Soil Properties Research Articles

Effect of Conservation Agricultural Practices on Crop Yield and Soil Properties Under Sorghum [Sorghum bicolor (L.) Moench] — Black Gram [Vigna mungo (L.) Hepper] System in Rainfed Alfisol

ABSTRACT A long-term study was conducted to assess the effect of tillage (conventional, CT and minimum, MT) and residue retention treatments on crop yields, sustainable yield index (SYI), rain water use efficiency (RWUE) and soil properties under sorghum – black gram system in resource poor Semi-Arid Tropical (SAT) Alfisol at Hyderabad, India. The results revealed that when averaged over residue retention treatments, MT recorded 12.32 and 5.21% higher sorghum and black gram grain yield, 19.61 and 25.93% higher sustainability yield Index (SYI), and 12.27 and 5.15% rain water use efficiency (RWUE), respectively, over conventional tillage. Residue retention treatments (averaged over tillage treatments) S2 (cutting at 60 cm height for sorghum and 100% retention for black gram) and S1 (cutting at 35 cm height for sorghum and 50% retention for black gram) recorded 33.16 and 16.16, and 32.18 and 14.88% higher sorghum and black gram yield, respectively, over S0 (no residue) and also recorded 26.0 and 9.0, and 48.0 and 22.0% higher SYI over S0 in sorghum and black gram, respectively. Increase in RWUE under S2 and S1 over S0 was 33.19 and 16.23% in sorghum and was 31.4 and 14.53% in black gram. Higher residue retention maintained significantly higher soil organic carbon (SOC), significantly lower bulk density (BD) and significantly influenced potential of hydrogen (pH) and electrical conductivity (EC) at all the depths and also increased available nitrogen (N), phosphorus (P), potassium (K), manganese (Mn), iron (Fe), zinc (Zn) and copper (Cu) by 35.43, 24.55, 12.12, 57.6, 53.99, 51.46 and 13.76%, respectively. Thus, the results of the present study are highly useful in improving the crop yields, yield sustainability and soil properties. Therefore, the conservation agriculture practices can be a resource saving and higher crop production technology in the rainfed Alfisols.

Microplastic Transport and Accumulation in Rural Waterbodies: Insights from a Small Catchment in East China.

Microplastic (MP) pollution in agricultural ecosystems is an emerging environmental concern, with limited knowledge of its transport and accumulation in rural waterbodies. This study investigates the distribution and sources of MP in drainage ditches influenced by pond connectivity, land use, and soil properties within a small catchment in Nanjing, East China. Sediment was collected from ditches in 18 sites across forest, agricultural, horticultural, and urban areas. Using laser-directed infrared spectroscopy (LDIR), 922 MP particles were identified. Six materials were dominant: fluororubber (FR), polyethylene terephthalate (PET), polyurethane (PU), acrylonitrile (ACR), chlorinated polyethylene (CPE), and polyethylene (PE). MP concentrations varied by land use and pond connectivity, with ditches above ponds exhibiting higher counts (1700 particles/kg) than those below (1050 particles/kg), indicating that ponds act as MP sinks. The analysis revealed site-specific MP sources, with FR linked to road runoff and PET associated with agricultural practices. Correlations between MP shape and soil properties showed that more compact and filled shapes were more commonly associated with coarser soils. PE particle size was negatively correlated with organic matter. This study highlights the need for targeted strategies to reduce MP pollution in rural landscapes, such as reducing plastic use, ditch maintenance, and improved road runoff management.

Long-term experiments to identify response patterns of available soil nitrogen, rice, and soybeans to rice straw compost in a paddy-upland rotation field in Akita, Japan

ABSTRACT Compost application can enhance soil fertility and is consequently presumed to increase crop production in Japan’s paddy-upland rotation fields. This study aimed to evaluate the effects of rice straw compost (RSC) application on available soil nitrogen (Av-N) levels and rice and soybean plants in a paddy-upland rotation field using data obtained from a long-term field experiment. Data collected between 2005 and 2020 were analyzed from a long-term paddy rice – upland soybean rotation field. The experimental design employed a split-plot arrangement, with RSC application (with and without RSC) representing the whole plot, N fertilizer application (no nitrogen vs. standard fertilizer) representing the split-plot, and years representing the replication factor. The datasets included eight years of rice and soybean cultivation, and the chemical properties of postharvest soil spanned 16 years. The data was analyzed via analysis of variance. Applying RSC increased the Av-N concentration significantly by 63%–67%. The RSC application significantly increased the N concentration in rice shoots at the mature stage by 8%–12% but decreased it in soybean shoots after the seed emergence stage by 4%–8%. Consequently, the rice yield displayed clear responses to RSC application, whereas the soybean yield did not. The lack of soybean yield response might be due to an inhibitory effect of the Av-N gain attributable to the RSC application on biological nitrogen fixation. While applying compost can enhance Av-N content as well as rice productivity in paddy-upland rotation fields, its impact on soybean productivity requires careful evaluation.

Improved chickpea growth, physiology, nutrient assimilation and rhizoremediation of hydrocarbons by bacterial consortia.

Soil pollution by petroleum hydrocarbons (PHCs) reduces yield by changing the physico-chemical properties of soil and plants due to PHCs' biotoxicity and persistence. Thus, removing PHCs from the soil is crucial for ecological sustainability. Microbes-assisted phytoremediation is an economical and eco-friendly solution. The current work aimed to develop and use bacterial consortia (BC) for PHCs degradation and plant growth enhancement in hydrocarbon-contaminated soil. Initially, the enriched microbial cultures (that were prepared from PHCs-contaminated soils from five distinct regions) were obtained via screening through microcosm experiments. Afterward, two best microbial cultures were tested for PHCs degradation under various temperature and pH ranges. After culture optimization, isolation and characterization of bacterial strains were done to construct two BC. These constructed BC were tested in a pot experiment for hydrocarbons degradation and chickpea growth in PHCs contaminated soil. Findings revealed that PHCs exerted significant phytotoxic effects on chickpea growth and physiology when cultivated in PHCs contaminated soil, reducing agronomic and physiological traits by 13-29% and 12-43%, respectively. However, in the presence of BC, the phytotoxic impacts of PHCs on chickpea plants were reduced, resulting in up to 24 - 35% improvement in agronomic and physiological characteristics as compared to un-inoculated contaminated controls. Furthermore, the bacterial consortia boosted chickpea's nutritional absorption and antioxidant mechanism. Most importantly, chickpea plants phytoremediated 52% of the initial PHCs concentration; however, adding BC1 and BC2 with chickpea plants further increased this removal and remediated 74% and 80% of the initial PHCs concentration, respectively. In general, BC2 outperformed BC1 (with few exceptions) in promoting plant growth and PHCs elimination. Therefore, using multi-trait BC for PHCs degradation and plant growth improvement under PHCs stress may be an efficient and environmentally friendly strategy to deal with PHCs pollution and toxicity.

Responses of soil properties and foliar traits of a dominant tree species Pseudotsuga sinensis to rocky desertification in a karst ecosystem

Rocky desertification is a prevalent environmental challenge across karst landscapes that hinders regional sustainable development. Understanding how soil properties and plant traits respond to increasing levels of rocky desertification is crucial for developing effective restoration strategies. Here, we investigated soil characteristics and intraspecific leaf stoichiometric traits of Pseudotsuga sinensis across a gradient of rocky desertification in a karst ecosystem. We employed principal component analysis to assess changes in soil properties and leaf chemical traits and used leaf trait network analysis to explore shifts in trait network topology. Our results revealed that severe desertification sites had soil with high bulk density and pH, and low levels of available nitrogen, phosphorus, magnesium, as well as soil organic carbon. Leaf stoichiometry shifted markedly along the gradient, with elevated nitrogen limitation and cation imbalance in degraded sites. Trait network analysis showed that network diameter and modularity increased while connectance decreased with rocky desertification, indicating reduced integration among traits. On the other hand, higher adaptation capacity to environmental harshness under moderate level of rocky desertification was also observed. These findings suggest that both soil properties and leaf traits would experience substantial shifts across rocky desertification gradient, with increasing functional fragmentation and nutrient limitation as degradation intensifies. Based on our results, we propose management strategies targeted to different levels of rocky desertification to mitigate its negative impacts and promote ecosystem recovery.

The mechanical and hydrochemical properties of cemented calcareous soil under long-term soaking

This study investigates the impact of long-term water immersion on the mechanical and hydrochemical properties of cemented calcareous soil, emphasizing the critical role of carbonate content in mechanical performance. Utilizing hydrochemical analysis and triaxial testing, the research revealed that prolonged immersion disrupts the acid-base balance of the solution, resulting in an increased concentration of ions and chemicals. Significant dissolution of carbonates and soluble minerals occurs, which reacts with carbon dioxide to generate bicarbonate ions, thereby elevating the alkalinity of the soaking solution. Additionally, the gradual dissolution of clay minerals compromises the cementitious structure, leading to particle reorientation and interlocking. The study quantitatively assesses the changes in soil properties, demonstrating a substantial reduction in soil cohesion by up to 86.1% and an increase in the internal friction angle by 37.5%. Furthermore, the gradual dissolution of clay minerals compromises the cementitious structure, resulting in particle reorientation and interlocking that contribute to the observed mechanical changes. The findings underscore the importance of understanding the effects of extended immersion on the stability and engineering applicability of cemented calcareous soils.

Биологическая активность горных почв Западного Кавказа после сведения леса

A study of a set of indicators characterizing the ecological state of forest soils in the mountains of the North-Western Caucasus under broad-leaved and mixed forests has been conducted. The aim of the study has been to assess changes in the biological activity of soils of different genesis after deforestation. The objects of the study have been rendzina, gray forest and gray forest-steppe soils of forest and disturbed ecosystems of the Republic of Adugeya at altitudes from 500 to 1635 m above sea level. Logging plots of different ages (from 10 to 40 years old) after deforestation have been considered. The analyzed indicators have included: the content of total and active carbon, the activity of soil enzymes (catalase, invertase, dehydrogenase, urease, phosphatase), the number of bacteria, as well as an integral index of the biological properties of the soil. The correlation of these indicators with hydrothermal conditions, density of soil structure, penetration resistance, medium reaction, hydrolytic acidity, total absorbed bases and other soil parameters has been evaluated. The level of biological activity of soils in logging areas in the low mountains of Adygea depends on the relief and the timing of restoration after deforestation. Even after several decades of restoration of woody vegetation on the slopes of 12–15° there is no complete return of biological activity to the values of Greyic Phaeozem Eutric of the background forest area. 40 years after logging, the integral index of biological properties of gray forest soil is still 17 % lower than in the control plot. The biological activity of post-forest soils can change in three main directions. On steep slopes, with severe disturbance of the soil and vegetation cover due to the operation of heavy machinery, the integral index of the biological properties of soils decreases by 25–40 % or more without a tendency to recovery. At an average level of disturbance in plots with slight slopes, after an initial decrease, the soils are restored to control values. Restorative successions with intensive development of herbaceous flora and the turf process with slight disturbance can lead to an increase in biological activity above the control values in just 2–3 years. Comprehensive biodiognostic studies using an integral index of the biological state of the soil have revealed, in general, increased stability of low-mountain terrain soils (gray forest and forest-steppe) compared to the soils of the middle mountains of Adygea (rendzina soils). The main degradation factor that reduces the biological activity of soils disturbed by logging is erosion.

Amelioration of Soil Fertility by the Application of Different Fruit Waste Composts

The soil health status of Bangladesh decreased day by day, particularly organic matter and major nutrient content. The organic matter content in most of the agricultural soil in Bangladesh is <2%, which indicates poor soil health condition. In Bangladesh, almost every day, an enormous amount of waste material is produced from different kinds of seasonal and unseasonal fruit’s peels. Lack of proper recycling methods, most of these wastes are thrown away in drains, cannels, rivers, etc. which indicates a major threat to environmental safety. Composts derived from the wastes of different fruit’s peels can be an excellent source of organic matter and essential nutrients for soil health improvement. Therefore, the present study was carried out to evaluate the changes in physicochemical properties and nutrient contents of experimental soil treated with compost prepared from different types of fruit’s waste. The compost was prepared accordingly using different types of fruits waste and then the collected compost was thoroughly mixed with the soil and kept for six months. The experimental treatment consisted of three organic composts (jackfruit peel compost, mango peel compost, and banana peel compost) and three rates of application (1000, 1500, and 2000 kg ha-1). The experiment was arranged in a factorial completely randomized design and replicated thrice. The analyzed data showed that, the physicochemical properties and nutrient contents of experimental soil varied significantly with the use of different types of fruit’s wastes compared to no waste added soil, except in the case of particle size. Soil mixed with mango peel compost at a rate of 2000 kg ha-1 resulted in a higher available N content (2520 mg kg-1) and available P content (42.56 mg kg-1), whereas the available K content (219.88 mg kg-1), EC (1.55 dS m-1) and CEC (1209.56 meq 100g-1) were found higher in soil treated with banana peel compost of 2000 kg ha-1. On the other hand, soil treated with jackfruit peel compost of 1500 kg ha-1 showed the higher available Ca content (1533.33 mg kg-1) and the jackfruit peel compost of 2000 kg ha-1 resulted in the higher organic carbon (1.98%) and organic matter (3.41%). The findings of this experiment revealed that, compost prepared from different types of fruit peels can be an excellent source of organic matter and nutrients and among the tested composts, mango peel compost was better to improve the physiochemical properties of soil and supply sufficient nutrients for plant growth.

The impact of combined application of biochar and fertilizer on the biochemical properties of soil in soybean fields.

Heilongjiang Province is a major soybean production area in China. To improve soil structure and increase soybean yield, this study examined the effects of combined biochar and chemical fertilizer application on the biochemical properties of soil in a maize-soybean rotation system. The research were conducted from 2021 to 2022 at Heshan Farm Science Park in Heilongjiang Province, this field plot experiment utilized two soybean varieties, Heihe 43 (a high-protein variety) and Keshan 1 (a high-oil variety). In 2021, two plots with similar fertility levels were selected for planting soybeans and maize. In 2022, a maize-soybean rotation was implemented with five treatments: conventional fertilization (CK), increased biochar+reduced fertilizer 1 (F1+B), reduced fertilizer 1 (F1), increased biochar+reduced fertilizer 2 (F2+B), and reduced fertilizer 2 (F2). The study systematically analyzed the effects of combined biochar and chemical fertilizer application on soil chemical properties and microbial characteristics. Over 2 years, results showed that combined application effectively improved soil chemical traits. Compared to conventional fertilization (CK) and reduced fertilization (F1, F2), t he combined application of biochar and chemical fertilizer (F1+B, F2+B) increased soil pH, EC and the absolute value of zeta potential of soil surface, the CEC of soil significantly increased by 15.6-44.3%, the soil surface charge density and the soil surface charge quantity significantly increased by 16.4-73.5%. The combined application of biochar and chemical fertilizer also effectively enhanced the abundance and diversity of soil microbes. Dominant bacterial groups in soybean field soils under different treatments included Actinobacteria, Acidobacteria, Chloroflexi, and Proteobacteria; while dominant fungal groups were Ascomycota, Basidiomycota, and Mortierellomycota. Alpha and Beta diversity analyses revealed that the F1+B treatment significantly enhanced the species richness and diversity of bacteria and fungi in the soil, increasing the proportion and evenness of dominant and beneficial genera.

Exploring Soil–Water Characteristic Curves in Transitional Oil Sands Tailings

Soil–water characteristics curves (SWCC) have proved useful in estimating parameters used in modeling unsaturated geotechnical properties of soils including permeability and strength. Either saturation, gravimetric, and instantaneous and initial volumetric water content designation can be used to develop SWCCs. Studies have shown that any of the designations will give good estimates for soils that do not undergo volume change with suction change whereas, for soils that undergo substantial volume change, only saturation and instantaneous volumetric water content designation obtained by incorporating shrinkage curves can give correct estimates. Transition oil sands tailings have fines content that cannot be categorized as sandy or fine materials, and research on volume change with suction change in these materials is limited. In this study, HyProps, Tempe cells, and a chilled-mirror water potential meter were used to measure suction and corresponding water contents for samples that were prepared by mixing coarse sand and Fluid Tailing by ratios that mimic transition zone tailings. Shrinkage tests were also performed to observe the extent of volume change with suction increase. Air Entry Values (AEV) estimated from SWCCs based on gravimetric water content were found to be lower than those estimated from saturation-based SWCCs due to substantial volume changes in these materials with suction increase. The use of saturation water content designation is recommended in estimating AEV for transitional oil sands tailings. This is useful information in predicting the long term unsaturated geotechnical behavior of these materials for environmental management and safety purposes.

Влияние насаждений Quercus robur L. и Juglans rupestris Engelm. на свойства степных почв

The aim of the study has been to determine the condition of Quercus robur L. and Juglans rupestris Engelm. and their influence on the properties of segregated chernozems. The study was conducted in 2020–2021 in the steppe Crimea. The control has been a perennial grass fallow. To characterize the general condition of the trees, a 4-point scale for assessing the condition of the introduced species has been used. Standard methods have been used for soil analysis. A better preservation and a greater number of 50-year old plants in excellent and good condition have been established for Q. robur (67 и 56 %, respectively) compared to J. rupestris (48 и 42 %, respectively) in these environmental conditions, which is explained by the greater adaptive capabilities of oak as an indegenous species. Both tree crops have influenced soil properties. In their phytocenoses, a litter has been formed, more significant under J. rupestris. The dark humus horizon has also turned out to be thicker under the J. rupestris plantation (80 cm) than under the Q. robur plantation and the fallow (72 and 70 cm, respectively). Under Q. robur the soil density has been lower than under J. rupestris by 0.02–0.18 g/cm3. Under the woody plants, the soil structure has improved: the number of lumpy aggregates has decreased, and the number of agronomically valuable and granular particles has increased. The maximum coefficient of structure has been in the soil under the oaks (4.4–6.6), which exceeded the control by 2.5–4.9 times. Under the woody plants, carbonates have been significantly washed out of the soil profile, especially under J. rupestris. The pHH2O value of the alkaline soil under the woody plants has decreased by 0.2–0.4 and has been closely related to carbonate content (r = 0.83–0.91). The humus content under both species has been significantly higher than under the fallow – by 0.30–0.86 %. Afforestation has resulted in the accumulation of total forms of nutrients, to a greater extent under J. rupestris, and the C:N ratio has decreased. Tree species have stored more labile forms of nutrients in the soil. Soil desalination has been noted in the tree cenoses. Thus, J. rupestris and Q. robur are ecologically stable in the conditions of the central steppe of Crimea and can be used to increase forest cover in steppe areas. This will help improve soil fertility.

Different characteristics of the soil in marmot habitats might be one of the factors that influcting Yersinia pestis prevalent in which than pikas.

Marmots are recognized as host animals for plague caused by Yersinia pestis infection. It is unclear that why plague prevalent in marmot rather than other rodents like pikas in the same habitats. This study aims to analyze the differences of the soil characteristics around marmots and pikas burrows to explore the soils factors impacting on different epidemic intensities of Yersinia pestis in these two rodents. Soil samples were collected from within and around marmot and pika burrows, as well as from the nearby areas not inhabited by them and Chinese baseline soil properties as control groups, in the Qilian Mountains of Gansu Province, China. The physicochemical properties and the bacterial 16S rRNA were measured to analyze the characteristics of soils from different groups. Subsequently, the data were analyzed using R studio. The analysis revealed that marmot habitats exhibited distinct soil characteristics, including lower organic matter and alkaline hydrolyzed nitrogen, but higher electrical conductivity and total soluble salts. And soil in marmot areas tended to have higher concentrations of nickel, chromium, and iron, also lower levels of zinc and selenium. Additionally, the alpha diversity of soil microorganisms in marmot habitats was significantly low. Simultaneously, redundancy analysis was conducted, which showed that the low alpha diversity of marmot-soil was influenced by its physicochemical properties. The alpha diversity of the soil was positively correlated with EC, TSS, Na, and Cr, etc., while it was negatively correlated with AHN, OM, Se, Zn, and Fe, etc. These characteristics in marmot habitats, including low levels of organic matter, alkaline hydrolyzed nitrogen, zinc, selenium, and bacterial alpha diversity, as well as high levels of electrical conductivity, total soluble salts, iron, and nickel, played a crucial role in the spread of plague. It was discovered that the unique characteristics of marmot-soils provided essential elements necessary for the survival of Yersinia pestis, including high levels of Fe and Ca, or facilitated the spread of plague. Thus, the transmission of the plague was facilitated.

Response of soil nitrogen mineralization, nitrification and denitrification to milk vetch (Astragalus sinicus L.) application in a paddy field

We conducted incubation experiments with a paddy soil collected from a long-term field experiment to explore the effect of Chinese milk vetch (Astragalus sinicus L., CMV) application on potential nitrogen (N) denitrification (PDA), nitrification (PNA), mineralization (PNM), soil chemical properties, microbial communities, enzyme activities, yields and nutrient uptake of rice under different fertilization treatments. Five treatments were included: no chemical fertilizers (C0), chemical fertilizers (C100), Chinese milk vetch (M), CMV combined with 100% chemical fertilizers (MC100) and with 80% chemical fertilizers (MC80). Results showed that the M, MC100, and MC80 treatments significantly increased PNM and PNA compared with the C100 treatment (P < 0.05). Meanwhile, the CMV application significantly increased total N, microbial biomass N, and carbon (C) concentrations, the abundances of the bacterial phylum Actinobacteria, and the genera Bradyrhizobium, Mycobacterium, Streptomyces and Reyranella, N-acetyl-glucosaminidase (NAG) activity, yields and N nutrient uptake of rice grain compared with the C100 treatment (P < 0.05). Correlation analyses indicated that grain yield and N uptake of rice, soil total N, microbial biomass C and N, the bacterial phylum Actinobacteria, the genera Bradyrhizobium, Mycobacterium, Streptomyces, Reyranella, and NAG were significantly correlated with PNM under different fertilization regimes, while microbial biomass C and N, Actinobacteria, Bradyrhizobium, and Reyranella were positively related to PNA (P < 0.05). Together, the application of CMV alone or in combination with chemical fertilizers can improve soil properties and rice growth, which may accelerate N mineralization and nitrification in this soil.

Effects of Vegetable Cover on the Regeneration Process in Degraded Dry Forest in Brazil

ABSTRACTThe Brazilian Caatinga is among the most diverse dry forests in the world, yet half of its original coverage has been degraded. Natural regeneration is influenced by climatic and edaphic conditions, as well as the existing adult stratum. Despite its significance, this process remains poorly understood in the Caatinga. Thus, our study aimed to analyze how anthropogenic disturbance, vegetation cover, and soil properties affect the regenerating stratum under different levels of Caatinga vegetation cover. The research was conducted in the driest region of Brazil. The selected sites represent low (Area I) and high (Area II) normalized difference vegetation index. Six vegetable plots (50 × 20 m each) were delimited to study adult stratum, and four vegetable plots (10 × 10 m each) to regeneration stratum. Topsoil was sampled in all vegetable plots. Our results reveal interactions between soil characteristics and the adult and regenerating strata. Area II exhibited higher diversity and a greater number of exclusive species, while Area I was dominated by species more resistant to limiting conditions, such as Aspidosperma pyrifolium Mart. & Zucc. The C and N content in the soil showed a positive and significant correlation with the diversity of the regenerating stratum. The data suggest that the area with less vegetation cover, richness, and diversity shows signs of desertification.

SPATIAL VARIABILITY OF THE GEOTECHNICAL PROPERTIES OF SOILS: A CASE STUDY OF ELIZADE UNIVERSITY

Soil variability can alter the mechanical behaviour of foundations. It is therefore, necessary to conduct site investigations specific geotechnical analysis before any construction. This study evaluated selected engineering index and properties of soils at three different locations (sites) and depths withing Elizade University (EU), Ilara-Mokin. Five soil samples were collected from each of these locations and their engineering index and properties were determined. Statistical analysis namely Analysis of Variance (ANOVA) was utilised to determine the effects of location within the campus on the selected engineering properties. The mean and standard deviation (SD) of the engineering properties of soils collected within each site were also determined. The study revealed that plastic index (Pi), liquid limit (LL), moisture content (Mc), and plastic limit (Pl) were in the range of 4 to 32, 38 to 58.5, 11.6 to 29.04 %, 20 to 42 and respectively. The engineering index of the soil and engineering properties of the soil were significantly affected by the location with F14,42 equal to 2.592212, p was 0.008673 and F14, 42 equal to 3.210318 and p was 0.001719, respectively (which are less than 0.05). The high SD also showed that the soil properties have a wide range of values within same site, this was particularly so, in the case of the Atterberg’s limits, shear strength parameters and bearing capacities. The concluded that there is variability in the soil properties within the location.

Assessing field scale spatiotemporal heterogeneity in salinity dynamics using aerial data assimilation

Soil moisture and salinity shifts within the root zone can significantly alter crop yields. Thus, spatiotemporal dynamics of these parameters are essential for precision crop management. Airborne or spaceborne earth observation methods based on vegetation and soil observations have sometimes been used with limited success to indirectly understand parameters like soil salinity. These datasets lack spatiotemporal resolution to discern field-scale heterogeneities, and estimates’ accuracy is poor. A Metropolis-Hasting Markov Chain-Monte Carlo (MCMC) based method was developed to estimate field-scale soil salinity by assimilating estimated evapotranspiration (ET) data obtained from aerial canopy temperature sensing with ET outputs from a one-dimensional soil-water transport model. By aligning the two estimated ET values, we inferred anticipated soil salinity levels in a mature pecan orchard (28,951 m2). Our results aligned closely with in-situ measurements with a spatial cross-correlation more than 0.86 and highlighted the expected heterogeneities and nonlinearities. This research offers an approach to refine the current state-of-the-art crop models by accounting for field scale heterogeneities using remotely sensed data. This assimilation method will pave the way for a more inclusive agricultural system modeling that can infer critical but hard-to-measure soil properties from easier-to-obtain remotely sensed datasets. Though this paper concentrates on aerial observations, we anticipate similar methods can be used for satellite-based imagery, especially those with high spatial, temporal, and spectral resolutions.

Enrichment of Phytopathogen Dominated by Volutella in the Rhizosphere May Be an Important Cause of Continuous Cropping Obstacles in Sweet Potatoes

ABSTRACTObstacles related to the continuous cropping of sweet potatoes (Ipomoea batatas (L.) Lam.) restrict its intensive production. However, the effects of continuous cropping on soil properties and/or the rhizosphere microbial community are largely unclear. In this study, we analyzed changes in rhizosphere soil chemical properties and microbial communities of sweet potatoes across different cultivation years. We observed that the microbial diversity and complexity of the fungal ecological network in rhizosphere soils of sweet potatoes were decreased after 5 years of continuous cropping, with significant enrichment in Sphingobium, Gemmatimonas, Volutella, and Neoidriella. Tuber yield, soil pH, and available potassium (AK) content were significantly reduced after continuous cropping, with the soil microbial community having the highest correlation with pH, AK, and ammonium nitrogen (NH4+‐N). Specifically, soil pH and AK were positively correlated with Bacillus and Gaiella, and negatively correlated with some plant‐pathogenic fungi (Volutella and Neoidriella), while NH4+‐N showed the opposite trend. In addition, soil pH, AK, and the relative abundance of Bacillus were positively correlated with tuber yield, while Volutella showed the opposite trend. In summary, the continuous cropping of sweet potatoes negatively affects rhizosphere soil health, resulting in imbalanced soil fertility and an increased abundance of pathogens. These results improve our understanding of factors driving obstacles faced with the continuous cropping of sweet potatoes, enabling future studies and the development of technologies to overcome these obstacles.

Leaching Studies for the Assessment of Individual Immobilization Potential of Chrysopogon zizanioides Root Micro Powder from Lead, Cadmium and Chromium Contaminated Soil

ABSTRACT Contemporary issues of ground contamination, exacerbated by elevated heavy metal levels due to industrial activities and improper waste disposal, significantly impact soil properties, the biosphere, and result in various geotechnical problems. This study delves into the efficacy of Chrysopogon zizanioides (vetiver) root micro powder (VRMP) in immobilizing Lead (Pb), Cadmium (Cd), and Chromium (Cr) within contaminated soil to prevent groundwater pollution and bioavailability. Leaching experiments were conducted to evaluate the individual immobilization of heavy metals and determine the optimal VRMP dosage, testing four dosages (0%, 1%, 5%, and 10%) for their effectiveness in immobilizing Pb, Cd, and Cr in contaminated soil. The findings suggest that addition of VRMP led to an increase in pH, facilitating the enhanced immobilization of Pb, Cd, and Cr from the contaminated soil due to the reduction in mobility of these metals. Soil treated with 10% VRMP exhibited exceptional immobilization efficiency, achieving over 90% removal across all treatments. However, agglomeration caused the leaching process to take slightly longer. Consequently, a 5% VRMP dosage is considered optimal. In conclusion, vetiver root micro powder promotes a sustainable approach to immobilize Pb, Cd, and Cr in contaminated soils, underscoring the effectiveness of eco-friendly methodologies.

Fertilization shapes microbial life strategies, carbon and nitrogen metabolic functions in Camellia oleifera soil

Mineral, organic and microbial fertilizers are crucial for maintaining and improving soil quality, ecosystem functions, and fruit yield in Camellia oleifera plantations. However, how the application of these fertilizers shapes the life strategies and functions of soil microbial communities is unclear. Here, we conducted a one-year field experiment with three types of fertilizers: mineral (NPK), manure (Man), and microbial (MicrF), and analyzed soil properties, bacterial and fungal communities to assess microbial life strategies, functional traits and their determinants. The application of MicrF strongly increased the diversity of both soil bacterial (by 6.4%) and fungal communities (by 23%). Organic matter inputs from Man and MicrF had greater effects on the life strategies of bacteria than fungi: the dominant r-strategy bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased with Man and MicrF, but K-strategists (Acidobacteria) decreased. Conversely, the abundance of r-strategy fungi (Ascomycota) decreased, but that of K-fungi (Basidiomycota) increased. Predictions of the functions indicated that microbial fertilization accelerated the bacterial carbohydrates, carbon and nitrogen metabolism, while also increasing the prevalence of wood saprotrophic fungi. The changes in the taxonomic and functional characteristics of the microbial communities induced co-metabolism priming effects, which were mainly regulated by soil organic carbon, available phosphorus, ammonium nitrogen contents, and carbon-nitrogen ratio. The application of MicrF is an effective approach to increase the diversity and multifunctionality of soil microbial communities in Camellia oleifera plantations, including organic matter decomposition, carbon and nitrogen metabolism. These findings provide valuable insights into the fertilizer regimes based on microbial ecological strategies and functional profiles in Camellia oleifera plantations.

Investigating the Synergistic Effect of Tillage System and Manure Application Rates on Selected Properties of Two Soil Types in Limpopo Province, South Africa

Sustainable agricultural practices are needed to find a solution to the problem of soil erosion and decreased soil quality. A study was conducted during the 2021/2022 and 2022/2023 cropping seasons to evaluate the synergistic effect of the tillage system (TS) and manure rates (MR) on selected soil properties at the University of Limpopo Experimental Farm (Syferkuil) and University of Venda Experimental Farm (UNIVEN). The experiment had a split plot design with three replications. The main plots used conventional (CON) and in-field rainwater harvesting (IRWH) tillage systems, while subplots used poultry and cattle manure at rates of 0, 20, and 35 t ha−1. Bulk density (BD), aggregate stability (AS), pH, total N, organic carbon (OC), available P, and exchangeable cations (Ca, Mg, and K) were determined. IRWH significantly increased AS in the 0–20 cm soil layer at Syferkuil. TS × MR interaction significantly influenced AS and total N in the 20–40 cm soil layer during the 2022/2023 season at Syferkuil. IRWH significantly increased Mg content in the 2021/2022 season and total N, OC, and Mg content in the 2022/2023 season at Syferkuil over CON. At UNIVEN, CON significantly increased total N, whereas IRWH increased available P in the 2022/2023 season. MR significantly increased AS, exchangeable Ca, Mg, and K at both sites. At Syferkuil, MR significantly increased total N, OC, and available P during both seasons, whereas at UNIVEN the significant increase was observed on OC and available P during both seasons and total N in the 2021/2022 season. It was found that IRWH and poultry manure (35 t ha−1) improved most soil properties at both sites; however, this study recommends long-term experiments to investigate the combined effect of IRWH and manure rate on soil properties to validate the findings observed in this study.