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Plant roots release various organic materials that may modify soil structure and affect heat and mass transfer processes. The objective of this study was to determine the effects of a synthetic root exudate (SRE) on penetrometer resistance (PR), thermal conductivity (λ), hydraulic conductivity (k) and evaporation of water in a sandy soil. Soil samples, mixed with either distilled water or the SRE, were packed into columns at a designated bulk density and water content, and incubated for 7 days at 18°C. Soil PR, λ, k and evaporation rate were monitored during drying processes. Compared with those incubated with water, samples incubated with SRE had visible hyphae, greater PR (0.7–5.5 MPa in the water content range of 0.11 to 0.22 m3 m−3) and λ (0.2–0.7 W m−1 K−1 from 0.05 to 0.22 m3 m−3), and increased k in the wet region but decreased k in the dry region. SRE treatment also reduced the overall soil water evaporation rate and cumulative water loss. Analysis of X‐ray computed tomography (CT) scanning showed that the SRE‐treated samples had a greater proportion of small pores (<60 μm). These changes were attributed mainly to SRE‐stimulated microbial activities. Highlights: The effects of incubating a sandy soil with a synthetic root exudate (SRE) on soil physical properties and evaporation are examined.SRE incubation increased the fraction of small pores.SRE incubation increased soil penetrometer resistance and thermal conductivity.Soil hydraulic conductivity was increased in the wet region but was reduced in the dry region.SRE incubation reduced the overall evaporation rate and cumulative water loss. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults that originates from glial cells. The prognosis of patients with high-grade glioma is poor. It is therefore crucial to develop effective therapeutic strategies. Long non-coding RNAs (lncRNAs) have been reported as potential inducers or suppressors of tumor progression. Previous studies have indicated that the lncRNA Feline Leukemia Virus Subgroup C Cellular Receptor 1 Antisense RNA 1 (FLVCR1-AS1) is involved in the development and progression of gastric and lung cancer, as well as hepatocellular carcinoma and cholangiocarcinoma; however, the biological effect of FLVCR1-AS1 in glioma is not completely understood. The aim of the present study was to investigate how FLVCR1-AS1 modulates cell proliferation and invasion in glioma. FLVCR1-AS1 expression was significantly upregulated in GBM tissues compared with adjacent normal brain samples, and was higher in GBM cell lines compared with normal human astrocyte cells. Furthermore, the microRNA (miR)-30b-3p was revealed to be a putative target of FLVCR1-AS1, and the suppressive effects of miR-30b-3p on cellular proliferation and invasion were reversed following FLVCR1-AS1-knockdown. The results from Cell Counting Kit-8 and Transwell assays confirmed that FLVCR1-AS1-knockdown inhibited GBM cell proliferation and invasion ability. In addition, FLVCR1-AS1 was found to directly interact with miR-30b-3p, and a rescue experiment further established that FLVCR1-AS1 contributed to glioma progression by inhibiting miR-30b-3p. The results from the present study demonstrated that FLVCR1-AS1 may serve an oncogenic role in GBM and promote disease progression by interacting with miR-30b-3p. These findings suggested that FLVCR1-AS1 may be considered as a novel therapeutic target and diagnostic biomarker for GBM. [ABSTRACT FROM AUTHOR]

Background/Aims: Alcohol consumption has been shown to cause neuroinflammation and increase a variety of immune-related signaling processes. Microglia are a crucial part of alcohol-induced neuroinflammation and undergo apoptosis. Even though the importance of these inflammatory processes in the effects of alcohol-related neurodegeneration have been established, the mechanism of alcohol-induced microglia apoptosis is unknown. In prior research, we discovered that alcohol increases expression of salt-inducible kinase 1 (SIK1) in rodent brain tissue. In this study, we sought to determine what role SIK1 expression plays in alcohol-induced neuroinflammation as well as whether and by what mechanism it regulates microglia apoptosis. Methods: Adult C57BL/6 mice were divided into four groups and for 3 weeks treated with either 0%, 5%, 10%, or 15% alcohol during 3 hour periods. The mice were sacrificed and their brains excised for analysis. Additionally, primary microglia were isolated from neonatal mice. SIK1 expression in alcohol-treated brain tissue and microglia was analyzed via RT-PCR and western blotting. TUNEL staining, caspase-3, and caspase-9 activity assays were performed to evaluate microglial apoptosis. Cell fluorescence staining and NF-κB luciferase activity assays were used to evaluate the effects of SIK1 expression on the NF-κB signaling pathway. Results:SIK1 expression was increased in the brains of mice that consumed alcohol, and this effect was seen in mouse primary microglia. SIK1 knockdown in microglia increased alcohol-induced apoptosis in these cells. Furthermore, SIK1 reduced NF-κB signaling pathway factors, and SIK1 knockdown in microglia promoted alcohol-induced NF-κB activity. TUNEL staining, caspase-3, and caspase-9 activity assays consistently revealed that alcohol-induced microglial apoptosis was inhibited by depletion of p65. Finally, we determined that NF-κB signaling is required for alcohol-induced, SIK1-mediated apoptosis in microglia. Conclusion: This study establishes for the first time not only that SIK1 is crucial to regulating alcohol-induced microglial apoptosis, but also that the NF-κB signaling pathway is required for its activity. Overall, our results help elucidate mechanisms of alcohol-induced neuroinflammation. [ABSTRACT FROM AUTHOR]

Penetrometer resistance is one of the important soil physical properties that can determine, or be strongly correlated with, both root elongation and yield. We used a field experiment, which was designed to explore the effects of no-tillage (NT) and ridge tillage (RT) on a Mollisols in Northeast China, to test an approach for predicting the effects of soil bulk density, matric potential of water, and depth on penetrometer resistance. The field experiment was initiated in the fall 2010 on a clay loam soil. Soil bulk density, water content, water release curve, and penetrometer resistance were measured during the corn growing seasons in 2012 and 2013. Compared with the RT treatment, NT significantly increased soil bulk density and reduced the fraction of macropores in the 0–20 cm soil layer. The increase in density under NT resulted in a higher soil penetrometer resistance, which was associated with a lower water uptake by roots compared with the RT treatment. It was possible to use a relatively simple model for penetrometer resistance to explain the effects of soil bulk density, water status and depth on penetrometer resistance. Depth was included by relating it to overburden pressure. In a penetrometer resistance model that excluded overburden pressure, or depth empirically, penetrometer resistance in deeper layers (>35 cm) could not be fitted accurately. The effects of depth on penetrometer resistance from this study were consistent with published data. Our data suggests that at the assessment of soil conditions for root growth, ignoring the effects of depth is likely to give misleading penetrometer resistance. [ABSTRACT FROM AUTHOR]

Background: In recent years, miRNAs have been suggested to play key roles in the formation and development of human glioma. The aim of this study is to investigate the effect and mechanism of miR-184 expression on the malignant behavior of human glioma cells. Methods: The relative quantity of miR-184 was determined in human glioma cell lines, and the expression of hypoxia-inducible factor-1 alpha (HIF-1α) was explored using western blotting. The effects of miR-184 inhibition on cell viability and apoptosis were explored, and the miR-184 target gene was determined using a luciferase assay and western blotting. Flow cytometry and Hoechst staining were used to evaluate cell growth and apoptosis. Matrigel invasion and scratch assays were performed to measure the ability of cell invasion and migration. Results: miR-184 and HIF-1α protein levels were significantly upregulated in human glioma cells. Downregulation of miR-184 inhibited cell viability and increased the HEB cell apoptotic rate. Luciferase and western blot assays verified that FIH-1 was the target gene of miR-184 and negatively controlled the protein level of HIF-1α. Inhibition of HIF-1α by siRNA facilitated the apoptosis of HEB cells and suppressed A172 cell invasion and migration. Conclusion: miR-184 upregulation enhanced the malignant phenotype of human glioma cancer cells by reducing FIH-1 protein expression. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Pores and old root‐channels are preferentially used by roots to allow them to penetrate hard soils. However, there are few studies that have accounted for the effects of pore‐rhizosheath on root growth. In this study, we developed an approach by adding the synthetic root exudates using a porous stainless tube with 0.1‐mm micropores through a peristaltic pump to reproduce the rhizosheath around the artificial pore, and investigated the effects of pores with and without rhizosheaths on maize root growth in a dense soil. The results indicated that the artificial rhizosheath was about 2.69 mm wide in the region surrounding the pores. The rhizosheath had a higher content of organic carbon, total nitrogen, and abundance of Actinobacteria than that of the bulk soil. Compared with the artificial macropores, the artificial root‐pores with a rhizosheath increased the opportunities for root utilisation of the pores space, promoting steeper and deeper root growth. It is concluded that the pore‐rhizosheath has a significant impact on root architecture by enhancing root distribution in macropores. Summary statement: There are few studies that have accounted for the effects of pore‐rhizosheath on root growth. This study reported that the artificial root‐pores with a rhizosheath increased the opportunities for maize root utilisation of the pores space, promoting steeper and deeper root growth. [ABSTRACT FROM AUTHOR]

• A simple model for penetrometer resistance is developed. • Input variables can be estimated from heat pulse and shear wave measurements. • Matric potential does not need to be measured to estimate penetrometer resistance. • Combined effects of compaction and drying are taken into account by the small strain shear modulus. • A method that could be used in the field is proposed. Continuous estimates of penetrometer resistance (Q) would be useful in root elongation and in soil management studies. However, penetrometers produce estimates of penetration resistance at discrete time points. In this paper, a method with the potential to provide continuous estimates of penetrometer resistance is developed. We use measurements of soil water content, shear wave velocity (V s) determined from piezo electric devices, and bulk density (ρ b) determined with the heat pulse (HP) method, to estimate penetrometer resistance. Soil samples of a loamy sand were packed into cylinders with axial pressures of 50, 100, and 200 kPa, and allowed to equilibrate at matric potentials of −2, −6, −10, −30, −100, −300, and −500 kPa. Thermal conductivity (λ), V s and Q were measured after equilibration. A λ -based approach was applied to estimate ρ b , and small strain shear modulus (G) was calculated from ρ b and V s. Our results confirmed a linear relationship between Q and G (where G = V s 2 ρ b), which provides a basis to estimate penetrometer data in the field using buried sensors and a physically based model. [ABSTRACT FROM AUTHOR]

While many studies have examined the role of biochar in carbon (C) accrual in short-term scale, few have explored the decadal scale influences of biochar on non-biochar C, e.g., native soil organic C (SOC) and added substrate. To address this knowledge gap, soils were collected from decade-old biochar field trials located in the United Kingdom (Cambisol) and China (Fluvisol), with each site having had three application rates (25–30, 50–60 and 75–100 Mg ha−1) of biochar plus an unamended Control, applied once in 2009. We assessed physicochemical and microbial properties associated with sucrose (representing the rhizodeposits) mineralization and the priming effect (PE) on native SOC. Here, we showed both soils amended with biochar at the middle application rate (50 Mg ha−1 biochar in Cambisol and 60 Mg ha−1 biochar in Fluvisol) resulted in greater substrate mineralization. The enhanced accessibility and availability of sucrose to microorganisms, particularly fast-growing bacterial genera like Arenimonas, Spingomonas, and Paenibacillus (r-strategists belonging to the Proteobacteria and Firmicutes phyla, respectively), can be attributed to the improved physicochemical properties of the soil, including pH, porosity, and pore connectivity, as revealed by synchrotron-based micro-CT. Random forest analysis also confirmed the contribution of the microbial diversity and physical properties such as porosity on sucrose mineralization. Biochar at the middle application rate, however, resulted in the lowest PE (0.3 and 0.4 mg of CO2-C g soil−1 in Cambisol and Fluvisol, respectively) after 53 days of incubation. This result might be associated with the fact that the biochar promoted large aggregates formation, which enclosed native SOC in soil macro-aggregates (2–0.25 mm). Our study revealed a diverging pattern between substrate mineralization and SOC priming linked to the biochar application rate. This suggests distinct mechanisms, biophysical and physicochemical, driving the mineralization of non-biochar carbon in a field where biochar was applied a decade before. Highlights: The application of biochar at a moderate rate (50–60 Mg ha−1) resulted in increased labile C mineralization and decreased priming of native SOC. Biochar amendments led to the reconfiguration of physicochemical properties, including pH, porosity, and the formation of aggregates. Modified microbial community structure towards more r-strategists caused greater sucrose mineralization. Biochar incorporation rate governed the C dynamics via (biophysical vs physicochemical mechanisms) in long-term biochar amended fields. [ABSTRACT FROM AUTHOR]

Mutations in ATRX constitute the most prevalent genetic abnormalities in gliomas. The presence of ATRX mutations in glioma serves as a marker of better prognosis with longer patient survival although the underlying mechanisms are poorly understood. In the present study, we found that ATRX biological function was significantly involved in DNA replication and repair. CRISPR/Cas9-mediated genetic inactivation of ATRX induced inhibition of cell proliferation, invasion and vasculogenic mimicry. In addition, temozolomide (TMZ) treatment induced greater DNA damage and apoptotic changes in ATRX knockout glioma cells. Moreover, we confirmed that ATRX knockout resulted in a failure to trigger ATM phosphorylation and finally restrained the activation of downstream proteins of the ATM pathway. The ATM-associated DNA repair pathway was extensively compromised in ATRX knockout cells owing to decreased histone H3K9me3 availability. Public databases also showed that patients with low ATRX expression exhibited preferable overall survival and profited more from TMZ treatment. These data suggest that ATRX is involved in DNA damage repair by regulating the ATM pathway and might serve as a prognostic maker in predicting TMZ chemosensitivity. [ABSTRACT FROM AUTHOR]

The stability and chemical composition of SOM are related to the changes of the proportions of old and young SOM. However, there are few studies that investigated the effects of no-tillage (NT) on the stability, chemical composition, and sources of SOM. In this study, the effects of 9-years of NT on the contents of total, thermally labile and stable SOM, their chemical composition and the contributions from C 3 and C 4 plants were determined. Before application of NT, the field has been used for C 4 maize cultivation under conventional tillage (CT) management about 80 years after initial C 3 grassland reclamation. Soil samples were collected in the 0–20 cm soil profile. Under NT treatment, the contents of total SOC, thermally labile and stable SOC, and C 4 -SOC decreased with soil depths. However, they were greater in the 0–10 cm layers than that in the 10–20 cm layer under CT. The contents of C 3 -SOC showed no change with depths under both of tillage treatments. NT had greater contents of total SOC, C 4 -SOC, thermal-labile SOC, and C 4 -SOC thermal-labile than CT in the 0–5 cm layer, but lower in the subsoil layers. The contents of C 3 -SOC thermal-labile decreased in the 0–5 cm layer under NT. The alkyl-C and O-alkyl-C were the main fractions of thermal-labile SOM and aromatic-C was the dominant fraction of thermal-stable SOM. C 4 -SOC (young SOC) was significantly positively correlated with alkyl-C and O-alkyl-C and negatively correlated with aromatic-C. Our results indicated that: (1) compared with continuously CT, applying NT resulted in SOC accumulation in the surface layer, (2) more maize residue input increased the new thermally labile and stable SOM yet lead to decrease the C 3 -SOC thermal-labile under NT, (3) the contributions of C 3 and C 4 -direved SOM determined the chemical compositions of various SOM pools. • The C 4 -SOC was greater under NT than CT in the 0–5 cm, but lower in 5–20 cm layer. • No-tillage accelerates the decomposition of thermal-labile SOC derived from old C 3 plant. • Alkyl-C and O-alkyl-C are thermal-labile and aromatic-C is thermal-stable. [ABSTRACT FROM AUTHOR]

Summary: Iron is virtually an essential nutrient for all organisms, to understand how iron contributes to virulence of plant pathogenic fungi, we identified ClFTR1 and ClNPS6 in maize pathogen Curvularia lunata (Cochliobolus lunatus) in this study. Disruption of ClNPS6 significantly impaired siderophore biosynthesis. ClFTR1 and ClNPS6 did mediate oxidative stress but had no significant impact on vegetative growth, conidiation, cell wall integrity and sexual reproduction. Conidial germination delayed and appressoria formation reduced in ΔClftr1 comparing with wild type (WT) CX‐3. Genes responsible for conidial germination, appressoria formation, non‐host selective toxin biosynthesis and cell wall degrading enzymes were also downregulated in the transcriptome of ΔClftr1 and ΔClnps6 compared with WT. The conidial development, toxin biosynthesis and polygalacturonase activity were impaired in the mutant strains with ClFTR1 and ClNPS6 deletion during their infection to maize. ClFTR1 and ClNPS6 were upregulated expression at 12–24 and 48–120 hpi in WT respectively. ClFTR1 positively regulated conidial germination, appressoria formation in the biotrophy‐specific phase. ClNPS6 positively regulates non‐host selective toxin biosynthesis and cell wall degrading enzyme activity in the necrotrophy‐specific phase. Our results indicated that ClFTR1 and ClNPS6 were key genes of pathogen known to conidia development and virulence factors. [ABSTRACT FROM AUTHOR]

The use of radiotherapy in tumor treatment has become increasingly prominent and has emerged as one of the main tools for treating malignant tumors. Current radiation therapy for glioma employs 125I seeds for brachytherapy, which cannot be combined with radiotherapy and chemotherapy. To address this limitation, this paper proposes a dual-microcavity capsule structure that integrates radiotherapy and chemotherapy. The Monte Carlo simulation method is used to simulate the structure of the dual-microcavity capsule with a 125I liquid radioactive source. Based on the simulation results, two kinds of dual-microcavity capsule structures are optimized, and the optimized dual-microcavity capsule structure is obtained. Finally, the dosimetric parameters of the two optimized dual-microcavity capsule structures are analyzed and compared with those of other 125I seeds. The optimization tests show that the improved dual-capsule dual-microcavity structure is more effective than the single-capsule dual-microcavity structure. At an activity of 5 mCi, the average absorbed dose rate is 71.2 cGy/h in the center of the optimized dual-capsule dual-microcavity structure and 45.8 cGy/h in the center of the optimized single-capsule dual-microcavity structure. Although the radial dose function and anisotropy function exhibite variations from the data of other 125I seeds, they are generally similar. The absorbed dose rate decreases exponentially with increasing distance from the center of the capsule, which can reduce the damage to the surrounding tissues and organs while increasing the dose. The capsule structure has a better irradiation effect than conventional 125I seeds and can accomplish long-term, stable, low-dose continuous irradiation to form local high-dose radiation therapy for glioma. • Development of a novel dual-microcavity capsule structure for integrated radiotherapy and chemotherapy of glioma. • Optimize capsule structure and achieve high dose rates in the tumor center using Monte Carlo simulation. • Orthogonal tests were performed to optimize the capsule design parameters. • Improved dual-capsule dual-microcavity structure shows better efficacy than single-capsule dual-microcavity structure. [ABSTRACT FROM AUTHOR]

Optimizing tillage management is one way to reduce the risk of soil compaction due to traffic load in Northeast China. In this study, we aimed to examine the responses of precompression stress (σ pc), compression index (C c), pore morphology (>30 µm), air-filled porosity (ε a60), air permeability at matric potential of − 60 hPa (k a60) and saturated hydraulic conductivity (K s) to harvest traffic on soil from two contrasting tillage practices using a 10-yr old field experiment. After the crop was harvested with a combine harvester, undistributed soil cores were collected in the 0–10 and 10–20 cm layers from non-traffic and traffic zones of no-tillage (NT) and moldboard plough (MP) plots. In the non-traffic zone, the MP management showed greater total porosity (ε total), ε a60 and macroporosity (ε X-ray) than the NT. There were no differences in pore connectivity, mean pore size and k a60 of the 0–10 cm layer and in K s of the 0–20 cm layer between the two tillage practices, however, more biopores were observed under NT. Harvest traffic showed no significant effects on NT soil. In the MP plots, the ε total , ε X-ray , and pore connectivity, were decreased and pores larger than 0.15 mm were preferentially compacted. As a result of traffic, MP soil displayed lower k a60 in the 0–20 cm layer and lower ε X-ray and connectivity in the 10–20 cm layer. In the NT management, the pore system had greater water and air conduction efficiencies and stable properties. Thus, compared to MP, NT can mitigate the negative effects of harvest compaction on soil in Northeast China. • Compared with MP, NT yields lower porosity and permeability before traffic pass. • After traffic pass, NT shows more stable soil pore system and better permeability. • NT mitigates the negative effects of harvest traffic on soil pores and permeability. [ABSTRACT FROM AUTHOR]

Soil structure influences the soil hydraulic properties, aeration and resistance to root penetration. Many indicators can be used to investigate the changes of soil structure, but using a single indicator or method has limitations. This study evaluates the effects of 15-years tillage management on soil structure with soil bulk density (BD) , penetrometer resistance (PR), soil water retention curve (SWRC), least limiting water range (LLWR) and X-ray computed tomography (CT). The treatments include no-tillage (NT), rotary tillage (RT), and mouldboard plough (MP). Soil bulk density of the 0–30 cm soil profile was measured after the establishment of tillage treatments for 7, 9, 12 and 14-years. The values of PR , SWRC, LLWR, and 3-D pore geometry of the 5–10 and 15–20 cm layers were determined in the 15th year of the experiment. The greater BD in the 0–5 cm layer of NT was not observed after 9 years, but an increased BD in the 5–20 cm layer was found in most years. Tillage had no effect on PR in wet soil. When soil had dried, the NT treatment had a greater PR and it was the lower limiting factor of LLWR, ultimately leading to a narrower LLWR of NT. Both NT and RT showed lower proportions of structural but higher textural pores. The macroporosity (> 50 µm) from X-ray CT was greater than that estimated from SWRC of the 15–20 cm layer. The characteristics of pore morphology were similar under three tillage treatments. Therefore, NT resulted in a narrower LLWR due to the denser soil layer, yet similar macropores may alleviate the negative impacts on crop growth caused by lower LLWR. It was suggested that using LLWR and characteristics of macropores from X-ray CT at the same time is a suitable way to assess soil structure under various tillage practices. • After 15-years no-tillage, the physical quality is poor in 5–20 cm layer reflected by greater BD, PR, and lower LLWR. • Similar properties of macropore weak the usefulness of LLWR for assessing soil structure under no tillage treatment. • Combining LLWR with macropores from X-ray CT is a suitable way to assess soil structure under various tillage practices. [ABSTRACT FROM AUTHOR]

• Erosion induced greater total and labile SOC storage on the depositional position. • Old C contributed to a large proportion of labile SOM on the eroding position. • New C was preferentially preserved in macroaggregates. • Aggregates played important roles in the physical sequestration of SOC. • Both silt and clay fractions and aggregates protected labile SOM. The characteristics of soil organic matter (SOM) such as stocks, sources and stability, are important for understanding soil functioning and C cycling in an eroding field. In this study we investigated the characteristics of SOM in bulk soil and aggregates collected from three positions (shoulder, back, and foot) on a sloping field in Northeast China using stable and radioactive isotope (13C and 14C) and thermogravimetry (TG) techniques. The field had originally been populated with C 3 grassland plants before conversion to C 4 corn dominated arable cropping approximately 80 years ago. Soil samples were collected from 0–120 cm soil profiles in 20 cm depth intervals. Erosion rates were estimated by 137Cs analysis to be 0.21 cm yr–1 and 0.08 cm yr–1 at the shoulder and back positions, respectively. A greater proportion of small macroaggregates (2–0.25 mm) and microaggregates (0.25–0.053 mm) were found in the topsoil and subsoil layers at the foot position compared with the shoulder position. The concentration and storage of soil organic C (SOC) in the bulk soil was significantly lower at the shoulder and back positions compared with the foot position. Greater thermal-labile SOM concentration and storage were observed at the foot position compared with the shoulder and back positions. Positive relationships between C 4 -derived SOC and the proportion of thermal-labile SOM suggested that most thermal-labile SOM was C 4 -derived from the recent corn (young SOC), while most stable SOM fractions were C 3 -derived from previous grassland vegetation (old SOC). However, labile SOM from old SOC was also an important part of total thermal-labile SOM, particularly in deep soil horizons (below 40 cm) at all sampling positions. Small macroaggregates had a greater SOC content, δ 13C, and thermal-labile SOM proportion, and younger SOC age, compared with microaggregates and silt + clay (<0.053 mm) fractions, except at the 40–60 cm depth at the foot position. As the mass of aggregates accounted for 32–50% of the bulk soil, about half of thermal-labile and total SOC were stored as associations with silt + clay fractions at erosional and depositional points. Our results indicated that: (1) more thermal-labile and total SOM were stored at depositional position, (2) compared with new carbon sources, old SOM contributed to a large proportion of thermal-labile SOM on an eroding slope, particularly in deep soil, and, (3) soil aggregates and silt + clay fractions had equivalent roles in SOC sequestration in both erosional and depositional locations. [ABSTRACT FROM AUTHOR]

• A soil penetrometer resistance (PR) model was developed and validated. • PR was estimated from relative bulk density, matric potential, and depth. • The model has a simplified form and fewer parameters than previous models. • The model provided more accurate PR results than previous models. Soil penetrometer resistance (PR), an indicator of soil strength, is often used to denote the force that roots need to exert to penetrate the soil. In this study, we propose an empirical model, which has a simplified form and fewer parameters than the previous ones, to estimate PR from relative bulk density, matric potential of soil water, and soil depth. The model was established by using field measurements of PR , bulk density, water content, and laboratory water retention data at various soil depths in a long-term tillage experiment during maize growing season in 2017. Relative bulk density was determined from soil texture, bulk density, and organic matter content. Model performance was evaluated by comparing the predictions from the new model against those obtained from four earlier models using independent field data collected from four soils of different textures in 2015, 2018 and 2019. The root mean square error of the new model ranged from 0.358 to 0.879 MPa, significantly lower than that of the other four models (0.404–2.689 MPa), indicating that the new model could be applied to estimate PR for a wide range of soil textures with improved accuracy. [ABSTRACT FROM AUTHOR]

• Soil water retention curve (WRC) shape is influenced by variable bulk density. • Available pedotransfer functions (PTFs) fail to account for bulk density effects. • New PTFs for WRCs are developed to better account for bulk density effects. • The accuracy of New PTFs is comparable to widely-used ones. Pedotransfer functions (PTFs) describing soil water retention curves (WRCs) have been widely used in crop, soil, and land surface models. A limitation of the available PTFs is that they fail to account for shape changes in WRCs due to bulk density variations caused by soil tillage, compaction, and other processes. This study develops new PTFs that include bulk density effects on the WRC shape. A new framework is introduced to build the bulk density-associated PTFs based on a widely-used WRC dataset. The new PTFs were validated by comparing the performance with two common PTFs from the literature using two independent datasets. The results show that the newly developed PTFs provide reliable WRC estimates for the validation datasets, with mean RMSE values of 0.055 and 0.059 m3 m-3, respectively. The accuracy of the new PTFs is comparable or in some cases better than the common PTFs. While the literature PTFs investigated do not always properly describe bulk density effects on WRC changes, the new PTFs effectively account for such effects on the WRC shape, thus have the potential to be integrated into crop and soil management models to represent bulk density impacts on WRCs due to anthropogenic (e.g., plowing and compaction) and natural (e.g., wetting/drying) processes. [ABSTRACT FROM AUTHOR]