Soil Productivity Research Articles

The Role of Sudanese Forests Agro-ecosystem in Improving the Cation Exchange Capacity and Exchangeable Bases of a Sandy Soil in Western Burkina Faso

The objective of this study is to evaluate the influence of Sudanese forests on the chemical equilibrium and exchangeable bases of sandy soils in the Bondoukuy region. The study examines the impact of forest cover on soil fertility and the mechanisms through which these natural ecosystems promote soil health and productivity in the region. The Cation Exchange Capacity (CEC) of soil represents its capacity to retain and exchange nutrient cations with plant roots. In Sudanian Forests Agro-ecosystem, sandy soils are characterized by a dominance of coarse particles, which exhibit a low specific surface area and low cation retention capacity, in contrast to clayey soils. A low CEC restricts soil fertility and the capacity of the soil to sustainably provide essential nutrients to plants. It was hypothesized that the CEC of the topsoil in forests of western Burkina Faso would demonstrate a significant increase due to substantial environmental changes during the fallow period. To test this hypothesis, a comparison was made between soil fertility in forests and fallows, and that of cultivated plots, which were considered the control for this increase. A total of 15 plots were selected, with five plots allocated to each situation. The vegetation and soil of the plots were described in detail. Composite soil samples were taken from the 0-20 cm horizon. The soil analyses in the laboratory were conducted on several parameters, including texture, pH-H2O, pH-KCl, carbon, nitrogen, CEC and exchangeable bases. The results of the observations enabled the classification of the soils as tropical ferruginous soils with iron and manganese sesquioxides. The original materials indicate that the soil exhibits sandy properties. This was demonstrated by the granulometric study, which revealed that the soils under investigation exhibited an essentially sandy texture on the surface horizon. This results in a low retention capacity for exchangeable bases. The woody vegetation of the forest exhibits a greater diversity of flora than that of the fallows. This has a significant impact on the enhancement of the CEC, due to the replenishment of the soil with plant debris of varying organic compositions. The overall pH is slightly acidic, with a range of 5.63 to 5.71. The soils of forests exhibit higher concentrations of carbon and nitrogen than those of the fallows and fields. The observation of chemical balances has enabled the identification of forests as an environment conducive to optimal plant nutrition. Overall, forests enhance the CEC and exchangeable bases, despite the values being below the threshold recommended for tropical sandy soils. It is therefore necessary to implement measures to promote sustainable agriculture and enhance agricultural productivity in this region, where soil nutrients are naturally scarce.

Nitrate toxicity and health hazards: Problems and mitigation challenges

Abstract Nitrogenous fertilizers are considered an essential input for productive agriculture and the factor highly responsible for higher biomass production. Unfortunately, intensive mineral fertilization brings tremendous changes in soil fertility and productivity, but productivity decreases rapidly in cereal-based cropping systems or without legumes. The excessive use of mineral nitrogenous fertilizers reported an increase in potential health hazards and environmental problems such as groundwater contamination, eutrophication, acid rain, the greenhouse effect, and methemoglobinemia in humans. With future applications’ elevated use and prognosis, this problem may expand to several folds in the approaching decades. Large consumption of defiled water or food with higher concentrations of nitrates (according to the US Environmental Protection Agency (EPA), the permissible limit is 7 mg.kg −1 body weight per day) causes severe infant diseases such as Blue Baby Syndrome, respiratory ailments, gastric cancer, birth malformation and other health problems which earlier were rarely explained or explored worldwide. The unsustainable agronomic practices resulted in our soil being stripped of natural health and blind dependency on mineral fertilizers, ultimately leading to poor human and environmental health. There is an immediate need for new technologies related to farming systems to meet Sustainable Development Goals (SDGs) in view of changing climate. Various sustainable practices such as applying organic manures, precision N management, Soil Test Crop Response (STCR) approach, and nitrogen (N) inhibitors hold tremendous potential to reduce the ill effects of nitrates and secure the food chain if adopted on a large scale.

Health Risk Assessment of Heavy Metals in Soil-crop System in Different Ecological Regions of Ningxia

Heavy metals are characterized by toxicity，non-biodegradability，and accumulation in the food chain；hence，o the distribution of heavy metals in farmland soils and crop food safety have attracted much attention. A total of 1 274 soil samples and crop samples were collected from farmland in Ningxia from 2017 to 2021 and bioconcentration coefficients were used based on the analysis of the elemental contents of Zn，Cr，Ni，Cu，Pb，As，Cd，and Hg. The ecological risk index and correlation analysis were used to characterize the heavy metal content and health risk assessment of the soil-crop system in Ningxia. The results showed that the soils in the study area were alkaline and the mechanical composition was dominated by pulverized and sandy grains，with a relatively small content of clay grains. The heavy metal contents in the soils were in the following order：Zn>Cr>Ni>Cu>Pb>As>Cd> Hg. Except for that of Cu and Ni，the contents of other heavy metals in the soils of the northern region were higher than those of the central and southern regions. The ecological risk index of soil heavy metals was Hg>Cd>As>Cu>Pb>Ni>Cr>Zn and the proportion of points with low and medium ecological risk index levels was high（98.58%），indicating that the soil environment was generally good. The average content of the eight heavy metals in crops did not exceed the limit value，and the average health risk index value was <1. However， the health risk index（HRI）of As in individual crops existed at points >1 in all three sub-regions and individual points with high values of HRI（HRI>1）for Cu and Ni were observed in crops in the northern region and for Pb in the north and south of the country，which require further attention. From the bioconcentration factor，crops showed no accumulation effect （BCF<1）for heavy metals such as As，Cd，Cr，Cu，Ni，Pb，and Zn and although the average uptake of Hg by crops did not show accumulation，a total of 31 crops in the three ecological zones showed some accumulation（BCF>1），which also requires further monitoring. Analysis using the Mantel's test showed that except for As and Ni in crops，which had a weak correlation with Cu content in the soil（0.05>Mantel's P>0.01），the other heavy metals in crops did not have a significant correlation with the corresponding soil heavy metals （Mantel's P≥0.05），indicating that the heavy metal contents in crops were less affected by soil heavy metals. RDA analysis showed that the sand content had a strong positive correlation with the transfer coefficients of heavy metals such as Hg，Ni，Pb，and Cd，while the powder content showed a strong negative correlation；however，the transfer coefficients of Cu，Zn，As，and Cr were not much affected by the mechanical composition of soils，and the correlation between the soil organic matter content and the transfer coefficients of heavy metals was also small. In summary，the quality of the soil environment and crops in the study area is generally good；however，attention must still be paid to the areas with high heavy metal content or exceeding the standard value to strictly control the input of pollutants，and at the same time，establishing long-term monitoring of the quality status of soil and agricultural products in the crop production area is a necessary control initiative.

The use of phosphate rock and plant growth promoting microorganisms for the management of Urochloa decumbens (Stapf.) R.D. Webster in acidic soils.

Forage production in tropical soils is primarily limited by nutrient deficiencies, especially nitrogen (N) and phosphorus (P). The use of phosphate rock by plants is limited by its low and slow P availability and microbial phosphate solubilization is the main mechanism for P bioavailability in the soil-root system. The objectives of this study were (i) select a nitrogen-fixing bacteria which could be used as a co-inoculant with the Penicillium rugulosum IR94MF1 phosphate-solubilizing fungus and (ii) evaluate under field conditions the effect of inoculation combined with phosphate rock (PR) application on yield and nutrient absorption of a Urochloa decumbens pasture which was previously established in a low-fertility, acidic soil. Various laboratory and greenhouse tests allowed for the selection of Enterobacter cloacae C17 as the co-inoculant bacteria with the IR94MF1 fungus. Later, under field conditions, a factorial, completely randomized block design was used to evaluate the inoculation with the IR94MF1 fungus, the IR94MF1+C17 co-inoculation, and a non-inoculated control. Two levels of fertilization with PR treatment (0 kg/ha and 200 kg/ha P2O5) were applied to each. During five consecutive harvests it was observed that the addition of biofertilizers significantly increased (p < 0.05) the herbage mass and N and P assimilation compared to the non-inoculated control. However, no statistically significant differences were observed for the PR application as P source. P. rugulosum IR94MF1 is capable of solubilizing and accumulating P from the phosphate rock, making it available for plants growing in acid soils with low N content. These inoculants represent a good option as biofertilizers for tropical grasses already established in acidic soils with low N content.

Biodiversity of key soil phylotypes is associated with increased plant richness and productivity following agricultural abandonment and afforestation

Abstract Anthropogenic land use modifications are causing severe degradation of terrestrial ecosystems, and multiple revegetation strategies are emerging globally to counteract the loss of plant richness and productivity. While soil microorganisms are essential for plant community dynamics, the role of soil microbial biodiversity in regulating changes in plant richness and productivity under different revegetation strategies remains unknown. We used multitrophic co‐occurrence networks to identify soil network modules of strongly co‐occurring phylotypes along a 50‐year revegetation chronosequence of agricultural abandonment and afforestation. Soil biodiversity within these modules was related to soil nutrient cycling functions, plant richness and productivity (understorey layer in afforestation), elucidating how these network modules are associated with changes in plant richness and productivity. Plant richness and productivity increased simultaneously following both agricultural abandonment and afforestation. However, the biodiversity of key soil taxa within distinct network modules was associated with these coupled increases through the regulation of different nutrient cycling functions. Key soil phylotypes within the network modules involved in nitrogen (N) cycling correlated with the simultaneous increase in plant richness and productivity following agricultural abandonment. In contrast, those involved in phosphorus (P) and sulphur (S) cycling were linked to the coupled responses of both plant richness and productivity under afforestation. This reflects the divergent microbial mechanisms associated with the coupled increase in plant richness and productivity along the revegetation chronosequence for both agricultural abandonment and afforestation. Synthesis. Our findings provide correlative evidence that the biodiversity of key phylotypes within soil network modules is closely associated with the simultaneous increase in plant richness and productivity following the cessation of agricultural management. We identify key soil taxa, specific to each revegetation strategy, that could serve as potential targets for genomic and cultivation‐based approaches to counteract plant community degradation. Revegetation efforts to enhance plant richness and productivity should focus on soil phylotypes associated with N cycling after agricultural abandonment and those involved in P and S cycling during afforestation.

Bacterial community present in the earthworm’s gut and its role in soil biology and health

Earthworms are known as ecological engineers due to their significant role in enhancing soil health and productivity. Various factors such as temperature, moisture, acidity, pH, sunlight and the availability of organic matter influence their presence in soil. Earthworms exhibit diverse feeding and burrowing behaviors, which lead to crucial ecological processes within terrestrial ecosystems. Their interactions with soil result in the colonization of their gut and surrounding soil by diverse bacterial communities, including key species such as Escherichia coli, Streptomyces, Bacillus and Pseudomonas. These bacteria aid in the digestion of organic and inorganic matter, thereby altering soil physio-chemical properties and enhancing nutrient mineralization, which promotes plant growth. Additionally, earthworms influence nutrient cycling by modifying microbial soil populations and the bacterial communities in their gut and adjacent soil contribute to phytoremediation. This review delves into the types of bacterial populations found in the earthworm’s gut and surrounding soil, elucidating their specific roles and contributions to the terrestrial ecosystem. By understanding these complex interactions, we can better appreciate the vital role earthworms and their associated bacterial communities play in soil biology. This knowledge is essential for developing sustainable agricultural practices and improving soil management strategies, ultimately contributing to healthier and more productive ecosystems.

Pollution Status, Ecological Effects, and Bioremediation Strategies of Phthalic Acid Esters in Agricultural Ecosystems: A Review.

Phthalic acid esters (PAEs) are common organic contaminants in farmland soil throughout agricultural systems, posing significant threats to human health and thus closely associated with food safety concerns. Here, we consolidate the latest findings regarding the distribution, ecological effects, bioremediation methods, and microbial degradation pathways of PAEs in agricultural ecosystems. Generally, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DnBP), and di-isobutyl phthalate (DiBP) exhibit the highest detection frequencies and concentrations in soil, air and agricultural products. The presence of these PAEs in agricultural ecosystems can significantly affect soil and plant-associated microbial communities, leading to decreased yield and quality of agricultural products. Bioremediation techniques, such as microbial degradation and phytoremediation, are frequently explored to address these issues. Overall, this review provides a comprehensive overview of current research on PAEs in China's agricultural systems and offers insights into potential problems and future research directions.

GmSTOP1-3 regulates flavonoid synthesis to reduce ROS accumulation and enhance aluminum tolerance in soybean

Aluminum (Al) toxicity is a significant limiting factor for crop production in acid soils. The functions and regulatory mechanisms of transcription factor STOP1 (Sensitive to Proton Rhizotoxicity 1) family genes in Al-tolerance have been widely studied in many plant species, except for soybean. Here, expression of GmSTOP1-3 was significantly enhanced by Al stress in soybean roots. Overexpression of GmSTOP1-3 resulted in enhanced root elongation and decreased Al content, which was accompanied by increased antioxidant capacity under Al treatment. Furthermore, RNA-seq identified 498 downstream genes of GmSTOP1-3, including genes involved in flavonoid biosynthesis. Among them, the expression of chalcone synthase (GmCHS) and isoflavone synthase (GmIFS) were highly enhanced by GmSTOP1-3 overexpression. Further quantitative flavonoid metabolome analysis showed that overexpression of GmSTOP1-3 significantly increased the content of naringenin chalcone, naringenin, and genistein in soybean roots under Al treatment, which positively correlated with the expression level of the genes relative to flavonoid biosynthesis. Notably, genistein had a significant positive correlation with the expression levels of GmIFS. Combination of Dual Luciferase Complementation (LUC) and Electrophoretic Mobility Shift Assays (EMSA) revealed that GmSTOP1-3 directly bound to the promoters of GmCHS/GmIFS and activated both genes’ transcription. Taken together, these results suggest that GmSTOP1-3 enhances soybean Al tolerance partially through regulating the flavonoid synthesis.

Key active mercury methylating microorganisms and their synergistic effects on methylmercury production in paddy soils

Rice contamination with neurotoxic methylmercury (MeHg) from paddy soils is an escalating global concern. Identifying the microorganisms responsible for mercury (Hg) methylation in these soils is essential for controlling Hg contamination in the food chain and mitigating health impacts. Current research often focuses on total Hg-methylating microorganisms, overlooking the contributions of active ones, which can lead to either overestimating or neglecting the specific roles of microorganisms in Hg methylation within paddy soils. In this study, active Hg-methylating microorganisms in paddy soils were identified using a combination of DNA-SIP, Hg isotope labelling, and Hg methylation gene sequencing techniques. Our findings revealed that Geobacter and Anaerolinea are pivotal active Hg-methylating microorganisms across a contamination gradient in paddy soils. Transcriptomic analysis of soils from major rice-producing provinces in China confirmed the widespread and synergistic involvement of these microorganisms. Microbial incubation further validated their interaction significantly enhances Hg methylation, with Me198Hg concentrations increasing 2.8-fold compared to Geobacter alone and 5.2-fold compared to Anaerolinea alone. These findings enhance our understanding of microbial Hg methylation in paddy soils, providing critical insights for accurately predicting soil MeHg load, rice grain MeHg contamination, and human MeHg exposure risks.

Iron forms regulate methane production and oxidation potentials in paddy soils

Paddy fields serve as significant sources of methane (CH4) emissions. The periodic flooding and draining in paddy soils induce alternating redox processes, leading to iron transformations and further influencing the production and oxidation of CH4. However, the relationships between CH4 production/oxidation and the concentrations/forms of iron oxides in rice paddies across different regions are largely unknown. Here we collected 26 paddy soil samples from various regions spanning from North to South China. We show that the CH4 production potential varies from 0.005 to 0.618 mg kg−1 d−1, which exhibits an overall trend of higher values in the south and lower values in the north. Moreover, the CH4 oxidation potential spans from 0.888 to 57.384 mg kg−1 d−1, showing no significant latitudinal trend. Highly weathered soils exhibit higher CH4 production potentials, mainly due to the high content of free iron oxides and the low reactivity of aged iron minerals. This hinders the protection of organic carbon (OC) by iron minerals, therefore increasing substrate availability for methanogenesis. In addition to the direct effect, iron forms also indirectly influence CH4 production and oxidation potentials by affecting soil pH, OC availability, and CH4-related microbial abundances. The coefficients of the indirect effect of iron forms on CH4 production and oxidation potential are 0.44 and 0.26, respectively, which are larger than that of the direct effects. Our research reveals the pivotal role of various iron forms in controlling CH4 production and oxidation processes in paddy soils, helping to expand the understanding of the effect of iron biogeochemistry on CH4 emissions in paddy soils and offering new perspectives for mitigating agricultural greenhouse gas emissions.

PEMANFAATAN KOTORAN TERNAK KAMBING SEBAGAI PUPUK ORGANIK CAIR DI DESA KALONG LIUD

The decrease in crop yields was caused by dry soil quality due to prolonged drought and excessive inorganic fertilizers in Kalong Liud village that were not adapted to plant needs, which could lead to a decrease in soil productivity. On the other hand, livestock waste (goat manure) that has not been managed optimally, often faced by livestock breeders and farmers, has good potential to help increase soil fertility on agricultural land at a reasonably low cost. The proposed solution to this problem is to switch to environmentally friendly organic fertilizer because it reduces the use of chemical substances. One of them is the use of goat manure, which contains high levels of nutrients such as phosphorus (P), nitrogen (N), and potassium (K). This community service activity aims to increase farmers' understanding that the use of organic fertilizer is a solution to overcome the problem of poor soil quality due to drought and excessive use of chemical fertilizers, as well as providing skills to farmers and breeders in Kalong Liud village in making liquid organic fertilizer from goat droppings. The method used includes the first stage of determining targets and implementing activities. The second stage of community outreach, Focus Group Discussion (FGD) and evaluation uses the test method, namely, comparing the pre-test and post-test results. The first stage of activities is determining targets, including surveys, outreach with breeders and farmers, observation, licensing, and activity planning, and then manufacturing liquid organic fertilizer. The second stage of activities carried out outreach with two topics: outreach to the community, discussions with the formed farmer groups, and evaluation through filling out questionnaires. After conducting community outreach and farmer group discussions, the results of this activity were that they understood how to make liquid organic fertilizer from goat manure and the dangers of using excess inorganic fertilizer on plants. After joint practice, the farmer group's understanding of liquid organic fertilizer obtained a post-test score of 98% of people who understood this program.

Enhancing the Photosynthetic and Yield Performance of Rice in Saline Soil by Foliar-Applying Cost-Effective Compounds as Sources of Carbon Dioxide and Potassium

Although rice is highly sensitive to salinity, it is considered one of the best crops to grow in salt-affected mudflat soils to alleviate the salinity problem. Applying chemical compounds for an increase in leaf CO2 and nutrient levels can help mitigate the negative impact of salinity on plants in a cost-effective manner. To identify the benefits of using lithovit (Liv), ethanol (Eth), and potassium carbonate (KC) as a source of CO2 and K to enhance rice production in salt-affected soils, a field study was conducted to assess the effects of these compounds on the agro-physiological parameters of two rice genotypes (Giza178 and Giza179) in saline soils. The compounds were applied as a foliar spray at a concentration of 30 mM each before and after the heading growth stage. The results indicated that the genotype, application time, compounds, and their potential two-way interactions significantly influenced all agro-physiological parameters, with only a few exceptions. The genotype Giza 179 exhibited higher pigment contents, photosynthetic capacity, relative water content (RWC), grain yield, and most yield components compared to Giza 178, with increases ranging from 2.1% to 37.9%. Foliar application of different compounds resulted in a 9.7–37.9% increase in various parameters and a 34.6–43.2% decrease in the number of unfilled grains (NUFG) per panicle compared to untreated treatment. Foliar application of different compounds before heading resulted in an increase in various parameters by 4.8–16.1% and a decrease in the NUFG per panicle by 22.9% compared to those applied after heading. Heatmap clustering analysis revealed that foliar application of Liv before heading was the most effective treatment in enhancing various parameters for both genotypes and mitigating the negative effects of salinity stress on the NUFG. This was followed by Eth and KC before heading for Giza 179. Applying Eth and KC to the leaves after heading had a moderate positive impact on most parameters for Giza 179, outperforming the application after heading for Giza 178. Overall, our findings indicate that spraying readily available compounds that elevate CO2 and K levels in rice leaves can help alleviate the negative impacts of salt stress and improve rice production in salt-affected soils in a cost-effective manner.

Glutathione mitigates aluminum toxicity in root-apex transition zone of rice through reducing aluminum absorption and maintaining redox balance

Aluminium (Al) toxicity is recognized as a major constraint on crop growth and production in acidic soils, and the transition zone (TZ) of plant root apex emerges as the major perception site of Al toxicity. Glutathione (GSH) is reported to be involved in plant responses to various abiotic stresses, but its role and mechanism under Al stress remain unknown. Here, we found that GSH significantly mitigated Al toxicity on rice as revealed by the promotion of root elongation, reduction of oxidative stress and Al absorption. GSH application scavenged Al-induced H2O2 burst by activating the ascorbate (AsA)-GSH cycle and proline synthesis in root-apex TZ, thereby alleviating oxidative stress. GSH effectively reduced Al-induced pectin increment and inhibits the H2O2-induced pectin methylesterase (PME) activity and demethylesterification degree in root-apex TZ, leading to a reduction in Al binding sites and subsequently Al deposition in cell walls, thereby attenuating the inhibitory effect of Al toxicity on cell elongation. In addition, GSH-derived phytochelatins (PCs) promoted the vacuolar Al sequestration in root-apex TZ, which alleviated Al toxicity to the cytoplasm. Taken together, our results indicate a mechanism underlying how GSH alleviates Al toxicity through influencing redox state and Al absorption in rice root-apex TZ.

Combined application of biochar and silicon nanoparticles enhance soil and wheat productivity under drought: Insights into physiological and antioxidant defense mechanisms

Agricultural drought periods are enhanced by the change in global climate that threatens food security. One of the main factors affecting soil and wheat productivity worldwide is drought stress. Especially, in semi-arid climates, studies are not found about adding organic amendments may be a viable way to reduce the adverse impacts of drought on crops while enhancing soil qualities and water use efficiency. In this study, we aimed to explore the effects of combined application of biochar (BC = 5 %) and silicon nanoparticles (SiNP = 900 mg/L) on soil and wheat drought resistance. Drought stress was applied at the three most critical growth stages of wheat, tillering (DTS), flowering (DFS), and grain filling (DGFS) stages, then evaluated the soil nutrients and wheat drought physiological resistance under applied treatments (BC, SiNP, BC+SiNP). Results showed that combined treatment of BC and SiNP greatly reduced the adverse effects of drought by enhancing plant height (9.36 %), spike length (25.63 %), number of fertile tillers (29.26 %), grains per spike (10.86 %), thousand-grain weight (18.25 %), and biological yield (16.34 %) with comparison to the control application. Additionally, physiological measures like water use efficiency (20.58 %), stomatal conductance (29.26 %), chlorophyll a (16.25 %), chlorophyll b (18.96 %), transpiration rate (21.65 %), photosynthetic rate (22.94 %), electrolyte leakage (-17.77 %), MDA (29.25 %), hydrogen peroxide (-19.88 %), superoxide dismutase (11.19 %), catalase (9.26 %), peroxidase (18.59 %), nitrogen (14.81 %), phosphorus (13.89 %), and potassium (17.61 %) were also meaningfully improved by treated application. BC and SiNP also significantly amended the organic carbon, nitrogen, and minerals percentage in soil. In conclusion, using the synergistic application of BC and SiNP could be a successful strategy to promote the biological soil properties, plant growth, yield, and quality of wheat crops as compared to all other treatments via dropping the dangerous effects of drought stress.

Erodibility Prioritization and Mapping of a Mid Himalayan Watershed Using Technique of Order Preference by Similarity to Ideal Solution (TOPSIS)

The productivity of soils is drastically affected owing to soil erosion in human activities in the decline of the Western Nayar watershed situated in the Pauri district of Uttarakhand. Therefore, evaluation of these erodible areas is of utmost importance so that the preventive measures can be taken accordingly. It assessed the sub-basins in the basin using morphometric parameters and several multi- criteria decision-making models, such as Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Utilizing Advanced Space Thermal Emission Radiometer (ASTER) data and a 30 m Digital Elevation Model (DEM), morphometric parameters were extracted and analyzed. To test the MCDM methods, percent and intensity of change indices were adopted. The ranking results were such that sub-watershed 2 was ranked at top as the most susceptible to erosion for TOPSIS model,In general, the morphometric parameters were effective for identifying erosion-prone areas.

Effects of nitrification and urease inhibitors on nitrous oxide emissions and concentrations driven by soil moisture in sandy soils

Soil moisture and nitrogen (N) fertilizer control the balance between nitrous oxide (N₂O) production and consumption in soil. However, the impact of nitrification and urease inhibitors on soil N₂O production and consumption under varying soil moisture levels remains insufficiently understood. In this study, a soil column experiment was conducted to investigate N₂O concentrations and accumulation at different soil depths (0, 5, 15, 30, and 60 cm) in sandy soil over two months. The soil was collected from a drip-irrigated field subjected to long-term cotton cultivation in an arid region. Four fertilizer treatments were applied: urea, urea + nitrification inhibitor (Dicyandiamide, DCD), urea + nitrification and urease inhibitors [N-(n-butyl) thiophosphoric triamide, NBPT], and an unfertilized control. These treatments were tested under three soil moisture levels [23%, 46%, and 70% water-filled pore space (WFPS)]. The results showed that treatments with inhibitors significantly reduced cumulative surface N₂O emissions by 33.2%–58.2% compared to urea alone. Notably, the treatment with both DCD and NBPT achieved the greatest reductions in surface emissions and in N₂O concentrations at 5 cm and 15 cm soil depths at 70% WFPS. Additionally, across all N fertilizer sources, 70% WFPS led to increased N₂O concentrations in the soil profile compared to lower soil moisture levels. Column N₂O accumulation was positively correlated with surface cumulative N₂O emissions under all three moisture conditions. Our study highlights that under high soil moisture conditions, DCD and NBPT can significantly mitigate intense N₂O emissions in sandy soils. This emission reduction is likely attributed to enhanced nitrification within the 0–15 cm soil layer rather than reduced N₂O diffusivity and denitrification along the soil profile. Therefore, we recommend applying nitrification and urease inhibitors under high soil moisture conditions as an effective strategy to reduce N₂O emissions in sandy soils.

A Review of Research on Obstacle Factor Reduction Techniques for Medium and Low Yield Fields

The proportion of low yield fields in China is large, and there are problems such as extensive utilization, low output rate, and poor soil quality. It is crucial to reduce obstacles and improve soil fertility and productivity in low yield fields. At present, the main obstacles to reducing soil acidification, salinization, nutrient imbalance, shallow tillage layer, continuous cropping obstacles, and soil erosion can improve soil quality and increase crop yield and quality. Future research should focus on developing more precise and efficient reduction technologies, introducing intelligent agricultural technologies for real-time monitoring and precise management, promoting soil nutrient management and integrated water and fertilizer technologies, and developing sustainable agricultural technologies to enhance farmland production potential and achieve efficient resource utilization.

Mechanism of stabilized sludge-driven remediation in saline-alkali soil: New insights from salt-discharge capacity and microbially mediated carbon/nitrogen cycles

Stabilized sludge products (SSP) are promising conditioners for saline-alkali soils, capable of enhancing soil physicochemical properties and stimulating microbial communities. However, there is limited knowledge regarding the effects of SSP on soil salt-discharge capacity and carbon/nitrogen cycles. Here, a six-month incubation experiment was conducted to evaluate SSP (0 % ~ 60 %) on saline-alkali soil properties, salt leaching, and microbial functions. It was found that after SSP (≥30 %) treatment, saline-alkali soils were significantly remediated (p < 0.01), with organic matter increasing by 5.3–9.8 times, nutrient levels rising to first-grade, porosity improving by 34.3 % ~ 93.3 %, and meso/macro-aggregates content increasing by 39.0 % ~ 201.3 %. The Na+ leaching rate increased from 1.1 % to 53.3 % ~ 79.3 %, indicating a substantial improvement in salt-discharge capacity. Correlation analysis revealed that SSP organics loosened pore spaces by promoting soil particle agglomeration, which in turn improved salt-discharge capacity. Further, the 30 % SSP significantly increased the microbial functions involved in nutrient cycling, such as carbon fixation (photosynthetic pathway), nitrogen fixation, dissimilatory nitrate reduction, and nitrification (p < 0.01). Contribution analysis implied that the up-regulation of gene abundance assigned to carbon/nitrogen cycle was attributed to balancing effect of SSP on dominant genera. Finally, the excellent growth of alfalfa seedlings verified the soil productivity restoration of degraded saline-alkali soils. These findings provide new insights into salt stress alleviation and nutrient cycling in degraded saline-alkali soils.

Physical and chemical properties of soils from different geological formations affecting Tuber melanosporum plantations: a case study in Acqualagna area (central Italy)

Soil properties play a pivotal role in the fructification of the Périgord black truffle (Tuber melanosporum Vittad.). However, the precise manner in which soil composition influences truffle production remains unclear. This study considered three plantation sites located in Acqualagna (central Italy), an important area for the cultivation of black truffles. The sites differed in terms of productivity and geological terrains. Site 1, which produced 4 kg yr−1, was on Schlier sediments (marls and clayey marls; Miocene age), site 2, which yielded 12 kg yr−1, was on alluvial deposits (heterogeneous, mainly sandy gravels and gravels; Holocene age), and site 3 produced 40 kg yr−1 was on Scaglia variegata (alternating marly limestones, calcareous marls, and marls; Eocene age). A total of 62 soil samples were collected and analyzed for their physical, chemical, organic, and mineralogical composition. Among the samples a control area without the presence of truffle was included. The soils composition differed for the content in phyllosilicates and calcite which ranged from 124 to 398 g kg−1 and 98 to 450 g kg−1, respectively. Principal component analysis extracted three factors, accounting for 82% of the total variance. Factor 1 (46.2% of the variance) was strongly and positively correlated with sheet silicates, smectite, clay and negatively with skeleton (fraction > 2 mm). The soils from Scaglia variegata and Schlier clustered around the active carbonate content which was 266 g kg−1 in Scaglia and 250 g kg−1 in Schlier. These soils clustered also for the clay fraction (389 g kg−1 and 428 g kg−1, respectively) as well as for the smectite (268 g kg−1 and 307 g kg−1, respectively). In spite, the soils from alluvial deposits clustered per skeleton (638 g kg−1). In terms of soil productivity, it can be posited that the contribution of the skeleton was always dominant. The carbonate contents allow for the differentiation between intermediate soils (alluvial deposits) and low-productivity soils (Schlier). Additionally, the clay component was found to be high in both low (428 g kg−1) and high productivity soils (389 g kg−1). Conversely, it was low in medium productivity soils (125 g kg−1). The automatic linear modelling (ALM) indicated that among all of the variables considered in this study, six of them were included in the equation and explained 94.3% of the variation in soil classified as suitable for black truffle production. In particular, calcite was identified as the most important predictor variable, followed by available P and K. Regarding the influence of functional groups of humic substances, amide I (1641 cm−1) exerted a positive effect while lignin residues (1510 cm−1) had a negative one. The findings of this study may assist in the selection of optimal soils for black truffle cultivation.

Exogenous GABA-Ca Alleviates Growth Inhibition Induced by a Low-P Environment in Peanuts (Arachis hypogaea).

Phosphorus (P) deficiency is a major global factor constraining peanut production. Exogenous γ-aminobutyric acid (GABA) and Ca2+ are essential to improve stress resilience in peanuts growing under low-P conditions. This study therefore examined the detailed physiological effects of GABA-Ca on restoring peanut growth under low-P conditions. These included the root-shoot ratio, leaf nutrients, photochemical activity, reactive oxygen species (ROS), cyclic electron flow (CEF), ATP synthase activity, and the proton gradient (∆pH), all of which were measured under low-P (LP, 0.5 mM) and optimized-P (1 mM) conditions. Specifically, supplying GABA-Ca under LP conditions regulated the ∆pH by causing adjustments in CEF and ATP synthase activities, buffering the photosystems' activities, restoring the antioxidant enzyme system, and lowering ROS production. Interestingly, exogenous GABA-Ca restored peanut growth under low-P conditions, possibly by the putative signaling crosstalk between GABA and Ca2+. The plausible signal amplification between GABA and Ca2+ suggested that the combination of GABA and Ca, may offer an effective strategy for enhancing peanut adaptation to low-P conditions. Moving forward, the strategic supplementation of GABA-Ca, either during cultivation or through the formulation of novel fertilizers, opens up many possibilities for better and more resilient plant production in soils with low P.