay loam soils 4/5‐time higher with respect to sandy loam ones. When cumulative rainfall is larger than potential evapotranspiration ETp (ETp/Rainfall ratios lower than 1), dilution promotes fast recovery to pre‐storm soil salinity conditions, especially in sandy loam soils. Field data collected after two storm surge events support the results obtained. Electrical conductivity (a proxy for salinity) increases when the ratio ETp/Rainfall is around 1.76, while recovery occurs when the ratio is around 0.92. In future climate change scenarios with higher temperatures and storm‐surge frequency, coastal vegetation will be compromised, because of soil salinity values much higher than tolerable thresholds. Key Points Evapotranspiration and rainfall affect post‐storm surge soil salinity in the root zone of coastal forests In clay loam soils, post‐storm surge salinity stratification is beneficial for root uptake Time to recover to pre‐storm soil salinity values depends on evapotranspiration and rainfall ratios and soil properties

Background and aim Plant exudates greatly affect the physical behaviour of soil, but measurements of the impact of exudates on compression characteristics are missing. Our aim is to provide these data and explore how plant exudates may enhance the restructuring of compacted soils following cycles of wetting and drying. Methods Two soils were amended with Chia (Salvia hispanica) seed exudate at 5 concentrations, compacted in cores to 200 kPa stress (equivalent to tractor stress), equilibrated to −50 kPa matric potential, and then compacted to 600 kPa (equivalent to axial root stress) followed by 3 cycles of wetting and drying and recompression to 600 kPa at −50 kPa matric potential. Penetration resistance (PR), compression index (CC) and pore characteristics were measured at various steps. Results PR decreased and CC increased with increasing exudate concentration. At 600 kPa compression, 1.85 mg exudate g−1 soil increased CC from 0.37 to 0.43 for sandy loam soil and from 0.50 to 0.54 for clay loam soil. After 3 wetting-drying cycles the clay loam was more resillient than the sandy loam soil, with resilience increasing with greater exudate concentration. Root growth modelled on PR data suggested plant exudates significantly eased root elongation in soil. Conclusion Plant exudates improve compression characteristics of soils, easing penetration and enhancing recovery of root induced soil compaction.

Abstract Manure is a key source of N for crops, especially in organic farming systems, but also a driver of N2O emissions from soil. Treatment technologies removing manure organic matter affect soil N2O emissions, but the direction and magnitude of these effects remain uncertain. We explored the effects of four fertilizer materials derived from cattle manure on soil N2O emissions. Treatments included: untreated cattle manure (CA), cattle manure co-digested with grass-clover silage (DD); a liquid fraction (LF) produced by mechanical separation of digestate; and a concentrated fertilizer with NH4+-N and sulfate (NS) produced from stripped H2S and NH3. These fertilizers were surface-applied to a sandy loam (Foulum) and a clay loam soil (Askov) at 55% water-filled pore space (WFPS) in 28-day laboratory experiments with monitoring of CO2 and N2O. Samples were sectioned during or after incubation to describe mineral N and microbial dynamics. Although the WFPS in both soils was 58–61%, N2O emissions varied greatly, and this was explained by differences in water potential, and in the relative gas diffusivity which was approx. 0.011 and 0.030 in Foulum and Askov soil, respectively. Unexpectedly, treatment LF with the lowest manure organic matter input had the highest N2O emissions. Denitrification was the main pathway producing N2O as determined by 15N enrichment of soil NO3−. The vertical distribution of mineral N and microbial activities, and PLFA, indicated that N2O emissions from the organic fertilizers depended on their interaction with the soil, as modified by soil water potential and gas diffusivity at the time of application.

Aims Recent laboratory studies revealed that root hairs may alter soil physical behaviour, influencing soil porosity and water retention on the small scale. However, the results are not consistent, and it is not known if structural changes at the small-scale have impacts at larger scales. Therefore, we evaluated the potential effects of root hairs on soil hydro-mechanical properties in the field using rhizosphere-scale physical measurements. Methods Changes in soil water retention properties as well as mechanical and hydraulic characteristics were monitored in both silt loam and sandy loam soils. Measurements were taken from plant establishment to harvesting in field trials, comparing three barley genotypes representing distinct phenotypic categories in relation to root hair length. Soil hardness and elasticity were measured using a 3-mm-diameter spherical indenter, while water sorptivity and repellency were measured using a miniaturized infiltrometer with a 0.4-mm tip radius. Results Over the growing season, plants induced changes in the soil water retention properties, with the plant available water increasing by 21%. Both soil hardness ( P  = 0.031) and elasticity ( P  = 0.048) decreased significantly in the presence of root hairs in silt loam soil, by 50% and 36%, respectively. Root hairs also led to significantly smaller water repellency ( P  = 0.007) in sandy loam soil vegetated with the hairy genotype (-49%) compared to the hairless mutant. Conclusions Breeding of cash crops for improved soil conditions could be achieved by selecting root phenotypes that ameliorate soil physical properties and therefore contribute to increased soil health.

Purpose Research on the impact of microplastics (MPs) on plant performance has primarily focused on MP type or concentration, often neglecting the role of soil texture. Methods In this study, a 42-day experiment was conducted in which winter wheat was grown in three soils of different textures, contaminated with two types of MPs: low-density polyethylene particles (LDPE) and polyester fibers (PES) at 0.4% concentration. The effects on soil water content, nutrient levels, and plant growth were examined. Results In silty loam, LDPE reduced root length and biomass, likely due to altered soil texture, which created more macropores and reduced water and nutrient availability. PES fibers had similar effects, indicating that changes in soil porosity impacted root access to resources. In sandy loam, both MP types reduced root growth, with PES fibers causing a significant 85% reduction in root length and decreasing nitrogen content, suggesting impaired nutrient availability due to reduced nitrification. Conversely, in silty clay loam, LDPE increased root length by 4.6 times, likely due to enhanced water movement pathways, although it also increased water loss. PES fibers showed minimal positive effects on root growth but reduced nutrient content. Conclusion Overall, soil texture had a significant impact on how MP affected plant growth, as the two types of MP had different effects on different soil textures. LDPE increased macroporosity in fine soils, promoting root growth, but reduced nutrient uptake in coarse soils. PES fibers influenced soil structure, affecting water retention and nutrient availability differently in different soil types. The study highlights the complexity of MP–soil–plant interactions. Moreover, it also calls attention to rethinking soil management in the future, such as using biodegradable alternatives, applying biochar or avoiding plastic-coated controlled-release fertilizers.