Differences In Soil Texture Research Articles

Nitrification inhibitor effect on manganese and phosphorus shoot concentrations in maize under different textured soils from northern Germany

High soil pH can result in Mn2+ and P deficiency, leading to crop yield losses. Therefore, supplying soil with NH4+-N fertilizer in stabilized or unstabilized form can increase soil Mn2+ availability and shoot concentration. Nitrification inhibitors (NIs) have been proposed to lower rhizosphere soil pH, thus improving plant P uptake and preventing P deficiency in soils with high pH. Thus, this study investigated whether NI-stabilized or unstabilized NH4+-N could increase Mn2+ availability in three differently-textured soils (sand, loamy sand, and silt loam) and promote Mn2+ and P shoot concentration in maize. Two greenhouse experiments were conducted to investigate the effects of applying NH4+-N fertilizer with or without the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) combined with different nitrogen (N) sources (calcium nitrate (CN), ammonium nitrate (AN), and ammonium sulphate (AS)). The measured variables were bulk and rhizosphere soil pH and Mn2+ availability, maize biomass, as well as Mn2+ and P shoot concentrations. The results indicated that DMPP-stabilized AS significantly decreased rhizosphere pH by 7.2 % in loamy sand soil texture compared with unstabilized AS. Similarly, only in the loamy sand texture, DMPP-stabilized AS increased Mn2+ availability and shoot concentration by 86 % and 47 %, respectively, relative to unstabilized AS. Furthermore, DMPP-treated AS and AN promoted P shoot concentration by 30 % and 21 % in the loamy sand and silt loam soil textures, respectively, relative to the corresponding N sources without DMPP. Conversely, DMPP did not impact the investigated variables in the sand texture for all N sources. Moreover, AN and AS increased biomass yield, Mn2+ availability, and shoot concentration by 72 %, 30 %, and 46 %, respectively, in relation to the CN fertilizer in the sand soil texture. In conclusion, this study confirmed the effectiveness of DMPP-induced rhizosphere acidification in enhancing Mn2+ and P shoot concentration in loamy sand soil textures, as well as P shoot concentration in fine-textured soil.

Investigating the Long-Term Effects of Anthropogenic Practices on Soil Features

Anthropogenic practices have been increasingly conducted on the rise in addressing the escalatingdemands for socioeconomic development, resulting in significant impacts on land ecosystems. This research seeks toevaluate the influence of anthropogenic activities on soil features in mountainous regions of Vietnam by focusing 84samples collected from 12 locations across Lam River Basin at seven soil profiles (0-10, 10-20, 20-30, 30-40, 40-60, 60-80 and 80-100 cm).The findings reveal notable differences in soil texture among land use types (LUTs). Forest cover lands (FCLs),showed the least amount of sand content, varying from 29.7% to 37.6%, while unplanted and bare lands (UBLs) had thehighest sand ratios, up to 53.9%. FCLs exhibited lowest bulk density (BD), soil porosity (SP) and soil electricalconductivity (EC) and C:N ratio with respective ranges of 0.93-1.29 g.cm-3, 32.7-36.5%, 0.526-0.743 mS.m-1 and6.74 -8.52, respectively.In contrast, crop cultivation lands (CCLs) demonstrated higher values for BD (1.17-1.25 g/cm3), SP (39.25-43.19%), EC (0.583-0.792 mS.m-1) and C:N ratio (11.27-15.77). UBLs, on the other hand, exhibited even highest valuesup to 1.23-1.36 g.cm-1, 43.19-49.62%, 0.437-0.619 mS.m-1 and 11.68-16.58% and displayed high levels of exchange ironsand soil organic content compared to FCLs. Other factors such as pH varied little in space between the sampled soillocations and along the soil profiles. Overall, the study indicates that anthropogenic practices have impacts on the soilfeatures across the study area.

Predicting unsaturated soil strength of coarse-grained soils for mobility assessments

Accurately estimating surficial soil moisture and strength is integral to determining vehicle mobility and is especially important over large spatial extents at fine resolutions. While methods exist to estimate soil strength across landscapes, they are empirical and rely on class average soil behavior. The Strength of Surficial Soils (STRESS) model was developed to estimate moisture-variable soil strength with a physics-based approach. However, there is a lack of field data from a diverse landscape to evaluate the STRESS model. To test the STRESS model, a field study was conducted in northern Colorado. Soil moisture and strength were measured on 10 dates. Data from the surficial layer (0–5 cm) were used to test the STRESS model and determine if soil strength trends could be estimated from topographical and soil textural differences. High variability was observed in soil strength measurements stemming from fine-scale terrain features and user variability. Observations show lower soil strengths for greater soil moistures, steeper slopes, higher vegetation, and lower soil fines content. STRESS estimated rating cone index values with a mean relative error of 37.5 %, while a pre-existing model had a mean relative error of 47.4 %. The STRESS model outperforms the current RCI prediction method, but uncertainty remains large.

Effects of parent material on soil hydraulic properties in subtropical hilly area of Southern China

The parent materials play an important role in soil hydrologic properties. However, in subtropical hilly areas with complex geological conditions, it appears that there is a lack of full understanding about the effect of parent material on soil water-holding and erosion resistance, which can be helpful for agricultural production and conservation of soil and water. In this study, five red soils developed from shale (Ds), quartz sandstone (Dqs), argillaceous nodular limestone (Danl), argillaceous limestone (Dal), and limestone conglomerate (Dlc) in subtropical China were selected. Soil properties, soil water-retention curves (SWRCs), water-stable aggregate fractions, and soil erodibility factor (K) were tested and calculated. The results showed that there are significant differences in soil texture among soils developed from different parent materials, soils with higher clay content have stronger water-holding capacity, and the average water-holding capacity of the five soils followed the order Dal > Danl > Ds > Dlc > Dqs. Furthermore, the erosion resistance of soil is closely related to the clay content and the stability of soil aggregates, and the sequence of average K-value among the five soil types is as follows: Danl > Dal > Dlc > Ds > Dqs. Partial least squares regression revealed that the stability of aggregates has a more significant influence on soil erodibility than the clay content. Therefore, soils with higher mean weight diameter (MWD) and geometric mean diameter (GMD) are more resistance to erosion. This paper evaluated the distinctions in basic properties and hydraulic properties between different parent materials under similar climatic conditions, elevations and vegetation in subtropical hilly area of Southern China, which can serve as a scientific foundation for soil and water conservation in the environments characterized by complex geological conditions.

Toward soil carbon storage: The influence of parent material and vegetation on profile-scale microbial community structure and necromass accumulation

Soil microbial communities play a crucial role in the accumulation and stabilization of soil organic carbon (SOC) through complex processes involving plant residue transformation and mineral interactions. These processes are influenced by plant inputs and modulated by soil properties that are mostly determined by the parent material. However, our understanding is limited regarding the manner in which vegetation and parent material affect microbial community structure, necromass accumulation, and their subsequent impact on SOC storage. To bridge this knowledge gap, we conducted an in-depth investigation focusing on the top-down influence of vegetation type and the bottom-up effect of parent material on microbial-mediated carbon transformation across soil profiles in a tropical region. Our study encompassed 42 sites on three parent materials (basalt, granite, and marine sediments) and four vegetation types (rubber, banana, areca plantations and uncultivated grassland). Soil samples were collected at 0–20, 20–40, 40–80, and 80–100 cm depth. Microbial community structure and necromass were quantified using microbial biomarkers of phospholipid fatty acids and amino sugars, respectively. In rubber plantations, we observed a trend toward higher microbial biomass that, though not significant when compared to other vegetation types, transformed to a significantly higher accumulation of microbial necromass. This increase in microbial necromass was linked to the accumulation of SOC facilitated by the presence of clay size minerals in clayey soils developed from basalt. In particular, basaltic soils were dominated by bacteria, which facilitated the accumulation of bacterial necromass that significantly bolstered its contribution to SOC. In contrast, in sandier soils developed from granite and marine sediments, fungal communities and necromass dominated due to the propensity of fungi for coarser soil environments. Overall, the main impact of vegetation on microbial communities and necromass accumulation was primarily demonstrated for the topsoil. Differences in soil texture arising from different parent materials exert significant effects on the fungal-to bacterial-biomass and necromass ratios, consequently influencing the contribution of fungal and bacterial necromass carbon to SOC across soil profiles. Our study underscores the pivotal role of parent material in governing tropical profile-scale soil carbon storage by shaping the structure of microbial communities and influencing the retention of microbial necromass.

Impacts of Organic and Non-Organic Cultivation Practices on Soil Fertility Parameters of Selected Paddy Lands Based on the Duration of Cultivation in Wet and Intermediate Climate Zones of Sri Lanka

Sri Lanka has been practicing the cultivation of rice as its main staple food in two major agricultural techniques; organic and non-organic. The major aim of the present study was to analyze and compare the time duration-based impacts of the above two agricultural practices on paddy soil fertility indicators as the preliminary step of a long-term research project. Organic and non-organic paddy fields that have been cultivated for 2 seasons in Thorapitiya in the Matale district were selected as short-term cultivated lands. Land cultivated for 10 years organically in Homagama and land with a non-organic cultivation history of 20 years in Kottawa was selected as long-term cultivated lands. A total number of 35 samples were collected including the control samples from adjacent uncultivated land during the first phase of the Maha season 2021/2022. The samples were dried, sieved and then analyzed in their physical and chemical properties; color, texture, particle size distribution, pH, electrical conductivity (EC), organic carbon content (OCC), total nitrogen content (TNC), available phosphorus content (APC), exchangeable potassium content (EPC), and exchangeable magnesium content (EMC). The soil samples from Thorapitiya had a reddish-brown nature while most of the samples from Kottawa and Homagama had a grayish-brown color. Higher clay percentages were found in the soil samples from long-term organically cultivated lands in Homagama. The uniformity coefficient (Cu) values for soils from study areas except Homagama lie in the range for well-graded soil while the coefficient of gradation (Cc) values of all three areas were not in the above range. Short-term cultivation using organic and non-organic fertilizers did not show a significant difference in soil texture, pH, EC, APC, EPC, and EMC values. Most of their cultivated lands had a lower pH (~5.5–6.0) than the corresponding control plots (~5.8–6.4). The TNC levels in non-organically cultivated lands were significantly higher than in organic lands. Practicing agricultural activities for a prolonged period has resulted in significant differences in soil texture, pH, EC, OCC, TNC and APC between organic and non-organic lands. Higher OCC and lower pH, EC and APC values have been obtained for long-term organically cultivated lands than their non-organic counterparts. The TNC, APC and EPC levels were higher in most of the long- term organic and non-organic lands than in their control samples. Several amendments have to be made to bring the fertility parameters to an optimum level in long-term cultivated lands. 
 Keywords: Soil fertility, Paddy soil, Cultivation history, Organic cultivation, Non-organic cultivation

Landscape controls on fuel moisture variability in fire-prone heathland and peatland landscapes

BackgroundCross-landscape fuel moisture content is highly variable but not considered in existing fire danger assessments. Capturing fuel moisture complexity and its associated controls is critical for understanding wildfire behavior and danger in emerging fire-prone environments that are influenced by local heterogeneity. This is particularly true for temperate heathland and peatland landscapes that exhibit spatial differences in the vulnerability of their globally important carbon stores to wildfire. Here we quantified the range of variability in the live and dead fuel moisture of Calluna vulgaris across a temperate fire-prone landscape through an intensive fuel moisture sampling campaign conducted in the North Yorkshire Moors, UK. We also evaluated the landscape (soil texture, canopy age, aspect, and slope) and micrometeorological (temperature, relative humidity, vapor pressure deficit, and windspeed) drivers of landscape fuel moisture variability for temperate heathlands and peatlands for the first time.ResultsWe observed high cross-landscape fuel moisture variation, which created a spatial discontinuity in the availability of live fuels for wildfire spread (fuel moisture < 65%) and vulnerability of the organic layer to smoldering combustion (fuel moisture < 250%). This heterogeneity was most important in spring, which is also the peak wildfire season in these temperate ecosystems. Landscape and micrometeorological factors explained up to 72% of spatial fuel moisture variation and were season- and fuel-layer-dependent. Landscape factors predominantly controlled spatial fuel moisture content beyond modifying local micrometeorology. Accounting for direct landscape–fuel moisture relationships could improve fuel moisture estimates, as existing estimates derived solely from micrometeorological observations will exclude the underlying influence of landscape characteristics. We hypothesize that differences in soil texture, canopy age, and aspect play important roles across the fuel layers examined, with the main differences in processes arising between live, dead, and surface/ground fuels. We also highlight the critical role of fuel phenology in assessing landscape fuel moisture variations in temperate environments.ConclusionsUnderstanding the mechanisms driving fuel moisture variability opens opportunities to develop locally robust fuel models for input into wildfire danger rating systems, adding versatility to wildfire danger assessments as a management tool.

Интродукция российских сортов люцерны в лесостепной зоне Монголии

There are two of commercial varieties of alfalfa (Medicago varia Mart.) ‘Vega 87’ and ‘Nakhodka’ originated from Russia, it are cultivated for introducing in Mongolian climate and ecological condition. Growth development of those varieties required from 136 to 143 days between regrowth in spring and the seed mature in the autumn. Wintering rate was 92.6% in ‘Nakhodka’ and 88.5% in ‘Vega 87’ in the first year and increased by 5.8 and 7.3% in the second year, respectively. Green biomass and hay yield of ‘Nakhodka’ were higher than ‘Vega 87’ and average green biomass of two years in ‘Nakhodka’ was 13.5 t/ha and 10.9 t/ha in ‘Vega 87’, the hay yield was 5.4 t/ha in ‘Nakhodka’ and 3.6 t/ha in ‘Vega 87’ at flowering stage. Moreover, humus content, phosphorus, potassium content and texture were determined in the depth of 0–10, 10–20, 20–30 cm in control and alfalfa cultivated areas. Humus content ranged between 3.1–3.6% in the depth of alfalfa cultivated areas while 2.8% in control area in the depth of 0–20 cm and humus content was increased by 9.36–14.5% (in relative terms) in alfalfa cultivated areas compared to the control. Then phosphorus content was 4.93 mg/100 g in ‘Nakhodka’ cultivated area, 4.11 mg/100 g in ‘Vega 87’ cultivated area and 3.70 mg/100 g in control area in the depth of 0–10 cm. Potassium content was ranged between 23.4–23.9 mg/100 g in alfalfa cultivated areas while it was 20.6 mg/100 g in 0–10 cm of depth. According to the soil survey result, there is no difference in soil texture between treatments (alfalfa cultivated areas and control area), but humus content and content of phosphorus, potassium had increased in alfalfa cultivated areas.

Growth response of clonal eucalyptus to varying levels of iron application and soil texture

Deficiency symptoms of iron (Fe) appear in eucalyptus (Eucalyptus spp.) plantations grown on different type of soils in Punjab, India. Therefore, a pot experiment was conducted to study the response of eucalyptus to application of Fe in soils of different textures. The treatments comprised of six levels of Fe as soil application (0, 15, 30, 45, 60, and 75 mg Fe kg−1 soil applied as chelated Fe through Fe-EDTA) and two foliar sprays (0.5% and 1% FeSO4·7H2O) replicated thrice in soils of three textures (loamy sand, sandy loam, and sandy clay) in a completely randomized design. Plant growth parameters, Fe concentration in soils, and Fe uptake by different plant parts were determined after nine months of eucalyptus growth. These parameters were significantly and positively influenced with the application of Fe. Dry weight of shoot and root was the highest at 30 mg Fe kg−1 whereas Fe concentration and uptake of Fe by shoot and root were the highest at 45 mg Fe kg−1. With 1% spray, the root dry weight, Fe concentration in leaves and its uptake by leaves and shoot were the highest. Loamy sand soil exhibited maximum shoot biomass and uptake response to applied Fe by eucalyptus. The Fe concentration in soil was positively and significantly related to Fe concentration (r = 0.436*–0.772**) and its uptake (r = 0.643**- 0.866**) by different plant parts. Conclusively, application of Fe to eucalyptus significantly increased the growth parameters, its uptake and response by the plants.

Soil health explains the yield-stabilizing effects of soil organic matter under drought

Soil organic matter (SOM) serves as an important indicator of soil health. Soils with high SOM are associated with high crop yield under drought conditions. However, a critical question remains unanswered: is the yield-stabilizing effect of SOM attributable to inherent soil properties, such as soil texture and taxonomy? Or is it driven by dynamic soil properties that reflect the overall health of the soil? Following the Soil Health Assessment Protocol and Evaluation, we derived a soil health score (SHS; range: 0–1) from the SOM concentration by accounting for site-specific variables, including climate, texture, and soil suborder. Using county-level data of rainfed corn across the U.S. from 2000 to 2016, we found that higher SHS were associated with higher yields. During the most severe drought events, an increase of 0.5 in SHS was associated with a 1.15 ​± ​0.18 ​Mg ​ha−1 increment in corn yield, suggesting that high SHS helps to stabilize yield in drought. Interestingly, smaller but statistically significant effects of SHS on yield were found during less intensive droughts. The SOM concentration was a slightly better predictor of corn yield than the SHS. We also found similar effects of SHS on corn yield across different soil types, i.e., different textures or soil suborders, under severe drought conditions. Our results suggest that soil health is a main factor in explaining the yield benefits of SOM, while the effects of soil health were not driven by differences in soil texture or suborder. We argue that the resilience of corn yield against drought can be potentially increased by adopting agronomic practices aimed at augmenting SOM and improving overall soil health across a broad spectrum of geographical locations and site characteristics.

Effect of Irrigation Water Quality and Wetting and Drying Cycles on the Release of Calcium and Magnesium in Two Soils of Different Textures

Abstract&#x0D; The study included two sites for two soils of different textures (Al-Mazara and Bashiqa) within Nineveh Governorate - Iraq. Soil samples were taken from the surface depth (30 cm) naturally by means of columns. The experiment was carried out by adding two types of water (river water and well water) to each column with a volume equivalent to The pore size, and alternating wetting and drying were done for ten cycles, and the period between one cycle and another was 10 days. Soil samples were analyzed after the first cycle, the fifth cycle, and the tenth cycle to find out the effect of the number of humidification cycles on the exchanged ions, the relative effectiveness, and the Gapon constant. The results indicated that the released amount of exchanged calcium ions in the soil of Bashiqa was higher than the amount released in the soil of the Al-Mazara, while the amount of magnesium ions released in the soil of Al-Mazara was higher than the amount released in the soil of Bashiqa and when using both types of water, while the relative effectiveness values for calcium, the values ​​were higher when wetting with well water, except for the first cycle in the soil of Al-Mazara and the tenth cycle in the soil of Al-Mazara and Bashiqa, while the relative effectiveness of magnesium in the two study soils, the values ​​were higher when wetting with well water and for all cycles except the fifth cycle in Bashiqa soil, while the Gapon constant for calcium in the two study soils had higher values ​​when wetting with river water in the fifth cycles, while in the first and tenth cycles the values ​​were higher when wetting with well water, except for the first cycle in Bashiqa soil, while the Gapon constant for magnesium in the two study soils, the values ​​were higher when wetting with well water and for all cycles except for the first and fifth cycle in Al-Mazara soil. Then the following kinetic equations were applied: zero order equation, first order equation, diffusion equation, Eluvich equation and power function equation, the power function equation was the best equation that describes the process of release calcium and magnesium ions in the study soil.

Analysis of spatiotemporal variations and influencing factors of soil erosion in the Jiangnan Hills red soil zone, China

Soil erosion is an important environmental problem in China. The hilly region of Jiangnan is characterized by severe soil erosion due to its unique climate and intensive human activities. Therefore, assessing soil erosion in this area is of great significance for achieving regional sustainable development. Based on the spatial zoning of natural resources and the spatial differences in precipitation, land cover, topographic features, and soil texture, we estimated soil erosion from 2000 to 2020 using the Revised Universal Soil Loss Equation (RUSLE) model. The study showed that micro-erosion dominates spatially in the subtropical forest subzone of the eastern hills, accounting for more than 60% of the total erosion area. Intense erosion was found in woodlands and grasslands and the erosion intensity tended to be lower in the plains. Erosion occurred mainly in areas with slopes >8°. The areas with significantly lower erosion were mainly distributed at the boundaries between forests, arable land, and artificial land surfaces. The areas where soil erosion significantly increased over the study period were mainly found in farmland areas (31.70%). Soil erosion occurred because of a combination of factors, among which vegetation cover played a prominent role. Elevation and slope were correlated with soil erosion intensity. Severe erosion in different parts of the study area showed two trends of spatial aggregation and discrete distribution. This analysis of soil erosion in the study area by the RUSLE model provides reference data for the eastern subtropical forest subregion including the Jiangnan Hills.

Variation in soil infiltration properties under different land use/cover in the black soil region of Northeast China

Soil infiltration properties (SIPs) of infiltration rate and saturated hydraulic conductivity significantly affect hydrological and erosion processes, thus, knowledge of SIPs under different land use/cover are vital for land use management to control soil erosion for realizing the sustainable development of the small agricultural watershed. Nevertheless, few studies have been carried out to investigate the differences in SIPs and their dominant influencing factors between different land use/cover in the black soil region of Northeast China. Therefore, eight typical land use/cover were selected to clarify the variations in SIPs between different land use/cover and further identify their dominant influencing factors. SIPs of initial infiltration rate (IIR), steady infiltration rate (SIR), and saturated hydraulic conductivity (Ks) were determined under eight typical land use/cover (forestland, shrub land, grassland, longitudinal shelterbelt, transverse shelterbelt, agricultural road, and cropland of Zea mays L. and Glycine max (Linn.) Merr) using a tension disc infiltrometer with three pressure heads of −3, −1.5, and 0 cm. The results of one-way ANOVA analysis showed that SIPs varied greatly between different land use/cover. Shelterbelt plant with Populus L. had the maximum IIR, SIR, and Ks, and then followed by shrub land, agricultural road, cropland, grassland, and forestland. Spearman correlation analysis indicated that SIPs were significantly correlated with soil and vegetation properties. Redundancy analysis revealed that differences in SIPs between different land use/cover were dominantly attributed to the differences in soil texture, field capacity, and plant root mass density, which explained 79.36% of the total variation in SIPs. Among these dominant influencing factors, the results of structural equation model indicated that the indirect effects of plant root and soil texture played the most important role in variations of SIPs via affecting soil texture and pore characteristics. These results have significant implications for the precise prediction of watershed hydrological and erosion processes, also provide a scientific basis for guiding the distribution pattern of land use in the cultivated watershed.

Impact of alternative soil data sources on the uncertainties in simulated land-atmosphere interactions

Numerical weather- and climate prediction models rely on soil data to accurately model land surface processes. However, as soil data are produced using soil profiles and maps with multiple sources of uncertainty, wide discrepancies prevail in global soil datasets. Comparison of four commonly used soil datasets in Earth system climate models, i.e., Food and Agriculture Organization soil data, Harmonized World Soil Database, Global Soil Dataset for Earth System Model, and global gridded soil information system SoilGrids, yields widespread differences in southern Africa. This study investigates the simulated land-atmosphere interactions in southern Africa in the context of the uncertainties from applying different global soil datasets. We conducted ensemble simulations using the fully coupled Weather Research and Forecasting Hydrological Modeling system (WRF-Hydro) incorporated with each of the global soil datasets mentioned above. Model simulations were performed at 4-km convection-permitting scale from January 2015 to June 2016. By quantifying model's internal variability and comparing the modeling results, results show that the simulated temperature, soil moisture, and surface energy fluxes are largely impacted by soil texture differences. For instance, changes in soil texture and associated hydrophysical parameters result in large differences in air temperature up to 1.7°C and surface heat flux up to 25 W/m2, and disparities in averaged surface soil moisture differ up to 0.1 m3/m3 in austral summer months. Differences in soil texture characteristics also regulate local climatic conditions differently in the wet and dry seasons as well as in different climatic regions. Furthermore, the thermodynamic differences in surface energy fluxes caused by soil texture demonstrate physical feedback perspective on atmospheric processes, resulting in distinct changes in planetary boundary layer height. This study demonstrates the non-negligible impact of soil data on land surface-atmosphere coupled modeling and highlights the need for consistent consideration of modeling uncertainties from soil data in modeling applications.

Impact of 30 years precipitation regime differences on forest soil physiology and microbial assemblages

Anthropogenic disturbances and climate change affect abiotic and biotic environmental drivers in forest ecosystems. Global warming impacts the soil moisture content, thus influencing the diversity, abundance and functioning of soil microfauna. However, limited studies have been conducted to evaluate the impact of long-term variation in precipitation on soil microfauna. A better understanding of soil microfauna functioning under various precipitation regimes can aid in formulating better prediction models for assessing future climate change impacts. The present study uses a multi-omics approach to capture the variability in the total organic carbon (TOC), total nitrogen (TN), pH, metabolites, microbial biomass and function due to the difference in soil water content mediated by long-term precipitation (30 years) and soil texture differences in two Norway spruce seed orchards. Results showed a positive correlation between TOC, TN, extracellular enzyme activities (EEAs) and phospholipid fatty acids (PLFA) content with higher precipitation, whereas microbial diversity showed an opposite trend. A distinct metabolic profile was observed between the two forest soils. Furthermore, variance partitioning canonical correspondence analysis (VPA) revealed a higher contribution of TOC and TN in shaping the microbial communities than soil pH and conductivity in Norway spruce seed orchards. Our study generates field data for modeling the impact of long-term precipitation variance supplemented by soil texture on soil microbial assemblage and function in Norway spruce stands.

Accurate Measurement of Frozen Soil Depth Based on I-TDR

In this study, a new method for determining the depth of frozen soil, Impulse Response Time Domain Reflectometry, is discussed. This method uses the principle of impedance measurement and the law of time–frequency domain convolution to convert the frequency-domain reflection signal into a time-domain signal and accurately determines the soil freezing front by measuring the difference between the impedance of frozen soil and unfrozen soil. The advantage of this method is that it solves the problems of small bandwidth, long rising edge time, and large measurement errors in the traditional TDR method to effectively improve the measurement accuracy of the soil-freezing front. Under laboratory conditions, soils of different textures (sand, loess, black soil, and red soil) were selected for experimental determination, and the results showed that compared with the traditional TDR method, the RMSE of the I-TDR method was small, and the method was applicable under different soil texture conditions, which could provide a new method for monitoring frozen soil in cold areas. In addition, the application of this method has important guiding significance for improving the efficiency of winter irrigation water, especially for guiding agricultural production, farmland irrigation, drainage engineering construction, meteorological frozen soil monitoring, and other aspects in cold and arid areas.

A Natural Moisture Gradient Affects Soil Fungal Communities on the South Shore of Hulun Lake, Inner Mongolia, China.

Soil moisture content (SWC) can change the diversity and composition of soil fungal communities by affecting soil texture and soil nutrients. To explore the response of soil fungal communities to moisture in the grassland ecosystem on the south shore of Hulun Lake, we set up a natural moisture gradient that was subdivided into high (HW), medium (MW), and low (LW) water contents. Vegetation was investigated by quadrat method, and aboveground biomass was collected by the mowing method. Soil physicochemical properties were obtained by internal experiments. The composition of the soil fungal community was determined using high-throughput sequencing technology. The results showed significant differences in soil texture, nutrients, and fungal species diversity under the moisture gradients. Although there was significant clustering of fungal communities in different treatments, the fungal community composition was not significantly different. According to the phylogenetic tree, the Ascomycota and Basidiomycota were the most important branches. The fungal species diversity was smaller when SWC was higher, and in this environment (HW), the fungal-dominant species were significantly related to SWC and soil nutrients. At this time, soil clay formed a protective barrier for the survival of the dominant classes Sordariomycetes and Dothideomycetes and increased their relative abundance. In summary, the fungal community responded significantly to SWC on the southern shore of the Hulun Lake ecosystem in Inner Mongolia, China, and the fungal community composition of the HW group was stable and easier to survive.

Construction and Assessment of a Drought-Monitoring Index Based on Multi-Source Data Using a Bias-Corrected Random Forest (BCRF) Model

Agricultural drought significantly impacts agricultural production, highlighting the need for accurate monitoring. Accurate agricultural-drought-monitoring models are critical for timely warning and prevention. The random forest (RF) is a popular artificial intelligence method but has not been extensively studied for agricultural drought monitoring. Here, multi-source remote sensing data, including surface temperature, vegetation index, and soil moisture data, were used as independent variables; the 3-month standardized precipitation evapotranspiration index (SPEI_3) was used as the dependent variable. Soil texture and terrain data were used as auxiliary variables. The bias-corrected RF model was used to construct a random forest synthesized drought index (RFSDI). The drought-degree determination coefficients (R2) of the training and test sets reached 0.86 and 0.89, respectively. The RFSDI and SPEI_3 fit closely, with a correlation coefficient (R) above 0.92. The RFSDI accurately reflected typical drought years and effectively monitored agricultural drought in Northeast China (NEC). In the past 18 years, agricultural drought in NEC has generally decelerated. The degree and scope of drought impacts from 2003 to 2010 were greater than those from 2010 to 2020. Agricultural drought occurrence in NEC was associated with dominant climatic variables such as precipitation (PRE), surface temperature (Ts), relative humidity (RHU), and sunshine duration (SSD), alongside elevation and soil texture differences. The agricultural drought occurrence percentage at 50–500 m elevations reached 94.91%, and the percentage of occurrence in loam and sandy soils reached 90.31%. Water and temperature changes were significantly correlated with the occurrence of agricultural drought. Additionally, NEC showed an alternating cycle of drought and waterlogging of about 10 years. These results have significant application potential for agricultural drought monitoring and drought prevention in NEC and demonstrate a new approach to comprehensively evaluating agricultural drought.

Ecological niches in the polyploid complex Linum suffruticosum s.l.

The high frequency of polyploidy in the evolutionary history of many plant groups occurring in the Mediterranean region is likely a consequence of its dynamic paleogeographic and climatic history. Polyploids frequently have distinct characteristics that allow them to overcome the minority cytotype exclusion. Such traits may enable polyploid individuals to grow in habitats different from their parentals and/or expand to new areas, leading to spatial segregation. Therefore, the successful establishment of polyploid lineages has long been associated with niche divergence or niche partitioning and the ability of polyploids to cope with different, often more stressful, conditions. In this study, we aimed to explore the role of environmental variables associated with the current distribution patterns of cytotypes within the polyploid complex Linum suffruticosum s.l.. The distribution and environmental niches of the five main cytotypes of Linum suffruticosum s.l. (diploids, tetraploids, hexaploids, octoploids and decaploids) were studied across its distribution range. Realized environmental niche of each cytotype was determined using niche modelling tools, such as maximum entropy modelling and niche equivalency and similarity tests. Differences in the environmental conditions of L. suffruticosum s.l. cytotypes were observed, with polyploids being associated with habitats of increased drought and soil pH, narrower temperature ranges and decreased soil water and cation exchange capacities. Diploids present the widest environmental niche, and polyploids occupy part of the diploid niche. Although some polyploids have equivalent potential ecological niches, cytotypes do not co-occur in nature. Additionally, the ecological niche of this polyploid complex is different between continents, with North African habitats being characterised by differences in soil texture, higher pH, and low cation exchange capacity, precipitation and soil water capacity and higher temperatures than habitats in southwest Europe. The different ecological conditions played a role in the distribution of cytotypes, but the mosaic distribution could not be entirely explained by the environmental variables included in this study. Other factors, such as reproductive isolation and competitive interactions among cytotypes, could further explain the current diversity and distribution patterns in white flax. This study provides relevant data on the niche requirements of each cytotype for further competition and reciprocal transplant experiments. further competition and reciprocal transplant experiments.

Analysis of critical water flow and solute transport parameters in different soils mixed with a synthetic zeolite

The addition of natural or synthetic zeolites alters a soil’s chemical, physical and biological properties. Due to the existence of a complex internal structure, zeolites have the potential to modify soil structure and texture with a direct impact on soil hydrological properties, introducing the possibility of controlling soil and groundwater pollution as well as irrigation management practices.In the present study, a series of laboratory tests were conducted on soil samples mixed with zeolite to investigate the possible changes in hydraulic and solute transport properties and related parameters. To determine the above properties, four soils of different textures were selected and two distinct groups of experiments were conducted on disturbed (i.e., repacked) soil samples by adding known amounts of zeolite (i.e., 1, 2, 5 and 10%; w/w). Solute transport properties were determined on one group of soil samples using the so-called Kachanoski approach to monitor miscible flow experiments. Soil hydraulic properties were determined on the second group of soil samples by measuring soil water retention curves (SWRCs) and saturated hydraulic conductivity (Ks). In general, we observed significant changes in the measured properties with zeolite percentages of 5% and 10%. However, some changes were also evident at 1% and 2% of zeolite addition. These observed differences may be mainly ascribed to changes in the soil’s pore size distribution due to the addition of a finer fraction (i.e., zeolite) to soils. This fraction reduces macropores (that are occluded in proportion to their amount) and thus enhances the formation of meso- and micropore regions.