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In this study, the impacts of long-term soil and crop management practices on crop productivity and soil health in oilseed brassica-based production systems were examined. Different tillage, crop residue recycling and cropping systems (fallow–mustard, cluster bean–mustard, green gram–mustard, maize–mustard, pearl millet–mustard and sesame–mustard) were studied for 5 years at two soil depths (0–15 and 15–30 cm) in a split-plot design with three replications. No-till permanent beds with crop residue (PB + R) noticeably improved soil organic carbon (SOC), microbial biomass carbon (MBC), enzymes (dehydrogenase (DHA) and alkaline phosphatase (AlP)), nitrogen fractions (available and total nitrate) and available phosphorus and potassium content in both soil layers compared to conventional tillage without crop residues. However, the plough soil layer (0–15 cm) showed higher concentrations of soil carbon, enzymes, N fractions and available P than in the subsoil (15–30 cm). The dynamic soil biological and chemical properties also varied with the crop stage, and higher MBC at 30 days, SOC and enzymatic activities at 60 days, and N fractions and available P and K during the harvesting of mustard crop were recorded. Green gram–mustard rotation showed higher values in terms of biological and chemical parameters. Thus, the legume-based mustard crop rotation following no-till permanent beds and residue recycling was found to be holistic in terms of improving soil health and nutrient cycling. [ABSTRACT FROM AUTHOR]

The full behaviour of natural clay minerals in soil organic carbon (SOC) stabilization in the presence of oxides and external C inputs is yet unknown. Thus, an incubation experiment was conducted in a sand–clay mixture with different soil clay fractions (SCFs) obtained from Alfisol, Inceptisol, Mollisol, and Vertisol in the presence of wheat residues to compare their C stabilization capacity. The C mineralization rates were higher in 1:1 type dominated SCFs (Alfisol and Inceptisol) compared to 2:1 interstratified mineral dominated SCFs (Vertisol). Wheat residues as C source altered SCFs' abilities to stabilize SOC at only moderate dosages of application (3–12 g kg−1). C mineralization and microbial biomass carbon (MBC) fell by 40% and 30%, respectively, as the amount of clay increased from 7.5 to 40%. However, removing sesquioxides from the SCFs boosted C mineralization and MBC by 22% and 16–32%, respectively, which matched with higher enzymatic activities in the sand–clay mixture. The increased C stabilization capacity of Vertisol-SCF may be attributed to its greater specific surface area (SSA) (506 m2 g−1) and cation exchange capacity (CEC) [meq/100 g]. Regression analysis revealed that SSA, CEC, and enzymatic activity explained approximately 86% of total variations in C mineralization. This study highlighted the critical role of 2:1 expanding clay minerals and sesquioxides in greater stabilization of external C input compared to its 1:1 counterpart. It also implied that the role of mineralogy or texture and sesquioxides levels in different soils (Vertisol, Mollisol, Inceptisol, Alfisol) should be prioritized while adding crop residues to reduce C footprint and enhance sequestration. [ABSTRACT FROM AUTHOR]

[Objectives] To study the effects of fungi Fusarium sp. to rhizosphere soil and physiological characteristics of Camellia oleifera Abel. [Methods] We investigated the effects of Fusarium sp. to rhizosphere soil nutrient element content and metabolites of C. oleifera. C. oleifera was inoculated with the suspension of Fusarium sp. in pot experiments and ammonium-N, available phosphorus, available potassium, organic matter, enzymes and pH of rhizosphere soil, MDA content, activity of SOD, POD of C. oleifera leaves were analyzed. [Results] Fusarium sp. stress significantly inhibited soil enzyme activities and significantly reduced available phosphorus content, especially for phosphatase and sucrase. Antioxidant enzyme activities in C. oleifera tissues showed that Fusarium sp. stress significantly increased MDA and SOD enzyme activities and decreased POD enzyme activity. Especially, SOD enzyme activity was elevated by 53.86% compared with the CK group. In addition, analysis of the content of major metabolites in C. oleifera leaves showed that Fusarium sp. stress significantly reduced the content of total flavonoids, quercetin, isoquercitrin and isoquercitrin in C. oleifera leaves by 7.80%, 50.00% and 75.90%, respectively. [Conclusions] Our results are an important step which showed strong resistance of C. oleifera and can give a novel insight for researches on the effects in the rhizosphere soil enzyme, soil nutrient elements and metabolites of C. oleifera under the Fusarium sp. too. [ABSTRACT FROM AUTHOR]

Heavy metals from mica waste not only deteriorate the soil quality but also results in the uptake of metals in the crop. The present investigation was conducted to evaluate the effects of different fractions of metals on the uptake in rice, soil microbial and biochemical properties in mica waste-contaminated soils of Jharkhand, India. From each active mine, soil samples were randomly collected at distances of < 50 m (zone 1), 50–100 m (zone 2), and >100 m (zone 3). Sequential metal extraction was used to determine the fractions of different metals (nickel (Ni), cadmium (Cd), chromium (Cr) and lead (Pb)) including water-soluble (Ws) and exchangeable metals (Ex), carbonate-bound metals (CBD), Fe/Mn oxide (OXD) bound metals, organically bound metals (ORG), and residues (RS). The Ni, Cr, Cd and Pb in rice grain were 0.83±0.41, 0.41±0.19, 0.21±0.14 and 0.17±0.08 mg/kg respectively. From the variable importance plot of the random forest (RF) algorithm, the Ws fraction of Ni, Cr and Cd and Ex fraction of Pb was the most important predictor for rice grain metal content. Further, the partial dependence plots (PDP) give us an insight into the role of the two most important metal fractions on rice grain metal content. The microbial and enzyme activity was significantly and negatively correlated with Ws and Ex metal fractions, indicating that water-soluble and exchangeable fractions exert a strong inhibitory effect on the soil microbiological parameters and enzyme activities. [Display omitted] [ABSTRACT FROM AUTHOR]

The results of studying the effect of fires on biological properties of cinnamonic soils of xerophytic forests (Skeletic Leptic Cambisol) of the Utrish State Nature Reserve, Krasnodar krai (crown fire of 2020), and burozem of mesophytic forests (Haplic Cambisol (Loamic)) of the Khamyshinsk forestry, Republic of Adygea (ground fire of 2018) are presented. Changes in the soil reaction, in the organic carbon content, and in the activity of enzymes: catalase, urease, phosphatase, and invertase involved in the cycle of carbon, phosphorus, and nitrogen have been studied. The reaction of enzymes to pyrogenic effects depends on the enzyme kind and the soil type. The factor analysis was also performed. The activity of catalase and invertase decreases by 47% on average for two soil types in the 0–3-cm-thick layer, while the reaction of phosphatase and urease depends on the soil type. Two years after the fire, the phosphatase activity in the surface layer of post-pyrogenic cinnamonic soils approached the control values; and the urease activity regenerated more slowly as compared to other enzymes. Four years after the fire, the values of urease activity in the 0–3-cm-thick layer of the post-pyrogenic acid burozem, on the contrary, approached the control values. An increase in pH by 30% on average and a decrease in the Corg content by 12% on average were also recorded for both two soil types. The mean activity of all the studied enzymes in the 3–10-cm-thick layer increased in cinnamonic soils and, on the contrary, decreased in acid burozem. The factor analysis showed a relationship between the soil reaction, the organic carbon content, and the activity of enzymes, and the strength and nature of relationships differed depending on the soil type. The results obtained testify to the effect of soil properties on the response of enzymatic activity to the pyrogenic impact. [ABSTRACT FROM AUTHOR]

Aim: We aim to find a simple agricultural waste processing method to improve soil water retention and soil enzymes vitality, control soil-borne pathogens, and enhance plant resistance against biotic stress. Methods: We extracted polysaccharides from different agricultural wastes. We tested the antimicrobial activity of the extracted polysaccharides on different soil-borne pathogens and the effect of the addition of these polysaccharides on the soil water status and soil enzymes. Besides this, we investigated the efficiency of the peanut shells polysaccharides in improving tomato growth and defense under Fusarium solani and Ralstonia solanacearum infection in a greenhouse study. Results: Results showed the efficiency of all extracted polysaccharides as antimicrobial agents against different soil-borne pathogens. In addition, all polysaccharides increased the soil water holding capacity by about 116% more than that in the non-treated soil and increased the water retention to reach about 30% after eight days, besides their positive role in improving the soil enzymes, which improves the soil health. The peanut shells polysaccharides, which are the best ones as antimicrobials and soil amendments, showed interesting improvements in tomato growth under normal and pathogen infection conditions. The polysaccharide treatment decreased the bacterial and fusarium wilt in tomato plants, and induced resistance mechanism through up-regulating secondary metabolism defense compounds defense enzymes such as phenylalanine ammonia-lyase, and antioxidant enzymes detoxify the oxidative stress markers. Conclusion: Polysaccharides from agricultural wastes can be a promising soil amendment to improve the soil properties and so improve plant growth and defense mechanism against pathogen infection. [ABSTRACT FROM AUTHOR]

Background and aims: Forage legumes form mutualistic interactions with specialized soil rhizobia bacteria that inhabit root nodules and fix atmospheric nitrogen. However, legumes are sensitive to drought stress, which can interrupt nodulation and symbiotic nitrogen fixation (SNF). We hypothesize that drought-impaired SNF may influence soil nitrogen availability and soil microbial diversity. Methods: Here, we evaluated the effects of drought on nodulation, plant growth, physiological parameters, SNF, soil nitrogen availability, soil extracellular enzyme activity, and soil microbiome of alfalfa (Medicago sativa) and red clover (Trifolium pratense). The drought treatments were imposed at the flowering stage by maintaining soil moisture contents at 20% field capacity (FC) (severe drought), 40% FC (moderate drought), and 80% FC (well-watered) for three weeks. Results: Drought significantly reduced nodulation, root and shoot growth, and SNF in alfalfa and red clover. Soil available nitrogen was significantly increased following severe drought conditions. The enzyme assays showed reduced activity of N-acetyl-glucosaminidase and β-D cellobiosidase enzymes under drought stress in alfalfa and red clover, respectively. Microbiome data showed shifts in the relative abundance of some key bacterial taxa under drought stress. Conclusion: Overall results indicate that drought has deleterious effects on SNF and plant growth, affecting carbon and nitrogen cycling enzymes, soil nitrogen availability, and soil microbial diversity. [ABSTRACT FROM AUTHOR]

Context. Limitation in soil organic matter interferes with plant growth and productivity. Chemical fertilisers can provide limiting nutrients to plants, especially in barren soil, but they have detrimental *Correspondence to: Sedat Çam Department of Biology, Faculty of Arts and Sciences, Harran University, Haliliye, S¸anlıurfa 63050, Turkey Email: sedatcam@harran.edu.tr effects on living organisms; therefore, plant growth-promoting (PGP) rhizobacteria may be an alternative to synthetic fertilisers to improve plant tolerance to nutrient stress. Aims. This study evaluated the effects of single and co-inoculation of two PGP rhizobacterial strains with macroalgae (Cladophora glomerata) extract on barley growth. We also tested the ability of the respective strains to produce biofilm and exopolysaccharide (EPS) at different pH values under in vitro conditions. Methods. Plants were cultivated in an organic matter-limited alkaline soil under Handling Editor: Caixian Tang field conditions. Key results. All treatments increased barley growth parameters to some extent. Growth parameters increased most in Bacillus + macroalgae extract (B + MA) and Bacillus + Azotobacter + macroalgae extract (B + A + MA) treatments. These two treatments significantly enhanced shoot length by 22.9-25.7%, dry weight of shoot + spike by 118.2-154.5%, total weight of grains by 76.5-78.1%, and number of grains per spike by 94.8-112.1% in comparison with the control. The respective two treatments also increased biofilm formation and EPS production in response to alkaline pH. Conclusions. Barley productivity may be increased by using PGP strains with greater potential to produce biofilm and EPS, and inoculating them with macroalgae extract. The B + MA treatment could be applied singly or in combination with Azotobacter. Implications. Single or co-inoculation of such PGP bacteria with macroalgae extract may be commercialised to enhance barley productivity in organic matter-limited soils. [ABSTRACT FROM AUTHOR]

Grazing management is a critical land-use requirement that facilitates the preservation of plant community composition, soil properties and environmental quality. Grazing density of livestock has a significant impact on soil health, and there is a need to study the interactions of grazing densities and topographical positions influencing soil biochemical and microbial properties. This study was conducted at Cottonwood Field Station in Philip, South Dakota to assess the influence of more than 7 years of low, medium, and high grazing stocking densities (0.33, 0.41, 0.72 animal units/ac, respectively) at summit and footslope landscape positions on soil carbon (C) and nitrogen (N) fractions, microbial community composition, and enzymatic activities in a mixed-grass prairie ecosystem. Medium grazing density showed a 16% increase in soil N at the footslope compared with summit. Low grazing density significantly reduced microbial biomass C (~269 µg g-1 soil) and N (~26 µg g-1 soil) at summit compared with other grazing densities and landscape positions, except, the summit at high grazing density. Medium grazing density significantly enhanced hot-water extractable N by 21-23% at footslope compared with low grazing density at the footslope and high grazing density at the summit. Low grazing density increased urease (3.64 µg NH4+ g-1 soil h-1) at footslope than all other grazing densities and landscape positions. Low grazing density enhanced β-glucosidase by 75% than high grazing density; alkaline phosphatase was significantly greater by 60% at footslope than summit. High grazing density at the summit decreased total PLFA (mean 56.53 nmol g-1 soil) due to lower AM fungi, G (+), G (-) and actinomycetes biomass. Microbial stress indicators such as G (+)/G (-), saturated/unsaturated, monosaturated/polysaturated, GNeg stress revealed that high grazing density especially at summit position posed elevated physiological stressed conditions to the microbial community. Overall, long-term medium grazing density of 0.41 animal units/ac may enhance soil N, microbial composition, microbial biomass C and N, hot-water extractable C and N fractions, and reduce stress conditions for microbial community at both footslope as well as summit landscape positions. Moreover, long-term overgrazing of pastures, particularly at summit slopes, appears to inhibit microbial populations and degrade overall soil health. [ABSTRACT FROM AUTHOR]

Edaphoclimatic conditions influence nitrous oxide (N2O) emissions from agricultural systems where soil biochemical properties play a key role. This study addressed cumulative N2O emissions and their relations with soil biochemical properties in a long-term experiment (26 years) with integrated crop–livestock farming systems fertilized with two P and K rates. The farming systems consisted of continuous crops fertilized with half of the recommended P and K rates (CCF1), continuous crops at the recommended P and K rates (CCF2), an integrated crop–livestock system with half of the recommended P and K rates (ICLF1), and an integrated crop–livestock at the recommended P and K rates (ICLF2). The ICLF2 may have promoted the greatest entry of carbon into the soil and positively influenced the soil's biochemical properties. Total carbon (TC) was highest in ICLF2 in both growing seasons. The particulate and mineral-associated fractions in 2016 and 2017, respectively, and the microbial biomass fraction in the two growing seasons were also very high. Acid phosphatase and arylsulfatase in ICLF1 and ICLF2 were highest in 2016. The soil properties correlated with cumulative N2O emissions were TC, total nitrogen (TN), particulate nitrogen (PN), available nitrogen (AN), mineral-associated organic carbon (MAC), and microbial biomass carbon (MBC). The results indicated that ICLF2 induces an accumulation of more stable organic matter (OM) fractions that are unavailable to the microbiota in the short term and result in lower N2O emissions. [ABSTRACT FROM AUTHOR]

The dynamic soil properties for soil health (DSP4SH) is a Science of Soil Health Initiative that was designed to collect, process, and publicize scientifically rigorous datasets that inform sound indicators and interpretations. The Soil and Plant Science Division of the United States Department of Agriculture - Natural Resources Conservation Service (USDA-NRCS) and university cooperators collected a suite of standardized soil health metrics across eight states (Oregon, Washington, Kansas, Minnesota, Illinois, Connecticut, North Carolina, and Texas) within five soil survey regions (Northwest, North Central, Northeast, Southeast, and South Central). The DSP4SH database provides a substantial dataset of soil health metrics assessed. The dataset is composed of dynamic soil properties (DSP) data collected from each management system or ecological state represented by one to three independent plot replicates. Each plot has a minimum of three pedons. Nine groups from the DSP4SH monitoring network provided datasets used in developing the database. The submitted data includes 37 laboratory measured parameters, 60 variables of layer/horizon descriptions, 41 variables for laboratory analysis conducted at the Kellogg Soil Survey laboratory, and 12 variables for the management systems. An additional 31 variables were developed for site or plot description. Additional variables were developed to normalize the dataset. In preparation for DSP assessment, all tables (except for dataset from KSSL lab) were categorized by management system or ecological state. The categories were business as usual (BAU), the reference condition (Ref) and the soil health management (SHM). The overarching goal of DSP4SH phase 1 and 2 dataset publication is to promote increased accessibility, further analysis of the data, and overall understanding of the benefits of surveying dynamic soil properties for soil health.

Despite the polluting potential olive mill wastewater (OMW) can be a useful source of nutrients and organic compounds to improve soil properties. The aim of this paper was to verify if biochar-based treatment of OMW could be an efficient method to contrast the richness in phenolic compounds and phytotoxicity of OMW making it more suitable. for soil amendment. In this study poplar biochar (BP) was more effective than conifer biochar (BC) in terms of adsorbing phenols and reducing phytotoxicity at different biochar rates (5 and 10 %). In soil amendment BP-treated OMW induced an increase of organic carbon by approximately 15 % and notably BP10 treated OMW enhanced available phosphorous by 25 % after 30 days of incubation. In soil amended with 10 % BP-treated OMW microbial biomass and enzymatic activities were significantly enhanced after 30 and 90 days, with no effect on cress seed germination. Therefore, biochar based-treatment could be cost-effective and able to facilitate the long-term management of OMW in terms of storage and disposal.

Fungicides play a role in managing plant diseases but raise concerns about environmental impact, emphasizing the need to understand and minimize their effects on non-target ecosystems. Flutriafol is a fungicide used to combat fungal diseases in crops. It has two enantiomers that exhibit different levels of efficacy and environmental impact. This study focuses on evaluating the effects of different doses of flutriafol on soil microorganism populations and enzyme activity and the possible specificity of enantiomer interactions with soil enzymes by combining experimental and computational approaches. The effects of different doses of flutriafol on the population of microorganism and on the activity of soil enzymes were experimentally assessed. Molecular docking of the enantiomers with soil enzymes was used to assess the possible stereoselectivity of the interactions. Regardless of the dose used (normal dose recommended by the manufacturer for cereal crops, half this dose, and double dose), flutriafol had no significant impact on soil microbial communities or on catalase activity. The half dose of flutriafol produced increases in the activity of dehydrogenases (8%), phosphatases (26%), and urease (33%) during the first 7 days of incubation. Molecular docking showed that both enantiomers were able to bind to the active sites of dehydrogenases and phosphatases. The average value of the interaction energy observed for (R)-flutriafol with dehydrogenases was −7.85 kcal/mol, compared to −7.45 kcal/mol for the interaction of (S)-flutriafol with these enzymes. Similarly, the interaction energy obtained for the interaction of (R)-flutriafol with phosphatase was −9.16 kcal/mol, compared to −9.04 kcal/mol for the interaction of (S)-flutriafol with this enzyme. This study confirms the need to implement optimized application practices when using flutriafol by considering the enantiomer that is most effective on the target organism and less toxic to non-target ecosystems.

The soil microbiota is a key component of agroecosystems, and understanding its traits is crucial for effective agronomic management. Among beneficial microorganisms, arbuscular mycorrhizal fungi (AMFs) are mutually associated with grapevine (Vitis vinifera L.), enhancing the ability of this cropping system to adapt to soil conditions and bolstering its resistance and resilience against abiotic stresses, particularly drought, by promoting root growth and enhancing the roots’ absorption surface. The objective of this on-field study was to determine AMF species richness and diversity along with their relation to soil chemical, physical, and biological characteristics in two adjacent organic vineyards in Central Italy. The two tested vineyards of the autochthonous cv. Aleatico differed by the presence of grafted (Vitis berlandieri × V. riparia rootstock; AL-420) or own-rooted (ungrafted V. vinifera L.; AL-ORV) vines. To this aim, soil and root samples were collected and geo-referenced. Analysis of the AMF species colonizing roots of both AL-ORV and AL-420 revealed the presence of four species: Scutellospora alterata, Paraglomus laccatum, Acaulospora laevis, and A. baetica, with S. alterata being the most frequent. Mycorrhization parameters were higher in the roots of grafted plants compared to ungrafted ones. A high beta-glucosidase (BG):N-acetylglusosaminidase (NAG) ratio in two tested vineyards indicated that microbes utilized more cellulose than chitin and peptidoglycan as dominant C resources. A negative correlation between mycorrhization rate (MyCP) and BG was observed, likely because AMFs form mutualistic relationships with plants, depending on the host plant for carbon. Results revealed a positive correlation between the degree of mycorrhizal association and the species involved, with the presence of copper and nickel among metals. Negative correlations were found concerning soil clay content along with beta-glucosidase. In conclusion, the grapevine root system was characterized by a differential symbiotic relationship with AMF species, whose development is influenced by the root genotype, soil texture, and biochemistry. Specifically, the increased frequency of AMFs in relation to copper content strengthens the evidence of their role in maintaining a vine’s production capacity in the event of soil contamination by this element.

Soil acidification is a global environmental problem with significant impacts on agricultural production, environmental protection, and ecosystem health. Soil acidification is widespread in China, affecting crop yields, agricultural product quality, and biodiversity. Since the 1980s, much work has been done on acidic soils in China, but it is controversial whether excessive nitrogen fertilizer application can lead to soil acidification mechanisms. To address the above issues, we conducted a meta-analysis of 115 published papers to integrate and analyze the effects of N fertilizer application on soil acidification and biological properties from 1980 to 2024. We also quantified the effect of nitrogen fertilization on soil acidification and biological changes under different climatic conditions. The results showed that under long-term application of nitrogen fertilizers in China from 1980 to 2024, soil pH decreased by an average of 15.27%, and the activities of soil urease, nitrate reductase, nitrite reductase, catalase, glutamate dehydrogenase, and glutamate synthetase decreased by an average of 9.82–22.37%. The soil microbial community richness (Chao1 index) increased by 6.53%, but the community diversity (Shannon index) decreased by 15.42%. Among the dominant soil microorganisms, the relative abundance of bacteria decreased by an average of 9.67–29.38% and the abundance of gene expression of nifH, amoA-AOA, amoA-AOB, and qnorB decreased by 9.92–19.83%. In addition, we found that the mean annual temperature and rainfall impacted soil acidification via their effect on soil microbial diversity and community composition. This study provides a scientific basis for an in-depth understanding of the spatial and temporal variation of soil acidification and biological properties in China.

Rapeseed meal, a nutritious organic fertilizer (OF), contributes to improving soil environment and crop productivity. However, there are also problems, namely slow fertilizer efficiency and low nutrient utilization during the growing season. This 2‐year field trial was conducted to explore the effect of biochar addition on improving the nutrient availability of OF through a comparative study of various biochar application rates under rice‐rapeseed rotation conditions. The findings revealed that, compared to the individual application of chemical fertilizers (CF), OF alone decreased rice yield (2%/2%) and rapeseed yield (6%/10%) in 2019/2020. Compared with OF, combining biochar (15 t ha−1) with OF (OF + B15) significantly increased rice yield (17%/10%) and rapeseed yield (25%/20%) in the first/second year. Additionally, OF + B15 still increased rice yield (14%/7%) and rapeseed yield (12%/13%) for two consecutive years compared to CF. The co‐application of biochar and OF had positive impacts on soil physicochemical properties and enzymes. Compared to OF, OF + B15 elevated soil organic carbon (SOC) by 57%–81%, soil catalase 19%, invertase 14%–20%, urease 17%–19%, and phosphatase 13%–17% during rice season, and similarly increased SOC by 77%–90%, soil catalase 14%–16%, invertase 14%–20%, urease 18%–24%, and phosphatase 16%–17% in rapeseed season. Biochar addition improved soil conditions and enzymatic activities, and the available nutrient supply of OF. Also, the co‐application of biochar and rapeseed meal surpassed the effect of chemical fertilizer alone on the growth and yield of crops. Therefore, biochar coupling with organic fertilizer is an effective fertilization strategy based on resource recycling, which promotes both crop yield and sustainable agriculture. [ABSTRACT FROM AUTHOR]

In long-term integrated nutrient management (INM) involving organic amendments with inorganic fertilizer application, understanding nitrogen (N) mineralization is key to assessing soil functioning. In this study, soil samples were collected following rice cropping from treatments consisting of various combinations of inorganic with organic fertilizers, including farm yard manure, wheat straw or Green Leaf Manuring, as well as 100% inorganic and a control (no fertilizer). The soil samples were incubated for 120 days at 30°C for determining N mineralization potential, and the mineralization patterns were fitted to double first-order kinetic models to separate the potentially mineralizable nitrogen (PMN) into readily available N (PMN-I) and resistant N (PMN-II) fractions. The half-lives of PMN-I and PMN-II ranged from 1.2 to 3.3 days and 22.4 to 63.0 days, respectively. In the organically amended soils, we observed that microbial biomass carbon (MBC) and nitrogen (MBN) increased by 43% and 41%, respectively, compared to inorganic fertilizer application alone. Moreover, the soil enzyme activity increased, revealing enhanced biological activity (dehydrogenase--31.96 µg TPF, Urease--35.69 µg urea-N, glucosidase--57.78 µg p-nitrophenol, fluorescein diacetate hydrolysis--45.84 µg fluorescein, N-acetyl ß-glucosaminidase--46.47 µg p-nitrophenol released g-1 dry soil h-1). We determined that PMN-I was affected by the soil urease activity; whereas, PMN-II was regulated by soil organic carbon, MBC, MBN, dehydrogenase activity and fluorescein diacetate hydrolysing capacity. These findings elucidate the soil biological indicators associated with nitrogen (N) mineralization, which can help optimize INM practice. [ABSTRACT FROM AUTHOR]

The scarcity of freshwater limits vegetable production in the coastal saline zone of the Sundarbans region. Low-cost, locally available, earthen pots (called pitchers) were tested for irrigation of vegetables along with paddy straw mulching (PSM) for soil water conservation. Field experiments were conducted in successive years (2021-22 and 2022-23) at ICAR-Central Soil Salinity Research Institute, Regional Research Station, Canning Town to increase the use efficiency of scarce good quality irrigation water for vegetable cultivation. The eight treatments consisted of: T1: Conventional check basin irrigation with best available water (BAW) with electrical conductivity (ECiw) of 1.27 dS m-1 in 2021-22 and 1.80 dS m-1 in 2022-23; T2: Check basin irrigation with saline water (ECiw: 5.82 dS m-1 in 2021-22 and 4.60 dS m-1 in 2022-23); T3: Check basin irrigation with BAW + paddy straw mulch (PSM); T4: Check basin irrigation with saline water + PSM; T5: Pitcher irrigation with BAW; T6: Pitcher irrigation with saline water; T7: Pitcher irrigation with BAW + PSM and T8: Pitcher irrigation with saline water + PSM. The experiment was conducted in triplicate in a split-plot design with irrigation methods (check basin and pitcher) as main-plots, the combination of water quality (saline and non-saline) and moisture conservation (PSM and non-mulching) in sub-plots. Clay pitchers of 9.75 liters capacity are buried inside the soil, around which seeds of bitter gourd (Momordica charantia L.) were sown. Check basin irrigation was followed as per the treatment. Lowest soil salinity development, higher bitter gourd yield and net return were observed when pitcher irrigation using BAW with PSM was followed. However, during the second year, check basin irrigation with PSM was at par with pitcher irrigation with PSM with respect to yield, net return and benefit cost ratio. The low cost (pitcher) irrigation with PSM was effective for growing vegetable crops with scarce water supplies in farmers' fields in the Sundarbans. [ABSTRACT FROM AUTHOR]

Root exudates serve as crucial mediators for information exchange between plants and soil, and are an important evolutionary mechanism for plants’ adaptation to environmental changes. In this study, 15 different abiotic stress models were established using various stress factors, including drought (D), high temperature (T), nitrogen deficiency (N), phosphorus deficiency (P), and their combinations. We investigated their effects on the seedling growth of Salvia miltiorrhiza Bunge and the activities of Solid-Urease (S-UE), Solid-Nitrite Reductase (S-NiR), Solid-Nitrate Reductase (S-NR), Solid-Phosphotransferase (S-PT), and Solid-Catalase (S-CAT), as well as the contents of polysaccharides in the culture medium. The results showed that the growth of S. miltiorrhiza was inhibited under 15 stress conditions. Among them, 13 stress conditions increased the root-shoot ratio. These 15 stress conditions significantly reduced the activity of S-NR, two combinations significantly improved the activity of S-NIR, they were synergistic stresses of high temperature and nitrogen deficiency (TN), and synergistic stresses of drought and nitrogen deficiency (DN) (p < 0.05). The activity of S-UE was significantly improved under N, D, T, synergistic stresses of drought and high temperature (DT), DN, synergistic stresses of drought and phosphorus deficiency (DP), and synergistic stresses of high temperature, nitrogen, and phosphorus deficiency (TNP) stress conditions (p < 0.05). Most stress combinations reduced the activity of S-PT, but D and T significantly improved it. (p < 0.05). The N, DN, and TN stress conditions significantly reduced S-CAT activity. The P, DT, and synergistic stresses of drought, high temperature, and phosphorus deficiency (DTP) significantly decreased the total polysaccharide content of the soil (p < 0.05). The research suggested that abiotic stress hindered the growth of S. miltiorrhiza and altered the behavior of root secretion. Roots regulated the secretion of several substances in response to various abiotic stresses, including soil nitrogen cycle enzymes, phosphorus transport-related enzymes, and antioxidant enzymes. In conclusion, plants regulate the utilization of rhizosphere substances in response to abiotic stresses by modulating the exudation of soil enzymes and polysaccharides by the root system. At the same time, soil carbon sequestration was affected by the adverse environment, which restricted the input of organic matter into the soil. [ABSTRACT FROM AUTHOR]

Casuarina equisetifolia (C. equisetifolia) is an economically important forest tree species, often cultivated in continuous monoculture as a coastal protection forest. Continuous planting has gradually affected growth and severely restricted the sustainable development of the C. equisetifolia industry. In this study, we analyzed the effects of continuous planting on C. equisetifolia growth and explored the rhizosphere soil microecological mechanism from a metagenomic perspective. The results showed that continuous planting resulted in dwarfing, shorter root length, and reduced C. equisetifolia seedling root system. Metagenomics analysis showed that 10 key characteristic microorganisms, mainly Actinoallomurus, Actinomadura, and Mycobacterium, were responsible for continuously planted C. equisetifolia trees. Quantitative analysis showed that the number of microorganisms in these three genera decreased significantly with the increase of continuous planting. Gene function analysis showed that continuous planting led to the weakening of the environmental information processing-signal transduction ability of soil characteristic microorganisms, and the decrease of C. equisetifolia trees against stress. Reduced capacity for metabolism, genetic information processing-replication and repair resulted in reduced microbial propagation and reduced microbial quantity in the rhizosphere soil of C. equisetifolia trees. Secondly, amino acid metabolism, carbohydrate metabolism, glycan biosynthesis and metabolism, lipid metabolism, metabolism of cofactors and vitamins were all significantly reduced, resulting in a decrease in the ability of the soil to synthesize and metabolize carbon and nitrogen. These reduced capacities further led to reduced soil microbial quantity, microbial carbon and nitrogen, microbial respiration intensity, reduced soil enzyme nutrient cycling and resistance-related enzyme activities, a significant reduction in available nutrient content of rhizosphere soils, a reduction in the ion exchange capacity, and an impediment to C. equisetifolia growth. This study provides an important basis for the management of continuously planted C. equisetifolia plantations. [ABSTRACT FROM AUTHOR]

Wood ash is sometimes used as an alternative to mineral fertilizers; however, there is still a paucity of reliable data concerning its effect on plants—and on biological properties of soil. The present study aimed to determine the possible extent of soil pollution with ash from Salix viminalis that does not disturb the growth of Zea mays L., intended for energetic purposes, in order to identify how the increasing ash doses affect biochemical and physicochemical properties of soil and to finally to establish the neutralizing effects of soil additives, i.e., compost and HumiAgra preparation, on this soil pollutant. The study demonstrated that the heating value of Zea mays L. was stable and not modified by the excess content of ash from Salix viminalis in the soil. This finding points to the feasibility of Zea mays L. cultivation on soils contaminated with ash from Salix viminalis and its use in bio-power engineering. The biomass of the aboveground parts of Zea mays L. was significantly reduced after soil contamination with Salix viminalis ash dose of 20 g kg−1 d.m. soil, whereas the smaller ash doses tested (5–10 g kg−1 d.m. soil) did not impair either the growth or the development of Zea mays L. The ash inhibited activities of all analyzed soil enzymes but increased soil pH and sorption capacity. Fertilization with compost proved more effective in neutralizing the adverse effect of ash on enzymatic activity of the soil. [ABSTRACT FROM AUTHOR]

A pot experiment was undertaken to investigate the effect of Cd, Pb and Zn multi-contamination on the physiological and metabolic response of carrot (Daucus carota L.) after 98 days of growth under greenhouse conditions. Multi-contamination had a higher negative influence on leaves (the highest Cd and Zn accumulation) compared to the roots, which showed no visible change in terms of anatomy and morphology. The results showed the following: (i) significantly higher accumulation of Cd, Zn, and Pb in the multi-contaminated variant (Multi) compared to the control; (ii) significant metabolic responses—an increase in the malondialdehyde content of the Multi variant compared to the control in the roots (by 20%), as well as in the leaves (by 53%); carotenoid content in roots decreased by 31% in the Multi variant compared with the control; and changes in free amino acids, especially those related to plant stress responses. The determination of hydroxyproline and sarcosine may reflect the higher sensitivity of carrot leaves to multi-contamination in comparison to roots. A similar trend was observed for the content of free methionine (significant increase of 31% only in leaves); (iii) physiological responses (significant decreases in biomass, changes in gas-exchange parameters and chlorophyll a); and (iv) significant changes in enzymatic activities (chitinase, alanine aminopeptidase, acid phosphatase) in the root zone. [ABSTRACT FROM AUTHOR]

High concentrations of arsenic in soil and plant systems are a threat to human health and ecosystems. The levels of phosphate ions in the soil strongly influence the soil efficacy and arsenic absorption by plants. This study investigated the effects of phosphate-solubilizing fungi (PSF) on environmental factors and structural changes in microbial community in soils contaminated with arsenic. Four experimental groups were created: control (CK), Penicillium GYAHH-CCT186 (W186), Aspergillus AHBB-CT196 (W196), and Penicillium GYAHH-CCT186 + Aspergillus AHBB-CT196 (W186 + W196), with Pakchoi (Brassica chinensis L.) as the test plant. Analysis of altered nutrient levels, enzyme activities and microbial community structure in the soil as well as the growth and physiological characteristics of Pakchoi, revealed a significant increase in the available phosphorus (AP), organic matter (OM), cation exchange capacity (CEC) and available arsenic (AAs) content of the soil following W186 + W196, W196 and W186 treatments. All experimental treatments enhanced the activity of soil β-glucosidase (β-GC) and soil catalase (S-CAT). W186 + W196 and W196 treatments significantly enhanced soil acid phosphatase (S-ACP) activity. Besides, W186 + W196 treatment significantly induced dehydrogenase (S-DHA) activity. Further, of the treatment with PSF increased the fresh weight, root length, plant height and chlorophyll levels while decreasing the arsenic accumulation in Pakchoi. Exposure to PSF also increased the activity of Ascomycota, Basidiomycota, Chytridiomycota, unclassified_Fungi, Mortierellomycota, Cryptomycota and Rozellomycota in the soil. The relative abundance of Ascomycota, Basidiomycota, and Mortierellomycota was positively correlated with the available nutrients (except iron) in the soil as well as enzyme activities. Consequently, the PSF improved the quality of soil and the safety of Pakchoi, suggesting that PSF can be utilized for the remediation of arsenic-contaminated soil. [ABSTRACT FROM AUTHOR]

Background and aims: Wheat growth and productivity need an exceptional approach to resist the deleterious effects of salt stress. Methods: This study proposed to assess the effectiveness of the exogenous application of plant growth-promoting rhizobacteria (PGPR; i.e., Azospirillum lipoferum SP2, Bacillus coagulans NCAIM B.01123, Bacillus circulance NCAIM B.02324, and Bacillus subtilis MF497446) at a rate of 950 g ha−1 and foliar application of zinc oxide nanoparticles (ZnO-NPs; 500 mg L−1) against irrigation with saline (from a groundwater well) and fresh water (from the Nile River water) of wheat (Triticum aestivum L.) in sodic-saline soil during 2021 and 2022 growing seasons under open field conditions. Results: The integrated application of PGPR and ZnO-NPs protected wheat plants against irrigation with saline water through increasing antioxidant enzyme activities, i.e., catalase (47%), peroxidase (102%), and superoxide dismutase (106%), and K+ uptake (27%) over control. Conversely, higher stress mitigation through the integrated application was illustrated by a considerable decline in electrolyte leakage (−62%), proline (−39%), MDA (−56%), and H2O2 levels (−60%). The N uptake by wheat grains increased by 57% upon treating plants with PGPR+ZnO-NPs, which also increased the Zn contents in grain and straw by 117% and 72%, respectively. Also, PGPR+ZnO-NPs increased the activity of soil urease and dehydrogenase by 80% and 232%, respectively, in plots irrigated with saline water. Conclusion: The results of the present investigation suggest the use of the integrated application of PGPR and ZnO-NPs to protect wheat plants against salinity of soil and/ or irrigation water. [ABSTRACT FROM AUTHOR]

Land use and management practices have a significant impact on soil microbial populations and community composition, thereby influencing ecosystem processes. Soil microbial and biochemical indicators serve as highly sensitive tools for assessing the effects of land use systems. In this study, we investigated soils under ten different land use systems in the Central Himalayas, India, including natural forests dominated by oak (Quercus incana), deodar (Cedrus deodara), or pine (Pinus roxburghii) trees, orchards dominated by apple trees, and crop-based systems in uplands and valleys. We examined phospholipid ester-linked fatty acid (PLFA) profiles, soil enzymes, Ribosomal Intergenic Spacer Analysis (RISA) profiles, microbial biomass carbon and organic carbon as affected by land use. The results revealed that forest soils had significantly higher levels of soil enzymes compared to agricultural soils. Microbial biomass carbon and organic carbon showed a close relationship with the PLFA profiles across different land uses. Gram-positive bacteria (15:0 iso, 16:1 iso G, 16:1 iso H), gram-negative bacteria (10:0 2OH, 12:0 3OH, 17:0 cyc, 19:0cyc 8c, 18:1ω7c11), fungi (18:1ω9c), and arbuscular mycorrhizal fungi (AMF) (16:1) exhibited higher relative abundance in forest systems, whereas gram-positive PLFA markers (C15:0 anteiso, C17:0 iso, C17:0 anteiso) were more prominent in agro-ecosystems. Principal component analysis (PCA) of the PLFA profiles demonstrated that the microbial communities in deodar forest soils were compositionally distinct from other forest soils, while the cultivated soils were grouped together and exhibited higher similarity, except for the organic farming soil. The correlation between PLFA profiles and soil enzymes, microbial biomass carbon, and organic carbon providesinsights into the impact of different land use and management practices on soil microbial health and, consequently, soil health. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the impact that three cultivation systems—conventional till (CT), reduced till (RT), and strip-till one-pass (ST-OP)—had on the biological parameters of the soil and their relationships with organic matter properties in the row zone (R) and inter-row zone (IR). For this purpose, a long-term static field experiment was carried out, from which soil samples were taken from a depth of 0–20 cm and the following were determined: TOC; TN content and fractional composition of organic matter; activity of dehydrogenases (DEHs), catalase (CAT), alkaline (AlP), and acid phosphatase (AcP); and the abundances of heterotophic bacteria (B), filamentous fungi (F), actinobacteria (Ac), and cellulolytic microorganisms (Ce). Soil samples for biological parameter tests were collected in summer (July) and autumn (October). RT and ST-OP increase the content of TOC, TN, carbon, and nitrogen in the humic and fulvic acid fractions. For the studied groups of microorganisms, the conditions for development were least favourable under CT cultivation. The results show that in July, the activities of DEH and CAT were the highest in ST-OP, whereas in October, they were the highest under CT. AlP and AcP activity were markedly the highest under ST-OP in both months. Enzyme activity was significantly the highest in the IR zone. The results indicate that, of the calculated multiparametric indicators, (AlP/AcP, GMea, BIF, BA12, and TEI), BA12 is a sensitive biological indicator of soil quality. [ABSTRACT FROM AUTHOR]

Soil carbon (C) and nitrogen (N) cycles and their complex responses to environmental changes have received increasing attention. However, large uncertainties in model predictions remain, partially due to the lack of explicit representation and parameterization of microbial processes. One great challenge is to effectively integrate rich microbial functional traits into ecosystem modeling for better predictions. Here, using soil enzymes as indicators of soil function, we developed a competitive dynamic enzyme allocation scheme and detailed enzyme-mediated soil inorganic N processes in the Microbial-ENzyme Decomposition (MEND) model. We conducted a rigorous calibration and validation of MEND with diverse soil C-N fluxes, microbial C:N ratios, and functional gene abundances from a 12-year CO2  × N grassland experiment (BioCON) in Minnesota, USA. In addition to accurately simulating soil CO2 fluxes and multiple N variables, the model correctly predicted microbial C:N ratios and their negative response to enriched N supply. Model validation further showed that, compared to the changes in simulated enzyme concentrations and decomposition rates, the changes in simulated activities of eight C-N-associated enzymes were better explained by the measured gene abundances in responses to elevated atmospheric CO2 concentration. Our results demonstrated that using enzymes as indicators of soil function and validating model predictions with functional gene abundances in ecosystem modeling can provide a basis for testing hypotheses about microbially mediated biogeochemical processes in response to environmental changes. Further development and applications of the modeling framework presented here will enable microbial ecologists to address ecosystem-level questions beyond empirical observations, toward more predictive understanding, an ultimate goal of microbial ecology.

Abstract Background The application of organic fertilizer is a sustainable approach to maintain soil fertility in agricultural crop production. In contrast to other organic fertilizers, the digestate from by-products of anaerobic digestion has not been well characterized in terms of its agronomic properties. In this study, different fertilization treatments were investigated to evaluate their impacts on growth, yield and fruit quality of tomatoes and on soil properties under greenhouse and field conditions. The experiments comprised a control (unfertilized) and three treatments with the same nitrogen dose: chemical fertilizer, digestate from by-product (organic fertilizer) and digestate combined with chemical fertilizer. Results The results showed that the application of digestate significantly increased the growth and fruit quality of tomato including height, stem diameter, leaf chlorophyll content index, and photosynthetic rate of tomato plant and sugar–acid ratio, protein content, and ascorbic acid content of the fruit. The nitrate contents in tomato fruit were lower in the digestate treatment and digestate combined with chemical fertilizer treatment than in the chemical fertilizer. The digestate combined with chemical fertilization resulted in the greatest increase in tomato yield, up to 26.29% and 10.78% higher than that in the chemical fertilizer treatment under field and greenhouse conditions, respectively. Moreover, fertilization with digestate treatment and digestate combined with chemical fertilizer treatment increased soil fertility, including soil nitrogen and carbon contents, and enhanced soil enzyme activities under both field and greenhouse conditions. In addition, the growth, yield, and fruit quality of tomato were significantly correlated with soil chemical characteristics and soil enzyme activities. Conclusions The effects of digestate treatments to maintain a stable tomato yield and improve fruit quality may be due to the enhanced soil enzymatic activities and chemical properties. These results suggest that the use of digestate as a full or partial replacement for chemical fertilizer could improve the growth and fruit quality of tomato, maintain the yield, and reduce the use of inorganic fertilizers in tomato production. Graphical Abstract

Rocky desertification is a devastating process in Karst areas of Southwest China and induces serious fragmentation in ecosystems. Therefore, vegetation restoration and the scientific evaluation of soil quality are key restorative strategies in these areas. In this study, a natural closed forest and a disturbed forest with three restoration models, including an evergreen broad-leaved forest, mixed forest, and deciduous forest, were investigated in Huanjiang County. More than nineteen soil properties (including physical, chemical, and biotic properties) were analyzed across treatments, and principal component analyses (PCA) were combined with a minimum data set (MDS) applied to evaluate the soil quality. Our study sought to identify a vegetation restoration model to improve the soil quality in this area. We demonstrated that soil physical and chemical properties, microbial biomass, and enzyme activities significantly differed across all of the models. Soil water content, capillary porosity, total porosity, organic carbon, total phosphorus, available phosphorus, and urease activity were high in the mixed forest, leading to better physical soil properties. Also, relatively high soil total nitrogen, total potassium, available nitrogen, available potassium, microbial biomass C and N, catalase, sucrose, and alkaline phosphatase levels were observed in the deciduous broad-leaved forest, resulting in improved soil chemical properties. Based on the minimum data set (MDS) method, six indicators, including non-capillary porosity, organic carbon, total phosphorus, pH, microbial biomass nitrogen, and urease activity, were selected to evaluate the soil quality across the models. Our data showed that, among the five models, the deciduous broad-leaved forest had the highest soil quality index (0.618), followed by the mixed forest (0.593). Stepwise regression analysis showed that soil organic carbon explained 79.9% of the variations in the soil quality indices, suggesting it was a major factor affecting the soil quality. Thus, vegetation restoration models mainly comprised of native tree species effectively improved the soil quality in Karst rocky desertification areas, with deciduous broad-leaved forests displaying the best effects, followed by mixed forests.

Fresh-cut leafy vegetables are produced in Southern Italy in very intensive crop systems under tunnel greenhouses in which continuous cropping has triggered soil organic carbon (SOC) depletion and the risk of degradation of soil fertility. A two-year trial of soil organic amendment was carried out on a private farm producing baby-leaf crops on a very poor OC soil (−1 as fresh matter without integration of mineral fertilizers. In our study, the SOC stock improved in the amended soils in a range of 4–6 Mg ha−1, except for dose 30 of buffalo manure, with the highest values where biowaste compost was applied. Our data showed an increase in biological parameters in all the amended soils with respect to Control. In soil amended with olive pomace, however, compost mineralization rates likely did not match crops’ nutrient needs so the yields of rocket were lower than with the biowaste compost and buffalo manure. Biowaste compost showed the best results as it balanced the best C conversion efficiency, the higher increment of SOC and yields of rocket.

Aviation mutagenesis is a breeding method for the rapid selection of superior plant varieties. In this study, rhizosphere soil chemical indexes, soil enzyme activities, and soil metabolites were measured in Dahongpao tea trees with aviation mutagenesis (TM) and without aviation mutagenesis (CK). The main soil metabolites distinguishing TM and CK and their relationships with soil chemical indexes and soil enzyme activities were analyzed and obtained. The results showed that there was no significant change in the rhizosphere soils’ pH of TM tea trees compared to CK (p = 0.91), while all other chemical indexes of TM were significantly higher than CK (p < 0.05). In addition, the activities of enzymes related to soil nutrient cycling such as urease, protease, sucrase, acid phosphatase and cellulase, and enzymes related to soil antioxidants such as superoxide dismutase, catalase, peroxidase, and polyphenol oxidase were significantly increased (p < 0.05) in the rhizosphere soils of TM tea trees compared to CK. Soil metabolite analysis showed that the main soil metabolites distinguishing CK from TM were carbohydrates, nitrogen compounds, and amines. Of these, carbohydrates and nitrogen compounds were significantly positively correlated with soil chemical indexes and soil enzymes, whereas amine was significantly negatively correlated with soil chemical indexes such as organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus; amine showed significant negative correlation with soil enzymes such as catalase, peroxidase, polyphenol oxidase, and urease. It can be seen that aviation mutagenesis is conducive to improving the ability of tea tree rhizosphere aggregation and transformation of soil nutrients, increasing the total amount of soil nutrients and the content of available nutrients, which is more conducive to promoting the uptake of nutrients by the tea tree, and thus promoting the growth of the tea tree.

Objectives: To slow down the chemical fixation of phosphate fertilizer, reduce the risk of active phosphorus leaching, stimulate the inherent phosphorus resource activity of soil, and improve phosphorus supply capacity. Methods: This study utilized a combination of field experiments and indoor chemical analysis. Six types of exogenous organic matter (fulvic acid, biochar, compound microbial fertilizer, high-energy microbial inoculum, pig manure-vermicompost, cow manure-vermicompost) were added based on conventional fertilization. The experiment was conducted under the wheat-maize rotation system in the Huang-Huai-Hai region. Results: Compared with control (CK) without exogenous organic matter (EOM), all the other treatments with EOM had an enhancing effect on the available phosphorus of the cultivated soil. During the maize harvest, the combined application of biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of available phosphorus in 0–20 cm soil by 45.87–56.59% compared with CK. The combined application of fulvic acid, biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of Ca2-P in 0–20 cm soil by 34.04–65.14%. The content of Ca10-P in each treatment with EOM exhibited a lower level compared to CK. EOM could slow down the fixation of phosphorus to some degree. Correlation analysis revealed significant associations between Ca2-P, Ca8-P, Al-P, Fe-P, neutral phosphatase activity, acid phosphatase activity, and the available phosphorus content in the soil. The combined application of fulvic acid, biochar, and cow manure-vermicompost could enhance the activity of neutral and acid phosphatase in topsoil to a certain extent, thereby facilitating the conversion of phosphorus into highly available Ca2-P. EOM could enhance the soil phosphorus availability and decelerate the conversion of soil phosphorus into O-P and Ca10-P forms with low availability. Among all treatments, biochar exhibited the most pronounced efficiency in mitigating phosphorus leaching downward. Conclusions: All the EOMs had the potential to enhance the conversion of phosphorus into soluble phosphorus (Ca2-P), thereby mitigating the chemical fixation of soil phosphorus and ameliorating non-point source pollution caused by phosphorus. EOM enhanced the activity of neutral and acid phosphatase, which was beneficial to the conversion of organic phosphorus to inorganic phosphorus and increasing the content of available phosphorus. All EOMs had good effects on the retention of soil effective phosphorus, among which biochar had the best effect on retaining effective phosphorus in the tillage layer and blocking phosphorus leaching downward.

Abstract Background In recent years, there have been several studies on the remediation of heavy metal pollution in soil by the application of biochar. However, little attention has been paid to understanding the effects and underlying mechanisms of biochar on soil carbon sequestration in manganese-contaminated farmlands. Therefore, in this study, bagasse biochar was applied to the soil in different proportions (0%, 0.5%, 2%, and 5%) and the test was conducted indoors for 100 days at a constant temperature. Soil physical and chemical properties, organic carbon mineralization, organic carbon components, and enzyme activities were analyzed in this study. Results In this study, when compared with the control, the application of 0.5%, 2%, and 5% bagasse biochar to the manganese-contaminated sugarcane field soil effectively reduced the cumulative CO2 emissions, i.e., decreased by 123.18 mg·kg−1, 208.28 mg·kg−1, and 287.79 mg·kg−1, respectively. Among the different treatment groups, the highest decrease in cumulative CO2 emissions was observed in the 5% bagasse biochar-treated soil when compared with the control. The application of bagasse biochar increased the soil microbial biomass carbon content by 12.72 mg·kg−1, 13.71 mg·kg−1, and 15.10 mg·kg−1, respectively when compared with the control. The soil nutrients and enzyme activities significantly increased with the increase in biochar application amount. Conclusions The application of bagasse biochar to manganese-contaminated sugarcane soil field effectively inhibited the mineralization of soil organic carbon, improved the carbon sequestration potential of manganese-contaminated sugarcane field soil, and provided a theoretical basis for the carbon sequestration mechanism in manganese-contaminated farmland soil. Graphical Abstract

Soil degradation is a major global concern due to its negative impact on soil quality and the sustainability of agricultural resources. The conservation agriculture (CA) approach, which includes three key principles such as zero tillage, retention of crop residue and crop rotation has gained widespread adoption to help mitigate the climate change effects on agricultural soils and meet the growing demand for increased production. Earthworm communities, along with microbial activity and diversity, are highly sensitive to tillage practices. Additionally, microbial activity and diversity quickly respond to different cropping systems, making them effective indicators for detecting short-term changes in soil functioning. We therefore, assess the effects of CA innovative approached after 6-years on biological and microbial diversity within earthworm cast in maize-wheat system (MWS). The treatments consist of PBM-RN0/ZTW-RN0 (permanent beds No-N control-both residues removed and wheat with zero tillage); PBM+RN0/ZTW+RN0 (permanent beds No-N control-both residues retained)-50% of maize stover and 25% of wheat residue retained; PBM-RN120/ZTW- RN120 (permanent beds with 120 kg N ha-1 both residues removed wheat with zero tillage); PBM+RN120/ZTW+RN120 (permanent beds with 120 kg N ha-1 both residues retained and wheat with zero tillage) and FBM-RN120/CTW-RN120 (fresh beds in maize/CT in wheat with 120 kg N ha-1 both residues removed). The result of present study showed that activities of carbon (C) cycle-related enzymes in the cast soils viz., dehydrogenase (DHA), β-glucosidase (β-glu), cellulase, and xylanase were significantly higher under PBM+RN120/ ZTW+RN120 than under PBM-RN0/ZTW-RN0. Specifically, the activities of these enzymes were 21.5, 26.8, and 76.5% higher under the PBM+RN120/ZTW+RN120 treatment, respectively. Moreover, the Alk-P activity was found to be 1.3 times higher in the PBM+RN120/ZTW+RN120 treatment than in the PBM-RN0/ZTW-RN0 treatment. The bacterial, fungal, and actinomycete counts in the cast soil ranged from 6.87 to 7.47 CFU (colony forming units) x 106 g-1 soil, 3.87–3.30 CFU x 104 g-1 soil, and 5.09–5.67 CFU x 104 g-1 soil, respectively. Total organic carbon (TOC) showed significant increases of 34.6% under PBM+RN120/ZTW+RN120 as compared to PBM-RN0/ZTW-RN0. The less labile C (Frac. 3), total carbohydrate carbon (TCHO), phenol oxidase (PHE) and peroxidase (PER) were observed as the sensitive indicators under different tillage, rate of nitrogen and residue management practices. This study suggests that permanent beds with crop residue retention with balance fertilization practices can be recommended and popularized to the overall improvement of soil biological pools within earthworm casts in MWS.

Abstract Rapeseed meal, a nutritious organic fertilizer (OF), contributes to improving soil environment and crop productivity. However, there are also problems, namely slow fertilizer efficiency and low nutrient utilization during the growing season. This 2‐year field trial was conducted to explore the effect of biochar addition on improving the nutrient availability of OF through a comparative study of various biochar application rates under rice‐rapeseed rotation conditions. The findings revealed that, compared to the individual application of chemical fertilizers (CF), OF alone decreased rice yield (2%/2%) and rapeseed yield (6%/10%) in 2019/2020. Compared with OF, combining biochar (15 t ha−1) with OF (OF + B15) significantly increased rice yield (17%/10%) and rapeseed yield (25%/20%) in the first/second year. Additionally, OF + B15 still increased rice yield (14%/7%) and rapeseed yield (12%/13%) for two consecutive years compared to CF. The co‐application of biochar and OF had positive impacts on soil physicochemical properties and enzymes. Compared to OF, OF + B15 elevated soil organic carbon (SOC) by 57%–81%, soil catalase 19%, invertase 14%–20%, urease 17%–19%, and phosphatase 13%–17% during rice season, and similarly increased SOC by 77%–90%, soil catalase 14%–16%, invertase 14%–20%, urease 18%–24%, and phosphatase 16%–17% in rapeseed season. Biochar addition improved soil conditions and enzymatic activities, and the available nutrient supply of OF. Also, the co‐application of biochar and rapeseed meal surpassed the effect of chemical fertilizer alone on the growth and yield of crops. Therefore, biochar coupling with organic fertilizer is an effective fertilization strategy based on resource recycling, which promotes both crop yield and sustainable agriculture.

Olive mill wastewater (OMW) is the effluent derived from the oil extraction processes from olives. Despite the polluting potential OMW can be a useful source of nutrients and organic compounds to improve soil properties. OMW could negatively affect soil and water quality as this waste is rich in phenolic compounds and has high COD and BOD5. Biochar-based treatment could be an efficient method to remediate OMW. In this study poplar biochar (BP) was more effective than conifer biochar (BC) in terms of adsorbing phenols and reducing phytotoxicity at different biochar rates (5 and 10 %). BP-treated OMW was used in soil amendment and induced an increase in chemical properties, especially in organic carbon after 30 days of incubation. In soil amended with 10 % BP-treated OMW microbial biomass, enzymatic activities, and cress seed germination were significantly enhanced after 30 and 90 days.

Aminopeptidases catalyze the hydrolysis of peptides into constituent amino acids and are therefore a key step in nitrogen (N) depolymerization and downstream mineralization. Differences in carbon (C):N as well as sulfur (S) content of amino acids present the possibility of amino acid-specific aminopeptidase activities revealing distinct information on N and non-N processes in soils. However, chromogenic assays of soil aminopeptidases using para-nitroaniline (pNA) substrates are underutilized and have largely focused on just two aminopeptidases to-date. We evaluated activities of eight amino acid-specific aminopeptidases using pNA substrates for arginine (ARG), glycine (GLY), alanine (ALA), lysine (LYS), glutamic acid (GLU), methionine (MET), proline (PRO) and leucine (LEU) aminopeptidases in a high-resolution sampling (30 samples per 0.01 ha−1 treatment plot) of nine 145-year treatment plots resulting from a factorial combination of three crop rotations and three fertility treatments on a Argiudoll in North Central United States. Across treatments, we identified non-detectable activities of ARG and PRO, and detectable activities of GLY, ALA, LYS, GLU, MET, and LEU ranging 0.2 to 400 nmol pNA h−1 g−1. Except for LYS and GLU activities, aminopeptidase activities were homogeneously distributed within treatments (n=30 locations per plot), and exhibited a mean coefficient of variation (CV) of 9 to 30 % and spatial range of 4.1 to 9.0 m. Activities of ALA and MET had the lowest CV and greatest contribution in explaining overall variability of aminopeptidase activities and were more sensitive to treatments compared to GLY and LEU activity. Multivariate analysis revealed a positive correlation among aminopeptidase activities, with major variation explained by β-glucosidase activity followed by pH and total N (TN). Absolute aminopeptidase activities generally reflected soil organic C (SOC) and TN concentrations, with greater activities under diverse rotation with organic fertilization (manure) and lower activities under continuous maize without fertilization. However, aminopeptidase activities normalized to SOC concentration were greater in soils without fertilization relative to organic fertilization. This study provides benchmark values of soil aminopeptidase activities assayed by pNA substrates using the world’s second oldest continuous agricultural experiment, including six aminopeptidases that have not been previously assayed with these substrates. Given their low magnitude of variability, high spatial correlation, and sensitivity to management, assays of aminopeptidase activities – particularly MET and ALA activities – could be fruitful tools for better understanding soil N cycling. Future work should evaluate assay optimization and expand to additional amino acid-specific substrates using pNA-based substrates.

Vermicomposting is an important strategy for restoring soil function and fertility. However, information on the effects of vermicompost application in intensive Pinelliaternata planting systems has rarely been reported. Here, we focus on the effects of different vermicompost levels and chemical fertilizer (CF) strategies on soil chemical properties, soil enzymes, and soil rhizosphere microbial communities (bacteria and fungi) in a field experiment. Compared to no added fertilizers (CK), vermicompost was more effective than the CF treatment in increasing P. ternata yield. We found that the 5 t ha−1 vermicompost treatment (VC2) significantly increased the tuber yield by 44.43% and 6.55% compared to the CK and CF treatment, respectively, and water-soluble exudates by 6.56% and 9.63% (P < 0.05). The vermicompost and CF treatments significantly increased the total phosphorus (TP), urease (Ure), and soil catalase (Cat) contents (P < 0.05). Compared to the vermicompost and CK treatments, the CF treatment significantly decreased soil organic carbon (SOC), C/N ratio, and soil acid phosphatase (Pac) (P < 0.05). Redundancy analysis (RDA) showed that Ure and total potassium (TK) were the major drivers in the bacterial community, whereas TP, total nitrogen (TN), Pac, and TK were the major drivers in the fungal community. We also found a positive correlation between soil enzyme activities, including between Ure and bacterial genera (Clostridium, Pseudoclavibacter, Stella, Hyphomicrobium, Mesorhizobium, and Adlercreutzia). In summary, vermicompost application promotes P. ternata soil microecosystems and improves soil fertility, soil enzyme activities, and rhizosphere microbial structure and function. Vermicomposting is a novel and promising approach to sustainable ecological cultivation of Chinese herbs via the promotion of soil properties and beneficial organisms. [ABSTRACT FROM AUTHOR]

Soil acidification is common in some Chinese tea plantations, which seriously affected growth of tea trees. Hence, it is essential to explore soil remediation in acidified tea plantations for sustainable development of the tea industry. We sought to determine how different fertilizers affect acidified soil and their N transformation in tea plantations.Different fertilizers were used on acidified tea plantation soils for 4 years (2017–2021), and changes in soil pH, indices related to soil N transformation and tea yield were analysed to construct interaction networks of these indices and find which had the largest influence on fertilization.Long‐term use of sheep manure reduced soil acidification, increased soil pH, enhanced the number and intensity of N‐fixing and ammonifying bacteria, urease, protease, asparaginase and N‐acetamide glucose ribosidase activity and nifH gene expression. This treatment reduced the number and intensity of soil nitrifying and denitrifying bacteria, nitrate reductase and nitrite reductase activity, while the expression of amoA‐AOA, nirK, nirS, narG and nosZ in turn increased ammonium N content of the soil, reduced nitrate N content, and enhanced tea yield. Topsis index weight analysis showed that ammonium N content in the soil had the largest impact among fertilization effects.Long‐term use of sheep manure was beneficial in restoring the balance of the micro‐ecosystem in acidified soil. This study provides an important practical basis for soil remediation and fertilizer management in acidified tea plantation soils. [ABSTRACT FROM AUTHOR]

Wood vinegar (WV) is a biostimulant and a biopesticide that contains pyroligneous acid and is used as a crop growth enhancer and biocontrol agent, but insufficient information exists on WV's effects on soil quality and cowpea production in Ghana. A field study (2 years) was conducted to determine the appropriate method of applying WV for soil health and cowpea production, and to determine the economic benefits of WV. Assessments were on nodulation, shoot biomass, yield, value–cost ratio, soil enzymes, soil respiration, microbial biomass nitrogen (MBN), permanganate-oxidizable carbon (POXC), mineralizable C, soil pH, available nitrogen and phosphorus. Results revealed soil drenching and foliar application are efficient methods of applying WV to achieve greater shoot dry matter, nodulation and grain yield of cowpea. Economically, soil drenching, followed by foliar application, generated better economic returns than the control. Adding WV to cowpea using soil drenching and foliar application improved soil health indicators. Soil enzymes and MBN were enhanced by WV applied foliarly and through soil drenching. Soil drenching with WV produced greater POXC and mineralizable C compared to the other treatments. Conclusively, WV applied foliarly and through soil drenching improved soil health, nodulation and yields of cowpea, and enhanced profitability. [ABSTRACT FROM AUTHOR]

Negative public sentiment built up around bisphenol A (BPA) follows growing awareness of the frequency of this chemical compound in the environment. The increase in air, water, and soil contamination by BPA has also generated the need to replace it with less toxic analogs, such as Bisphenol F (BPF) and Bisphenol S (BPS). However, due to the structural similarity of BPF and BPS to BPA, questions arise about the safety of their usage. The toxicity of BPA, BPF, and BPS towards humans and animals has been fairly well understood. The biodegradability potential of microorganisms towards each of these bisphenols is also widely recognized. However, the scale of their inhibitory pressure on soil microbiomes and soil enzyme activity has not been estimated. These parameters are extremely important in determining soil health, which in turn also influences plant growth and development. Therefore, in this manuscript, knowledge has been expanded and systematized regarding the differences in toxicity between BPA and its two analogs. In the context of the synthetic characterization of the effects of bisphenol permeation into the environment, the toxic impact of BPA, BPF, and BPS on the microbiological and biochemical parameters of soils was traced. The response of cultivated plants to their influence was also analyzed. [ABSTRACT FROM AUTHOR]

[ Objective]The effect of tillage depth on the physical and chemical properties, soil-related enzyme activities and ammonia oxidizing functional flora of tobacco-growing soil were studied to explore the effects of tillage measures and soil environmental factors on ammonia oxidation microbial change characteristics. [Method] Different tillage depths of 10 cm ( CK), 20 cm ( Sl ) and 30 cm ( S2) were set in Baoshan, Yunnan province, using a randomized block experimental design to explore the effects of different tillage depths on physicochemical properties, soil enzyme activities and ammonia oxidizing microorganisms of tobacco-planting soil in different soil layers. [Result] In the 0 - 20 cm soil layer, compared with CK, the soil bulk density of Sl and S2 treatment decreased significantly, the decrease rate was 5. 87%, 5. 10%, respectively; In the 0 - 20 and 20 - 40 cm soil layer, compared with CK, the contents of soil organic matter, nitrate nitrogen, and available potassium in the S2 treatment increased significantly, and the increase rates were 10. 68% and 11. 45%, 103. 26% and 159. 74%, 90. 59% and 103. 52%, respectively; In the 0 - 20 cm soil layer, compared with CK, soil nitrate nitrogen in the Sl, S2 treatments increased significantly, and the increase rate was 106. 42%, 103. 26%, respectively; In the 20 -40 cm soil layer, compared with CK, soil nitrate nitrogen in the S2 treatment increased significantly, and the increase rate was 28. 19% ; Compared with CK, the soil microbial carbon and urease activity in the S2 treatment were significantly reduced by 27. 77% and 36. 84%, respectively; The composition of the bacterial flora was the same under different tillage depths, and the proportions of each flora were slightly different Proteobacteria abundance in the AOB flora under the S2 treatment increased; Different tillage depth treatments changed the community abundance of ammonia oxidizing microorganisms AOA and AOB, among which NH4+ was the environmental factor that had the greatest impact on the AOA community structure, and organic matter was the environmental factor that had the greatest impact on the AOB community structure. [Conclusion] Deep planting is beneficial for improving soil physical structure, increasing soil nutrient content, and changing the AOA and AOB community structures. [ABSTRACT FROM AUTHOR]

Crop residue burning or removal from fields has detrimental impacts on crop productivity and soil quality due to decreased carbon (C) sustainability under intensive rice–wheat system (RWS). The conservation agriculture (CA) based on reduced tillage coupled with crop residue retention and raising leguminous green manure (GM) (Sesbania aculeata) during the intervening period between wheat harvest and rice establishment offers opportunities for the restoration of C sustainability. We studied the impacts of tillage intensity, crop residue management, and GM on soil organic C dynamics within the macro- and micro-aggregates after 6 years of RWS. Four main plot treatments in rice including combinations of wheat straw and GM were conventional till puddled transplanted rice with no wheat straw (CTRW0), CTR with 25% wheat stubbles retained (CTRW25), CTRW0 plus GM (CTRW0 + GM), and CTRW25 plus GM (CTRW25 + GM). Three sub-plot treatments in subsequent wheat were CT with rice straw removed (CTWR0), zero tillage with rice straw removed (ZTWR0), and the ZT with 100% rice straw retained as surface mulch (ZTWR100). The ZTWR100 significantly (p < 0.05) increased the soil moisture retention at field capacity (FC) (Ψm = 0.33bar) and available moisture content (AWC) (Ψm = 0.33–15 bar), compared with CTWR0. The ZTWR100 treatment also significantly increased the dehydrogenase (DHA), cellulase, and β-glucosidase activities by ~54, 56, and 45% and the easily extractable glomalin (EEG)- and total glomalin (TG)-related soil protein concentration by ~30.5 and 9.4%, respectively, compared with the CTWR0 treatment. The four C fractions of variable oxidizability increased significantly within both soil macro- and micro-aggregates under CTRW25 + GM and ZTWR100 over their respective control treatments (CTRW0 and CTWR0). Crop residue retention plus GM significantly improved the proportion of total water-stable aggregates (WSA), mean weight diameter (MWD), and aggregate ratio (AR), compared with the treatments involving residue removal and no GM. The principal component analysis (PCA) elucidated FC, TG in macro-aggregates, non-labile C in micro- and macro-aggregates, WSA, and the permanent wilting point (PWP) as the most dominant indicators for assessing soil quality under CA based sustainable practices in RWS. [ABSTRACT FROM AUTHOR]