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Nitrous oxide (N₂O) is a major agricultural greenhouse gas. Its direct emission factor (EF) is a key parameter for greenhouse gas inventories and developing mitigation strategies. However, the Intergovernmental Panel on Climate Change (IPCC) default EF may not reflect actual emissions from Chinese croplands. This study compiled extensive field observations from key agricultural regions in China. A systematic meta-analysis was conducted to evaluate annual N₂O emissions and nitrogen fertilizer-induced direct emission factors. Subgroup analyses revealed that fertilizer type, land use, soil texture, and climate zone all significantly influence EF. Univariate meta-regression indicated that EF is positively correlated with nitrogen (N) application rate and mean annual temperature but negatively correlated with soil pH, highlighting these factors as key drivers of N₂O emissions. The mean EF in Chinese croplands was about 0.68%, much lower than the 1% global default recommended by the IPCC. The combined effects of optimized agricultural management, cropping systems, and local environmental conditions help explain these lower emission factors. These findings provide a scientific basis for developing region-specific emission factors, improving cropland mitigation strategies, and enhancing the accuracy of greenhouse gas inventories. Full article

Efficient soil fertility monitoring is essential for sustainable agriculture, food security, and environmental management across Africa, yet conventional laboratory methods remain prohibitively costly and slow for continental-scale applications. Soil spectroscopy is considered as a rapid, non-destructive alternative with transformative potential. This review provides a systematic synthesis of spectroscopic applications across Africa, encompassing laboratory, field, airborne, and satellite-based platforms, while examining major data sources including the Africa Soil Information Service (AfSIS) and GEO-CRADLE spectral libraries. We critically evaluate the evolution of modeling approaches, revealing that Partial Least Squares Regression (PLSR) dominates, but a shift toward advanced frameworks like hybrid physically based models, ensemble learning and deep neural networks is essential. Critically, we identify a pronounced imbalance wherein laboratory spectroscopy prevails while imaging and satellite-based approaches remain comparatively underutilized, despite their unparalleled potential for scaling point measurements to continental extents. The review consolidates findings on key soil properties, demonstrating consistent successes for primary constituents with direct spectral responses (i.e., organic carbon), while revealing relative uncertainty for properties inferred indirectly via covariance (e.g., available phosphorus, potassium). Despite significant local and regional progress, the absence of a standardized pan-African spectral library and the intractable transferability problem remain formidable barriers. Future research must pivot decisively toward imaging spectroscopy and satellite platforms, mitigating PLSR dominance through systematic adoption of ensemble methods, transfer learning, and model harmonization frameworks to fully operationalize these technologies in support of Africa’s sustainable development goals. Full article

Aluminum (Al) toxicity constrains plant performance in acidic volcanic soils, yet nitrogen (N) fertilization may influence Al availability and plant responses. This study evaluated the effects of N source and rate under contrasting soil liming conditions on vegetative growth, mineral nutrition, and physiological performance of non-bearing northern highbush blueberry (Vaccinium corymbosum L. cv. Blue Ribbon^®) plants. A split–split-plot experiment was conducted in southern Chile using urea or potassium nitrate applied at 0, 20, or 40 kg N ha⁻¹ to plants grown in unlimed soil or soil amended with calcium carbonate or magnesium oxide. Vegetative growth, tissue mineral composition, stomatal conductance, chlorophyll fluorescence, and leaf chlorophyll were monitored during the first season. Growth responded primarily to soil liming rather than N supply, indicating low N demand and substantial soil N mineralization under the experimental conditions. Foliar N increased from 1.36 to 1.70% with increasing N rates. Urea nutrition reduced foliar Al concentration by 12% compared with nitrate. Under unlimed conditions, representing maximal soil Al availability, urea fertilization was associated with 70% higher Al retention in roots relative to nitrate. Chlorophyll content was consistently higher under urea supply, while the maximum photochemical efficiency of photosystem II remained unaffected. These findings indicate that N form influences plant Al partitioning independently of growth responses. Although the underlying mechanisms were not directly assessed, the observed patterns suggest that urea fertilization may reduce Al translocation to shoots under conditions of high Al availability. Full article

Optimizing tillage and fertilization practices is of vital importance for enhancing soil carbon retention, improving soil quality and increasing crop productivity in the intensive wheat (Triticum aestivum L.)–maize (Zea mays L.) double cropping system (WM). However, the combined effects of subsoiling (ST) and liquid manure (LM) application on yield sustainability and the dynamic changes in labile organic carbon (LOC) fractions (LOCs) remain insufficiently quantified in WM in the North China Plain (NCP). A two-year field experiment evaluated the responses of grain yields, the sustainable yield index (SYI), soil organic carbon (SOC), LOCs, C pool management indexes (CPMIs), and the soil quality index (SQI) to both patterns of tillage [conventional shallow rotary tillage (RT) and ST] and fertilization [conventional fertilization (CF), LM broadcast (LMB), and LM injection (LMI)] in WM in the NCP. Compared with RT, ST significantly enhanced crop grain yields (3.5~4.1%) and the annual SYI (4.1%) (p < 0.05). The contents of SOC, total labile OC (TLOC), high LOC (HLOC), and medium LOC (MLOC) and the values of SQI were higher in soil layers at both 0–20 cm and 20–40 cm under ST than those under RT. Compared with CF, LMI significantly enhanced grain yields (5.8~6.1%) and the annual SYI (5.4%). LMI significantly increased the contents of SOC, TLOC, HLOC, and MLOC and the SQI values in both soil layers relative to CF, while no significant difference was observed for grain yields, the annual SYI, and the SQI between LMB and CF. The higher contents of SOC and LOC led to an increase in the values of CPMIs based on TLOC (TCPMI), HLOC (HCPMI), and MLOC (MCPMI). The combination of both ST and LMI enhanced SOC retention through the increase in recalcitrant organic carbon (ROC) content and the transformation process of LOCs. It was obvious that HLOC and MLOC affected SOC, HCPMI, and MCPMI in the soil layers at both 0–20 cm and 20–40 cm, and thus can be regarded as sensitive indicators reflecting the dynamic changes in SOC and soil quality. Therefore, the combination of subsoiling and liquid manure injection can promote labile OC transformation, SOC retention, soil quality, and yield sustainability, providing an effective management strategy for the achievement of sustained agricultural production in the NCP or other regions with similar conditions. Full article

Availability of phosphorus (P) is thought to limit bole growth in wet tropical forests, raising concern that removing P through repeated logging in P-limited stands may be unsustainable. Motivated by a study in Indonesia, we analyzed Olsen extractable and total soil P in the upper 10 cm in paired samples we collected under vs. near decaying boles of two contrasting species in a wet tropical forest in Puerto Rico. Guarea guidonia had higher wood and leaf P concentrations than Dacryodes excelsa. G. guidonia colonized valleys with higher soil P concentrations than ridge sites dominated by D. excelsa. We used two age cohorts of trees > 30 cm diameter, felled by hurricanes Hugo in 1989 (11 years old) and Georges in 1998 (1.5 years old), but soil P did not differ with age. Soil Olsen P concentrations were significantly higher under versus away from boles of both species. Paradoxically, augmentation of soil P was greater under boles of D. excelsa than G. guidonia despite having lower wood P. Soil % C and Olsen P were strongly positively correlated in D. excelsa but not in G. guidonia, suggesting that regulation of soil P-availability differs between ridges and valleys. Both soil C and P may be critical for maintaining soil fertility on ridges in a wet tropical forest. Our results are discussed in the context of prior experiments at our site, including two where bole growth increased with wood addition and/or decreased after removal of woody debris. These studies in Puerto Rico, together with others elsewhere, suggest that reduced forest productivity could potentially result from repeated logging of forest stands on ridges with low P-availability in humid tropical areas since decaying wood could directly and indirectly maintain P-availability in sites with low soil P-availability. We suggest several hypotheses on P-cycling in montane humid tropical forests that need further research to elucidate mechanisms controlling soil P-availability and identify sites where repeated logging is likely to be unsustainable. Full article

Modern agriculture is increasingly reliant on imported fertilizers and subject to price volatility, compounded by environmental pressures arising from the overuse of synthetic fertilizers. This study assessed the impact of Furcellaria lumbricalis algal biostimulant, produced by anaerobic fermentation, on dry matter yield and plant development indicators of garden radish (Raphanus raphanistrum subsp. sativus) in five soil substrate types. Biostimulant doses aimed at reducing mineral fertilizer application to 75% of the full rate while maintaining or improving yield were evaluated; yet no statistically significant effect on dry matter yield was observed, and the hypothesis was therefore not statistically confirmed. The experiment included five substrate types (sandy clay, sandy clay with organic matter, sand, sand with organic matter, and peat) and six fertilizer/biostimulant treatments, including 75% mineral fertilizer combined with 3%, 6%, and 12% algal biostimulant concentrations. Linear mixed models showed that substrate type (F = 19.58; p < 0.001) and fertilizer variant (F = 5.00; p < 0.001) had statistically significant effects on total dry matter yield, but their interaction was not statistically significant. All 75% and 100% mineral fertilizer variants with and without biostimulant produced statistically significantly higher yields than the unfertilized control (p = 0.0016–0.0337). The leaf development indicator (AtLeaf) index was statistically significantly higher in all biostimulant variants compared to the unfertilized control. Principal component analysis (PCA) and redundancy analysis (RDA) demonstrated that substrate type determines the primary structure of the substrate–plant system, while biostimulant effects were expressed as modulation of existing processes within the substrates. The results indicate substrate-specific responses to Baltic Sea algal Furcellaria lumbricalis digestate with statistically significant effect observed only in peat, consistent with previous findings, while no significant effects were detected in other substrates. Although the effects of the biostimulant on dry matter yield were not consistently statistically significant, the observed trends in plant development indicators and substrate–plant system responses suggest that Furcellaria lumbricalis digestate may have potential as a nutrient recycling component within a circular bioeconomy framework. Full article

Treated wastewater (TWW) reuse mitigates water scarcity but may induce soil salinization and trace metal accumulation if improperly managed. This field study evaluated the combined effects of irrigation water quality (TWW vs. well water) and irrigation method (surface vs. subsurface drip irrigation, SDI) on soil chemical properties, okra growth, yield, and nutrient/trace element dynamics under semi-arid Mediterranean conditions. Soil pH remained stable across treatments. Electrical conductivity was not significantly affected by water quality but increased in deeper layers under surface drip irrigation, indicating salt migration. SDI promoted more uniform nutrient distribution and favored Na⁺ displacement toward deeper layers, reducing root-zone exposure. Cations stratified vertically, with Ca²⁺, Mg²⁺, and K⁺ concentrated in surface layers and Na⁺ at depth. Water quality exerted a stronger influence than irrigation method. The fertilizing effect of TWW significantly enhanced plant height (53%), leaf dry matter (43%), aboveground biomass (81%), and fruit yield (16.3%). When combined with SDI, TWW improved irrigation water use efficiency by 20%. Although fruit Cd concentrations increased under TWW irrigation, all trace metals remained below international food safety standards. These findings indicate that integrating TWW with SDI enhances productivity and water use efficiency while maintaining short-term food safety, though long-term monitoring remains essential. Full article

The growing global food demand has increased the use of chemical fertilizers, causing environmental issues. Previous studies have often assessed waste-derived fertilizers separately in terms of soil improvement or environmental impact, with limited integration of these aspects across different recycling processes. This study evaluated the effects on soil quality and the environmental impact of fertilizers produced with different percentages of food wastes and different recycling processes. The fertilizers investigated include vermicompost (VC, 70% wood sawdust + 30% food wastes), Compost 1 (C1, 50% wood sawdust + 50% food wastes), Compost 2 (C2, 10% straw + 90% food wastes), and sulfur–bentonite (SBC, 90% SB + 10% food wastes). Six months post-fertilization, vermicompost significantly improved soil properties, increasing soil organic matter from 3.01% to 4.70% (+56%) and total nitrogen from 0.15% to 0.22%, along with an increase in microbial biomass compared to the unfertilized control. Compost treatments also improved soil quality, although to a lesser extent. A Life Cycle Assessment (LCA) was performed across the entire life cycle of the fertilizers. Vermicompost showed the lowest environmental impact, with a global warming potential of 45 kg CO₂ eq ton⁻¹, compared to 93 and 100 kg CO₂ eq ton⁻¹ for C1 and C2, respectively, and 167 kg CO₂ eq ton⁻¹ for SBC. The results evidenced that vermicompost improved soil quality by increasing soil organic matter, total nitrogen, microbial biomass, and biological activity and that it emitted less CO₂ eq, SO₂ eq and PO₄³⁻ during the vermicomposting process, emphasizing its environmental sustainability. The two composts improved soil quality with a moderate environmental impact. SBC positively affected soil properties but with a strong negative environmental impact. From the benefit–cost perspective, the sustainable fertilizer ranking was VC > C2 > C1 > SBC. These findings underscore that these waste management processes represent a possible transition to sustainable fertilizers derived from waste materials to mitigate the environmental degradation associated with the production and use of conventional fertilizers. By adopting these practices, the agricultural sector can boost productivity while maintaining environmental sustainability standards. Full article

Agriculture in the Pacific is driven primarily by small-scale private farmers, many of whom do not have access to soil testing services or advice, nor the means to interpret analytical results into soil management and agronomic recommendations. Soil degradation through the process of acidification poses a significant risk to food and income security as it directly threatens crop productivity. The nutritional quality of food crops may also be affected through sub-optimal nutrient uptake by plants and nutrient imbalances. The dataset reported here provides a useful platform for the development of a decision-support tool (DST) that will assist Fiji farmers in understanding and managing soil pH and soil acidity. The DST will enable making informed decisions about liming to help correct soil pH. To support this development, historical soil pH data available from the Pacific Soils Portal were combined with updated analyses of agricultural soils from 17 locations in Viti Levu Island (Fiji) collected during a field campaign undertaken in August 2025. The soils were sampled at two depth intervals (0–15 and 15–30 cm) and analyzed for pH using a variety of methods. These methods included direct field measurements using a portable pH-meter as well as traditional laboratory determinations. Of the soils sampled, it was found that most soils exhibited pH levels below 7, which were observed for both depth intervals. Across all samples taken in 2025, it was found that 54.3% of them had soil pH < 5, 38.6% had soil pH between 5 and 6, and 7.1% had pH > 6 (based on soil pH_1:5 soil-to-water method). Depending upon specific land uses, climate and cropping intensity, it was recommended that routine liming be built into soil fertility management programs to help farmers overcome soil acidity-related constraints to production. Liming frequency, timing of application and application rate will need to be determined for specific soil and cropping situations; however, it was suggested that soil pH was not changed by more than 1 unit each time lime was applied. Such an approach should reduce the risk of soil organic matter loss through accelerated mineralization, which would be challenging to restore in that environment if soils remained under continuous cropping. The analytical information contained in this article expanded and updated the datasets available in the Pacific Soils Portal. Furthermore, this work provided an opportunity to build analytical expertise in aspects of soil chemistry at local organizations to support academic and extension activities as well as the ongoing development of the Pacific Soils Portal. Full article

The release of heavy metals into the environment due to human activities is increasing, and this has led to concern about heavy-metal contamination on farmland. Prior studies have primarily focused on short-term investigations or specific pollution sources, lacking systematic monitoring of cadmium’s long-term input-output fluxes and their mass balance at the scale of a complete farmland ecosystem. This study clarified the cadmium (Cd) pollution trends for a typical paddy system in southern China. A six-year long-term monitoring study (2019–2024 inclusive) of a Cd-contaminated paddy system in Ningxiang City, Hunan Province, China, was conducted. The Cd flux dynamics for three input pathways (atmospheric deposition, irrigation water, and fertilizer) and three output pathways (crop harvesting, surface runoff, and subsurface infiltration) were investigated. The results showed that atmospheric deposition is the primary source of Cd input, accounting for 76% of total inputs, and leads to persistent net accumulation of soil Cd. Straw removal serves as the dominant output mechanism, facilitating substantial Cd removal, representing 77% of total Cd exports, while straw retention significantly reduces export fluxes. The study found that the net Cd fluxes from 2019 to 2024 were 1.994, 2.624, 8.984, 11.299, 9.944, and 20.162 g·(hm²·a)⁻¹, straw removal was primarily adopted during the period. A net flux analysis showed that progressive soil Cd accumulation had occurred over the study period. The results suggest that science-based straw management is critical when attempting to mitigate soil Cd pollution and enhance safe land utilization. These findings can be used to improve region-specific pollutant source control strategies and soil management policies. Full article

Climate change-induced variability in temperature and precipitation increasingly constrains crop production on sandy-textured soils with low water-holding capacity and limited nutrient retention. Such soils, classified as Brunic Arenosols, are widespread across the temperate climate zone of Central Europe, particularly in post-glacial landscapes, where they constitute a significant proportion of marginal agricultural lands. This study evaluated the relative influence of growing-season weather conditions and selected soil physicochemical properties on the yield of Camelina sativa and Brassica carinata cultivated under low-input management on Brunic Arenosols in northwestern Poland during the 2023 season. Yields varied markedly among sites. Camelina sativa produced yields from 300 to 930 kg ha⁻¹, with the highest yield recorded at the site characterized by higher BS and phosphorus availability. Brassica carinata produced yields from 0 to 370 kg ha⁻¹, including complete yield loss at one location due to severe pathogen infestation. Spearman’s correlation analysis revealed that temperature was a key determinant for both crops (r = 0.77 for C. sativa; r = 0.82 for B. carinata). For Camelina sativa, yield was strongly associated with BS (r = 0.80) and available P (r = 0.69), whereas Brassica carinata was more sensitive to climatic variability, showing a negative relationship with precipitation (r = −0.63). The results indicate species-specific responses to soil fertility and weather conditions under water- and nutrient-limited conditions typical of Central European sandy soils. While Camelina sativa performance was more closely linked to soil chemical status, Brassica carinata appeared predominantly climate-driven. These findings highlight the broader relevance of the study for temperate regions of Central Europe and support the integration of soil fertility management with climate-adaptive strategies when introducing alternative oilseed crops to marginal lands. Full article

The Ningxia Yellow River Irrigation District in China has long been influenced by flood irrigation and intensive fertilizer input under its particular geological and climatic constraints, and this region is characterized by low soil organic matter, poor nutrient status, low permeability, high pH, and widespread salinization. This cross-sectional field study compared the soil physicochemical properties and microbial communities among saline–alkali soil (SAS), straw-returning farmland (SR), and traditionally managed farmland (FM). EC was higher in SAS (approximately 4.21 dS·m⁻¹) than in SR and FM (approximately 0.23 and 0.30 dS·m⁻¹, respectively), whereas TOC and C/N were higher in SR (approximately 1.00% and 10.58, respectively) than in FM (approximately 0.78% and 8.69) and SAS (approximately 0.43% and 8.81). Bacterial and fungal communities showed different distribution patterns among the three farmland types. Compared with fungi, bacterial community structure and richness varied more clearly across soils differing in salinity and organic matter status. Variations in microbial community composition were accompanied by differences in soil salinity and carbon- and nitrogen-related properties. Acidobacteriota was positively correlated with soil carbon and nitrogen variables and negatively correlated with pH and EC, while Ascomycota was positively correlated with total carbon (TC) and TOC. These results show that straw-returning farmland differed from saline–alkali soil and traditionally managed farmland in both soil properties and microbial community characteristics, highlighting potential soil–microbe associations in saline-affected agricultural systems. Full article

Cadmium contamination threatens safe vegetable production in arable soils. This study evaluated whether soil-applied selenium (Se) could reduce Cd accumulation in Artemisia selengensis while keeping Se enrichment within a practical safety range. A field plot experiment was sampled at 75, 110, and 150 d, and two pot experiments were conducted under normal and elevated Cd backgrounds. Six sodium selenite rates (0.5–8.0 mg kg⁻¹; Se1–Se6) plus a control were applied. In the field experiment, Se5–Se6 (6.5–8.0 mg kg⁻¹) reduced stem Cd by 33.0–39.3% at 75 d and 34.3–36.5% at 110 d, but the reduction declined to 24.8% at 150 d. Se application increased tissue Se (leaf > stem > rhizome), while stem total Se remained within the dry-weight reference window under 12Se–Se (0.5–2.0 mg kg⁻¹). Se5–Se6 also increased soil pH and reduced bioavailable Cd by 8.8–10.2%, whereas stem Cd reduction under an elevated Cd background was limited and non-significant. Overall, 0.5–2.0 mg kg⁻¹ (Se1–Se2) provided a practical window for Cd mitigation, while 6.5–8.0 mg kg⁻¹ (Se5–Se6) increased the risk of excessive Se accumulation in edible tissues. Full article

Understanding the dynamics of soil organic carbon (SOC) in farmland is crucial for assessing soil health, quantifying ecosystem potential for SOC enrichment, and guiding sustainable agricultural management. Existing research on SOC sequestration and mineralization has focused mainly on the topsoil layer (0–20 cm), whereas systematic evidence on how deep SOC (>20 cm) responds to agricultural management, and on strategies to enhance deep carbon sequestration, remains limited. This study uses long-term fixed-site monitoring data from 120 farmland plots across 21 typical farmland ecosystem stations and farmland–complex ecosystem stations within the Chinese Ecosystem Research Network (CERN) over 17 years (2004–2020). Using spatial analysis, we characterize the spatiotemporal dynamics of SOC below 20 cm along soil profiles across seven major geographical zones in China. We then estimate the heterogeneous effects of fertilization and straw-management practices (S, straw returning; SCF, straw returning with chemical fertilizer; OF, organic fertilizer; OCF, organic fertilizer with chemical fertilizer), tillage modes, and farmland types on SOC in the 20–40 cm, 40–60 cm, and 60–100 cm layers using a panel fixed-effects model. The results indicate pronounced vertical heterogeneity in SOC below 20 cm and a clear spatial gradient. The 60–100 cm layer shows a significant increase in SOC content during the study period, with a cumulative increase of 4.07%. Relative to single organic inputs, the co-application of organic and inorganic materials improves deep soil SOC enhancement efficiency. Compared with reduced tillage and no-tillage, conventional tillage is less conducive to SOC enhancement in layers shallower than 60 cm, yet it has a significant positive impact on SOC in the 60–100 cm layer. Compared with dryland and irrigated land, paddy fields are less favorable for SOC enhancement below 20 cm. Consequently, regarding agricultural practice, a composite tillage regime combining “surface conservation tillage with periodic deep tillage” should be promoted to foster deep SOC enhancement. Full article

The occurrence and concentration of potentially toxic elements (PTE) in fertilizers are a concern in tropical regions, and soil properties affect their bioavailability for crops. Cadmium is the most easily bioavailable for plants and so the food chain, and it represents a stepping-stone toward safe food production. So, this study aimed to evaluate the ionomics, metabolism, and growth of potato, tobacco, and rice in response to liming and to monoammonium phosphates (MAP) from different geographic origins and PTE contents (MAP 1, MAP 2, MAP 3). For this, independent experiments were conducted with each crop using MAP fertilizers as a phosphorus source applied to a Red-Yellow Latosol, with and without liming. Our findings indicated that physiological changes were primarily influenced by liming rather than PTE. Most acidic soils negatively impacted plant growth and sugar content and induced metabolic adjustments related to proline. The higher level of Cd in MAP 3 reduced manganese and zinc and increased sugar in plant shoots. Rice also had a lower Cd bioaccumulation than potato and tobacco, followed by a higher tolerance to acidic soil. The concentrations of As, Cd, and Cr present in fertilizers did not impair the growth and life cycle of the evaluated plants; however, metabolic adjustments were observed. Full article