Search Results (521)

Soil contamination with heavy metals often resulting from industrial activities and wastewater discharge is a major ecological problem. Bone meal, a by-product of the agri-food industry, is a promising material for remediating soils affected by heavy metal pollution. Bone meal, rich in phosphorus, calcium, and other essential minerals, provides advantages both in immobilizing inorganic pollutants and in improving soil fertility. This study explores the potential of bone meal as an ecological and sustainable solution for the retention of zinc from soils polluted with wastewater. This study analyzes the physicochemical properties of bone meal, the mechanisms of its interaction with metal ions through adsorption processes as revealed by equilibrium and kinetic studies, and its effects on plant germination. The results indicate a maximum adsorption capacity of 2375.33 mg/kg at pH = 6, according to the Langmuir model, while the pseudo-second-order kinetic model showed a coefficient of R² > 0.99, confirming the chemical nature of the adsorption. At pH 12, the retention capacity increased to 2937.53 mg/kg; however, parameter instability suggests interference from precipitation phenomena. At pH 12, zinc retention is dominated by precipitation (Zn(OH)₂ and Zn–phosphates), which invalidates the Langmuir assumptions; accordingly, the Freundlich isotherm provides a more adequate description. Germination tests revealed species-specific responses to Zn contamination and bone meal amendment. In untreated contaminated soil, germination rates were 84% for cress, 42% for wheat, and 50% for mustard. Relative to the soil + bone meal treatment (100% performance), the extent of inhibition reached 19–21% in cress, 24–29% in wheat, and 12% in mustard. Bone meal mitigated Zn-induced inhibition most effectively in wheat (+31% vs. soil; +40% vs. control), followed by cress (+23–27%) and mustard (+14%), highlighting its species-dependent ameliorative potential. Thus, the experimental results confirm bone meal’s capacity to reduce the mobility of zinc ions and improve the quality of the agricultural substrate. By transforming an animal waste product into a material with agronomic value, this study supports the integration of bone meal into modern soil remediation strategies, aligned with the principles of bioeconomy and sustainable development. Full article

Rice cultivation has the ability to ameliorate saline soils, but this monoculture pattern can lead to negative plant–soil feedback. In a previous study, we investigated the effects of long-term rice cultivation on saline soil chemistry, salt ions, root characteristics, and agglomerate formation, and concluded that the optimal rice planting period is 5 years. However, we do not know which crop rotation is most effective in improving this negative soil feedback and enhancing soil quality. In this study, we carried out an experiment on saline land planted with rice over 5 years and set up four different rotations, including rice–Hunan Jizi, rice–maize, rice–sweet sorghum, and rice–soybean, with perennial rice planting as CK, to analyze soil texture under different treatments. Physicochemical properties and enzyme activities were also analyzed under different treatments, and the soil quality index (SQI) was constructed using principal component analysis and correlation analysis for comprehensive evaluation of each treatment. The results showed that (1) the saline-alkali soil texture of perennial rice planting in the Yinbei Plain was silty soil, and different rice drought rotation methods changed the soil texture from silty to silty loam, which improved the fractal dimension of the soil. The fractal dimension of saline-alkali soil was significantly positively correlated with the clay volume content, negatively correlated with silt volume content, and negatively correlated with sand volume content. (2) There was no risk of structural degradation (SI > 9%) in saline-alkali soil planted in perennial rice, and it appeared that RS (rice–soybean) could improve the stability coefficient of soil structure in the 0~40 cm soil layer. (3) Different rice and drought rotation methods could significantly affect the physical and chemical properties and enzyme activities of soil, and the quality of soil in the 0~40 cm soil layer was evaluated; RS (rice–soybean) and RC (rice–maize) were suitable for rice drought rotation in the Yinbei area. The structural equation model showed that salinity and soil nutrients were the key factors restricting the improvement of saline-alkali soil quality in Yinbei. These results will deepen the current understanding of bio-modified saline soils. Full article

In this study, the effects of biochar and compost on the amelioration of coastal saline soil were investigated through indoor leaching experiments and soil culture experiments. The results revealed that the multivoid structure of biochar and compost, when applied to soil, effectively improved soil hydraulic conductivity, promoted the leaching of salt ions, and reduced soil electrical conductivity. Owing to the high pH value of biochar and the lower pH value of compost, the combined application of the two has a complementary effect on improving the pH value of coastal saline soils. The calcium (Ca²⁺) and magnesium (Mg²⁺) contained in biochar and compost are exchanged with Na⁺ adsorbed by soil colloids, which reduces the sodium (Na⁺) adsorption ratio (SAR) value of the soil. Biochar and compost improve the physical properties of the soil, and the organic matter they contain helps soil particles aggregate with each other and form stable clusters, thus promoting the formation of soil agglomerates, which are conducive to the formation of clusters with a diameter of ≤0.25 mm. Biochar and compost are rich in nutrients, and their application significantly increased the contents of available nutrients and organic matter as well as the activities of urease, phosphatase, and dehydrogenase in saline soils. However, too high of an application rate of biochar increases the soil pH value, and excessive application of compost can lead to greater soil conductivity, which inhibits the activities of soil urease, phosphatase and dehydrogenase. Therefore, rational control of application rates is essential for improving coastal saline soils. Future research should further explore the synergistic effects of biochar and compost in improving soil structure, nutrient effectiveness, and microbial activity to promote their effective application in coastal saline–alkaline soil improvement. Full article

Driven by both natural and anthropogenic factors, farmland abandonment and recultivation constitute complex and widespread global phenomena that impact the ecological environment and society. In the Inner Mongolia Yellow River Basin (IMYRB), a critical tension lies between agricultural production and ecological conservation, characterized by dynamic bidirectional transitions that hold significant implications for the harmony of human–nature relations and the advancement of ecological civilization. With the development of remote sensing, it has become possible to rapidly and accurately extract farmland changes and monitor its vegetation restoration status. However, mapping abandoned farmland presents significant challenges due to its scattered and heterogeneous distribution across diverse landscapes. Furthermore, subjectivity in questionnaire-based data collection compromises the precision of farmland abandonment monitoring. This study aims to extract crop phenological metrics, map farmland abandonment, and recultivation dynamics in the IMYRB and assess post-transition vegetation changes. We used Landsat time-series data to detect the land-use changes and vegetation responses in the IMYRB. The Farmland Abandonment and Recultivation Extraction Index (FAREI) was developed using crop phenology spectral features. Key crop-specific phenological indicators, including sprout, peak, and wilting stages, were extracted from annual MODIS NDVI data for 2020. Based on these key nodes, the Landsat data from 1999 to 2022 was employed to map farmland abandonment and recultivation. Vegetation recovery trajectories were further analyzed by the Mann–Kendall test and the Theil–Sen estimator. The results showed rewarding accuracy for farmland conversion mapping, with overall precision exceeding 79%. Driven by ecological restoration programs, rural labor migration, and soil salinization, two distinct phases of farmland abandonment were identified, 87.9 kha during 2002–2004 and 105.14 kha during 2016–2019, representing an approximate 19.6% increase. Additionally, the post-2016 surge in farmland recultivation was primarily linked to national food security policies and localized soil amelioration initiatives. Vegetation restoration trends indicate significant greening over the past two decades, with particularly significant increases observed between 2011 and 2022. In the future, more attention should be paid to the trade-off between ecological protection and food security. Overall, this study developed a novel method for monitoring farmland dynamics, offering critical insights to inform adaptive ecosystem management and advance ecological conservation and sustainable development in ecologically fragile semi-arid regions. Full article

The performance of lettuce, pepper, and chili pepper, and the biological soil quality, in a ground-mounted PV system under cultivation conditions typical of the Mediterranean environment of the Puglia region were evaluated. Microclimatic parameters, plant growth and yield response, soil quality assessed using the QBS-ar index, and land equivalent ratio (LER) were determined in three different cultivation areas: a cultivation area outside the photovoltaic plant but immediately adjacent to it (‘Control’); the inter-row area closest to the row of panels exposed to sunlight (‘Area close PV structure’); the inter-row area distant from the row of panels (‘Area distant PV structure’). Cumulated solar radiation, in particular during the summer growing cycles, was only slightly affected in the Area distant PV structure (1616 and 2130 MJ m⁻² for pepper and chili pepper, respectively, in the control area, in comparison to 1630 and 2044 MJ m⁻², in the Area distant PV structure), while it was strongly reduced in the Area close PV structure (883 and 1091 MJ m⁻² for pepper and chili pepper, respectively). In general, a reduction in air temperature and wind speed, as well as an increase in relative air humidity, was observed under PV conditions. On average, the evapotranspirative demand was reduced in the PV growing conditions compared to open field, with a more relevant effect in the sub-zone close to the photovoltaic structures, where cumulative ET0 was 28% and 34% lower than the Control in the pepper and chili pepper growing cycle, respectively. Lettuce growth was impaired by PV cultivation conditions, with an average reduction of 15% in plant height and 37% in marketable yield per plant, with no significant differences between the two sub-zones in the PV system. For pepper, the best growing conditions were observed in open field control compared to PV, but with differences related to the PV sub-zone. The plants grown in the Area distant PV structure were more negatively affected by the modified growing conditions, showing the lowest shoot and fruit fresh weight, the latter reduced by 51% compared to the Control; intermediate values were observed for these parameters in the Area close PV structure, with a less severe tendency to yield reduction. For chili pepper, both shoot and fruit fresh weight were lower in PV conditions, regardless of the sub-zone, with a reduction of 82% in yield per plant compared to the Control. However, despite the yield reductions, the LER was improved (1.60 and 1.40 in case of a lettuce + pepper or lettuce + chili pepper annual cropping program, respectively), highlighting a more efficient use of land, without negative or even ameliorative impacts on biological soil quality and biodiversity in terms of QBS-ar and microarthropods taxa abundance. Knowledge of the response of different crops under cultivation conditions typical of specific environments is necessary to define optimal cropping programs aimed at maximizing resource-use efficiency and land use. Full article

Given the pressing global food security crisis and climate change-induced constraints on agricultural productivity, crop rotation proves critical for boosting yield and grain quality of winter wheat (Triticum aestivum) alongside ameliorating soil quality. However, the legacy effect of different preceding crops on synergistic increments of wheat productivity and soil fertility remains to be fully clarified. Five different preceding crop–winter wheat rotations were conducted in a field experiment established in Huanghua, China. Maize (Zea mays), sorghum (Sorghum bicolor), and millet (Setaria italica) were designated as preceding gramineous crops, and soybean (Glycine max) and mung bean (Vigna radiata) were assigned as preceding legume crops. Grain yield, protein fraction, and soil nutrients were measured to elucidate the legacy effect of the preceding crops on the subsequent winter wheat. Leguminous predecessors significantly evaluated the grain yield of winter wheat compared to gramineous predecessors, particularly that the mung–winter wheat rotation (Mun-W) was 11.56% higher than that of the maize–winter wheat rotation (Mai-W). This rising yield was attributed to the increase of 4.05% in spike number per hectare and 14.31% in kernel number per spike. The Mun-W facilitated the highest gluten protein content (8.22%) in winter wheat among five treatments, which was 6.06% higher than that in the sorghum–winter wheat system. Soil organic matter (SOM) showed an advantage in legume–winter wheat rotations (Leg-Ws) compared to gramineous crop–winter wheat systems (Gra-Ws). Notably among these, the Mun-W significantly enhanced SOM content by 0.99% relative to the Mai-W. The soybean–winter wheat system decreased soil pH by 0.36 compared to the Mai-W system. Coupling coordination degree (CCD) and co-benefit index (CBI) in the Leg-Ws exhibited significant superiority of 62.41% and 42.22% over the Gra-Ws, respectively, and the Mun-W attained maximum CCD by 0.84 and CBI by 0.77. From a multi-objective assessment perspective of the legacy effect of the preceding crops, legume-based rotations facilitate synergistic improvements of yield, protein quality, and soil nutrients in winter wheat. Full article

Manganese (Mn) excess and low pH often coexist in some citrus orchard soils. Little information is known about the underlying mechanism by which raising pH reduces Mn toxicity in citrus plants. ‘Sour pummelo’ (Citrus grandis (L.) Osbeck) seedlings were treated with 2 (Mn2) or 500 (Mn500) μM Mn at a pH of 3 (P3) or 5 (P5) for 25 weeks. Raising pH mitigated Mn500-induced increases in Mn, iron, copper, and zinc concentrations in roots, stems, and leaves, as well as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper, iron, and zinc distributions in roots, but it mitigated Mn500-induced decreases in nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and boron concentrations in roots, stems, and leaves, as well as nutrient imbalance. Raising pH mitigated Mn500-induced necrotic spots on old leaves, yellowing of young leaves, decreases in seedling growth, leaf chlorophyll concentration, and CO₂ assimilation (A_CO2), increase in root dry weight (DW)/shoot DW, and alterations of leaf chlorophyll a fluorescence (OJIP) transients and related indexes. Further analysis indicated that raising pH ameliorated Mn500-induced impairment of nutrient homeostasis, leaf thylakoid structure by iron deficiency and competition of Mn with magnesium, and photosynthetic electron transport chain (PETC), thereby reducing Mn500-induced declines in A_CO2 and subsequent seedling growth. These results validated the hypothesis that raising pH reduced Mn toxicity in ‘Sour pummelo’ seedlings by (a) reducing Mn uptake, (b) efficient maintenance of nutrient homeostasis under Mn stress, (c) reducing Mn excess-induced impairment of thylakoid structure and PEPC and inhibition of chlorophyll biosynthesis, and (d) increasing A_CO2 and subsequent seedling growth under Mn excess. Full article

Salinization of olive orchards constitutes a front-line agronomic challenge for farmers, consumers, and the scientific community as food security, olive logistics, and land use become more unsustainable and problematic. Plantlets of two olive varieties (var. Kalamon and var. Koroneiki) were tested for their performance under soil saline conditions, in which L-methionine, choline-Cl, and L-proline betaine were applied foliarly to alleviate adverse effects. The ‘Kalamon’ variety ameliorated its photosynthetic rates when L-proline betaine and L-methionine were administered at low saline exposure. The stressed varieties achieved higher leaf transpiration rates in the following treatment order: choline-Cl > L-methionine > L-proline betaine. Choline chloride supported stomatal conductance in stressed var. Kalamon olives without this pattern, which was also followed by var. Koroneiki. Supplementation regimes created a mosaic of responses on varietal water use efficiency under stress. The total phenolic content in leaves increased in both varieties after exogenous application only at the highest levels of saline stress. None of the substances applied to olive trees could stand alone as a tool to mitigate salinity stress in order to be recommended as a solid agronomic practice. The residual exploitation of amino acids by the olive orchard microbiome must also be considered as part of an environmentally friendly, integrated strategy to mitigate salinity stress. Full article

Hydrogels are widely known for their ability to increase soil water retention and for their potential slow nutrient release mechanism. They have been constantly improved to meet the growing demand for sustainability in agriculture. Research focused on the development of biodegradable hydrogels, produced from industrial cellulose waste, are an ecological and efficient alternative soil ameliorant for the improvement of agricultural land. The objective of this study was to evaluate the impacts of two types of hydrogel (processed in a glass reactor versus a twin-screw extruder) on soils with different textures (clay and sandy loam), testing their water retention capacity, nitrogen leaching, and effects on seed germination. The methodology included the evaluation of water retention capacity at different pressures with different hydrogel addition rates in the soil, leaching tests in columns filled with soil and hydrogel layers, and germination tests of sorghum and corn. The results indicated that the addition of hydrogel significantly improved water retention, especially in sandy loam soils. The hydrogels also reduced nitrogen leaching, acting as nitrification inhibitors and limiting the conversion of ammonium to nitrate, with greater effectiveness in clayey soils. In the tested formulations, it was observed that the hydrogel doses applied to the columns favored nitrogen retention in the region close to the roots, directly influencing the initial stages of germination. This behavior highlights the potential of hydrogels as tools for directing nutrients in the soil profile, indicating that adjustments to the C:N ratio, nutrient release rate, and applied doses can optimize their application for different crops. Full article

Soil organic nitrogen (SON) positively influences crop productivity, greenhouse gas (GHG) emissions, and sustained nitrogen (N) supply. Herein, we observed the effect of different treatments; no fertilizers (CK), chemical fertilizers (nitrogen, phosphorus, and potassium (NPK)), organic manure, and NPK + OM (NPKOM). This study was performed in a randomized complete block design (RCBD) with three replications. The results indicated that NPKOM treatment significantly decreased the nitrous oxide (N₂O) emissions by 19.97% and 17.47% compared to NPK in both years. This was linked with improved soil nutrient availability, soil organic carbon, soil organic nitrogen (SON) storage (10.06% and 12.38%), SON sequestration (150% and 140%), increased soil particulate (44.11% and 44%), and mineral-associated organic N (26.98% and 26.47%) availability. Furthermore, NPKOM also enhanced nitrate reductase (NR: 130% and 112%), glutamine synthetase (GS: 93% and 88%), sucrose phosphate synthase (SPS: 79% and 98%), SSs (synthetic direction; 57% and 50%), and decreased SSs activity in the decomposition direction (18% and 21%). This, in turn, inhibited the decomposition of sucrase and enhanced starch conversion into carbohydrates, thus leading to an increase in rice yield and a decrease in N₂O emissions. All fertilizations, particularly NPKOM, significantly enhanced grain protein contents by increasing N uptake and its availability. Therefore, NPKOM is an effective practice to enhance rice productivity, and SON sequestration and mitigate the N₂O emissions and subsequent climate change. Full article

The ameliorative mechanism of biochar in reducing soil greenhouse gas emissions in arid saline farmland remains unclear. A two-year field study in sorghum farmland in China’s Hetao Irrigation District was conducted to assess the influence of corn straw-derived biochar on GHG emissions and explore the role of soil physicochemical properties in regulating GHG fluxes. Four different biochar application rates were tested: 0 (CK), 15 (C15), 30 (C30), and 45 t hm⁻² (C45). Compared to CK, C15 reduced CH₄ emissions by 15.2% and seasonal CH₄ flux by 77.0%. The N₂O flux followed CK > C45 > C30 > C15 from 2021 to 2022. C15 and C30 significantly decreased GWP, mitigating GHG emission intensity. Biochar application enhanced sorghum grain yield. Soil temperature was the primary determinant of CH₄ flux (total effect = 0.92). In the second year, biochar’s influence on CH₄ emissions increased by 0.76. Multivariate SEM identified soil moisture (total effect = −0.72) and soil temperature (total effect = −0.70) as primary negative regulators of N₂O fluxes. C40 lead to salt accumulation, which increases CH₄ emissions but inhibits N₂O emissions. Averaged over two years, GWP under C15 and C30 decreased by 76.5–106.7% and 5.3–56.1%, respectively, compared to CK. Overall, the application of biochar at a rate of 15 t hm⁻² significantly reduced CH₄ and N₂O emissions and increased sorghum yield. Full article

Pyrochar has been identified as a favorable soil conditioner that can effectively ameliorate soil acidification. Hydrochar is considered a more affordable carbon material than pyrochar, but its effect on the process of soil acidification has yet to be investigated. An indoor incubation and a soil column experiment were conducted to study the effect of rice straw hydrochar application on nitrification and NO₃⁻-N leaching in acidic red soil. Compared to the control and pyrochar treatments, respectively, hydrochar addition mitigated the net nitrification rate by 3.75–48.75% and 57.92–78.19%, in the early stage of urea fertilization. This occurred mainly because a greater amount of dissolved organic carbon (DOC) was released from hydrochar than the other treatments, which stimulated microbial nitrogen immobilization. The abundances of ammonia-oxidizing archaea and ammonia-oxidizing bacteria were dramatically elevated by 25.62–153.19% and 12.38–22.39%, respectively, in the hydrochar treatments because of DOC-driven stimulation. The cumulative leaching loss of NO₃⁻-N in soils amended with hydrochar was markedly reduced by 43.78–59.91% and 61.70–72.82% compared with that in the control and pyrochar treatments, respectively, because hydrochar promoted the soil water holding capacity by 2.70–9.04% and reduced the residual NO₃⁻-N content. Hydrochar application can dramatically diminish total H⁺ production from soil nitrification and NO₃⁻-N leaching. Thus, it could be considered an economical soil amendment for ameliorating soil acidification. Full article

With the rapid expansion of the aquaculture scale, the environmental pollution caused by the accumulation of fish pond sediment (FPS) has become increasingly prominent, making it urgent to establish sustainable resource utilization solutions. This study investigates the potential of using FPS as a soil amendment to improve saline–alkali soil (SAS) quality and enhance vegetable growth, while also quantifying ecological benefits through Gross Ecosystem Product (GEP) accounting. A pot experiment was conducted to evaluate the effects of different FPS mass percentages (0%, 20%, 40%, 80%, and 100%) on the growth of three vegetables (water spinach, lettuce, and chili) and soil quality. The results demonstrated that FPS addition at ≥40% significantly improves SAS quality, reducing the pH and salinity (p < 0.05), while enhancing organic matter, nutrient availability, and microbial activity. Among the treatments, 80% FPS maximized vegetable yields, with water spinach achieving the highest edible biomass (37.32 g). Compared to the control, nutritional quality under ≥80% FPS treatment showed substantial increases: vitamin C (133.33–307.03%), soluble sugars (49.97–73.53%), and protein (26.14–48.08%). An economic analysis revealed that 80% FPS with water spinach cultivation generated peak ecological benefits (274,951 CNY·ha⁻¹; 185% above control). These findings provide a scientific basis and effective model for the resource utilization of FPS and the improvement of saline–alkali soil, offering significant implications for the sustainable development of agriculture and environmental protection. Full article

Biochar is a carbon-rich material produced through the pyrolysis of agricultural waste. It effectively enhances the physical, chemical, and biological properties of salinity-affected soils. Chickpea (Cicer arietinum L.) is the world’s third most important legume crop, currently cultivated in over 50 countries. However, no study has yet established recommended biochar application rates for this crop under saline soil conditions. Therefore, this study aimed to assess the chemical properties of a clay soil following the application of varying rates of biochar and NaCl, and to evaluate their subsequent effects on the growth and yield of Cicer arietinum L. To evaluate the effect of biochar, a completely randomized experimental design with ten replicates was implemented. The biochar was produced from corncobs (Zea mays) and applied at two rates (1.5% and 3%). Soil salinity levels were classified into three groups: non-saline (S1 = 1.2 dS·m⁻¹), low/moderate salinity (S2 = 4.2 dS·m⁻¹), and moderate salinity (S3 = 5.6 dS·m⁻¹). The treatments were placed in pots for 100 days. The results demonstrated that biochar applications at 1.5% and 3% rates improved both soil chemical properties (pH, EC, SAR, and ESP) and the growth of C. arietinum across all evaluated treatments. The 3% biochar treatment showed superior effects compared to the 1.5% application. Therefore, biochar application in C. arietinum production emerges as an effective agronomic strategy to mitigate abiotic stress while simultaneously enhancing crop productivity and sustainability. Full article

Soil salinization has become a major obstacle to global agricultural sustainability. While microbial inoculants show promise for remediation, the functional coordination between Trichoderma and PGPR in saline alkali rhizospheres requires systematic investigation. Pot studies demonstrated that while individual inoculations of Trichoderma longibrachiatum (M) or Bacillus aryabhattai (A2) moderately improved rice growth and soil properties, their co-inoculation (A2 + M) synergistically enhanced stress tolerance and nutrient availability—increasing available nitrogen (AN +28.02%), phosphorus (AP +11.55%), and potassium (AK +8.26%) more than either strain alone, while more effectively mitigating salinity (EC −5.54%) and alkalinity (pH −0.13 units). High-throughput sequencing further revealed that the A2 + M treatment reshaped the rhizosphere microbiome, uniquely enriching beneficial taxa (e.g., Actinomycetota [+9.68%], Ascomycota [+50.58%], Chytridiomycota [+152.43%]), and plant-growth-promoting genera (e.g., Sphingomonas, Trichoderma), while drastically reducing saline-alkali-adapted Basidiomycota (−87.96%). Further analysis identified soil organic matter (SOM), AN, and AP as key drivers for the enrichment of Chytridiomycota and Actinomycetota, whereas pH and EC showed positive correlations with Mortierellomycota, Aphelidiomycota, unclassified_k__Fungi, and Basidiomycota. Collectively, the co-inoculation of Trichoderma and PGPR strains enhanced soil microbiome structure and mitigated saline alkali stress in rice seedlings. These findings demonstrate the potential of microbial consortia as an effective bio-strategy for saline alkali soil amelioration. Full article