Decreased Soil pH Research Articles

Intensive Citrus Cultivation Suppresses Soil Phosphorus Cycling Microbial Activity

Soil microbes are key drivers in regulating the phosphorus cycle. Elucidating the microbial mineralization process of soil phosphorus-solubilizing bacteria is of great significance for improving nutrient uptake and yield of crops. This study investigated the mechanism by which citrus cultivation affects the soil microbial acquisition strategy for phosphorus by measuring the abundance of the phoD gene, microbial community diversity and structure, and soil phosphorus fractions in the soils of citrus orchards and adjacent natural forests. The results showed that citrus cultivation could lead to a decrease in soil pH and an accumulation of available phosphorus in the soil, with a content as high as 112 mg·kg-1, which was significantly higher than that of natural forests (3.7 mg·kg-1). Citrus cultivation also affected the soil phosphorus fractions, with citrus soil having higher levels of soluble phosphorus (CaCl2-P), citrate-extractable phosphorus (Citrate-P), and mineral-bound phosphorus (HCl-P). The phosphorus fractions of natural forest soils were significantly lower than those of citrus soils, whereas the phoD gene abundance and alkaline phosphatase activity were significantly higher in natural forest soils than in citrus soils. High-throughput sequencing results showed that the Shannon diversity index of phosphate-solubilizing bacteria in citrus soils was 4.61, which was significantly lower than that of natural forests (5.35). The microbial community structure in natural forests was also different from that of citrus soils. In addition, the microbial community composition of phosphate-solubilizing bacteria in citrus soils was also different from that of natural forests, with the relative abundance of Proteobacteria being lower in natural forest soils than in citrus soils. Therefore, citrus cultivation led to a shift of soil microbial acquisition strategy for phosphorus, with external phosphorus addition being the main strategy in citrus soils, whereas microbial mineralization of organic phosphorus was the main strategy in natural forest soils to meet their growth requirements.

Green Manuring Enhances Soil Multifunctionality in Tobacco Field in Southwest China.

The use of green manure can substantially increase the microbial diversity and multifunctionality of soil. Green manuring practices are becoming popular for tobacco production in China. However, the influence of different green manures in tobacco fields has not yet been clarified. Here, smooth vetch (SV), hairy vetch (HV), broad bean (BB), common vetch (CV), rapeseed (RS), and radish (RD) were selected as green manures to investigate their impact on soil multifunctionality and evaluate their effects on enhancing soil quality for tobacco cultivation in southwest China. The biomass of tobacco was highest in the SV treatment. Soil pH declined, and soil organic matter (SOM), total nitrogen (TN), and dissolved organic carbon (DOC) content in CV and BB and activity of extracellular enzymes in SV and CV treatments were higher than those in other treatments. Fungal diversity declined in SV and CV but did not affect soil multifunctionality, indicating that bacterial communities contributed more to soil multifunctionality than fungal communities. The abundance of Firmicutes, Rhizobiales, and Micrococcales in SV and CV treatments increased and was negatively correlated with soil pH but positively correlated with soil multifunctionality, suggesting that the decrease in soil pH contributed to increases in the abundance of functional bacteria. In the bacteria-fungi co-occurrence network, the relative abundance of key ecological modules negatively correlated with soil multifunctionality and was low in SV, CV, BB, and RS treatments, and this was associated with reductions in soil pH and increases in the content of SOM and nitrate nitrogen (NO3--N). Overall, we found that SV and CV are more beneficial for soil multifunctionality, and this was driven by the decrease in soil pH and the increase in SOM, TN, NO3--N, and C- and N-cycling functional bacteria.

Biological mitigation of soil nitrous oxide emissions by plant metabolites.

Plant metabolites significantly affect soil nitrogen (N) cycling, but their influence on nitrous oxide (N2O) emissions has not been quantitatively analyzed on a global scale. We conduct a comprehensive meta-analysis of 173 observations from 42 articles to evaluate global patterns of and principal factors controlling N2O emissions in the presence of root exudates and extracts. Overall, plant metabolites promoted soil N2O emissions by about 10%. However, the effects of plant metabolites on N2O emissions from soils varied with experimental conditions and properties of both metabolites and soils. Primary metabolites, such as sugars, amino acids, and organic acids, strongly stimulated soil N2O emissions, by an average of 79%, while secondary metabolites, such as phenolics, terpenoids, and flavonoids, often characterized as both biological nitrification inhibitors (BNIs) and biological denitrification inhibitors (BDIs), reduced soil N2O emissions by an average of 41%. The emission mitigation effects of BNIs/BDIs were closely associated with soil texture and pH, increasing with increasing soil clay content and soil pH on acidic and neutral soils, and with decreasing soil pH on alkaline soils. We furthermore present soil incubation experiments that show that three secondary metabolite types act as BNIs to reduce N2O emissions by 32%-45%, while three primary metabolite classes possess a stimulatory effect of 56%-63%, confirming the results of the meta-analysis. Our results highlight the potential role and application range of specific secondary metabolites in biomitigation of global N2O emissions and provide new biological parameters for N2O emission models that should help improve the accuracy of model predictions.

Phosphorus Distribution within Aggregates in Long-Term Fertilized Black Soil: Regulatory Mechanisms of Soil Organic Matter and pH as Key Impact Factors

Understanding soil phosphorus (P) distribution and its key drivers is fundamental for sustainable P management. In this study, a 21-year fertilization experiment on black soil was carried out, setting up five fertilization treatments: unfertilized control (CK), nitrogen and potassium (NK), nitrogen, P and potassium (NPK), NPK plus straw (NPKS), and NPK plus manure (NPKM). The distribution and effecting factors of P pools within soil aggregates were investigated. Compared to CK, the NK and NPK treatments decreased calcium-associated P concentration in all aggregate fractions. Meanwhile, the NPK treatment significantly increased the organic P extracted from NaOH in unaggregated particles (<0.053 mm). This was mainly due to the reduction in soil pH. The NPKS and NPKM treatments increased almost all P forms in aggregates, especially Ca-P. For the NPKM treatment, inorganic P extracted from resin, NaHCO3, and NaOH increased as aggregate size increased. This was mainly because straw or manure addition promoted soil organic carbon (SOC) storage in aggregates, creating more sorption sites via association with amorphous metallic minerals, and, thus, facilitating P accumulation. In conclusion, decreasing soil pH by chemical fertilizers is an effective strategy for mobilizing soil P, whereas increasing SOC by straw or manure facilitates P accumulation.

Microorganisms facilitated the saline‐alkali soil remediation by biochar: Soil properties, microbial communities, and plant responses

AbstractSaline‐alkali soil degradation is a significant environmental problem with a negative impact on sustainable agroforestry development. Therefore, efficient remediation methods are urgently required. A potential solution to this problem is using biochar produced from bamboo waste and inoculated with plant growth‐promoting microbes as cleaner production materials for saline‐alkali soil. The present study investigated the potential of combining biochar, microbes, and dwarf bamboo to improve saline‐alkali soil. Different application rates (1%, 3%, and 5% of soil mass) of biochar were added to coastal saline soil planted with dwarf bamboo (Pleioblastus argenteastriatus) in pot experiments. Soil physicochemical properties, microbial communities, and plant responses were systematically studied. Bamboo and microbial‐modified biochar effectively decreased soil pH and electrical conductivity and increased soil nutrient contents. Compared with untreated soil, the relative abundance of the dominant bacterial phyla Acidobacteria, Actinobacteria, and Chloroflexi, and dominant fungal phyla Basidiomycota increased after applying biochar and modified biochar. With the increase in application concentration, the antioxidant activities of modified biochar decreased, biochar peroxidase and catalase content decreased, and the malondialdehyde content of bamboo biochar and microbial‐modified bamboo biochar decreased. The biomass of bamboo with added biochar and modified biochar was significantly higher than that of untreated soil. Comprehensive correlation and redundancy analyses showed that the bacterial and fungal communities were greatly affected by soil factors, especially soil pH, electrical conductivity, total organic carbon, potassium, and sodium ions. The findings of this study suggest that 5% bamboo biochar and 3% modified biochar benefit soil remediation, improve the stress resistance of dwarf bamboo, and enhance plant growth. Therefore, combined biochar–microbe remediation has great potential for the sustainable improvement of saline‐alkali soil.

Fertilizer application alters cadmium and selenium bioavailability in soil-rice system with high geological background levels

The co-occurrence of cadmium (Cd) pollution and selenium (Se) deficiency commonly exists in global soils, especially in China. As a result, there is great interest in developing practical agronomic strategies to simultaneously achieve Cd remediation and Se mobilization in paddy soils, thereby enhancing food quality/safety. To this end, we conducted a field-plot trial on soils having high geological background levels of Cd (0.67 mg kg−1) and Se (0.50 mg kg−1). We explored 12 contrasting fertilizers (urea, potassium sulfate (K2SO4), calcium-magnesium-phosphate (CMP)), amendments (manure and biochar) and their combinations on Cd/Se bioavailability. Soil pH, total organic carbon (TOC), soil available Cd/Se, Cd/Se fractions and Cd/Se accumulation in different rice components were determined. No significant differences existed in mean grain yield among treatments. Results showed that application of urea and K2SO4 decreased soil pH, whereas the CMP fertilizer and biochar treatments increased soil pH. There were no significant changes in TOC concentrations. Three treatments (CMP, manure, biochar) significantly decreased soil available Cd, whereas no treatment affected soil available Se at the maturity stage. Four treatments (CMP, manure, biochar and manure＋urea＋CMP＋K2SO4) achieved our dual goal of Cd reduction and Se enrichment in rice grain. Structural equation modeling (SEM) demonstrated that soil available Cd and root Cd were negatively affected by pH and organic matter (OM), whereas soil available Se was positively affected by pH. Moreover, redundancy analysis (RDA) showed strong positive correlations between soil available Cd, exchangeable Cd and reducible Cd with grain Cd concentration, as well as between pH and soil available Se with grain Se concentration. Further, there was a strong negative correlation between residual Cd/Se (non-available fraction) and grain Cd/Se concentrations. Overall, this study identified the primary factors affecting Cd/Se bioavailability, thereby providing new guidance for achieving safe production of Se-enriched rice through fertilizer/amendment management of Cd-enriched soils.

Fertility and heavy metal pollution in silage maize soil irrigated with different levels of recycled wastewater under conventional and no-tillage practices

AbstractIrrigation with recycled domestic wastewater has been known to obtain positive effects on improving soil fertility, but it may also become a risk factor in case of causing an increase in soil salinity and/or heavy metal concentration of soil. No-tillage can retain soil moisture, helping to reduce irrigation water necessity, and thus lower amounts of heavy metals and salts are added to soil under wastewater irrigation conditions. The objective of this study was to analyze the effects of wastewater irrigation at different levels of on silage maize cultivation under conventional tillage and no-tillage conditions by comparing to full irrigation with fresh water. The two-year experiment was planned according to the split-plots design in the random blocks with three replications. The results indicated that full irrigation with wastewater increased soil salinity, organic matter content, total nitrogen, plant available phosphous, exchangeable cations, exchangeable sodium percentage and soil essential and non-essential heavy metal contents, but decreased soil pH and lime content. Increasing rates in organic matter content, total nitrogen, plant available phosphorus and exchangeable potassium were higher, but in electrical conductivity, and heavy metal accumulation were lower in soil under no-tillage as compared to conventional tillage. Contamination and enrichment factors and geographic accumulation index showed that non-essential heavy metal contamination due to cadmium and nickel, increased in full irrigation with wastewater. Irrigation with wastewater also increased heavy metal accumulation in silage maize. No-tillage can be a recommendable water management practice considering that the risks of soil salinity and heavy metal accumulation can be reduced and that soil fertility can be increased. Also, in reducing the risk of accumulation of cadmium and nickel in soil, 33% deficit irrigation with wastewater can make no-tillage more available.

How do green manure management practices affect ammonia emissions from maize fields?

The use of “green manure”—crops that are cultivated specifically to be incorporated into the soil to increase its organic matter content—has been proposed as an alternative to chemical fertilizer because of its benefits in terms of crop yield. Nonetheless, the differential impacts of green manure on ammonia volatilization remains underexplored. In this study, the influence of various green manure management strategies on ammonia volatilization in maize cultivation were examined. Field experiments conducted from 2020 to 2022, the field experiment applied common vetch after the spring wheat harvest, with five distinct treatments: conventional tillage without green manures as a control (CT); tillage with total green manure incorporation (TG); no-tillage with total green manure mulching (NTG); tillage with only root incorporation (T); and no-tillage with removal of aboveground green manure (NT). The results showed that under TG and NTG, the maize yields were 12.3%-33.2% higher than under CT, and 6.8%-18.8% higher than under T and NT. Compared with CT, all four green manure management practices also significantly increased NH3 emissions in maize fields, and they increased ammonia volatilization by 12.0%-13.7% in NTG and TG compared to root retention patterns, with NTG exhibiting higher rates than TG. NTG significantly increased soil organic matter, total nitrogen, mineral nitrogen, water-filled pore space (WFPS), microbial biomass carbon and nitrogen, and C: N, and it decreased soil pH compared to TG. Regression analysis showed that these factors were correlated with NH3 volatilization. In addition, soil urease and ammonia-oxidation functional genes (amoA) showed differences under green manure management practices. Structural equation modeling showed that NH4+-N had the greatest positive impact on NH3, and urease activity and total nitrogen had positive effects on NH4+-N. Furthermore, microbial biomass carbon and pH had positive and negative effects on urease activity, respectively, both of which were only related to SOM. At the same time, WFPS had a positive impact on total nitrogen. In summary, no-tillage with total green manure mulching increases maize yield but also increases NH3 emissions. NH4+-N formed by the hydrolysis of urea by soil urease and the conversion of total nitrogen were found to be the main reasons for high NH3 emissions. In addition, SOM can promote urease activity, increase NH4+-N content and NH3 volatilization by increasing MBC and decreasing soil pH.

Enhancing Soil Health and Sustainability: The Impact of Melia Dubia-based Agroforestry in a Semi-Arid Region of Haryana, India

This study investigates the impact of a Melia dubia-based agroforestry system on soil properties in Gillan Khera, Fatehabad district, located in the semi-arid region of Haryana. Soil samples were collected from a 7-year-old plantation with a 3m × 3m spacing, where three oat varieties were intercropped. Parameters such as pH, electrical conductivity (EC), organic carbon, soil moisture, and available nitrogen, phosphorus, and potassium were analysed at depths of 0-15 cm and 15-30 cm. Results revealed a decrease in soil pH and EC under trees, with values decreasing from 8.09 to 7.89 and 0.46 to 0.44 dSm-1, respectively. However, intercropped conditions exhibited higher levels of nitrogen (131.38 kg/ha), phosphorus (16.00 kg/ha), potassium (301.10 kg/ha), and organic carbon (0.46%) at both soil depths. Additionally, there was more soil moisture under the plantation. These findings suggest a positive correlation between tree growth and soil health. The study recommends the Melia dubia-based agroforestry system as a promising approach for enhancing soil fertility and promoting environmental sustainability.

Nitrification-induced acidity controls CO2 emission from soil carbonates

Nitrification acidifies soil, and the produced H+ are neutralized by inorganic carbon (C) in soil leading to irreversible CO2 emissions. CO2 released by nitrogen (N) fertilizer-induced acidification is partitioned between solid (CaCO3 re-precipitation), liquid (dissolved HCO3− and CO32−) and gaseous (CO2) phases. Therefore, quantifying the effects of N fertilization on CO2 emissions from soil inorganic C is an enormous challenge. 14C-labeled CaCO3 was used as a model inorganic C to trace the released CO2 caused by acidification by five fertilizers: chicken manure, urea, KNO3, NH4NO3, and (NH4)2SO4 added at three N rates. Cropland soil was homogenously mixed with Ca14CO3 powder and fertilizers, and the emitted CO2 was trapped in NaOH solution to determine total CO2 and 14CO2 efflux originated from inorganic C. Fertilization, particularly ammonium-based fertilizers ((NH4)2SO4, NH4NO3), strongly decreased soil pH by 0.35 units over 40 days. All fertilizers except KNO3 increased total CO2 emissions by 21%–490% compared to the unfertilized control soil. The fertilization effects on cumulative 14CO2 emission induced by CaCO3 neutralization, corresponded to acidification and decreased in the order (NH4)2SO4 > NH4NO3 > urea > KNO3 > chicken manure. Ammonium-based fertilizers induced the strongest CO2 emissions originated from inorganic C, emitting 1.6–4.5 times more 14CO2 than non-fertilized soils during the first nine days. The total CO2 emissions from SIC were proportional to the fertilizer dose applied. Therefore, we conclude that both the choice of N fertilizers and their application rates need to be considered to control CO2 emissions originated from inorganic C. The soil inorganic C losses should be prevented not only because of their irreversible contribution to atmospheric CO2, but also to safeguard ecosystem services of CaCO3, such as organic matter preservation, soil structure stabilization, and C sequestration.

Nutrient retention after crop harvest in a typic hapludults amended with biochar types under no-tillage system

The utilization of biochar’s as soil amendments for enhancing nutrient retention in subsoils present potential limitations. To address this issue, we conducted a greenhouse experiment to assess the effects of various biochar’s derived from animal manures (swine manure, poultry litter, cattle manure) and plant residues (rice straw, soybean straw, corn straw) when applied to surface of an acidic soil. Our study focused on wheat crops under a no-tillage system, with a subsequent evaluation of the residual impacts on soybeans. The experimental design involved the application of biochar’s at different rates i.e. 10 and 20 Mg ha−1, followed by the assessment of their influence on NPK levels, pH, and exchangeable Al in stratified soil layers (0–5, 5–10, 10–15, and 15–25 cm). Furthermore, we investigated the interplay between biochar doses and the application of nitrogen (N) in the top 5 cm of soil, specifically examining NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NO}}_{{3}}^{ - }$$\\end{document}, NH4+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NH}}_{{4}}^{ + }$$\\end{document}, P and K levels. Our findings revealed that in the top 5 cm of soil, biochar doses and N application significantly affected NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NO}}_{{3}}^{ - }$$\\end{document}, NH4+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{NH}}_{{4}}^{ + }$$\\end{document}, P and K concentrations. However, in deeper soil layers, no significant differences were observed among biochar doses with or without N application. Interestingly, K levels were impacted throughout all soil depths, regardless of the presence or absence of N application. Moreover, biochar application up to a 5 cm depth induced favorable changes in soil pH and reduced exchangeable Al. In contrast, deeper layers experienced a decrease in soil pH and an increase in exchangeable Al following biochar treatment. In conclusion, our study demonstrates that biochar’s can effectively retain NPK nutrients, enhance soil pH, and decrease exchangeable Al, independent of the type and dosage of application under a no-tillage system. Nonetheless, the efficacy of biochar amendments may vary with soil depth and type of nutrient, warranting careful consideration for maximizing their benefits in sustainable agricultural practices.

Effect of Humic Acid Fertilizer on Mercury Release from Greenhouse Soils

The elemental mercury (Hg0) release characteristics from the Hg-contaminated soil applied with Humic acid fertilizer (HAF) in the greenhouse were identified. The adsorption features of mercuric ion (Hg2+) on HAF under different reaction times and pH were investigated to elucidate the influencing mechanism of HAF on soil Hg0 release. Besides, the microstructure of HAF loading with Hg2+ was characterized by using Fourier transform infrared spectroscopy (FTIR) and scanning electron micrograph-energy dispersive spectrometry–EDS). The results showed that with the increasing HAF dosage, soil oxidation-reduction potential (Eh), and organic matter (SOM) content, as well as the decreasing soil pH, the soil Hg0 release fluxes showed a decreasing tendency. The soil pH, Eh, SOM, and total Hg content are the key factors that can affect the soil Hg0 release fluxes. The interior air temperature, light intensity, soil moisture, and soil temperature have little impact on soil Hg0 release fluxes when the greenhouse soil is applied with HAF. The HAF can immobilize Hg2+ and reduce its activity by surface precipitation and specific adsorption, then affecting the soil Hg0 release fluxes. The results of this study provide a basis for the application of HAF to reduce soil Hg0 release fluxes in the greenhouse of Hg-contaminated areas.

Effects of thiobacillus bacteria on physiology and vegetative growth of pomegranate

The climate change and consequent degradation of soil and water resources have led to difficult conditions for farmers; thus, they should make intelligent decisions to face these statuses. Managing soil nutrient and mineral uptake by plants and its feasibility under harsh environment must be considered. Therefore, the present research was conducted to investigate the response of pomegranate variety Shishe Kab to Thiobacillus bacteria (B) and sulfur (S) fertilization. Treatments included sulfur fertilization (three levels: 0, 500 and 1000 g−1 tree) and inoculation with Thiobacillus bacteria (two levels: inoculated and non-inoculated). Totally, sulfur fertilization and inoculation with bacteria improved physiological and biochemical aspects and fruit production of pomegranate. Supplying S decreased soil pH, which the lowest value (5.2) was recorded in 500 g S tree−1 when accompanied with bacteria. Soil electrolyte leakage (EL) increased, when sulfur incorporated or when bacteria added to the soil. The interactive effects of B × S was significant on fruit diameter and weight, chlorophyll (Chl), carotenoid and potassium content, which were improved, although non-inoculated plants also showed high values of potassium content. Anthocyanin and total carbohydrate improved when bacteria inoculation was done; however, total acidity (TA) and total soluble solids (TSS) showed a significant decrease. The EL variable significantly decreased and tissue water content increased in this experiment, when inoculation or sulfur fertilization was used. The results obtained from present study emphasized on the necessity of using sulfur and Thiobacillus bacteria in increasing growth and yield and also chilling tolerance of pomegranate trees.

Pengaruh Kombinasi Pupuk Kandang Ayam dan Ekstrak Kompos Ampas Kopi terhadap Sifat Kimia Tanah Ultisol

Ultisol has problems such as soil acidity <5.5, high Al saturation >42%, low organic matter <1.15%, low nutrients such as 0.14% N, P 5.80 ppm, and low base saturation < 35%. Chicken manure is an organic material that alters soil pH and increases total N, total P, and P uptake. Coffee grounds can increase pH, N nutrients, organic matter, available P, prevent fungal growth. The purpose of this study was to determine the effects of feeding chicken manure and coffee grounds compost extract in increasing pH, increasing N availability, decreasing exchangeable Al, and increasing P availability of Ultisol. The research method used was a one-factor Completely Randomized Design (CRD). Factors tested were chicken manure, coffee grounds compost extract, and a combination of the two up to five treatments. K0 = Control, no chicken manure and coffee grounds compost extract; K1 = Coffee grounds compost extract 4 kL ha-1; K2 = Chicken manure 2 tons ha-1; K3 = Chicken manure 2 tons ha-1 + coffee grounds compost extract 4 kL ha-1; K4 = Chicken manure 4 tons ha-1 + coffee grounds compost extract 8 kL ha-1. Each treatment was replicated four times for 20 experiments. The results showed that the application of chicken manure and coffee grounds compost extract decreased soil pH, and soil exchangeable Al and increased soil ammonium, nitrate and available P levels.

Nitrogen deposition suppresses soil respiration by reducing global belowground activity

Soil respiration (Rs) indicates below-ground biological activities. Previous studies have suggested that higher nitrogen (N) deposition due to human activities exerts an increasingly negative effect on Rs. However, the mechanisms underlying this negative effect remain highly uncertain on a global scale. Using a global dataset of 262 N addition experiments, here we show the overall N addition effects on Rs changed from positive to negative with increasing N addition rate and duration. By constructing a structural equation model (SEM) that explained 41 % variation in the responses of Rs to N addition, we revealed that Rs under increasing N addition was simultaneously associated with decreases in soil pH, root biomass and microbial biomass, with the strongest influence by root biomass. Decreasing soil pH had cascading effects on root and microbial biomass, while N-addition-induced root biomass reduction further manifested a decrease in microbial biomass. Across global variations in the environment, lower background soil pH amplified the negative impacts of N addition on root and microbial biomass, which consequently exhilarated the negative impact of high N on Rs. Our results highlight that predicting the response of belowground biological activities to global changes is complex with the essence of integrative understanding for the multivariate pathways through soil physical properties, plants and microorganisms.

Evaluation of Organic Sources and Mineral N Fertilizer on Soil Fertility and Coriander Plant (Coriandrum sativum L.) Productivity and Quality under Saline Soil

Two field experiments were carried out at Gelbana, North Sina government during successive winters 2021/2022 and 2022/ 2023 to study the evaluation of organic sources (compost, biochar, and organic farm) combined with or without mineral N different rates on soil fertility and Coriander productivity. Lies coast of Sinai, between 32o_ 350 and 32o_ 450 E and 31o_ 000 and 31o_ 250 N. Lies in the north-western Mediterranean coast of Sinai, between 32o_ 350 and 32o_ 450 E and 31o_ 000 and 31o_ 250 N. Each experiment was carried out in a split-plot design with three replicates in both seasons. Results showed that applying compost combined with or without mineral N fertilizer at different rates improved soil fertility (decreased soil pH, soil salinity, and increase of available macronutrients and micronutrient contents in soil) compared with other treatments. Also, the maximum mean values of Plant height (cm); No. of branches /plant; the weight of seeds /plant (g); the weight of seeds yield (ton/fed), fresh green leaves (ton/fed), and dry yield leaves (ton/fed) for soil treated with compost combined with mineral fertilizer different rate, while the weight of 1000 (g) seeds as affected by organic farm combined with mineral N fertilizer rate. The highest values of N, P, K, Fe, Mn, and Zn concentrations in seeds were treating with compost combined with mineral N fertilizer at a 100 kg N /fed rate than other treatments. As well as, the application of compost combined with mineral N fertilizer at different rates was an increase in protein (%), oil (%), and carbohydrate (%). chlorophyll while the proline was decrease value.

Impact of simulated acid rain on chemical properties of Nyalau series soil and its leachate

Greenhouse gases can cause acid rain, which in turn degrades soil chemical properties. This research was conducted to determine the effects of simulated acid rain (SAR) on the chemical properties of Nyalau series (Typic paleudults). A 45-day laboratory leaching and incubation study (control conditions) was conducted following standard procedures include preparing simulated acid rain with specific pH levels, followed by experimental design/plan and systematically analyzing both soil and leachate for chemical changes over the 45-day period. Six treatments five of which were SAR (pH 3.5, 4.0, 4.5, 5.0, and 5.5) and one control referred to as natural rainwater (pH 6.0) were evaluated. From the study, the SAR had significant effects on the chemical properties of the soil and its leachate. The pH of 3.5 of SAR treatments decreased soil pH, K+, and fertility index. In contrast, the contents of Mg2+, Na+, SO42−, NO3−, and acidity were higher at the lower SAR pH. Furthermore, K+ and Mg2+ in the leachate significantly increased with increasing acidity of the SAR. The changes in Ca2+ and NH4+ between the soil and its leachate were positively correlated (r = 0.84 and 0.86), whereas the changes in NO3− negatively correlated (r = − 0.82). The novelty of these results lies in the discovery of significant alterations in soil chemistry due to simulated acid rain (SAR), particularly impacting soil fertility and nutrient availability, with notable positive and negative correlations among specific ions where prolonged exposure to acid rain could negatively affect the moderately tolerant to acidic and nutrient-poor soils. Acid rain can negatively affect soil fertility and the general soils ecosystem functions. Long-term field studies are required to consolidate the findings of this present study in order to reveal the sustained impact of SAR on tropical forest ecosystems, particularly concerning soil health, plant tolerance, and potential shifts in biodiversity and ecological balance.

Impact of cellulose and lignin on restoration of vegetation and soil chemical properties for saline-alkali soil of songnen plain.

To explore the effects of cellulose and lignin on stimulating vegetation restoration and improving soil chemical properties in saline-alkali soil, a large area test was carried out, and 2 treatments were set up: T (cellulose and lignin+ Planted seeds) and CK (Planted seeds). In this study, the species, quantity, plant height, above-ground biomass, biodiversity of vegetation in the treated plots, the determination of soil chemical nutrient content, and the effect of cellulose and lignin on vegetation restoration in saline-alkali land were investigated. The results showed that: 1) Cellulose and lignin contributed to vegetation growth. Compared with CK treatment, plant height and aboveground biomass of T increased by 158.73% and 240.13%, respectively; 2) Cellulose and lignin improved soil structure, and soil porosity, and decreased soil compaction (21.95%); 3) Compared with CK treatment, T treatment decreased soil pH by 0.5 units, total salt content decreased by 30.95%, exchangeable Na+ decreased by 63.00%, and exchangeable sodium percentage (ESP) decreased by 61.51%. Furthermore, cellulose and lignin effectively improved the physical and chemical properties of saline-alkali soil, promoted the recovery of ecological environment in saline-alkali soil, and improved regional biodiversity, which will provide new methods for soil remediation and improvement in saline-alkali areas.

The impact of high-temperature treatments on maize growth parameters and soil nutrients: A comprehensive evaluation through principal component analysis.

In contrast to prolonged exposure to high temperatures, investigating short-term high-temperature stress can provide insights into the impact of varying heat stress durations on plant development and soil nutrient dynamics, which is crucial for advancing ecological agriculture. In this study, five heating temperatures were set at 200°C, 250°C, 300°C, 350°C, and 400°C, along with five heating time gradients of 6s, 10s, 14s, 18s, and 20s, including a control. A total of 26 treatment groups were analyzed, focusing on maize growth parameters and soil indicators. Principal component analysis was used for comprehensive evaluation. The results showed that high-temperature treatments with different heating times significantly influenced maize growth and soil properties. For instance, the treatment of 300°C+6s resulted in the longest total root length, while 200°C+6s led to the highest average root diameter. Plant height and leaf length were notably increased with the treatment of 400°C+6s. Most treatments resulted in decreased soil pH and organic matter content. Notably, the treatment of 350°C+16s showed the highest available phosphorus content, reaching 24.0 mg/kg, an increase of 4.5 mg/kg compared to the control. The study found that the average levels of active organic carbon and peroxidase were 1.26 mg/g and 3.91 mg/g, respectively. Additionally, the average mass fractions of clay, silt, and sand particles were 8.99%, 66.75%, and 24.26%, respectively. Through principal component analysis, six principal components were able to extract 19 indicators from the 26 treatments, covering 86.129% of the information. It was observed that 16 treatment methods performed better than the control in terms of soil comprehensive quality. The optimal treatment temperature and time identified for improving soil physicochemical properties and crop growth were 300°C+6s. These findings can be used to guide agricultural management and soil improvement practices, ultimately enhancing field productivity and providing valuable insights for sustainable agricultural development.

Investigating ecosystem resiliency in different flood zones of south Brooklyn, New York

With climate change and rising sea levels, south Brooklyn is exposed to massive flooding and intense precipitation. Previous research discovered that flooding shifts plant species distribution, decreases soil pH, and increases salt concentration, nitrogen, phosphorus, and potassium levels. We predicted a decreasing trend from Zone 1 to 6: high-pH, high-salt, and high-nutrients in more flood-prone areas to low-pH, low-salt, and low-nutrient in less flood-prone regions. We performed DNA barcoding to identify plant species inhabiting flood zones with expectations of decreasing salt tolerance and moisture uptake by plants' soil from Zones 1-6. Furthermore, we predicted an increase in invasive species, ultimately resulting in a decrease in biodiversity. After barcoding, we researched existing information regarding invasiveness, ideal soil, pH tolerance, and salt tolerance. We performed soil analyses to identify pH, nitrogen (N), phosphorus (P), and potassium (K) levels. For N and P levels, we discovered a general decreasing trend from Zone 1 to 6 with low and moderate statistical significance respectively. Previous studies found that soil moisture can increase N and P uptake, helping plants adopt efficient resource-use strategies and reduce water stress from flooding. Although characteristics of plants were distributed throughout all zones, demonstrating overall diversity, the soil analyses hinted at the possibility of a rising trend of plants adapting to the increase in flooding. Future expansive research is needed to comprehensively map these trends. Ultimately, investigating trends between flood zones and the prevalence of different species will assist in guiding solutions to weathering climate change and protecting biodiversity in Brooklyn.