Search Results (344)

Soil salinisation is a critical problem in northern China’s arid and semi-arid irrigated regions, posing a substantial impediment to the sustainable advancement of agriculture in these areas. This research utilises the Donghaixin Irrigation District, located on the southern bank of the Yellow River in Inner Mongolia, as a case study. This study examines the spatial distribution and determinants of soil salinisation through macro-environmental variables and micro-ion composition, integrating regression models and groundwater ion characteristics to elucidate the patterns and causes of soil salinisation systematically. The findings demonstrate that soil salinisation in the study region displays notable spatial clustering, with surface water-irrigated regions exhibiting greater salinisation levels than groundwater-irrigated areas. More than 80% of the land exhibits moderate salinity, predominantly characterised by the ions Cl⁻, HCO₃⁻, and SO₄²⁻. The hierarchy of ion concentration variation with escalating soil salinity is as follows: Na⁺ > K⁺ > SO₄²⁻ > Cl⁻ > Mg²⁺ > HCO₃⁻ + CO₃²⁻ > Ca²⁺. The susceptibility of ions to soil salinisation is ordered as follows: Ca²⁺ > Na⁺ > HCO₃⁻ + CO₃²⁻ > Mg²⁺ > K⁺ > Cl⁻ > SO₄²⁻. In contrast to the ordinary least squares (OLS) model, the geographic weighted regression (GWR) model more effectively elucidates the geographical variability of salinity, evidenced by an adjusted R² of 0.68, particularly in high-salinity regions, where it more precisely captures the trend of observed values. Ecological driving elements such as organic matter (OM), pH, groundwater depth (GD), total dissolved solids (TDS), digital elevation model (DEM), normalised difference vegetation index (NDVI), soil moisture (SM), and potential evapotranspiration (PET) govern the distribution of salinisation. In contrast, anthropogenic activities affect the extent of salinisation variation. Piper’s trilinear diagram demonstrates that Na cations mainly characterise groundwater and soil water chemistry. In areas irrigated by surface water, the concentration of SO₄²⁻ is substantially elevated and significantly affected by agricultural practises; conversely, in groundwater-irrigated regions, Cl⁻ and HCO₃⁻ are more concentrated, primarily driven by evaporation and ion exchange mechanisms. Full article

European grasslands are vital carbon (C) sinks, contributing to climate change mitigation. Grazing intensity significantly influences soil C and nitrogen (N) cycles through effects on soil conditions and microbial communities. While heavy grazing is linked to soil C loss and altered N processes, existing studies show conflicting outcomes. This study examines the impact of cattle grazing on soil C and N cycles in a historical alpine pasture in the eastern Italian Alps (1868 m a.s.l.). The following three grazing intensities were analyzed: heavy (8.19 LU ha⁻¹), moderate (0.59 LU ha⁻¹), and light (0.06 LU ha⁻¹). Soil was sampled from two depth layers (0–5 cm, 5–10 cm) and analyzed for bulk density, C and N content, C/N ratio, exchangeable N, δ¹⁵N, and microbial genes targeting general abundance (16S), N fixation (nifH), nitrification (amoA), and denitrification (nirK, nosZ) using real-time PCR. The results revealed decreased C and N concentrations with increasing grazing intensity, exclusively in the 0–5 cm soil layer. Higher δ¹⁵N and enhanced nitrification and denitrification suggest a more open N cycle under heavy grazing. These findings highlight the potential of microbial gene markers and δ¹⁵N isotopic ratios to monitor N cycle dynamics in alpine pastures, informing sustainable grazing management. Full article

The objective of this study was to evaluate the effect of four cycles of six biannual rotations and four levels of incorporation of residues for each crop on the chemical properties of a volcanic soil from central-southern Chile. Methods: After six biannual rotations (canola–bread wheat, bean–bread wheat, canola–durum wheat, bean–durum wheat, canola–corn, and bean–corn) and four levels of residue incorporation (0, 50, 100, and 200%), we evaluated the chemical properties of a volcanic soil through eight years of cultivation. Results: The chemical properties of the soil were affected mainly by crop rotation and to less extent by the dose of residue incorporated. Beans showed a positive relation with soil pH, unlike canola with a negative effect (p < 0.05). Corn was also noticeably negative for available P. The application of increasing doses of residue positively affected the exchangeable K and Mg (p < 0.01). There were also positive correlations between pH and exchangeable Ca, exchangeable Ca and Mg, and available S and exchangeable Al and negative correlations between pH and exchangeable Al, pH and available S, and available S with exchangeable Ca and Mg. Conclusions: Carrying out different crop rotations seems to be a boost for chemical properties of the soil, while the incorporation of residues allows higher concentrations of exchangeable K and Mg. Full article

The efficiency of heat transfer through borehole heat exchangers is influenced by the thermal resistances of both the borehole and the surrounding soil. Optimizing these resistances can improve the heat transfer performance and reduce system costs. Soil thermal resistance is geographically specific and challenging to reduce, according to previous research; in contrast, borehole resistance can be minimized through practical approaches, such as increasing the thermal conductivity of the grout or adjusting the shank spacing in the U-tube configuration. The previous literature also suggests that coaxial pipes are a more efficient design than a single U-tube borehole heat exchanger. A novel approach involves inserting a physical barrier between the U-tube’s inlet and outlet legs to reduce the thermal short-circuiting and/or to improve the temperature distribution from the inlet leg in a U-tube borehole. Limited studies exist on the barrier technique and its contribution to reducing thermal resistance. The effects of two different barrier geometries, flat plate and U-shape, made from different materials, with various grout and soil thermal conductivities and shank spacing configurations, were considered in this study. Using FlexPDE software version 6.51, this study numerically assesses thermal resistances through the borehole. This study focuses on the sole contribution of a barrier in mitigating the thermal resistance of a U-tube borehole heat exchanger. This study suggests that the barrier technique is an effective solution for optimizing heat transfer through U-tube borehole heat exchangers, especially with reduced shank spacing and lower thermal conductivity soil. It can reduce the length of a U-tube borehole by up to 8.1 m/kW of heat transfer, offering a viable alternative to increasing shank spacing in the U-tube borehole or the enhancing thermal conductivity of the grout. Moreover, under specific conditions of soil and grout with low to medium thermal conductivity, a U-tube borehole heat exchanger with a barrier between the legs demonstrates a reduction of up to 43.4 m per kW heat transfer (22.7%) in the overall length compared to coaxial pipes. Full article

Pollution of soil by heavy metals has become a critical environmental issue. This study investigated an innovative approach to heavy metals removal, focusing on the desorption of nickel and zinc from vermiculite using a combination of leaching and ultrasonic (US) irradiation at 20 or 362 kHz. When 0.1 M HCl was used as a washing solution, Zn²⁺ desorption yields around 85% were obtained in all conditions. Under 20 kHz US, fragmentation of the particles occurred, leading to the formation of new sites where released Zn²⁺ could sorb, allowing improved decontamination by cation exchange. Even higher yields were obtained with the biobased citric acid. Ni²⁺ desorption yields were lower due to its distribution in less accessible Tessier fractions. They significantly increased under US, especially at 362 kHz. It is shown that US leads to transfer of the contaminant from less accessible fractions (in particular the residual one) to more accessible ones, and that at low frequency, new sorption sites are created by fragmentation, leading to readsorption in the exchangeable fraction. This study brought to light for the first time the potential of high-frequency US in enhancing soil washing, to a higher extent compared to low-frequency (20–50 kHz) US. Full article

Calcareous soils, prevalent in arid and semi-arid regions, often limit agricultural productivity due to their alkaline nature and poor nutrient availability. This study assessed the effects of mineral sulfur (312 kg ha⁻¹), nano-sulfur (12, 24, and 36 kg ha⁻¹), and compost (4.8 tons ha⁻¹) on the physical and chemical properties of saline calcareous soils and their impact on maize and wheat yields. The field experiment on new extended agriculture in Mallawy, Egypt, utilized a randomized complete block design. The results showed that nano-sulfur treatments outperformed mineral sulfur. Specifically, the combination of 36 kg ha⁻¹ nano-sulfur with 4.8 tons ha⁻¹ compost improved key soil physical properties, including bulk density, porosity, and hydraulic conductivity. This treatment also significantly reduced soil pH, electrical conductivity, and exchangeable sodium while enhancing the availability of essential nutrients such as nitrogen (N), phosphorus (P), potassium (K), and total sulfate (SO₄²⁻). These enhancements in soil health led to notable increases in both maize and wheat yields, as well as better crop nutrient uptake. The findings suggest that nano-sulfur, when used in conjunction with compost, is a highly effective amendment for improving the health of saline calcareous soils, enhancing crop productivity, and promoting sustainable agricultural practices in arid and semi-arid regions. This combination provides a promising alternative to excessive chemical fertilizers, fostering soil health and long-term agricultural sustainability. Full article

In many sustainable agricultural systems, combining soil ameliorants with deficit irrigation is a viable strategy. However, little is known about how this approach affects soil quality, crop water productivity (CWP), and sugar beet (Beta vulgaris L.) yield in sandy soils. This study investigates the effects of different soil ameliorants―potassium polyacrylate (PPA), polyacrylamide (PAM), and humus (HA)―on the soil chemical properties, water productivity, and sugar beet yield under three irrigation regimes (100%, 80%, and 50% of crop water requirement (CWR). The results demonstrated that applying these amendments signficantly enhances soil pH, cation exchange capacity (CEC), organic matter (OM), and the availability of essential nutrients (N, P, and K). Notably, the combination of PAM and HA under 50% CWR resulted in the highest improvements in sugar beet biomass, increasing shoot and root growth by 73.43% and 71.68%, respectively. It also led to a 97.91% increase in sugar yield and a 4.22% improvement in sugar quality. However, this treatment had the lowest economic benefit, with a negative outcome. In contrast, PAM treatment under 50% CWR produced a 61.49% increase in sugar yield and a 2.44% improvement in sugar quality, ensuring economic viability. These findings suggest that the use of PAM under reduced irrigation conditions can optimize water use efficiency and sustain crop productivity in sandy soils. Full article

Soil calcium is a vital component in plant growth and soil health. Earthworm activities impact metal distribution and speciation a lot by changing soil pH. Nevertheless, little is known about how ecological earthworm species, particularly in Terra Rossa soil, affect soil Ca speciation distribution. This research examined the effects of the activities of four different earthworm species (epigeic species Eisenia fetida (noted as EF), endogeic species Amynthas robustus (noted as AR) and Pontoscolex corethrurus (noted as PC), anecic species Amynthas aspergillum (noted as AA)) on Ca speciations (water-soluble (Ca_Ws), exchangeable (Ca_Ex), acid-soluble bound (Ca_Ac), organic-bound (Ca_Or), and residual (Ca_Re)), soil pH, the release contents of exchangeable cations (Ca, Mg, K, and Na), total calcium (Ca_Total) contents, total nitrogen (TN) contents, soil organic carbon (SOC) concentrations, cation-exchange capacity (CEC), and NIRS spectral characteristics in Terra Rossa soil for 40 days under lab conditions. In contrast to control soil, 108.3%, 158.3%, 91.7%, and 125.0% of Ca_Ws contents in casts and 116.6%, 108.3%, 58.3% and 91.6% of Ca_Ws in uningested soil increased significantly with the inoculation of EF, PC, AR, and AA, respectively. In addition, compared with control, for casts, the contents of exchangeable Ca, Mg, K, CEC, and available-K were significantly increased in the presence of EF, PC, AR, and AA, respectively. In the casts of EF, PC, AR, and AA, soil pH values declined by 0.72, 0.80, 0.45, and 0.60 units relative to control soil, while they decreased by 0.65, 0.84, 0.34, and 0.59 units in uningested soil. The soil inoculated with PC had higher soil pH values and Ca_Ws contents than those with the other three earthworm species. Principal component analysis revealed significant differences in soil pH, Ca speciation, NIR spectra, and exchangeable base cation release between casts and uningested soil in treatments with EF, PC, AR, and AA inoculation. These findings expand, for the first time, to the ecological functions of earthworm species, especially for PC, demonstrating a capacity to alter soil Ca speciation, decrease soil pH, affect the exchangeable base cations’ release, and participate in and regulate the geochemical circulation processes in limestone regions. Full article

Biochar is a multifunctional tool that enhances soil quality, with particularly positive effects on acidic soils with low nutrient content, common in tropical regions worldwide, such as in the Amazon region in Brazil. This study investigates the effects of açaí fruit waste biochar (Euterpe oleracea Mart.) amendment and phosphate fertilisation on the chemical characteristics of a Ferralsol and on the biological components of cowpea (Vigna unguiculata (L.) Walp). In a greenhouse setting, a randomised block design was employed, testing five doses of biochar (0, 7.5, 15, 30, and 60 t ha⁻¹) combined with four doses of phosphorus (P) (0, 40, 80, and 120 kg ha⁻¹), resulting in 20 treatments with three replicates and 60 experimental units. Cowpea responded to inorganic fertilisation, with lower doses of P limiting the biological components (height, leaves, leaf area, dry biomass, and dry root mass). Higher doses of biochar and P increased the soil’s available P content by up to 2.3 times, reflected in the P content of cowpea dry biomass. However, this increase in biochar and P levels led to a maximum increase of 7.7% in agronomic phosphorus efficiency (APE) in cowpea in the short term. The higher doses of biochar promoted increases in pH value, cation exchange capacity (CEC), and the contents of potassium (K), calcium (Ca), and total nitrogen (N). In contrast, a decrease in magnesium (Mg) and aluminium (Al) levels was observed, while the concentration of easily extractable glomalin (EE-GRSP) was not significantly affected during the evaluated period. We conclude that biochar altered the soil environment, promoting the increased solubility and availability of phosphorus. Full article

Many agricultural fields are no longer sustainable due to inadequate replenishment of soil nutrients through organic and inorganic inputs, particularly in smallholder farming systems. As a result, achieving potential crop yields in these systems has proven to be difficult. Field trials were conducted in two long rainy growing seasons in 2021 and 2023 to assess the effects of urea fertilizer and cattle manure as sources of nitrogen (N) on (i) maize crop yields and (ii) soil chemical properties at two sites (Kwa Sadala and Mungushi) located in Hai district, northern Tanzania. The trials employed a randomized complete block design with three replicates, including eight treatments. The treatments were: 0 fertilizer (control), 25, 50, 75 kg N ha⁻¹ (sole urea), 12.5 kg N (urea) + 12.5 kg N (cattle manure), 25 kg N (urea) + 25 kg N (cattle manure), and 50 and 75 kg N (sole cattle manure). Results show that the highest application rate of urea (75 kg N ha⁻¹) produced the highest grain yields of 4.21 and 4.09 t ha⁻¹ in the 2021 season and 4.32 and 4.04 t ha⁻¹ in the 2023 season at Kwa Sadala and Mungushi, respectively. The application of cattle manure at the highest rates increased the soil pH by 3.15 and 2.26% at Kwa Sadala and Mungushi, respectively. Similarly, soil total N, OC, available/extractable P, and exchangeable K increased by 100%, 56.3%, 52.36%, and 19.67%, respectively, at Kwa Sadala and by 16.67%, 18.13%, 20.95%, and 6.76%, respectively, at Mungushi. The use of urea alone at the higher rates or in combination with cattle manure at 50% each resulted in the highest net benefit (NB) in all sites. The findings from this study suggest that a comprehensive approach to managing soil nutrients, such as combining inorganic and organic inputs, may improve crop yields while maintaining soil health. Full article

Intensive agriculture is the chief cause of soil degradation, particularly in regions with low soil organic carbon status, such as semi-arid southern India. In the quest to attain sustainable yield and improved soil quality, conservation agriculture (CA) is being advocated and adopted globally, including in India. In this experiment, CA was implemented to investigate the synergistic impacts of tillage and weed management on soil quality index and system yield and to identify a remunerative treatment combination that can sustain system yield and enhance soil quality. Contrasting tillage practices (main plots) included the T₁: conventional tillage with cotton–conventional tillage with maize–fallow, i.e., no Sesbania rostrata (Farmers’ practice), T₂: conventional tillage with cotton–zero tillage with maize–zero tillage with Sesbania rostrata and T₃: zero tillage with cotton + Sesbania rostrata residues–zero tillage with maize + cotton residues–zero tillage with Sesbania rostrata + maize stubbles. Weed management tactics (sub-plots) were W₁: chemical weed control, W₂: herbicide rotation, W₃: integrated weed management and W₄: single hand-weeded control in a split-plot design with cotton–maize–Sesbania cropping system over 3 years, in a split-plot design. Principal component analysis (PCA) was performed using the soil quality index (SQI)-CAL Version 1.0 software tool to extract minimum datasets from measured soil properties. A total of 40 soil variables were analyzed at 60 DAS and after the maize harvest, then subjected to principal component analysis (PCA) and subjected to PCA in soil quality index (SQI)-CAL software as to choose variables, minimum dataset and obtain soil quality index. The following soil properties, soil organic carbon (SOC), silt fraction, available soil zinc (Zn), iron (Fe), potassium (K), nitrogen (N), pH, electrical conductivity (EC), soil carbon to nitrogen (C:N) and cation exchange capacity (CEC), were selected as indicators based on correlations, calculated PCA and adept opinions on texture and lime concretions of experimental soil. The soil quality index improved by 23.34% in the T₃W₄ compared to T₁W₁. The system yield was 51.79% higher with the adoption of T₃W₃ compared to T₃W₄ combinations. Therefore, considering both system yield and soil quality index, T₃ and W₃ were remunerative and the best treatment combination among all others to sustain both soil and crop productivity in this region. Full article

Increasing soil salinity threatens almond production globally, driving the need for the development of salt-tolerant cultivars. This study investigated the salt tolerance mechanisms of four self-rooted almond genotypes (Vialfas, Guara, Penta, and Avijor) under controlled conditions. Young plants were exposed to four salinity levels (0, 25, 50, and 75 mM NaCl) for 5 months. Growth parameters (trunk diameter, shoot length, fresh and dry weights), physiological responses (chlorophyll fluorescence, gas exchange, Soil–Plant Analysis Development (SPAD)), and mineral content were analyzed. Results show significant genotype-specific responses at the critical salinity threshold of 50 mM NaCl. Under these conditions, Guara and Vialfas maintained higher stem fresh weights (31.4 g and 37 g, respectively), while Avijor showed significant declines. Trunk diameter measurements revealed Vialfas’ superior performance (7 mm) compared to Guara and Penta (both around 6 mm), while Avijor exhibited the most significant reduction (5 mm). Chlorophyll fluorescence parameters indicated stress impact, with F_v/F_m values decreasing to 0.84 compared to control values of 0.87. Guara maintained higher K⁺/Na⁺ ratios in leaves (3.05) compared to Avijor (1.95), while Penta showed better Na⁺ exclusion ability with the lowest leaf Na⁺ content (0.57%). Cl⁻ accumulation patterns also differed among genotypes, with Avijor and Vialfas showing higher leaf Cl⁻ concentrations (0.74% and 0.73%, respectively) compared to Penta (0.44%). Genotype responses across all salinity levels revealed distinct tolerance patterns: Guara maintained growth and physiological functions across treatments, while Penta showed remarkable stability under high salinity. Vialfas exhibited vigor at low salinity but declined sharply at 75 mM NaCl. Avijor demonstrated the highest salt sensitivity. These findings highlight the genetic variability in salt tolerance among almond cultivars and identify potential sources of salt-tolerant traits for breeding programs. The study also provides insights for optimizing genotype selection and management strategies in salt-affected orchards, contributing to more sustainable almond production in challenging environments. Full article

This experiment examined the effects of blending bottom ash produced after combusting dry livestock manure (BACL, 2–4 mm particle) as a soil amendment on the physicochemical properties of the root zone and growth response of creeping bentgrass in sandy soil. The treatments were designed as follows: control [100% sand], 3% BACL (3% BACL + 97% sand), 5% BACL (5% BACL + 95% sand), 7% BACL (7% BACL + 93% sand), and 10% BACL (10% BACL + 90% sand). Although BACL improved the soil physical properties, such as the capillary porosity, total porosity, and hydraulic conductivity, it reduced the cation exchangeable capacity. The BACL treatments increased the pH, EC, Av-P₂O₅, and Ex-K compared to the control. The turf color index, chlorophyll content, shoot length, clipping yield, and shoot dry weight after the BACL treatments were similar to the control. The growth and nutrient uptake of the roots in the BACL treatment were higher than those of the control. The BACL application amount was positively correlated with the capillary porosity and total porosity of the root zone (p ≤ 0.01) and with the growth and nutrient levels of the roots (p ≤ 0.05). These results suggest that applying BACL as a soil amendment enhanced the uptake of phosphorus and potassium in the roots of creeping bentgrass by improving the soil porosity in the root zone and by supplying phosphate and potassium. Full article

Drought is one of the key challenges of climate change. The basic global problem related to the increasing water deficit is that the vast majority of crops are species and varieties that are the result of breeding work that did not anticipate such a rapid decrease in water availability in the soil. The main objective of the conducted research was to compare the physiological and biochemical response to water deficit of plants of the species Fragaria vesca—two cultivated varieties, and one collected from the natural environment. A two-year pot experiment was conducted in a polyethylene tunnel. The substrate moisture level was monitored using tensiometer readings. Measurements of gas exchange parameters, chlorophyll “a” fluorescence, content of photosynthetic pigments in leaves, index of relative water content in leaves, total fruit yield, single fruit mass and content of K, Ca, Mg, Na, Cu, Zn, Mn, Mo and the ratio of mono- to divalent cations in leaves, roots and plant crowns were taken three times each year during the experiments. Based on one-way and two-way analysis of variance, statistically significant differences were observed between wild-growing plants and cultivated varieties under control conditions, particularly in terms of chlorophyll fluorescence values and the content of photosynthetic pigments. A significant main effect of the soil moisture level was identified for most measured parameters across the majority of assessment time points. However, a significant interaction effect between soil moisture level and genotype was less frequently observed. Significant changes in response to water deficit varied depending on the parameter and genotype, ranging from 2.5% to 106.1%. For the content of chemical elements, the changes reached up to 157.1%. The results suggest that plants obtained from natural environments exhibit better adaptation to water deficit conditions, making them suitable for use in breeding programs aimed at developing varieties resistant to soil water deficits. However, the study’s limitations, particularly the absence of molecular analyses regarding the plants’ adaptive mechanisms, should be taken into consideration. Full article

Saline-alkali soil imposes severe adverse effects on soil utilization and agriculture production worldwide. Amelioration of saline-alkali soil is crucial to ensure global food security and promote sustainable agricultural development. Here, the effects of the combined application of soil amendment desulfurization gypsum (G) and KIA (K, an industrial organic by-product) on soil improvement and plant growth were investigated. Two experiments, a soil column leaching test and a pot experiment for plant growth, were carried out. The results showed that the combined application of G and K reduced soil pH significantly. Although the soil Na⁺ contents had no change in the combined treatments, the K⁺, Ca²⁺ and Mg²⁺ contents were significantly higher, and the HCO₃⁻ and Cl⁻ contents were significantly lower, compared to the control. Furthermore, maize plants exhibited a higher photosynthetic rate and greater dry weight in the combined treatments. Additionally, after plant growth, the soil enzyme activities increased. These results showed that the combined application of G and K could have a more favorable impact on soil improvement by reducing soil pH, enhancing soil ion exchange, increasing soil nutrient contents, and promoting plant growth. Our study suggests that KIA is an effective and eco-friendly soil amendment for improving saline-alkali soil. Full article