Combination Of Soil Properties Research Articles

Does biochar mitigate rainfall-induced soil erosion? A review and meta-analysis

Biochar has emerged as a promising soil amendment for improving soil structure. Yet, its impact on rainfall-induced soil erosion varies across individual studies. To address this gap, we conducted a statistical meta-analysis of 174 paired comparisons from 45 published studies to integratedly evaluate the impacts of biochar on rainfall-induced soil erosion through biochar and soil properties, as well as experimental conditions. Overall, biochar significantly reduced soil erosion by 27.86%. The response ratio (lnRR) of biochar-induced soil erosion exhibited significant variability across different subgroups. Concerning biochar properties, a more favorable influence was observed in other sources biochar (e.g., manure and sewage sludge biochar) compared to wood based and crop waste biochar, and those produced at lower pyrolysis temperatures (< 500 °C). Increasing biochar dosage was not consistently effective. The optimal range was 0.8%–2%, resulting in a 36.07% reduction in soil erosion. Regarding the soil properties, a higher sand/clay ratio of soil significantly enhanced the performance of biochar (p < 0.0001). Specifically, an insignificant effect was observed in fine-grained soils, whereas the highest reduction of 52.97% was noted in coarse-grained soils. Moreover, long-term field experiments induced greater reductions in soil erosion with biochar (35.30%) compared to short-term laboratory studies (29.62% and 12.59%). This meta-analysis demonstrates that biochar, as a potential soil amendment, could effectively mitigate rainfall-induced soil erosion by considering a combination of soil properties along with specific biochar properties.

Effect of polylactic acid microplastics on soil properties, soil microbials and plant growth

Biodegradable plastic is considered one of the most promising alternatives to agricultural mulch. However, the impact of biodegradable microplastics on agricultural ecosystems is still lacking. We conducted a controlled experiment with polylactic acid microplastics (PLA MPs) to examine the effects of biodegradable plastic on soil properties, corn growth, the microbial community and hotspots of enzyme activity. The results showed that PLA MPs in soil significantly reduced the soil pH value but increased the soil C:N ratio. High levels of PLA MPs significantly reduced the biomass of plant shoots and roots as well as chlorophyll, leaf C and N and root N contents. PLA MPs increased bacterial abundance but decreased the abundance of dominant fungal taxa. As the level of PLA MPs increased, the soil bacterial community structure became more complex, while the fungal community became more singular. The results of the in situ zymogram showed that low levels of PLA MPs increased the hotspots of enzyme activity. The effect of PLA MPs on enzyme activity hotspots was regulated by a combination of soil properties and microbial diversity. Generally, the addition of PLA MPs at high concentrations will have a negative impact on soil characteristics, soil microbials and plant growth in a short period of time. Therefore, we should be aware of the potential risks of biodegradable plastic to agricultural ecosystems.

An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation

A simple explicit formula was derived to determine the maximum irrigation depth (Dmax) that can be applied per irrigation without any runoff under a center pivot and/or linear move irrigation system. The analysis is built on the assumption that Dmax is achieved when the water application rate is tangential to the Green-Ampt infiltration rate function. The surface storage was not considered here but tillage effects can be inherently incorporated if parameters of the Green-Ampt equation are properly measured. A power form formula was proposed to simulate the infiltration rate, while the application rate pattern had a parabolic shape. The proposed equation for Dmax is a function of soil saturated hydraulic conductivity, sorptivity, and the peak application rate. Numerical examples covering different combinations of soil properties and peak application rates indicated the high accuracy of the proposed formula with maximum and average absolute errors of 1 and 0.4 mm from the numerical stepwise solution, respectively. The quick calculation of Dmax here allows us to easily estimate a minimum lateral speed that will not trigger runoff under center pivots.

Агроэкологическая оценка засоления почв

In the conducted studies, the influence of salinization on the soil-plant system on the soils of Russia and Vietnam was evaluated. It is shown that the nature and degree of soil salinization vary over time and in space, including on individual elements of meso- and microrelief. For soils, plants and biota, it is advisable to allocate their optima and maximum permissible salinity concentrations. They differ for different soils, for individual plant species and microorganisms. It is shown that optimal and acceptable indicators of soil salinity differ from a combination of parameters of plant life factors and soil functioning: temperature, humidity, combination of soil properties, phases of soil and plant development, etc. It was found that the composition of the soil extract differs significantly from the composition of the soil solution not only in the concentration of salts, but also in their composition, which must be taken into account in the agroecological assessment of salinity. The possibility of increasing the resistance of plants to soil salinization when they are fed with biophilic elements, stimulants, complexons is shown. Keywords: SALINIZATION, PLANTS, MAXIMUM PERMISSIBLE CONCENTRATIONS, OPTIMIZATION

Проблемы агроэкологической оценки плодородия почв

The paper proves the need to clarify the agroecological assessment of soils, taking into account the migration of substances, the non-exchange fixation of biophilic elements by the soil, the relationship between the properties of soils, the intensity and speed of soil-forming processes, and the manifestation of the law of decreasing fertility. It is shown that on well-cultivated sod-podzolic soils of the Moscow region, the losses of elements with high water and ground water averaged 19.3 and 6.9 kg/ha of N-NO3, 0.7 and 1.2 N-NH4 in the crop rotation. Losses with surface-runoff waters were: nitrogen-2.2 kg / ha, potassium-7.0; calcium-11.0; magnesium-6.0; phosphorus-0.9 kg / ha per year. When the Ca/K ratio in the soil solution of this soil was 0.44±0.03 and 2.7±0.1, the content of water – soluble iron was 57.9±7.4 and 5.3±0.7 mg/l, respectively; manganese-2.3±0.4 and 1.1±0.2 mg/l. It is shown that plants consume biophilic elements from different soil horizons, which must be taken into account in the balance of biophilic elements. It is shown that the optimal soil properties differ depending on the hydrothermal conditions of the territory, the combination of soil properties. It is proved that in order to choose the optimal crops for growing on certain soils, it is necessary to take into account the alienation of energy with the crop. Keywords: SOIL FERTILITY, FERTILIZERS, BALANCE, ECONOMIC EFFICIENCY

Soil nematode communities on five oceanic islands across a latitudinal gradient in the north of the South China Sea: Influence of biotic and abiotic factors

Factors that influence the composition and diversity of soil nematode communities on oceanic islands are poorly understood. In this study, we evaluated the soil nematode communities and associated biotic and abiotic factors on five oceanic islands in the north of the South China Sea. We detected 38 nematode genera and found that bacterivores and fungivores were the dominant trophic groups, representing 54.2–70.4% and 15.1–35.3%, respectively, of total soil nematode abundance. The abundances of total soil nematodes and of all trophic groups, maturity, structure indices and nematode diversity were positively correlated with island latitude and area, and were negatively correlated with soil total K and annual temperature. In addition, the abundances of total soil nematodes, bacterivores, herbivores and nematode dominance index were positively associated with soil available K. The abundances of total soil nematodes, fungivores, herbivores, predators and omnivores, maturity, structure, Shannon diversity indices were positively related to soil moisture. Variation partitioning analysis showed that the combination of soil properties and climatic-geographical factors explained more of the variation (26.8–61.5%). The results suggest that larger island can maintain greater nematode diversity than smaller islands due to the greater diversity of habitats on larger island. The key climatic-geographical and edaphic factors affecting soil nematode communities were latitude, annual temperature, soil moisture and total K, respectively

Maximum dry density of sand–kaolin mixtures predicted by using fine content and specific gravity

Numerous studies have covered the comparison of maximum dry density (MDD) toward the combination of soil properties and compaction parameters. These combinations are dominated by Atterberg limits, moisture content, and compaction effort. Nevertheless, minimal efforts have been expended in predicting the MDD using two simple soil properties, i.e., fine content (FC) and specific gravity (Gs). Sand–kaolin mixtures were compacted and then used to examine the correlation between MDD, FC, and Gs through different moisture content, and FC ranged from 20 to 70%. The results showed the importance of considering both Gs and FC in the correlation estimation in order to reduce the uncertainty of using only FC as a single parameter. A linear relationship was obtained with an excellent correlation coefficient (R2 = 0.99) between MDD and the ratio of FC/Gs2. The empirical correlation equation was justified using data from 163 measured MDD obtained from previous studies. All predicted MDD were within the confidence interval of ± 10, which confirmed a low error range of the predicted MDD. The application of the equation was limited to FC and FC/Gs less than 77% and 0.302, respectively. It should, however, be noted that the presence of a high amount of gravel in the soil mixture will not be applicable for this correlation.

Properties, processes and regimes of soil solutions and surface waters

Soil solutions and the surface waters are characterized by properties, processes and regimes. Soil solutions of different soils and their surface water have different biological activity and change the activity of dissolved stimulants and inhibitors. The object of the study are soil solutions of the main types of soils obtained in the model experiments with the ratio of soils: water equal to 1:1 and 1: 2, soil solutions and surface water in the flooding of soils with water for 1 week – 3 months. The research method consisted in the assessment of pH, Eh, activity of K, NO3, NH4, Ca, Mg by conventional methods, assessment of concentrations of water-soluble compounds extracted from soils by ionite membranes, in the assessment of biological activity of solutions using biotests. The following is suggested for additional evaluation: the using of cation and anion membranes, determination of interrelation between the properties of waters, equation of pair correlation and multiply regression. The informative value of the gradient of surface water concentrations at different distances from the floor of the reservoir, at different depths of the overwatered soils is shown. The mobility of Ca, Mg, Fe, Mn in soils and the content of their water-soluble forms depends on both pH and Eh, whose influence on the content of water-soluble forms of the considered cations shows the effects of synergy and antagonism. The rate of change in the composition of soil solutions during soil flooding depends on a combination of soil properties, temperature, and duration of flooding. Soil solutions of different soils and their surface waters have differentrates.

Combinations of soil properties, carbon inputs and climate control the saturation deficit dynamics of stable soil carbon over 17-year fertilizaiton

The soil organic carbon (SOC) saturation deficit (Csd) of silt and clay fractions represents the potential for SOC sequestration in a stable form and can influence organic C stabilization efficiency. Little is known, however, about temporal changes of stable soil Csd and how it is affected by soil properties, climate and C inputs. We investigated the temporal changes in the Csd of fine fractions (<53 μm) and examined the factors controlling these changes at three dry-land sites with 17-year fertilizer management histories in China. The rates of change in the stable soil Csd under manure treatments varied from −0.72 to −1.24% yr−1 after 17 years of fertilization, indicating that stable C levels under manure treatments were significantly higher than those under other treatments. Stable soil Csd was controlled by a combination of soil properties, temperature, and C inputs at all sites, and the higher variance of Csd of fine fractions can be explained by the soil properties (up to 50%). Furthermore, the quantity of C inputs was the most influential variable for stable soil Csd. These results revealed key controls on stable C sequestration potential and indicated the need to develop management strategies to promote stable C sequestration under long-term intensive fertilization.

Estimation of infiltration rate from soil properties using regression model for cultivated land

ABSTRACTThe study was conducted on cultivated land at College of Agricultural Engineering and Post Harvest Technology (CAEPHT campus), Ranipool, Gangtok, Sikkim, India. Twenty five points were identified at 10 m grid interval and field measurements were performed using double ring infiltrometer method. Result of soil analysis suggests sandy loam and loamy sand texture and the bulk density and particle density have varied from 1.412–1.716 g/cm3 and 2–3.03 g/cm3, respectively. The basic infiltration rate has varied from 0.3 cm/h to 6.8 cm/h. Result show that sand, particle density and organic carbon content have a positive correlation with infiltration rate by 0.75, 0.18 and 0.22, respectively, whereas silt, clay, bulk density and moisture content, have a negative correlation with infiltration rate by −0.41, −0.73, −0.33 and −0.22, respectively. The analysis performed for five classes considering the combination of soil properties and subjected to regression analysis. Result shows that in order to predict soil infiltration rate based on few properties of soil with seven independent variables, multi-linear regression model EIR = -30,578.81–305.56(sand%)-306.16(silt%)-0.306.33(clay%)-5.18(BD%)+.34(MC%)+4.18(PD)+16.85(OC%) with R2(0.80), mean RMSE (1.52) and standard error (2.39) is the best model for the estimation of infiltration rate and recommended for the study area.

Multiple linear modeling between soil properties, magnetic susceptibility and heavy metals in various land uses

Land use and intrinsic soil properties play vital role in variability of heavy metals and magnetic susceptibility within a landscape. This study was conducted to use multiple linear regressions modeling to explore the variability of magnetic susceptibility and heavy metals within five different land uses and to find the interaction of these variables with intrinsic soil properties in Ahvaz district, Khuzestan Province, Southern Iran. Five land uses included urban area, agricultural land, steel company, Zargan Power Plant, and Ramin Power Plant. Twenty soil samples from each land use and totally one hundred samples from 0 to 5 cm topsoil were randomly collected. Some chemical and physical soil properties, magnetic susceptibility as well as concentration of some heavy metals were measured. The results showed that significant correlations were found between heavy metals and magnetic susceptibility at low frequency (χlf), showing high capability of magnetic susceptibility for prediction of heavy metals. Calcium carbonate equivalent and soil organic matter (SOM) showed negative correlation with χlf, while SOM and clay content had substantial influences on variability of heavy metals in the studied area. The results of the comparison among land uses showed that Cr, Ni were the highest in agricultural land because of the application of the sewage sludge and fertilizers, while the metals (ZN, Mn, Cu, Co and Fe) and χlf were the highest in steel company due to the industrial activities. Multiple linear regression analysis showed that the combination of soil properties and magnetic susceptibility could explain 94, 62, 69, 53, 81, 77 and 57% of the variability in Fe, Mn, Cu, Zn, Ni, Co and Cr, respectively.

FORMATION OF ENVIRONMENTALLY FRIENDLY AGRICULTURAL LAND AS A PRIORITY OF GREENING THE ECONOMY OF REGIONAL SYSTEM

Questions of creation the environmentally friendly agricultural land as a priority direction of greening the economy of regional system are considered. The role of environmentally friendly land as part of a balanced agricultural nature, quality characteristics which are the basis of agro-ecosystems preservation, productivity increasing, prevent degradation and agricultural landscapes restoration is analyzed. The article presents the issue of improving soil quality continues needs to be urgent. In particular, the task of improving the quality of agricultural land and considering the qualitative characteristics as an object of management remains unresolved, which necessitates further systematic research in this direction. The purpose of the article is to substantiate the essence of soil quality management, the creation of land masses with appropriate soil characteristics as a means of obtaining safe products of standardized quality, maintaining the quality of the natural environment, preventing its degradation and using innovative industrial technologies in alternative agricultural systems. It is substantiated that qualitative soil properties and fertility are inextricably linked. The processes of soil formation and soil fertility are determined by a number of natural factors and the nature of economic activity, which affects not only the arable layer but also deeper soil horizons, as well as groundwater and groundwater. The optimal parameters of fertility indices should be established for each type of soil, ie they can vary according to the fertility patterns as a combination of soil properties and modes that ensure the productivity of the land, the high quality and safety of the agricultural products derived from them. It is determined that the management of ecological agriculture will facilitate the creation of land uses with special characteristics, which are achieved through the implementation of the general laws of agriculture and a number of principles, among which the principles of environmental orientation are combined with the principles that facilitate their implementation.

QUALITY OF SOIL IN THE SYSTEM OF AGRO ECONOMIC NATURAL USE SUPPLYING

The article presents the issue of improving soil quality continues needs to be urgent. In particular, the task of improving the quality of agricultural land and considering the qualitative characteristics as an object of management remains unresolved, which necessitates further systematic research in this direction. The purpose of the article is to substantiate the essence of soil quality management, the creation of land masses with appropriate soil characteristics as a means of obtaining safe products of standardized quality, maintaining the quality of the natural environment, preventing its degradation and using innovative industrial technologies in alternative agricultural systems. It is substantiated that qualitative soil properties and fertility are inextricably linked. The processes of soil formation and soil fertility are determined by a number of natural factors and the nature of economic activity, which affects not only the arable layer but also deeper soil horizons, as well as groundwater and groundwater. The optimal parameters of fertility indices should be established for each type of soil, ie they can vary according to the fertility patterns as a combination of soil properties and modes that ensure the productivity of the land, the high quality and safety of the agricultural products derived from them. It is determined that the management of ecological agriculture will facilitate the creation of land uses with special characteristics, which are achieved through the implementation of the general laws of agriculture and a number of principles, among which the principles of environmental orientation are combined with the principles that facilitate their implementation.

Delineation of irrigation management zones in a Quartzipsamment of the Brazilian semiarid region

Abstract The objective of this work was to delineate irrigation management zones using geostatistics and multivariate analysis in different combinations of physical and hydraulic soil properties, as well as to determine the optimal number of management zones in order to avoid overlaping. A field experiment was carried out in a Quartzipsamment, for two years, in an irrigated orchard of table grape, in the Senador Nilo Coelho Irrigation Scheme, in the municipality of Petrolina, in the state of Pernanbuco, Brazil. Soil samples were collected for the determination of soil physico-hydraulic properties. A portable meter was used to measure soil apparent electrical conductivity. Spatial distribution maps were generated using ordinary kriging. Management zones for five different combinations of soil properties were defined using the fuzzy c-means clustering algorithm, and two indexes were applied to determine the optimal number of management zones. Two combinations of soil properties can be used in the management zone planning in order to monitor soil moisture.

Relationships of soil shrinkage parameters and indices with intrinsic soil properties and environmental variables in calcareous soils

This study was conducted to derive the relationships of soil shrinkage parameters and indices with soil and environmental variables in calcareous soils. Ninety nine undisturbed clods were collected from surface soils in hilly regions of Cherlgerd, western Iran. Soil shrinkage curve was measured based on Archimedes' principle, by covering the clods with an acrylic resin. The shrinkage curve data were modeled using Peng and Horn (2005) model. The model's fitting parameters and several shrinkage indices (i.e. relative void ratio changes, mean slopes at various shrinkage zones, coefficient of linear extensibility, and total and relative shrinkage capacities) were predicted using multiple linear regression models by including soil properties (pedotransfer functions, PTFs) and by combination of soil properties and environmental variables (soil spatial prediction functions, SSPFs) as inputs. The results showed that, on average, the structural, proportional, residual and zero shrinkage zones comprised 17.2, 66.2, 15.2 and 1.4% of total shrinkage for the studied soils. The shrinkage capacity (ShC) and relative shrinkage capacity (Δetotal-rel) varied, respectively, in the ranges 0.204–0.641 and 0.288–0.589 in the studied soils. While clay fraction increased the ShC and Δetotal-rel, organic matter had a diminishing effect on the Δetotal-rel. An extended structural zone was observed in fine-textured soils, presumably due to greater aggregation. Volume change in the structural shrinkage zone was greater in weakly-structured calcareous soils because carbonates would minimize resistance of aggregates against the shrinkage forces. PTFs could explain 12–48% of variability of the model's parameters, and the inclusion of topographic attributes (i.e. SSPFs) significantly increased R2 values. Developed PTFs could explain 11–41% of variability of the shrinkage indices. The particle size fractions and relative bulk density were identified as most important soil properties for the prediction of shrinkage indices. Overall, the use of SSPFs by including topographic attributes such as dispersal area, elevation, surface curvature and plan curvature and normalized difference vegetation index (NDVI) could improve the performance of the prediction functions for soil shrinkage indices.

Effects of soil properties on the uptake of pharmaceuticals into earthworms

Pharmaceuticals can enter the soil environment when animal slurries and sewage sludge are applied to land as a fertiliser or during irrigation with contaminated water. These pharmaceuticals may then be taken up by soil organisms possibly resulting in toxic effects and/or exposure of organisms higher up the food chain. This study investigated the influence of soil properties on the uptake and depuration of pharmaceuticals (carbamazepine, diclofenac, fluoxetine and orlistat) in the earthworm Eisenia fetida. The uptake and accumulation of pharmaceuticals into E. fetida changed depending on soil type. Orlistat exhibited the highest pore water based bioconcentration factors (BCFs) and displayed the largest differences between soil types with BCFs ranging between 30.5 and 115.9. For carbamazepine, diclofenac and fluoxetine BCFs ranged between 1.1 and 1.6, 7.0 and 69.6 and 14.1 and 20.4 respectively. Additional analysis demonstrated that in certain treatments the presence of these chemicals in the soil matrices changed the soil pH over time, with a statistically significant pH difference to control samples. The internal pH of E. fetida also changed as a result of incubation in pharmaceutically spiked soil, in comparison to the control earthworms. These results demonstrate that a combination of soil properties and pharmaceutical physico-chemical properties are important in terms of predicting pharmaceutical uptake in terrestrial systems and that pharmaceuticals can modify soil and internal earthworm chemistry which may hold wider implications for risk assessment.

Soil quality index for evaluation of reclaimed coal mine spoil

Success in the remediation of mine spoil depends largely on the selection of appropriate tree species. The impacts of remediation on mine soil quality cannot be sufficiently assessed by individual soil properties. However, combination of soil properties into an integrated soil quality index provides a more holistic status of reclamation potentials of tree species. Remediation potentials of four tree species (Acacia auriculiformis, Cassia siamea, Dalbergia sissoo, and Leucaena leucocephala) were studied on reclaimed coal mine overburden dumps of Jharia coalfield, Dhanbad, India. Soil samples were collected under the canopies of the tree species. Comparative studies on the properties of soils in the reclaimed and the reference sites showed improvements in soil quality parameters of the reclaimed site: coarse fraction (−20.4%), bulk density (−12.8%), water holding capacity (+0.92%), pH (+25.4%), EC (+2.9%), cation exchange capacity (+46.6%), organic carbon (+91.5%), N (+60.6%), P (+113%), K (+19.9%), Ca (+49.6%), Mg (+12.2%), Na (+19.6%), S (+46.7%), total polycyclic aromatic hydrocarbons (−71.4%), dehydrogenase activity (+197%), and microbial biomass carbon (+115%). Principal component analysis (PCA) was used to identify key mine soil quality indicators to develop a soil quality index (SQI). Selected indicators include: coarse fraction, pH, EC, soil organic carbon, P, Ca, S, and dehydrogenase activity. The indicator values were converted into a unitless score (0–1.00) and integrated into SQI. The calculated SQI was significantly (P<0.001) correlated with tree biomass and canopy cover. Reclaimed site has 52–93% higher SQI compared to the reference site. Higher SQI values were obtained for sites reclaimed with D.sissoo (+93.1%) and C.siamea (+86.4%).

Estimating wet soil aggregate stability from easily available properties in a highly mountainous watershed

A comparison study was carried out with the purpose of verifying when the adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN), generalized linear model (GLM), and multiple linear regression (MLR) models are appropriate for prediction of soil wet aggregate stability (as quantified by the mean weight diameter, MWD) in a highly mountainous watershed (Bazoft watershed, southwestern Iran). Three different sets of easily available properties were used as inputs. The first set (denoted as SP) consisted of soil properties including clay content, calcium carbonate equivalent, and soil organic matter content. The second set (denoted as TVA) included topographic attributes (slope and aspect) and the normalized difference vegetation index (NDVI). The third set (denoted as STV) was a combination of soil properties, slope, and NDVI. The ANN and ANFIS models predicted MWD more accurately than the GLM and MLR models. Estimation of MWD using TVA data set resulted in the lowest model efficiency values. The observed model efficiency values for the developed MLR, GLM, ANN, and ANFIS models using the SP data set were 60.76, 62.98, 77.68 and 77.15, respectively. Adding slope and NDVI to soil data (i.e. STV data set) improved the predictions of all four methods. The obtained correlation coefficient values between the predicted and measured MWD for the developed MLR, GLM, ANN, and ANFIS models using STV data set were 0.24, 0.35, 0.84 and 0.73, respectively. In conclusion, the ANN and ANFIS models showed greater potential in predicting soil aggregate stability from soil and site characteristics, whereas linear regression methods did not perform well.

Scale dependent effects of environmental factors on vegetation pattern and composition in Horqin Sandy Land, Northern China

Understanding the relationship between vegetation–environment is very important to manage arid and semiarid ecosystems. However, information on how environment factors influence the vegetation patterns at different spatial scales in semiarid area ecosystem is lacking. We measured vegetation compositions and environment characteristics form 55 sample sites in grassland habitat (flood plain grassland, wet meadow, dry meadow) and sand dune habitat (fixed dune, semi-fixed dune, mobile dune) in Horqin Sandy Land. Multivariate analyses were used to examine the relationship between vegetation patterns and environment factors at the two scales of habitat and region. Vegetation cover, aboveground biomass, soil organic carbon (C), total nitrogen (N) and soil water content decreased from grassland habitat to sand dune habitat. Vegetation cover increased with the increase in soil water content in grassland habitat. Vegetation cover, species diversity and aboveground biomass increased with the increase in soil organic C, total N and EC in sand dune habitat. The most important complex gradient determining vegetation pattern and composition showed a region scale relationship with the combination of soil properties and topography features. Soil water content, EC and altitude were closely related to the vegetation distribution in grassland habitat, whereas soil organic C, total N and EC were significantly related to the vegetation distribution in sand dune habitat. Our results suggest that vegetation–environment relationships are dependent on the scale of observation. Thus, the interpretation of the vegetation pattern and composition in semiarid area needs to consider the spatial scales and habitats at which important environmental variables actually vary.

AEOLIAN PROCESSES AND THE BIOSPHERE

Aeolian processes affect the biosphere in a wide variety of contexts, including landform evolution, biogeochemical cycles, regional climate, human health, and desertification. Collectively, research on aeolian processes and the biosphere is developing rapidly in many diverse and specialized areas, but integration of these recent advances is needed to better address management issues and to set future research priorities. Here we review recent literature on aeolian processes and their interactions with the biosphere, focusing on (1) geography of dust emissions, (2) impacts, interactions, and feedbacks, (3) drivers of dust emissions, and (4) methodological approaches. Geographically, dust emissions are highly spatially variable but also provide connectivity at global scales between sources and effects, with “hot spots” being of particular concern. Recent research reveals that aeolian processes have impacts, interactions, and feedbacks at a variety of scales, including large‐scale dust transport and global biogeochemical cycles, climate mediated interactions between atmospheric dust and ecosystems, impacts on human health, impacts on agriculture, and interactions between aeolian processes and dryland vegetation. Aeolian dust emissions are driven largely by, in addition to climate, a combination of soil properties, soil moisture, vegetation and roughness, biological and physical crusts, and disturbances. Aeolian research methods span laboratory and field techniques, modeling, and remote sensing. Together these integrated perspectives on aeolian processes and the biosphere provide insights into management options and aid in identifying research priorities, both of which are increasingly important given that global climate models predict an increase in aridity in many dryland systems of the world.