Higher Soil pH Research Articles

Annual bluegrass and creeping bentgrass tiller response to phosphate fertilizer and soil pH

AbstractCreeping bentgrass (CB; Agrostis stolonifera L.) grows well in low phosphorus (P) soils in monoculture, however, the soil P concentration range that provides CB an advantage over annual bluegrass (AB; Poa annua L.) in mixed swards is unknown. The objective of this research was to determine how P and soil pH influence species composition when AB and CB are established from tillers in polyculture. Replicate greenhouse experiments evaluated five P rates (0, 3, 6, 9, and 12 kg ha−1 P via triple superphosphate) and two soil pH levels (5.6 and 7.1). The highest P rate in the high pH soil resulted in the most AB cover (61%). Phosphate applied at 3 kg ha−1 P in the low pH soil provided the greatest CB cover (72%), which was fivefold greater than AB cover. All P‐receiving treatments in the low pH soil had similar green cover, but a species advantage for CB was only observed in the 3 kg ha−1 P treatment. Turfgrass quality was greatest when ≥6 kg ha−1 P was applied to low pH soil but was only slightly reduced at 3 kg ha−1 P. Regardless of pH, withholding P resulted in the lowest AB cover (<4%); however, these treatments resulted in poor turfgrass quality and low green cover (<30%). Aboveground shoot biomass increased linearly with P rate and was greater at the lower pH. In moderately acidic sand, AB was less competitive than CB when Mehlich‐3 P ranged from 4 to 6 mg kg−1.

Assessing the impacts of soil and water conservation practices on soil physicochemical properties in contrasting slope landscapes of Southern Ethiopia

In Ethiopia in general and in the study area, soil erosion, which is the main cause of land degradation, is a significant environmental and agricultural problem. The efficiency of various land management strategies used over time to reduce their detrimental effects on soil quality and health has been questioned. The purpose of this study was to determine the efficacy of soil and water management methods applied to the Offa District of the Wolaita Zone in southern Ethiopia. A total of 36 composite and core soil samples were taken from the topographies of both conserved and non-conserved fields from the top 20 cm soil depth. The collected soil data were examined using analysis of variance (ANOVA), and the mean values of the treatments were separated using the Fisher multiple range test. The results revealed that the physical and chemical properties of soil (pH, Organic carbon, Total nitrogen, Available phosphorus, Cation exchange capacity (CEC), exchangeable basic cations (Ca2+, Mg2+, K+, and Na+), Soil texture, and Bulk density showed a significance difference (p < 0.05) between the measures of soil and water conservation (SWC). The treated soils of Fanya juu, stone bund, and soil bund had the highest soil pH (6.56, 6.56, and 6.11), organic carbon (1.80, 1.62, and 1.76 %), total nitrogen (0.18, 0.16, and 0.17 %), accessible phosphorus (2.72, 2.77, and 1.94 ppm), and all exchangeable basic cations showed higher amount than untreated. The results showed that the implemented SWC structures had high value in restoring and preserving soil nutrients and improving the productive capacity of the soil. This study confirmed the effectiveness of SWC practices in improving soil quality. To achieve soil quality, it's essential to maintain awareness and use of the latest technology. It is strongly advised to highlight the urgent need for SWC training, public awareness, and government support.

Linking soil adsorption-desorption characteristics with grain zinc concentrations and uptake by teff, wheat and maize in different landscape positions in Ethiopia

AimZinc deficiencies are widespread in many soils, limiting crop growth and contributing to Zn deficiencies in human diets. This study aimed at understanding soil factors influencing grain Zn concentrations and uptake of crops grown in different landscape positions in West Amhara, Ethiopia.MethodsOn-farm experiments were conducted in three landscape positions, with five farmers’ fields as replicates in each landscape position, and at three sites. Available Zn from the soil (Mehlich 3, M3, Zn) and applied fertilizer (NET_FERT Zn, estimated based on adsorption/desorption characteristics and applied Zn) were related to the actual grain Zn concentration and uptake of teff, wheat, and maize. Zinc fertilizer treatments tested were Zn applied at planting (basal), basal plus side dressing and a control with no Zn applied.ResultsZn treatments had a significant effect on grain Zn concentration (increase by up to 10%) but the effect on grain yield was variable. Differences in crop Zn concentrations along the landscape positions were observed but not at all sites and crops. Trial results showed that soils with higher soil pH and Soil Organic Carbon (SOC) (typical of footslope landscape positions) tended to adsorb more applied Zn (reduce NET_FERT Zn) than soils with lower soil pH and SOC (typical of upslope landscape positions). Zn availability indicators (M3, NET_FERT Zn, clay%) explained 14-52% of the observed variation in grain Zn concentrations, whereas macronutrient indicators (Total N, exchangeable K) together with M3 Zn were better in predicting grain Zn uptake (16 to 32% explained variability). Maize had the lowest grain Zn concentrations but the highest grain Zn uptake due to high yields.ConclusionWe found that the sum of indigenous and fertilizer Zn significantly affects grain Zn loadings of cereals and that the associated soil parameters differ between and within landscape positions. Therefore, knowledge of soil properties and crop characteristics helps to understand where agronomic biofortification can be effective.

Associations between recent land use history and urban forest composition

More than half of the world’s population lives in urban areas. Sustaining healthy urban forests is increasingly relevant to this population given the wide range of economic, ecological, and social benefits that urban forests provide. Yet forests in cities grow in sites that are fragmented, with frequent disturbance, altered soils, and complex land use history, which can lead to the degradation of forest conditions and the benefits they provide. We measured forest composition and structure in 1124 plots across 53 parks in New York City’s (NYC) 2,497-ha natural area forests and uplands. To better understand the factors responsible for their current condition, we documented historical land use in each plot using aerial imagery going back 90 years, quantified edge effects using remote sensing, and field-measured contemporary disturbances, soil characteristics and light. In the last 90 years, the majority of contemporary natural areas in NYC have recolonized from farmland, built, landscaped lawn, and open field cover-types to forests (from a mean of 37% to 76% forest cover). Areas previously documented as having human land use (e.g. arable agriculture), now have double the amount of invasive species cover compared to sites that were forested or natural areas in the last 90 years. Contemporary measures of forest edge, light, and soil pH have a stronger association with native species basal area, species richness, and invasive species cover, but have an additive effect with measures of historical land cover and local site-level disturbances. We find that a history of non-forest cover, in combination with high soil pH and edge adjacency, was associated with the most invaded contemporary forests. Overall, it appears that a non-forest land use history may be a precursor to altered environmental conditions, making it an important lens upon which to understand forest succession more broadly in complex human-dominated forests, like those in New York City.

A bio-assay to screen Ilex crenata for tolerance to high soil pH and black root rot resistance

A bio-assay to screen <i>Ilex crenata</i> for tolerance to high soil pH and black root rot resistance

Soil pH influences the toxicity of Basamid® eluates to non-target species of primary consumers

Basamid® is a fumigant nematicide and fungicide known to break down in several volatile compounds, mainly methyl isothiocyanate (MITC), when in contact with water. Soil abiotic parameters, such as pH, influences this breakdown process, and thus, the toxic effects of Basamid® to aquatic biota. This work studied the influence of soil pH (5.5, 6.5 and 7.5) on the toxicity of eluates (1:4, m:v), obtained from Basamid®-contaminated soils (with the recommended dose of 145 mg of dazomet/Kg of soil), on two primary consumers: Daphnia magna and Brachionus calyciflorus. For this, lethal and sublethal toxicity of eluates originated from soils at pH 5.5, 6.5 and 7.5, contaminated with Basamid® (Ba-E 5.5; 6.5 and 7.5, respectively), were assessed (dilutions between 0.096 - 100%). The LD50,24h of Basamid® eluates for D. magna varied from 3.07% to 7.82% (Ba-E 6.5 and Ba-E 5.5 respectively), while for B. calyciflorus varied from 18.1% to 84.7% (Ba-E 6.5 and Ba-E 7.5, respectively). Both species were less sensitive to Basamid® eluates originated from soils with pH 7.5 and more sensitive to those obtained from soils with pH 6.5. Regarding the sublethal effects, a lower soil pH was associated with a higher toxicity of Basamid® to D. magna reproduction (LOED: 0.125% Ba-E 5.5), while for B. calyciflorus such a higher toxicity was observed at the highest soil pH (ED20: 7.42% [5.10-9.74] at Ba-E 7.5). These results show a negative association between soil pH and the lethal toxicity of Basamid® contaminated eluates. However, such a pattern was not observed at sublethal level, at which a species dependency was observed regarding the influence of soil pH in the observed toxicity. Nevertheless, it is to highlight that very low concentrations of eluates (as 3.07%) caused significant mortality, indicating a high risk for freshwater biota. Considering that Basamid® is likely to reach the aquatic systems is real, for which reason the recommended dose must be reviewed at environmentally-relevant scenarios.

Is green manure a viable substitute for inorganic fertilizer to improve grain yields and advance carbon neutrality in paddy agriculture?

Green manure is a widely applied to increase grain yield, while it also attributes to greenhouse gas (GHG) emissions in agriculture ecosystems. Combining green manure with inorganic fertilizer inputs is a common practice that can influence soil GHG emissions and grain yield, however, its impacts on grain yield and global warming potential (GWP) under different initial soil conditions before rotating experiments and agronomic management in paddy fields remain unclear. We synthesized 508 data pairs to evaluate the responses of CO2 emissions, CH4 emissions, N2O emissions, and grain yield to combined inputs of green manure plus inorganic fertilizer compared with only inorganic fertilizer application. Our findings indicate that both inorganic fertilizer plus extra green manure (GM-E) and green manure substitutes for inorganic fertilizer (GM-S) could increase CO2 emissions (22.5 %−76.8 %), CH4 emissions (100 %−103 %), N2O emissions (29.8 %−50.9 %), and yield (2.21 %−19.6 %). Except for GM-E, which showed a non-significant increase in grain yield. The initial soil properties before rotating experiments, the types and timing of green manure application were key drivers of GHG emissions and yield, and extra green manure applied in areas with low initial soil pH and high C:N can increase GWP and yield. Overall, the mixed green manure application had greater impact than leguminous or non-leguminous green manure applied alone. The responses of GHG emissions and yield to GM-S were modulated by mean annual precipitation and initial soil properties before rotating experiments, and green manure substitutes for inorganic fertilizer in areas with high initial soil pH and low C:N can increase GWP and yield. Meanwhile, excessive precipitation caused a reduction in yield and a significant increase in GWP intensity. Our results showed that extra green manure applications of less than 68.1 kg N ha−1 would not significantly increase GWP. Therefore, an effective green manure strategy can achieve a win-win situation for the dual challenge of agricultural production and climate change mitigation.

Influence of soil depth, irrigation, and plant genotype on the soil microbiome, metaphenome, and carbon chemistry.

Carbon is cycled through the air, plants, and belowground environment. Understanding soil carbon cycling in deep soil profiles will be important to mitigate climate change. Soil carbon cycling is impacted by water, plants, and soil microorganisms, in addition to soil mineralogy. Measuring biotic and abiotic soil properties provides a perspective of how soil microorganisms interact with the surrounding chemical environment. This study emphasizes the importance of considering biotic interactions with inorganic and oxidizable soil carbon in addition to total organic carbon in carbonate-containing soils for better informing soil carbon management decisions.

Simultaneous mitigating the bioavailability of cadmium and arsenic in paddy soil by two carbon-iron composites: A field-scale evaluation

Cadmium and arsenic have become the difficulty of soil inorganic pollution control due to their opposite chemical properties. Field experiments were performed to evaluate the performance and mechanism of the carbon-iron composites in mitigating the bioavailability of soil Cd and As. The mitigating performance for Cd bioavailability decreased as follows: ZVI-biochar > ZVI-peat > biochar > wood peat > ZVI, and the mitigating performance for As bioavailability was in the order of ZVI-peat > ZVI-biochar > ZVI; Biochar and wood peat enhanced the bioavailability of soil As. Both ZVI-biochar and ZVI-peat composites showed superior immobilization performance due to its higher soil pH, formation of soil amorphous Fe oxyhydroxides and roots iron plaque. The increased Fe nutrition inhibited the transportation of Cd and As from roots to grains. Both ZVI-biochar and ZVI-peat resulted in a more than 42 % reduction for grain Cd and 33.8 % reduction for grain As.

A controlled experiment to verify the effect of magnesium fertilizers on soil pH and available soil nutrients in acid soil of Nilgiris, India

An incubation experiment was conducted in laboratory conditions for 60 days to observe the impact of different Magnesium fertilizers on soil chemical properties, i.e. pH, available nitrogen, phosphorus, potassium, and DTPA extractable micronutrient cations. A complete factorial complete randomized block design (FCRD)with two replications and six levels was selected as the experimental layout. The levels included were (L0) Absolute control (L1) soil + Mg @ 10 kg ha-1, (L2) soil + Mg @ 20 kg ha-1, (L3) soil + 30 kg ha-1, (L4) soil + 40 kg ha-1, (L5) soil + 50 kg ha-1. Findings revealed that applying magnesium fertilizers to soil significantly (p ≤ 0.05) affects soil parameters. The impacts of magnesium fertilization on soil pH altered with sources and incubation period. The application of CaMg(CO3)2 @ 50 kg ha-1 recorded significantly (p ≤ 0.05) higher soil pH (5.67) as compared to MgCO3 @ 50 kg ha-1 that increased the pH up to 5.57 due to the impact of carbonate ion whereas MgSO4.7H2O decreased the soil up to 4.80 because of dissolution of SO42- ions to the soil solution. Applying CaMg(CO3)2 significantly (p ≤ 0.05) influenced soil available N, P, K, Fe, Mn, and Cu content which is due to the decrease in acidity, which indirectly enhanced the nutrient availability. The positive effects persisted throughout the experimental duration, indicating the potential long-term benefits of magnesium fertilization in acid soil management. This study contributes to the current body of knowledge by providing novel insights into applying magnesium fertilizers as an effective strategy for addressing soil acidity and improving nutrient availability in acid soil.

Soil Sampling Depth in No-Till Acid Soils

ABSTRACT Ammonia-based fertilizers acidify the soil during the nitrification process. No-till and other reduced till system soils are more susceptible to stratified acidification than conventionally tilled soils as there is little soil mixing. Many long-term no-till soils have acidified in North Dakota, but there is little guidance on soil sampling depth. This project evaluated what soil depth/s should be collected to remediate acid soils. Twelve differing acidic soil types across North Dakota were sampled at the 0–5.1, 5.1–10.2, 10.2–15.2, 0–7.6, 7.6–15.2, and 0–15.2 cm depths and analyzed for pH. The comparison of means procedure determined that the 0–7.6 cm soil pH was the most acidic (p-value < .001). The 0–5.1, 0–15.2, and 5.1–10.2 cm depths were similar. The highest soil pH was observed at the 7.6–15.2 and 10.2–15.2 cm depth. Soil acidity management of no-till soils when acidification is caused by nitrification should be sampled at the 0–7.6 cm depth as that pH was the most acidic and encompasses the soil environment that surrounds relatively shallow and deeply sown North Dakota crops.

Effects of exposure to carbon nanomaterials on soil microbial communities: A global meta‐analysis

AbstractCarbon nanomaterials (CNMs) are extensively employed in diverse fields and will inevitably be discharged into the soil to affect the soil microbial community. Numerous related studies have investigated the effects of exposure to CNMs on soil microbial communities, yet a consensus on their effects still needs to be discovered. This study conducted a global meta‐analysis by synthesizing 474 pairs of experiments from 20 screened publications in the literature from 2000 to 2022. The findings indicate that: exposure to CNMs significantly reduced microbial biomass carbon (MBC) by 17.02% and increased soil Shannon index by 2.63% (p &lt; 0.05), which had no significant effect on soil microbial community composition and only reduced the proportion of Proteobacteria by 6.83%. The type of CNMs was one of the important influencing factors. The exposure to multi‐walled carbon nanotubes (MWCNTs) significantly reduced the soil MBC (p &lt; 0.05). It reduced the proportion of Acidobacteria, Bacteroidetes, and Proteobacteria in soil, which had less effect on soil microbial diversity and was more suitable as a crop growth promoter. The exposure of single‐walled carbon nanotubes exhibited a comparable impact on soil microbial biomass as MWCNTs while significantly increasing soil microbial diversity. The exposure of fullerene (C60) had no significant effect on soil microbial biomass but significantly decreased microbial diversity (p &lt; 0.05). In addition, soil pH, CNMs exposure dose, and exposure time significantly affect the effects of CNMs (p &lt; 0.05). This research recommends that CNMs be used in high pH soil with high electrical charge intensity while avoiding exposure doses exceeding 1000 mg/kg and limiting exposure time to 50–100 days to minimize long‐term exposure effects on the soil. MWCNTs are less toxic to microbial communities compared with the other CNMs and are more suitable as crop growth promoters. In conclusion, CNMs show great potential for promoting agricultural production.

Effects of Forest Fire on Soil Properties

One of the most harmful challenges to our forest is fire. The impact of forest fires on soil physical properties had an emphasis on texture, bulk density, porosity, aggregate stability, and water content and repellency. Following the fire, the surface soil of the burned region had higher soil pH, total nitrogen, accessible phosphorus, potassium, calcium, and magnesium levels than the unburned area. The low intensity of the fire caused the organic matter in the soil and the litter to burn, increasing the availability of nutrients and -promoting herb regeneration and post-fire community expansion. Higher-intensity fires completely destroy soil organic matter, volatilize nitrogen, phosphorus, and potassium, and kill microorganisms, while Mn, Mg, and other micronutrients are completely burnt at very high temperatures. Some nutrients were more readily available by the burning of soil organic matter (OM), such as N, P, and S, while others were volatilized. Controlled fire did not result in any significant changes to the nutrients or physico-chemical composition of soil and can be utilized as an efficient management technique to reduce the harm caused by wildfires to soil. Remote sensing and GIS technology are the highly advanced tools used to detect forest fires, calculate burned areas, and determination of changes in land use.

Back to the future: Using ancient Bere barley landraces for a sustainable future

Societal Impact StatementBere is an ancient barley (Hordeum vulgare L.) that was once widely grown in northern Britain, where its ability to grow on poor soils and under challenging climatic conditions made it a valuable staple. By the end of the 20th century, Bere had largely been replaced by higher‐yielding modern varieties and only survived in cultivation on a few Scottish islands. This article reviews the recent revival of Bere, driven by its use in high‐value food and drink products and multidisciplinary research into its genetics, valuable sustainability traits and potential for developing resilient barley varieties.SummaryIn Britain, modern cereal varieties have mostly replaced landraces. A remarkable exception occurs on several Scottish islands where Bere, an ancient 6‐row barley (Hordeum vulgare L.), is grown as a monocrop or in mixtures. In the Outer Hebrides, the mixture is grown for animal feed, and cultivating it with traditional practices is integral to the conservation of Machair, an important coastal dune ecosystem. In Orkney, Bere is grown as a monocrop, and in situ conservation has recently been strengthened by improved agronomy and new markets for grain to produce unique foods and beverages from beremeal (flour) and malt. In parallel, a recently assembled collection of British and North European barley landraces has allowed the genotypic and phenotypic characterisation of Bere and several associated multidisciplinary studies. Genotyping demonstrated Bere's unique identity compared with most other barleys in the collection, indicating an earlier introduction to Scotland than the Norse settlement (c. 9th century AD) suggested previously. Valuable traits found in some Bere accessions include disease resistance, an early heading date (reflecting a short period from sowing to harvest), the ability to grow on marginal, high pH soils deficient in manganese and tolerance to salinity stress. These traits would have been important in the past for grain production under the region's challenging soil and Atlantic‐maritime climatic conditions. We discuss these results within the context of Bere as a genetic, heritage and commercial resource and as a future source of sustainability traits for barley improvement.

Invasion by the annual grass, Ventenata dubia does not impact mycorrhizal fungal abundance in an endangered prairie

One of the challenges in ecological restorations is that some native plant species are difficult to reestablish in disturbed or invaded landscapes. Some invasive plant species negatively impact soil biota, such as arbuscular mycorrhizal (AM) fungi, which can lead to feedbacks that facilitate their dominance in a landscape. The winter annual grass, Ventenata dubia, is rapidly invading North American grasslands, however, the effect of its invasion on AM fungi, plant communities, and soil properties is not well known. In a greenhouse and field experiment, we tested (1) whether the abundance of viable AM fungal propagules is altered in soil invaded by V. dubia; (2) how plant community composition, species richness, and/or diversity may be impacted by V. dubia; and (3) whether soil properties, such as pH and organic matter (OM) vary across invasion levels. We found that the effect of V. dubia on the abundance of mycorrhizal propagules varied among sites and did not reduce the species richness or diversity of resident plant communities. Higher canopy cover of V. dubia was associated with higher soil pH and OM, which suggests either V. dubia invasions change these soil properties, or that V. dubia preferentially invades these areas. Our findings suggest V. dubia does not consistently alter above‐ or belowground communities; however, the potential link between V. dubia invasions and soil pH and OM deserves additional investigation. A better understanding of how invasive annual grasses impact plant and soil communities will be useful in informing restoration efforts in landscapes impacted by invasive species.

Ecosystem‐level decoupling in response to reduced precipitation frequency and degradation in steppe grassland

Abstract Grasslands across arid and semi‐arid regions are predicted to experience reductions in precipitation frequency. Besides, grassland degradation has become a serious problem in many of these areas. Despite increasing evidence suggesting compound effects of these synchronous alterations on biotic and abiotic ecosystem constituents, we still do not know how they will impact the coupling among ecosystem constituents and its consequences on ecosystem functioning. Here, we assessed the effects of decreased precipitation frequency and grassland degradation on ecosystem coupling, quantified based on the mean strength of pairwise correlations among multispecies communities and their physicochemical environment, individual functions and ecosystem multifunctionality, and reported their relationships within a mechanistic plant–nematode–micro‐organism–soil interactions framework. Decreased precipitation frequency led to poorly coupled ecosystems, and reduced aboveground plant biomass, soil water content, soil nutrient levels, soil biota abundance and multifunctionality. By contrast, belowground plant biomass and soil potential enzyme activities increased under decreased precipitation frequency treatment. Severe degradation resulted in decoupled ecosystems and suppressed most of individual functions and multifunctionality. Using structural equation modelling, we showed that coupling had a strong direct positive effect on multifunctionality (standardized total effect: 0.74), while multifunctionality was weakened by greater soil water variation (−0.54) and higher soil pH (−0.53). The great sensitivity of ecosystem coupling to altered precipitation regimes and degradation highlights the importance of considering interactions among biotic and abiotic components when predicting early ecological impacts under changing environments. Moreover, the positive relationship between ecosystem coupling and functioning suggests that restoration of degraded grasslands may be achieved by intensifying ecological interactions. Read the free Plain Language Summary for this article on the Journal blog.

Dolomitic limestone was more effective than calcitic limestone in increasing soil pH in an untilled olive orchard

AbstractIn acid soils, when no‐tillage farmers intend to apply lime, the question arises as to whether it should be incorporated into the soil or whether it can be left on the soil surface. In this study, two types of limestone, calcitic (Lcal) and dolomitic (Lmag), were tested in two olive groves of cv. Cobrançosa, with an initial pH of 4.9 (S. Pedro) and 5.5 (Raparigas). In S. Pedro, limestone was incorporated into the soil (Lburied) and in Raparigas, it was left on the floor (Lfloor). The use of limestone significantly increased soil pH in the 0–0.10 m layer in both experiments. In the 0.10–0.20 m soil layer, only Lmag increased significantly the soil pH in comparison with the control. Lmag was more effective than Lcal in increasing cation exchange capacity (CEC) and reducing exchangeable acidity (EA) and aluminium (Al3+) in the Lfloor experiment. Both limes increased leaf calcium (Ca) concentration, and Lmag increased the leaf levels of magnesium (Mg). In Lfloor experiment (higher soil pH), soil microbial carbon (C) decreased, and microbial nitrogen (N) increased with liming, which may indicate an increase in bacteria in the soil and a decrease in fungi. In Lburied experiment (initial pH of 4.9), liming significantly increased accumulated (2018–2021) olive yield (56 and more than 67 kg tree−1, respectively, in the control and liming treatments). In Lfloor experiment (initial pH of 5.5), the accumulated olive yields did not differ significantly between treatments (average values between 105 and 115 kg tree−1). The results of this study provide evidence that liming may increase olive yield in very acid soils and that dolomitic limestone should preferably be used by no‐tillage farmers, due its higher solubility and faster effect on soil and trees.

Cd isotope fractionation in a soil-rice system: Roles of pH and mineral transformation during Cd immobilization and migration processes

Cd speciation in soil and its transport to rice roots are influenced by the soil pH, oxidation-reduction potential, and mineral transformation; however, the immobilization and migration of Cd in soil-rice systems with different pH values under distinct water regimes remain unclear. This study used Cd isotope fractionation, soil physical analysis, and root gene quantification to elucidate the immobilization and transport of Cd in different soil-rice systems. In drainage soils, the high soil pH enhanced the transformation and magnitude of negative fractionation of Cd from MgCl2 extract to FeMn oxide-bound pool; however, it favored Cd uptake and root-to-grain transport. Compared with drainage regimes, the flooding regimes shifted fractionation toward heavy isotopes from MgCl2-extracted Cd to FeMn oxide-bound Cd in acidic soils (∆114/110CdMgCl2 extract – FeMn oxide-bound Cd = −0.09 ± 0.03 ‰) and to light isotopes from MgCl2-extracted Cd to carbonate-bound Cd in neutral and alkaline soils (∆114/110CdMgCl2 extract – carbonate-bound Cd = 0.29–0.40 ‰). The submerged soils facilitated the forming of carbonate and poorly crystalline minerals (such as ferrihydrite), which were transformed into highly crystalline forms (such as goethite). These results demonstrated that the dissolution-precipitation process of iron oxides was essential for controlling soil Cd availability under flooding regimes, and the relative contribution of carbonate minerals to Cd immobilization was promoted by a high soil pH. Flooding regimes induced lower expressions of OsNRAMP1 and OsNRAMP5 to limit the uptake of light Cd isotopes from MgCl2-extract pool, whereas a teeter-totter effect on gene expression patterns in roots (including those of OsHMA3 and OsHMA2) limited the transport of heavy Cd isotopes from root to grain. These findings demonstrate that flooding regimes could exert multiple effects on soil Cd immobilization and Cd transport to grain. Moreover, alkaline soil was conducive to forming carbonate minerals to sequester Cd.

Synergistic benefits of lime and 3,4-dimethylpyrazole phosphate application to mitigate the nitrous oxide emissions from acidic soils

Acidic soils cover approximately 50 % of the arable land with high N2O emission potential. 3,4-dimethylpyrazole phosphate (DMPP) inhibits N2O emission from soils; however, its efficiency is affected by acidity. Liming is used for soil conditioning to ameliorate the effects of acidity. In the present study, we investigated the effects of liming on the efficiency of DMPP in inhibiting N2O emission in acidic soils and the mechanisms involved. We evaluated the impact of liming, DMPP, and combined application and its microbial responses in two acidic soils from Zengcheng (ZC) and Shaoguan (SG) City, Guangdong Province, China. Soils were subjected to four treatments: un-limed soil (low soil pH) + urea (LU), un-limed soil + urea + DMPP (LD), limed soil (high soil pH) + urea (HU), and limed soil + urea + DMPP (HD) for analyses of the mineral N, N2O emissions, and full-length 16S and metagenome sequencing. The results revealed that, HU significantly decreased and increased the N2O emission by 17.8 % and 235.0 % in ZC and SG, respectively, compared with LU. This was caused by a trade-off between N2O production and consumption after liming, where microbial communities and N-cycling functional genes show various compositions in different acidic soils. LD reduced N2O emission by 23.5 % in ZC, whereas decreased 1.5 % was observed in SG. Interestingly, DMPP efficiency considerably improved after liming in two acidic soils. Compared with LU, HD significantly reduced N2O emissions by 61.2 % and 48.5 % in ZC and SG, respectively. Synergy of mitigation efficiency was observed by lime and DMPP application, which was attributed to the changes in the dominant nitrifiers and the increase in N2O consumption by denitrifiers. The combined application of lime and DMPP is a high-efficiency strategy for N2O mitigation can ensure agricultural sustainability in acidic arable soils with minimal environmental damage.

Assessing the synergistic effect of acidified carbon, inorganic fertilizer, and biofertilizer on fenugreek antioxidant levels, and quality traits

The use of inorganic fertilizers has become increasingly necessary due to the depletion of soil fertility. Inadequate nutrient levels in both plants and soil can be remedied with the application of fertilizers. However, to achieve optimal results, it is recommended to supplement inorganic fertilizers with organic alternatives such as biochar. Despite its benefits, the high pH of activated carbon presents a significant challenge to its use in alkaline soil. Recent studies have shown that acidified carbon can be used instead of alkaline activated carbon. Moreover, the use of biofertilizers is crucial for maintaining soil quality. The purpose of the current study was to investigate the effects of using biofertilizers, inorganic nitrogen fertilizer, and acidified carbon fertilizer in combination on fenugreek growth and chlorophyll concentrations. A pot experiment was conducted using calcium ammonium nitrate (CAN) and three levels of acidified carbon (BC) at 0, 0.75, and 1.50%, with and without the addition of biofertilizer (BF). The results revealed that 1.50CANBC + BF was the most effective supplement for improving soil characteristics such as pH, EC, and overall organic matter. The application of 0.75CANBC + BF was found to be a successful treatment for promoting fenugreek growth and enhancing nitrogen absorption. To achieve better fenugreek quality by reducing electrolyte leakage and MDA, and increasing chlorophyll levels, gardeners are advised to use 1.50CANBC + BF. However, to establish 1.50CANBC + BF as the optimal method for fenugreek growth in poor fertility and high pH soils, further experimental studies in various agro-climatic conditions are necessary.