Soil Physical Conditions Research Articles

Field-Based Environmental Chemistry Course for Interdisciplinary, Project-Based Learning

Faculty in the Chemistry and Environmental Science programs at St. Mary’s University in San Antonio, Texas, collaborated to develop an undergraduate course in Field-Based Environmental Chemistry. The course was developed and implemented as a 2-semester, 1-semester, and online, synchronous course offered during the 2020/21 COVID-19 pandemic. As part of the course, chemistry and environmental science majors designed and executed a sampling and laboratory analysis plan for monitoring the physical and chemical conditions of soil and/or water in a local, urban setting. As part of a goal to help students develop communication skills, they presented their work to stakeholders from the local community. Through participation in an active learning model, students demonstrated significant gains in the student learning outcomes. Students in the 2-semester sequence showed gains in their understanding of the scientific process, more comfort with the uncertainty and the ambiguity of natural environments, and appreciation for the importance of statistics in data analysis. The online course and COVID-19 pandemic restrictions did not allow for student field or laboratory work but did engage students in a project typical of a work environment.

Terroir Traceability in Grapes, Musts and Gewürztraminer Wines from the South Tyrol Wine Region

This study arose from the need to relate specific terroir aspects with experienced sensory properties of Gewürztraminer wines from Tramin (northern Italy). A multidisciplinary approach was used to investigate seven vineyards’ ecological characteristics, including geology and geographical features. A geopedological method using Vineyard Geological Identity (VGI) and Solar Radiation Identity (SRI) for topoclimatic classification, as well as multi-parameter measuring stations of air and soils, elicited analytical data for qualitative and quantitative terroir characterisations. Furthermore, wide-ranging and targeted oenological and chemical analyses were conducted on grapes, musts and wines to correlate their biochemical compositions with the measured terroir conditions. The study identified strong connections between vineyard geo-identity and wine mineral fingerprint, confirming mineral traceability of Rb/Sr ratio and of some minerals common to the local geology, such as Ba, Rb, Mn and Be. In particular, the most differing geo-mineral and physical soil conditions of two studied vineyards are apparent in the oenological components, flavours and aromas of their musts and finished wines. Amino acids, primary varietal aromas and polyphenols, thiol compounds with tropical scents, phenolic compounds with spicy notes and terpenic compounds, such as geraniol and citronellol, were related differently between fine-textured, more siliceous soils of glacial origin and coarser-textured, more dolomitic soils of local debris flow origin.

Ecological resilience of physical plant-soil feedback to chronic deer herbivory: Slow, partial, but functional recovery.

Ecological resilience to ungulate overbrowsing is an important issue in forest ecosystems. After chronic herbivory, the recovery rate of understory vegetation and its related functions can be slow even with decreasing grazing intensity; thus, detecting elasticity during alternative successional trajectories is fundamental to understanding state perturbations. In this context, we focused on physical plant-soil feedback (functional interactions between plant growth and soil physical conditions) and evaluated elasticity and recovery processes according to deer density. The effects of 40 years of chronic herbivory by sika deer (average density 14.7 individuals km-2 ) on the recovery of understory plant communities and associated changes in soil physical properties in headwater catchments were assessed. Using 8 years of catchment-wide exclusion (fenced) and reduction (only culled; average 4.3 individuals km-2 ) treatments, plot sampling was conducted in 2010 (before treatment) and 2018 (after treatment). The recovery of vegetation and soil physical properties were evaluated, and functional plant-soil relationships and spatial variability were assessed to detect recovery processes during alternative successional trajectory. Woody species increased only under the exclusion treatment and the average soil bulk density was lower than that under reduction treatments. Soil bulk density was negatively correlated with root biomass in the fenced catchment, and root biomass was positively associated with woody species richness. Reduced soil bulk density (~0.5g cm-3 ) was observed with greater root biomass and woody species richness on upper hillslopes in the deer-excluded catchment where plant coverage was minimal. Successional failure under the reduction treatment suggested slow recovery with a depressed threshold according to deer density, indicating a clockwise hysteretic response to deer density. Unlike plant coverage during the earlier period of overbrowsing, woody species root development led the recovery of functional physical plant-soil feedback; however, this was probably limited by the higher soil erosion rate in riparian areas and an under-developed herb layer. Our results highlight an alternative recovery trajectory of physical plant-soil feedback driven by an alternative plant element (woody roots) to recovery trajectory with increasing plant cover. However, riparian erosion and herb layer would still suppress recovery. Therefore, recovery might be slower at the landscape scale.

Swot analysis of utilization of palm oil mill effluent to improve soil quality and crop productivity (case study at PT X, Lampung, Indonesia)

Crude Palm Oil (CPO) manufacturing in palm oil processing plants produces by- products known as palm oil mill effluent (POME). POME can improve the physical and chemical properties of the soil because it contains nutrients N, P, K, Mg, and Ca. One of the companies that have processed and utilized POME is PT X, Lampung Province, Indonesia. This study was conducted to analyze the strengths, weaknesses, opportunities, and threats (SWOT) of the effect of using POME on oil palm plantations for waste quality, physical soil conditions, soil chemical conditions and productivity of oil palm plants. The methodology of the research was using descriptive statistical methods of the secondary data and SWOT analysis. The results showed that the palm oil effluent applied in the PT X complied with the national quality utilization and waste management standards. The POME application has a beneficial effect on soil conditions. The involved area had higher pH, N, P, K, Ca, and Mg than control, but C- Organic and CEC in the application area were lower. Furthermore, the application of palm oil effluent tends to increase crop productivity in a range of 7.57 - 63.23%. The primary strategy obtained from the SWOT analysis is that it is necessary to conduct an intensive assessment and to implement appropriate and proper management and application. This recommended strategy is to get the value of the application of palm oil liquid waste suitable for a long-term sustainable waste application for soil and plants to improve the physical and chemical properties of the soil optimally.

The influence of seed-drill choice on crop performance in a semi-arid production region of South Africa

A seed-drill should facilitate seed placement in an environment conducive to uniform seedling emergence. In semi-arid rain-fed production regions, low rainfall intensity and erratic rainfall events can result in non-uniform emergence. Evaluation of seed-drills is necessary to supply small grain producers with potential solutions to combat non-uniform seedling emergence. The aim of this study was to investigate the influence of three seed-drills on seeding depth, crop emergence, biomass production and yield over the duration of two growing seasons. Barley, canola and wheat were established with three seed-drills, each equipped with a different opener. Seed-drills contained either double disc openers, tine openers, or a combination of both tines and single discs. Crops responded variably to seeding equipment under different climatic conditions. For example, accuracy of seeding depth varied between the three seed-drills utilised. Seed-drills, together with their associated seed placement characteristics, influenced crop emergence. Biomass production was variable over the course of the growing season. Biomass production of crops established with the double disc seed-drill tended to be higher than that of crops established with tine seed-drills. Additional research about adaptations of agronomic practices and seed-drill openers may increase resilience to adverse climatic conditions in semi-arid small grain production regions. Various factors, including soil physical conditions, environmental conditions, economic feasibility and practical applications must be taken into consideration when selecting a seed-drill.

Soil erodibility assessment of laterite dominant sub-basin watersheds in the humid tropical region of India

Sub-basin prioritization is an essential aspect of watershed development initiatives as a part of the sustainable management program for natural resources. The present work aims to analyse the soil erodibility at sub-basin scale in the Pathro River Basin area of Jharkhand, India. Degradation of land resources is multifaceted, and its severity leads to soil detachment, thus rendering it a complex and interlinked system. Sixteen closely correlated morphometric attributes of the erosion process are considered for prioritizing watersheds by applying the frequency ratio (FR) method. This work assigns Support Vector Machine (SVM) algorithm to evaluate the existing soil risk condition with the help of twelve soil erosion influencing geo-environmental factors at the sub-basin area. Soil samples were examined using scanning electron microscopy with energy dispersive x-ray analysis (SEM-EDX) to acquire the micro-graphic and physical condition of dominant soil forming minerals and their influences to develop susceptibility of peds to erode. The prioritisation results from both approaches show a reasonably similar output, identifying nine sub-watersheds as very high soil erosion-prone, while four sub-watersheds are recognised as low-risk. Field observation reveals that lowering of plunge pool and head retreat are dominant processes of gully extension in very high to high sub-basin prioritization areas. The final output provides a comprehensive platform for the urgency of policy interventions to minimize erosion risk and ecological damage in prioritized areas of Pathro River Basin, Jharkhand.

Soil Chemistry Character, the N, P, and K Uptake, and the Growth and Yield of Corn (Zea mays L.) Due to the Application of Ela Sago Palm Waste Compost and Liquid Organic Fertilizer in Ultisols

Application of organic matter (compost Sago Ela palm waste and Liquid Organic fertilizers (LOF)) to the soil could have major benefits, such as to improve the soil physical condition (soil structure, water retention), and soil chemical properties (binding and providing nutrients, increasing CEC). The purpose of this study are (1) to improve the soil chemical properties of Ultisols, and (2) to increase plant uptake of N, P, and K, and the growth and yield of corn (Zea mays L.). The research was conducted in the field, namely in Telaga Kodok Village, Leihitu Sub District, and Central Maluku District. The experiment was designed in a factorial, and arranged in a randomized completed block design (RCBD). The first factor was the provision of compost Sago Ela palm waste (K) and the second factor was the provision of liquid fertilizer (C). The results showed that the compost combined with LOF could improve pH, Al-exchangeable, Total-N, P-available soil, Uptake-P, Uptake-K, and the dry weight of seed corn. While the treatment of sago Ela palm waste compost and LOF can independently raise the K-available soil, N-uptake, and affect corn’s plant growth (height and trunk diameter). The treatment doses of sago Ela palm waste compost of 60 Mg ha-1 and LOF of 20 mL L-1 solution can increase the exchangeable Al, Total-N, and P-available soil, respectively 0.56 cmol(+)kg-1, 0.21%, and 31.00 mg kg-1; also able to increase the uptake of P, K, and weight dry seed corn respectively 0.21% and 1.26%, and 121.33 g plant-1. The treatment doses of Sago Ela palm waste compost of 60 ton ha-1 and liquid organic fertilizer of 10 mL L-1 solution can increase the soil pH by 5.70.

Ecological management model for the improvement of soil fertility through the regulation of rare microbial taxa in tea (Camellia sinensis L.) plantation soils

Agricultural management is essential to enhance soil ecosystem service function through optimizing soil physical conditions and improving nutrient supply, which is predominantly regulated by soil microorganisms. Several studies have focused on soil biodiversity and function in tea plantation systems. However, the effects of different agriculture managements on soil fertility and microbes remain poorly characterized, especially for what concerns perennial agroecosystems. In this study, 40 soil samples were collected from 10 tea plantation sites in China to explore the effects of ecological and conventional managements on soil fertility, as well as on microbial diversity, community composition, and co-occurrence network. Compared with conventional management, ecological management was found to significantly enhance soil fertility, microbial diversity, and microbial network complexity. Additionally, a significant difference in community composition was clearly observed under the two agriculture managements, especially for rare microbial taxa, whose relative abundance significantly increased under ecological management. Random forest modeling revealed that rare taxa (e.g., Rokubacteria and Mortierellomycota), rather than dominant microbial taxa (e.g., Proteobacteria and Ascomycota), were key variables for predicting soil fertility. This indicates that rare taxa might play a fundamental role in biological processes. Overall, our results suggest that ecological management is more efficient than conventional management in regulating rare microbial taxa and maintaining a good soil fertility in tea plantation systems.

Conservation systems change soil resistance to compaction caused by mechanised harvesting

Soil compaction in sugarcane plantation has increased in recent times due to intense mechanization of the production process and the increasing axle load of the machines. As such, there are need to evolve conservation systems which will minimize soil disturbance in sugarcane production thereby preventing soil structure degradation and maintain the soil quality, using appropriate compaction models. Thus, the objective of this study was to evaluate the impact of sugarcane harvesting operation under cover crop management systems and soil tillage practices implemented before sugarcane planting using load-bearing capacity models (LBCM). The experiment was set up in a randomised block design with three soil management systems (no tillage, minimum tillage, and minimum tillage combined with a deep subsoiler) and two crop rotations (peanut and sorghum). Soils samples were collected at three depths before and after sugarcane harvesting. The undisturbed soil samples were submitted to the uniaxial compression test, their precompression stress was determined and, afterwards the load-bearing capacity model for each treatment was developed. The load-bearing capacity models showed soil structure degradation under conventional tillage and pasture management, while there was a recuperative effect of soil structure in crop rotation management. However, peanut as a crop rotation made the soil more susceptible to compaction, regardless of soil tillage treatment. At harvest time, the soil was more susceptible to compaction under the following conditions: in the surface layer, with the use of deep subsoiling and with the use of cover crops (peanuts and sorghum). From a practical point of view, this indicates that the better soil physical condition obtained by soil tillage and the use of cover crops can be wiped out by the harvesting operation, thus traffic control actions (including soil moisture and traffic reduction) need to be adopted.

Organic Farming Improves Soil Aggregation and Organic Carbon Status in the Rice-Wheat Cropping System in an Inceptisol

The paper deals with the long-term (11 yr.) impact of organic farming on soil aggregates and different forms of organic carbon namely, total, oxidizable and recalcitrant pools, and particulate organic matter-C in rice-wheat (R-W) and rice-wheat-mung bean (R-W-M) rotations in an Inceptisol. Soil aggregate stability (AS) was higher in R-W-M (86%) in the 0-7.5 cm layer than under R-W (83%). Organic nutrients resulted in 88-94% aggregate stability compared to 75% in the control (no nutrient supply). The R-W rotation recorded greater aggregate mean weight diameter (MWD) of 0.50 and 0.52 mm compared to 0.43 and 0.40 mm in R-W-M in 0-7.5 and 7.5-15 cm layer, respectively. The farmyard manure (FYM) with crop residues resulted in the highest total organic carbon (CTOC) content in both layers (1.88-2.05%). Large amounts of particulate organic matter-C (CPOM) were recorded in organic nutrient treatments as 0.4-0.5% in 0-7.5 cm compared to 0.3-0.4% in 7.5-15 cm layer. The MWD of aggregates correlated the best with CPOM (r=0.51) among the C pools, while AS showed the highest correlation with CTOC (r=0.53). The tensile strength of aggregates showed wide variability among the organic treatments and decreased with an increase in CTOC. An overall consideration of the results indicates that crop residue application with vermicompost or FYM has the most potent impact on soil physical condition and soil C status, holding a promise for sustaining the R-W cropping system in Inceptisol.

Effects of long-term (70 years) nitrogen fertilization and liming on carbon storage in water-stable aggregates of a semi-arid grassland soil

Grasslands cover up to 40.5% of the world's landmass and store 30% terrestrial carbon (C). Various practices, including mineral fertilization and liming, are used to manage these ecosystems with potential long-term effects on the size and distribution of soil aggregates and inevitably carbon dynamics. The objective of this study was to examine the long-term effects of nitrogen fertilization and liming on soil carbon storage and its dynamics in water-stable aggregates of a semi-arid grassland. Soil samples (0–10 cm) were collected from Ukulinga long-term grassland trial in Pietermaritzburg, South Africa where nitrogen fertilizers have been applied annually and lime every five years for 70 years. Ten treatments were studied: the control (0 kgN/ha and unlimited), lime at 2250 kg/ha (L), ammonium sulphate at 70 kg/ha (AS70) and 211 kg/ha (AS211); ammonium nitrate at 70 kg/ha (AN70) and 211 kg/ha (AN211); AS70 + lime (AS70L); AS211 + lime (AS211L); AN70 + lime (AN70L) and AN211 + lime (AN211L).Nitrogen fertilizers significantly reduced soil pH and increased total soil N. Liming increased soil pH with no effect on total soil N. Lime and lime + N fertilizer treatments had no effect on mean weight diameter (MWD) while separate N application decreased MWD and large macro-aggregates (LMA). Lime only treatment had no effect on water stable aggregate (WSA) fractions. Nitrogen fertilization and liming (separately or in combination) did not affect total C concentration and stocks. Overall, soils had very high total soil organic carbon ranging from 49.7 – 57.6 g/kg across treatments. Nitrogen fertilization decreased organic carbon in LMA in AS70 (1.52%) and AN211 (1.67%) treatments compared to the control (3.40%) which was in concert with increases in C associated with small macro-aggregates (SMA) and micro-aggregates (MiA and SCA). Organic carbon in SMA was 2.67 % (AS70); AS211 (2.62 %); AN70 (2.02 %); AN211 (2.49 %) compared to 1.26 % in the control. Lime + N fertilizer treatments increased C storage in all aggregate fractions compared to N fertilizer only treatments. The lack of response in total SOC to 70 years of N fertilization and liming suggests possible C saturation given the high soil C concentration. Changes in C associated with WSA fractions suggests their importance as diagnostic indicators of N fertilization and liming induced changes in SOC. Findings also show that ammonium-based N fertilization is associated with soil acidification, dispersion of LMA resulting in an increase of microaggregates and C stored in them. Liming can counteracts acidifying and the dispersive effect on NH4+ associated with ammonium-based fertilizers thus restoring macro-aggregation in N fertilized grasslands. These findings suggests that long-term N addition may result in poor soil physical condition and possible stabilization of C in stable fractions.

Lettuce production with rates of biochar from babassu palm rachis

ABSTRACT Use of biochar produced from biomass residues may improve physical, chemical, and biological conditions of soil, reduce greenhouse gas emissions, and increase crop yields. This study evaluated production of lettuce (Lactuca sativa L., cv. Babá de Verão) in a dystrophic Yellow Latosol (LAd) by adding biochar from the babassu palm (Attalea speciosa Mart.) rachis at 0, 10, 20, or 30 t∙ha−1 in pot culture, and growth and production of lettuce evaluated. Lettuce grown with 30 t∙ha−1 of biochar improved plant height, number of leaves, and total fresh mass. Rates that promoted greater accumulation of fresh mass of the aerial part, aerial part dry mass, fresh root mass, root dry mass, and total dry mass ranged between 17.3 and 27 t∙ha−1 of biochar. Use of biochar may be an alternative to improve physical and chemical conditions of LAd soil in successive crops of lettuce in pot culture. The correction of the LAd soil with increasing rates of biochar increased growth and yield of lettuce in pot culture.

Utilization of phytohormones for successful crop production under environmental stress conditions

Stress is an external factor that exerts a detrimental effect on overall growth of a plant. Environmental stress is a serious threat for sustainable crop production, and a main cause for food insecurity. Agricultural crops are exposed to a variety of environmental stresses including extreme temperatures and unfavorable chemical and physical soil conditions. Drought stress adversely affects some physiological and biochemical processes in plants, including transpiration, translocation of assimilates and nutrient metabolism. Salinity stress is responsible for loss of turgor, reduction in growth, wilting, leaf abscission, reduction in photosynthesis and respiration, loss of cellular integrity, tissue necrosis and finally death of the plant. Drought and salinity stress negatively affects the growth and yield of crop plants more than all the other stresses combined. Cold stress affects cellular components and metabolism, and temperature extremes impose stresses of variable severity that depend on the intensity and duration of the stress. Many approaches are being used to alleviate the deleterious effects of environmental stresses on successful agricultural crops production in recent years. Application of phytohormones (Abscisic acid, Indole-3-Aacetic Acid, Jasmonic acid and salicylic acid) is one of the curative measures to mitigate the environmental stresses in agricultural crops. Phytohormones play a significant role in enhancing stress tolerance and therefore, reduce the yield loss in crop plants. In this paper, the impacts of environmental stresses on productivity and physiological activities of crop plants, and the effective role of some phytohormones in alleviation of environmental stresses have been reviewed.

بررسی تأثیر نسبت های مختلف کلسیم به منیزیم آب آبیاری بر خصوصیات رشدی و عملکرد کینوا (.Chenopodium quinoa Willd)

Introduction Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte with very high adaptability to varied climatic conditions and high nutritional value. Different quinoa cultivars can have economical and stable yield in saline soil and water conditions. In addition to salinity, the chemical composition of irrigation water and thus soil solution affect the uptake and transfer of water and nutrients, and so plant yield. The intensity of this effect depends on various factors such as plant species. Calcium to magnesium ratio (Ca/Mg) is one of the quality indicators of irrigation water that can affect soil physical conditions and nutrient uptake independent of salinity level. A Ca/Mg < 1 and exchangeable magnesium percentage more than 25% in irrigation water are considered high enough to reduce soil quality and crop yields. Currently, frequent droughts and high water extraction have caused a sharp drop in water levels, increase in salinity, and in some cases a decrease in the Ca/Mg in the groundwater of most arid regions of the country. Since the effect of Ca/Mg in irrigation water on growth and yield of quinoa has not been studied so far, so the aim of this study was to investigate the effect of different Ca/Mg in irrigation water on growth parameters and quinoa grain yield in saline conditions. Materials and methods To study the effect of different Ca/Mg of irrigation water on quinoa growth and yield, three separate experiments in a randomized complete block design with four replications were conducted at the Research Greenhouse of Soil and Water Research Institute in 2018. Experimental treatments included three different Ca/Mg in irrigation water consisting of 0.25, 0.5 and 1, which were made by sodium chloride, magnesium and calcium as nutrient solutions fit to the salinity tolerance threshold of quinoa at different growth stages. In the previous research, yield reduction thresholds for Titicaca cultivar at different growth stages in a soilless culture (perlite) were a: 8 dS m-1 for emergence, b: 15 dS m-1 for flowering and c: 20 dS m-1 for grain filling. To conduct this research, 100 quinoa seeds were planted in pots, and the pots were irrigated with 8 dS m-1 water along with the desired Ca/Mg treatments. After establishing the quinoa seedlings and thinning to six plants per pot, pot irrigation was done with 15 dS m-1 salinity along with the desired treatments. After ensuring the end of the flowering stage, the remaining pots were irrigated with 20 dS m-1 salinity with the desired treatments until physiological ripening. Finally, the analysis of variance of the data was performed using SAS software and the means were compared with the protected LSD at 5% probability level. Results and discussion The results showed that the emergence percentage and non-uniformity of quinoa were not affected by Ca/Mg of irrigation water, however, increasing the magnesium amount significantly improved the emergence rate of quinoa seeds. Although the results showed that the fresh and dry weight at the flowering stage was significantly affected by Ca/Mg of irrigation water, the yield and yield components were not significantly affected. Therefore, the quinoa growth and yield are not affected by the ionic composition of irrigation water in terms of low Ca/Mg, however, the composition of absorbed and accumulated ions in plant tissues are significantly changed. So, compared to other conventional crops, quinoa has the potential to produce economic yield in saline conditions and is not affected by the Ca/Mg of water sources. Conclusion The results of this study showed that different Ca/Mg in irrigation water do not reduce the growth and yield of quinoa. Therefore, if the salinity tolerance threshold of the plant is considered, low water quality in terms of high magnesium concentration does not damage the plant and so can be cultivated with saline water sources such as diluted seawater.

Functional identity regulates aboveground biomass better than trait diversity along abiotic conditions in global forest metacommunities

Although several studies have identified the effects of functional trait diversity (FTD) and/or identity, i.e. the community‐weighted mean (CWM) of a trait, on aboveground biomass (AGB) along abiotic conditions, these effects on AGB in global forest metacommunities are still largely unexplored. Here, we modelled the effects of abiotic (i.e. climate, soil and plot physical conditions) and biotic [i.e. FTD, CWM of conservative traits (CWMCT), CWM of acquisitive traits (CWMAT) and functional dominance (FunDom; based on CWM of plant maximum height or diameter)] factors on AGB in 76 forest metacommunities (from 24 studies). Using multiple linear regression models and piecewise structural equation modeling (pSEM), we tested the hypothesis that both abiotic and biotic factors regulate AGB but that the mass ratio mechanism underpins AGB of metacommunities in global forests better than the niche complementarity mechanism. We found that abiotic and biotic factors contributed 45.39% and 54.07%, respectively, to the explained variance in AGB (R2 = 0.59), and as such, abiotic factors shaped FTD (R2 = 0.42–0.48), CWMCT (R2 = 0.33–0.36), CWMAT (R2 = 0.27–0.33) and FunDom (R2 = 0.59–0.61) through divergent effect sizes and directions. The final best‐fitted pSEM showed that FunDom increased (β = 0.49) but CWMCT (β = −0.35) and CWMAT (β = −0.11) decreased AGB (R2 = 0.52) as compared to the negligible effect of FTD (β = 0.04). This study supports the mass ratio effect, specifically the overruling role of tall‐stature or dominant trees on AGB, at a macroecological scale, and hence, suggests that a suitable species' functional strategy is important to promote carbon sequestration in forest metacommunities that underpins human well‐being. We expect that our study will advance the field of biodiversity–ecosystem functioning at a macroecological scale by using the metacommunity concept and approach.

Counterions, smectite, and palygorskite increase microstructural stability of saline-sodic soils

Saline-sodic soils are susceptible to wind and water erosion when the dispersive effect of sodium overcomes inter-particle bonds. Rheological parameters of viscoelasticity can help to quantify inter-particle attractive forces and account for the effect of salinity in these soils. The main objective of the present study was to investigate the viscoelasticity behavior of saline-sodic soils of the Sirjan playa in south-central Iran. Three representative pedons were excavated and described by horizon. Soil physicochemical properties and rheological properties were determined, namely the micromechanical parameters flow point (γf), loss factor tan δ, and integral z, with samples analyzed at three matric potentials (0, −6, and −15 kPa). Results showed that soil microstructural stiffness was mainly influenced by soil texture, clay minerals, gypsum, calcium carbonate equivalent (CCE), and matric potential. The dispersive effect of sodium, as indicated by low integral z and γf values, decreased with increasing gypsum content in − 6 and − 15 kPa matric potentials (0.6 < r < 0.8) and CCE percentage in the quasi-saturated (0 kPa) condition (r > 0.8). However, greater microstructural stability (i.e., higher integral z and γf) was observed for fine-textured soils with relatively high amounts of smectite and palygorskite and low pH. Furthermore, integral z and γf increased with lower matric potentials due to the stabilizing effect of menisci forces. Therefore, the viscoelastic behavior of the saline-sodic soils was negatively associated with water content and high sodium concentration, while the presence of smectite, palygorskite, gypsum, and CCE improved the soil physical conditions and thus the rigidity of the porous system. These results demonstrate that rheological measurements can identify saline-sodic soils that have strongly degraded microstructural stability and would most benefit from active management and amelioration.

Exploring the genetic variation for sodicity tolerance in Melia dubia evolved in Indian conditions

AbstractSoil sodicity is one of the major constraints for the success of afforestation worldwide. High sodicity causes poor soil physical conditions and thus adversely affect tree growth and biomass production. However, considerable intraspecific variation for sodicity tolerance exists in most of the trees species. Presently, no information is available on sodicity tolerance in the genotypes of the industrially important Melia dubia tree. Therefore, we examined twenty‐five genotypes of M. dubia, that has evolved in different parts of India, to elucidate mechanisms and identify traits imparting sodicity tolerance in these genotypes. The experimental evidence showed the significant genetic variability and relationships in genotypes for various morphological and physiological traits in response to the sodicity stress. On an average, sodicity stress reduced plant height, collar diameter, and shoot biomass by 15%, 18%, and 60%, respectively. The shoots Na+ concentration had negative correlation with the growth traits. Shoot Na+ ions exclusion was found to increase sodicity tolerance and conferred salt tolerance mechanism in M. dubia. Path analysis revealed that the plant height, collar diameter, number of leaves, and branches were major determinants of shoot biomass production. Cluster analysis validated the genotypes response to sodicity and classified the germplasm into sensitive, moderately tolerant, and tolerant category each consisting of nine, eleven, and five genotypes, respectively. Among genotypes, the MDSS06, MDSS13, and MDSS21 produced greater growth and biomass under sodic stress and indicated good growth potential in such soil. The results showed the presence of a high genetic diversity for salt tolerance in Melia, and the identified genotypes can be considered for strengthening the breeding programs aiming at improving the sodicity tolerance of the species. Our result concluded that genetic variation and breeding approaches using the MDSS06, 13, and 21 genotypes have tremendous potential to improve the growth, biomass, and overall productivity of M. dubia under sodic soil conditions.

Zero and controlled traffic improved soil physical conditions and soybean yield under no-tillage

Soil compaction can negatively affect a range of soil hydraulic, biogeochemical and plant physiological processes. A study conducted in Luján (Argentina) investigated the effect of three traffic treatments (zero, controlled, and random traffic) on soil physical properties and soybean yield over a period of eight years. The soil at the site (Typic Argiudoll) had been managed under continuous no-tillage for nine years. Field-wheeled areas under controlled and random traffic management were 3309 m2 ha−1 or 33.1% and 4622 m2 ha−1 or 46.2%, respectively. ‘Random’, non-controlled traffic farming represented the standard mechanisation management practice. The three traffic treatments relied on commercially available (unmodified) farm equipment. Results showed that soil cone Index (depth range: 0–450 mm) increased in the order: zero (1.90 ± 0.31 MPa) > controlled (2.46 ± 0.19 MPa) > random (3.75 ± 0.21 MPa) traffic, respectively, which therefore explained treatment differences in root biomass. Water infiltration rates decreased significantly with increased traffic footprint (by up to 35% in random traffic), which therefore reduced plant available water and influenced crop performance. Grain yields with zero traffic were fairly consistent between-years, but increased with controlled traffic (which progressively approached the yields achieved with zero traffic) and decreased in random traffic at average rates of 33 and 29 kg ha−1 per year, respectively. Treatment differences in grain yield widened in drier compared with wetter years when plant growth and yield were less constrained by water availability. An average yield penalty of ≈ 30% was recorded in random traffic relative to the other treatments. Gross income with random traffic was USD787 per ha, which compared to USD1179 and USD1116 per ha with zero and controlled traffic, respectively. The proposed approaches to mitigating adverse effects of compaction on crop productivity, sustainability and profitability appear to be cost-effective options and may be adopted when fully-matched machinery is not available. There is potential for future development of controlled traffic farming in Argentina.

Biofertilizers for Sustainable Production of Strawberry: A-Review

Modern-day intensive strawberry cultivation relies on huge application of inorganic fertilizers, which not only disrupt the balance of nature but also reduce the economic efficiency; however, it cannot be eliminated at this time without drastically decreasing its production. Hence, to tackle these problems for sustainable production of crops, bio-fertilizers and organic manures are the best alternatives. The principle of this review is based on the goal of reducing synthetic fertilizers and other chemical input usage in strawberry production. The review discusses the diffuse nature of current reports in the literature concerning microbes as inputs towards a better use efficiency of fertilizers and the possibility of reducing the total amount of fertilizer usage and sustainable and quality strawberry production. Studies with bio-inoculants in combination with inorganic nutrients have proved that some inoculants such as Azotobactor, Azospirillum, Pseudomonas, Bacillus, Mycorrhizae fungi Aspergillus and Penicillium can increase the nutrient uptake of strawberry plant and increased fertilizers use efficiency. Biofertilizers in combination with inorganic fertilizers and organic manures have significant impact on plant growth (i.e., state some of the parameters here), yield (i.e., state some of the parameters here) and quality (i.e., state some of the parameters here). Likewise, organic manures improve soil physical conditions and supply all essential macro elements and microelements. These confirmations of concept studies will serve as the basis for vigorous future research into integrated nutrient management in strawberry.

Gas diffusivity‐based characterization of aggregated soils linking to methane migration in shallow subsurface

AbstractMethane transport in soil is primarily affected by soil physical conditions such as soil texture and soil structure, soil moisture, soil‐gas diffusivity, permeability, and soil temperature. Aggregated soils have distinct soil structure with two pore regions characteristics (i.e., interaggregate and intraaggregate regions) and therefore show bimodal behavior with respect to soil physical properties controlling gas migration. This study characterized an aggregated soil retrieved near a natural gas (NG) extraction site at Denver–Julesburg (D‐J) basin in northeast Colorado (USA) with respect to soil‐water characteristic (SWC), pore‐size distribution, gas diffusivity and thermal conductivity. The investigated soil exhibited distinctive two‐region characteristics, which were adequately parameterized with extended, existing, and newly developed bimodal functions. We carried out an analysis with integrated model parameters to obtain a graphical insight on the correlation of properties. In addition, CH4 concentration profiles originated from a point source representing a buried pipeline leakage at three different flow rates (6, 12, and 24 L min–1) were simulated with a numerical tool that can simulate the multiphase flow of gas mixture under dry and different saturation conditions of the soil. Simulated results highlighted pronounced effects of soil moisture and, to a lesser degree, of gas leakage rate on subsurface CH4 concentrations profiles, suggesting diffusion‐dominated movement of CH4 in subsurface.