Search

The spatial heterogeneity of potentially toxic elements (PTEs) in a typical green tea-producing area in Zhejiang was investigated with application of geostatistics. The positive matrix factorization (PMF) was conducted for analysis of pollution sources and risk assessment of the soil of the tea garden. The results revealed that 93.52% of the study area did not exceed the PTEs risk screening value in the soil pollution risk control standard of agricultural land. The results of the spatial heterogeneity analysis showed that Cd and Pb had moderate spatial auto-correlation, exhibiting similar spatial distribution patterns. The high-value locations were distributed in the southeast of the study area, while low-value locations were distributed in the southwest of the study area. The Cr, As, and Hg had strong spatial auto-correlation, while Cr and As had similar spatial distribution patterns whose high-value areas and low-value areas were concentrated in the west and center of the study area, respectively. The Cd, Pb, and As originated from the agricultural source, transportation source, and industrial source, respectively, while Cr and Hg were from the natural source on the basis of the results of the PMF model. The results of a potential ecological risk assessment revealed that five PTEs in the study area were of low potential risk. The single-factor ecological risk ranking was Cd > As > Hg > Cr > Pb. The overall ecological risk in the study area was slight. The human health risk model indicates that there was a non-carcinogenic risk for children in the study area, and the high-value area was concentrated in the northwest of the study area. It is concluded that emphasis shall be given to excessive Cd caused by agricultural sources in the southeast of the study area, and control and monitoring will be strengthened in the northwestern part of the study area. The relevant measures for prevention of soil pollution must be conducted. [ABSTRACT FROM AUTHOR]

Lushan Yunwu tea quality is limited by soil acidity and sterility. This article examined a 3-year localization experiment at 1100 m altitude to demonstrate the sustainable management of conditioners, calcium magnesium phosphate (P), rapeseed cake (C), and combination application (P + C) by one-time application on the soil-tea system in Mount Lushan. The study found that conditioners (P, C, P + C) reduced soil acidification and maintained a pH of 4.75–5.34, ideal for tea tree development for 3 years. Phosphorus activation coefficient (PAC), nitrogen activation coefficient (NAC), and organic matter (OM) content were significantly higher (P < 0.05) in the first year after conditioner treatment, with P + C being the best. After P + C, PAC, NAC, and OM rose by 31.25%, 47.70%, and 10.06 g kg−1 compared to CK. In comparison to the CK, tea's hundred-bud weight (BW), free amino acids (AA), tea polyphenols (TPC), and chlorophyll (Chl) content of P + C treatment got 29.98%, 14.41%, 22.49%, and 28.85% increase compared to that of the CK, respectively. In the second year, the three treatments of P, C and P + C still had significant moderating effects on the physicochemical properties of the soil and the quality indexes of the tea leaves. The PAC of the soil under the three treatments increased by 0.06%, 0.07% and 0.18%, respectively, as compared to the control.P + C increased BW, AA, TPC and Chl of tea for 2 years. Three conditioners had 2-year regulatory impacts on soil fertility indicators, tea output, and quality. C and P + C both increased soil OM by 18.59% and 21.78% compared to CK in the third year, outperforming P treatment. Redundancy analysis revealed that the primary physicochemical factors influencing tea output and quality were soil OM and pH, with available phosphorus, urease, acid phosphatase, and available nitrogen following closely afterwards. [ABSTRACT FROM AUTHOR]

The issue of soil acidification in tea plantations has become a critical concern due to its potential impact on tea quality and plant health. Understanding the factors contributing to soil acidification is essential for implementing effective soil management strategies in tea-growing regions. In this study, a field study was conducted to investigate the effects of tea plantations on soil acidification and the associated acid–base buffering capacity (pHBC). We assessed acidification, pHBC, nutrient concentrations, and cation contents in the top 0–20 cm layer of soil across forty tea gardens of varying stand ages (0–5, 5–10, 10–20, and 20–40 years old) in Anji County, Zhejiang Province, China. The results revealed evident soil acidification due to tea plantation activities, with the lowest soil pH observed in tea gardens aged 10–20 and 20–40 years. Higher levels of soil organic matter (SOM), total nitrogen (TN), Olsen phosphorus (Olsen-P), available iron (Fe), and exchangeable hydrogen (H+) were notably recorded in 10–20 and 20–40 years old tea garden soils, suggesting an increased risk of soil acidification with prolonged tea cultivation. Furthermore, prolonged tea cultivation correlated with increased pHBC, which amplified with tea stand ages. The investigation of the relationship between soil pHBC and various parameters highlighted significant influences from soil pH, SOM, cation exchange capacity, TN, available potassium, Olsen-P, exchangeable acids (including H+ and aluminum), available Fe, and available zinc. Consequently, these findings underscore a substantial risk of soil acidification in tea gardens within the monitored region, with SOM and TN content being key driving factors influencing pHBC. [ABSTRACT FROM AUTHOR]

The spatial heterogeneity of potentially toxic elements (PTEs) in a typical green tea-producing area in Zhejiang was investigated with application of geostatistics. The positive matrix factorization (PMF) was conducted for analysis of pollution sources and risk assessment of the soil of the tea garden. The results revealed that 93.52% of the study area did not exceed the PTEs risk screening value in the soil pollution risk control standard of agricultural land. The results of the spatial heterogeneity analysis showed that Cd and Pb had moderate spatial auto-correlation, exhibiting similar spatial distribution patterns. The high-value locations were distributed in the southeast of the study area, while low-value locations were distributed in the southwest of the study area. The Cr, As, and Hg had strong spatial auto-correlation, while Cr and As had similar spatial distribution patterns whose high-value areas and low-value areas were concentrated in the west and center of the study area, respectively. The Cd, Pb, and As originated from the agricultural source, transportation source, and industrial source, respectively, while Cr and Hg were from the natural source on the basis of the results of the PMF model. The results of a potential ecological risk assessment revealed that five PTEs in the study area were of low potential risk. The single-factor ecological risk ranking was Cd > As > Hg > Cr > Pb. The overall ecological risk in the study area was slight. The human health risk model indicates that there was a non-carcinogenic risk for children in the study area, and the high-value area was concentrated in the northwest of the study area. It is concluded that emphasis shall be given to excessive Cd caused by agricultural sources in the southeast of the study area, and control and monitoring will be strengthened in the northwestern part of the study area. The relevant measures for prevention of soil pollution must be conducted.

Selenium (Se)-enriched tea is a well-regarded natural beverage that is often consumed for its Se supplementation benefits. However, the production of this tea, particularly in Se-abundant tea plantations, is challenging due to soil acidification. Therefore, this study aimed to investigate the effects of changes in Se under acidified soil conditions. Eight tea plantation soil monitoring sites in Southern Jiangsu were first selected. Simulated acid rain experiments and experiments with different acidification methods were designed and soil pH, as well as various Al-ion and Se-ion concentrations were systematically determined. The data were analyzed using R statistical software, and a correlation analysis was carried out. The results indicated that as the pH value dropped, exchangeable selenium (Exc-Se) and residual selenium (Res-Se) were transformed into acid-soluble selenium (Fmo-Se) and manganese oxide selenium (Om-Se). As the pH increased, exchange state aluminum (Alex) and water-soluble aluminum (Alw) decreased, Fmo-Se and Om-Se declined, and Exc-Se and Res-Se increased, a phenomenon attributed to the weakened substitution of Se ions by Al ions. In the simulated acid rain experiment, P1 compared to the control (CK), the pH value of the YJW tea plantation decreased by 0.13, Exc-Se decreased by 4 ug mg−1, Res-Se decreased by 54.65 ug kg−1, Fmo-Se increased by 2.78 ug mg−1, and Om-Se increased by 5.94 ug mg−1 while Alex increased by 28.53 mg kg−1. The decrease in pH led to an increase in the content of Alex and Alw, which further resulted in the conversion of Exc-Se to Fmo-Se and Om-Se. In various acidification experiments, compared with CK, the pH value of T6 decreased by 0.23, Exc-Se content decreased by 8.35 ug kg−1, Res-Se content decreased by 40.62 ug kg−1, and Fmo-Se content increased by 15.52 ug kg−1 while Alex increased by 33.67 mg kg−1, Alw increased by 1.7 mg kg−1, and Alh decreased by 573.89 mg kg−1. Acidification can trigger the conversion of Exc-Se to Fmo-Se and Om-Se, while the content of available Se may decrease due to the complexation interplay between Alex and Exc-Se. This study provides a theoretical basis for solving the problem of Se-enriched in tea caused by soil acidification. [ABSTRACT FROM AUTHOR]

The application of biochar is one of the promising management practices to alleviate soil acidification and improve soil fertility. However, it has been found to reduce the content of ammonium nitrogen ( NH 4 + −N) in the soil, which is the most important form of nitrogen (N) for tea tree growth. To investigate the response of soil NH 4 + −N content to the combined application of biochar and pruned tea plant litter, a pot trial was performed with three treatments: control (CK); biochar (BC); biochar + tea plant litter (BC + L). Soil chemistry properties and ammonification rates were determined, and the microbial community composition was analyzed by high-throughput sequencing. The results showed that the NH 4 + −N content in BC + L treatment was 1.7–9.5 fold higher than CK and BC treatments after 15 days of application, with no difference in the proportion of ammonia oxidation phyla such as Nitrospirae. The proportion of soil fungus Ascomycota was strongly correlated with the content of soil available nitrogen (p = 0.032), and the relationship was well described by a linear equation (R2 = 0.876, p = 0.01). Further redundancy analysis revealed that soil pH, soil organic carbon (SOC), the ratio of SOC to total nitrogen and the ratio of SOC to alkaline hydrolyzable nitrogen appeared to be important factors influencing the separation of BC + L from CK and BC groups. In summary, the addition of biochar and pruned tea plant litter alters soil properties and may influence the composition of microorganisms with various trophic groups, thus affecting ecosystem function. Our results also highlight the importance of returning pruned materials with biochar application in tea plantation ecosystems. [ABSTRACT FROM AUTHOR]

Biofertilizers have been suggested as alternatives to synthetic fertilizers, which could reduce soil degradation brought on by excessive chemical fertilization and have an impact on the bacterial diversity and community in the soil. The diversity and community of soil bacteria in tea plantations treated with wheat straw compost have, however, received relatively little attention. In this research, a two-year field trial was run to examine the effects of applying wheat straw compost on the characteristics of the soil and the quality of the tea. We also used high-throughput sequencing to investigate the response of the soil bacterial community, and Spearman's rank correlation was used to estimate the relationship between the soil bacterial community, soil characteristics, and tea quality. It was noticed that applying chemical fertilizer along with compost increased the fertility of the soil and the quality of the tea. Based on a two-year thorough data analysis, the T4 treatment (compost fertilizers 15,000 kg ha−1 + chemical fertilizers 1050 kg ha−1, chemical fertilizer reduction 30%) was determined to be the best group. The diversity and community makeup of soil bacteria were impacted by fertilization management. After the initial compost replacement, soils with compost had a greater bacterial richness than soils with inorganic fertilizers. After the second compost substitution, PCoA analysis revealed that compost fertilizer could be easily differentiated from chemical fertilizer. In 2019, Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, and Patescibacteria were the most prevalent bacterial phyla. In 2020, Firmicutes and Chloroflexi overtook Bacteroidetes and Patescibacteria as the two major bacterial phyla. In addition to increasing the diversity of soil bacteria and having an impact on the bacterial population, the application of wheat straw compost mixed with chemical fertilizers can also control the soil's characteristics and the quality of the tea produced in tea plantations. So, as a fertilization way with less environmental impact, wheat straw compost fertilization can be used in tea plantations. [ABSTRACT FROM AUTHOR]

Tea, sold as tea bags or loose tea, is a popular drink worldwide. We quantified microplastics in loose tea during various stages of production, from planting to processing and brewing. The quantity of microplastics in tea ranged from (70–3472 pcs/kg), with the highest abundance detected during processing, mainly in the rolling stage (2266 ± 1206 pcs/kg tea). Scanning electron microcopy revealed scratches and pits on the surface of microplastics fibers from tea plantation soil and processed tea, and their degradation was characterized by cracks and fractures. Exposure risks, based on an estimated dietary intake of 0.0538–0.0967 and 0.0101–0.0181 pcs /kg body weight /day for children and adults, respectively, are considered very low. This study not only evaluates the extent of research on microplastics pollution in tea, but also assess the risk of people's exposure to microplastics through drinking tea. [Display omitted] • The overall change trend of MPs in tea was higher in processing than in cultivation than in tea brewing. • The abundance and characteristics of soil MPs significantly depended on the proximity of plantations to roads. • In terms of dietary exposure risks, the risks of children and adults ingesting microplastics from drinking tea are small. • MPs fibers of tea plantation soil and leaves were mainly cylindrical, flat and spiral, which covered with scratches and pits. • Methods for extraction of MPs from tea has higher accuracy than the traditional extraction methods. [ABSTRACT FROM AUTHOR]

Selenium (Se)-enriched tea is a well-regarded natural beverage that is often consumed for its Se supplementation benefits. However, the production of this tea, particularly in Se-abundant tea plantations, is challenging due to soil acidification. Therefore, this study aimed to investigate the effects of changes in Se under acidified soil conditions. Eight tea plantation soil monitoring sites in Southern Jiangsu were first selected. Simulated acid rain experiments and experiments with different acidification methods were designed and soil pH, as well as various Al-ion and Se-ion concentrations were systematically determined. The data were analyzed using R statistical software, and a correlation analysis was carried out. The results indicated that as the pH value dropped, exchangeable selenium (Exc-Se) and residual selenium (Res-Se) were transformed into acid-soluble selenium (Fmo-Se) and manganese oxide selenium (Om-Se). As the pH increased, exchange state aluminum (Alex) and water-soluble aluminum (Alw) decreased, Fmo-Se and Om-Se declined, and Exc-Se and Res-Se increased, a phenomenon attributed to the weakened substitution of Se ions by Al ions. In the simulated acid rain experiment, P1 compared to the control (CK), the pH value of the YJW tea plantation decreased by 0.13, Exc-Se decreased by 4 ug mg−1, Res-Se decreased by 54.65 ug kg−1, Fmo-Se increased by 2.78 ug mg−1, and Om-Se increased by 5.94 ug mg−1 while Alex increased by 28.53 mg kg−1. The decrease in pH led to an increase in the content of Alex and Alw, which further resulted in the conversion of Exc-Se to Fmo-Se and Om-Se. In various acidification experiments, compared with CK, the pH value of T6 decreased by 0.23, Exc-Se content decreased by 8.35 ug kg−1, Res-Se content decreased by 40.62 ug kg−1, and Fmo-Se content increased by 15.52 ug kg−1 while Alex increased by 33.67 mg kg−1, Alw increased by 1.7 mg kg−1, and Alh decreased by 573.89 mg kg−1. Acidification can trigger the conversion of Exc-Se to Fmo-Se and Om-Se, while the content of available Se may decrease due to the complexation interplay between Alex and Exc-Se. This study provides a theoretical basis for solving the problem of Se-enriched in tea caused by soil acidification.

Background: Soil microbial community diversities and compositions are sensitive indicators of soil quality, but little is known about the changes in community diversity and composition of fungi in soils after planting different tea varieties. Methods: The differences in soil fungal community between the four tea varieties (Chuancha No.3 (CC3), Chuanmu No.217 (CM217), Chuannong Huangyazao (CN), and C. Sinensis 'Fuding Dabaicha' (FD)) were investigated by high-throughput sequencing. Results: Results showed significant differences in soil fungal β diversity, fungal community composition, and functional guilds in the soils planted with the four tea varieties, except α diversity. FD soil had the lowest number of phylum and class but the greatest relative abundance of Ascomycota; this occurred in conjunction with both a lower pH and soil organic carbon (SOC), total nitrogen (TN), and total phosphorous (TP) concentrations, but with a greater bulk density. A lower relative abundance of pathotroph-saprotroph-symbiotroph was detected in both CM217 and CN soils. A higher relative abundance of both saprotroph and saprotroph-symbiotroph was detected in both CM217 and CN soils; these fungal trophic modes had significantly positive correlations with soil pH, TN, and TP concentrations. CM217 and CN soils indicated the highest potential for maintaining the diversity of fungal communities and enhancing soil organic C and N accumulation. Conclusions: Soil properties play important roles in explaining the differences in soil fungal community composition and functional guild within a tea plantation system. Over 15 years tea planting, the soils grown with CM217 and CN tea varieties showed better soil quality. [ABSTRACT FROM AUTHOR]

The application of biochar is one of the promising management practices to alleviate soil acidification and improve soil fertility. However, it has been found to reduce the content of ammonium nitrogen (NH4+−N) in the soil, which is the most important form of nitrogen (N) for tea tree growth. To investigate the response of soil NH4+−N content to the combined application of biochar and pruned tea plant litter, a pot trial was performed with three treatments: control (CK); biochar (BC); biochar + tea plant litter (BC + L). Soil chemistry properties and ammonification rates were determined, and the microbial community composition was analyzed by high-throughput sequencing. The results showed that the NH4+−N content in BC + L treatment was 1.7–9.5 fold higher than CK and BC treatments after 15 days of application, with no difference in the proportion of ammonia oxidation phyla such as Nitrospirae. The proportion of soil fungus Ascomycota was strongly correlated with the content of soil available nitrogen (p = 0.032), and the relationship was well described by a linear equation (R2 = 0.876, p = 0.01). Further redundancy analysis revealed that soil pH, soil organic carbon (SOC), the ratio of SOC to total nitrogen and the ratio of SOC to alkaline hydrolyzable nitrogen appeared to be important factors influencing the separation of BC + L from CK and BC groups. In summary, the addition of biochar and pruned tea plant litter alters soil properties and may influence the composition of microorganisms with various trophic groups, thus affecting ecosystem function. Our results also highlight the importance of returning pruned materials with biochar application in tea plantation ecosystems.

Biofertilizers have been suggested as alternatives to synthetic fertilizers, which could reduce soil degradation brought on by excessive chemical fertilization and have an impact on the bacterial diversity and community in the soil. The diversity and community of soil bacteria in tea plantations treated with wheat straw compost have, however, received relatively little attention. In this research, a two-year field trial was run to examine the effects of applying wheat straw compost on the characteristics of the soil and the quality of the tea. We also used high-throughput sequencing to investigate the response of the soil bacterial community, and Spearman’s rank correlation was used to estimate the relationship between the soil bacterial community, soil characteristics, and tea quality. It was noticed that applying chemical fertilizer along with compost increased the fertility of the soil and the quality of the tea. Based on a two-year thorough data analysis, the T4 treatment (compost fertilizers 15,000 kg ha−1 + chemical fertilizers 1050 kg ha−1, chemical fertilizer reduction 30%) was determined to be the best group. The diversity and community makeup of soil bacteria were impacted by fertilization management. After the initial compost replacement, soils with compost had a greater bacterial richness than soils with inorganic fertilizers. After the second compost substitution, PCoA analysis revealed that compost fertilizer could be easily differentiated from chemical fertilizer. In 2019, Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, and Patescibacteria were the most prevalent bacterial phyla. In 2020, Firmicutes and Chloroflexi overtook Bacteroidetes and Patescibacteria as the two major bacterial phyla. In addition to increasing the diversity of soil bacteria and having an impact on the bacterial population, the application of wheat straw compost mixed with chemical fertilizers can also control the soil’s characteristics and the quality of the tea produced in tea plantations. So, as a fertilization way with less environmental impact, wheat straw compost fertilization can be used in tea plantations.

We studied the effects of soil nitrogen and pH in tea plantation soil on tea tree yield and quality in 90-tea plantations in Anxi county, Fujian province, China. The tea tree rhizosphere soil samples were collected for soil pH, ammonium nitrogen and nitrate nitrogen content from 90-tea plantations. The yield of tea tree and the contents of tea polyphenols, theanine and caffeine in tea leaves increased with the increase in soil pH. Secondly, as the soil pH increased, the content of ammonium nitrogen and the ratio of ammonium nitrogen to nitrate nitrogen in tea tree rhizosphere soil also increased, but the content of nitrate nitrogen decreased. Further the yield of tea tree and the contents of tea polyphenols, theanine and caffeine increased, with the increase in ratio of ammonium nitrogen to nitrate nitrogen in the soil. The pH of tea plantation soil was significantly positively correlated with the tea tree yield and quality, and the content of soil ammonium nitrogen, but negatively correlated with nitrate content in soil. This study provides basis for the scientific and rational use of nitrogenous fertilizers in tea plantations. [ABSTRACT FROM AUTHOR]

Abstract Background Cow manure is not only an agricultural waste, but also an organic fertilizer resource. The application of organic fertilizer is a feasible practice to mitigate the soil degradation caused by overuse of chemical fertilizers, which can affect the bacterial diversity and community composition in soils. However, to our knowledge, the information about the soil bacterial diversity and composition in tea plantation applied with cow manure fertilization was limited. In this study, we performed one field trial to research the response of the soil bacterial community to cow manure fertilization compared with urea fertilization using the high-throughput sequencing technique of 16S rRNA genes, and analyzed the relationship between the soil bacterial community and soil characteristics during different tea-picking seasons using the Spearman’s rank correlation analysis. Results The results showed that the soil bacterial communities were dominated by Proteobacteria, Bacteroidetes, Acidobacteria and Actinobacteria across all tea-picking seasons. Therein, there were significant differences of bacterial communities in soils with cow manure fertilization (CMF) and urea fertilization (UF) in three seasons: the relative abundance of Bacteroidetes in CMF was significantly higher than that in UF and CK in spring, and the relative abundance of Proteobacteria and Bacteroidetes in CMF was significantly higher than that in UF and CK in autumn. So, the distribution of the dominant phyla was mainly affected by cow manure fertilization. The diversity of bacterial communities in soils with cow manure fertilization was higher than that in soils with urea fertilization, and was the highest in summer. Moreover, soil pH, OM and AK were important environmental properties affecting the soil bacterial community structure in tea plantation. Conclusions Although different fertilizers and seasons affect the diversity and structure of soil microorganisms, the application of cow manure can not only improve the diversity of soil bacteria, but also effectively regulate the structure of soil bacterial community in tea plantation. So, cow manure fertilization is more suitable for tea plantation.

Abstract Background Different mulches have variable effects on soil physicochemical characteristics, bacterial and fungal communities and ecosystem functions. However, the information about soil microbial diversity, community structure and ecosystem function in tea plantation under different mulching patterns was limited. In this study, we investigated bacterial and fungal communities of tea plantation soils under polyethylene film and peanut hull mulching using high-throughput 16S rRNA and ITS rDNA gene Illumina sequencing. Results The results showed that the dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria and Chloroflexi, and the dominant fungal phyla were Ascomycota, Mortierellomycota and Basidiomycota in all samples, but different mulching patterns affected the distribution of microbial communities. At the phylum level, the relative abundance of Nitrospirae in peanut hull mulching soils (3.24%) was significantly higher than that in polyethylene film mulching soils (1.21%) in bacterial communities, and the relative abundances of Mortierellomycota and Basidiomycota in peanut hull mulching soils (33.72, 21.93%) was significantly higher than that in polyethylene film mulching soils (14.88, 6.53%) in fungal communities. Peanut hull mulching increased the diversity of fungal communities in 0–20 cm soils and the diversity of bacterial communities in 20–40 cm soils. At the microbial functional level, there was an enrichment of bacterial functional features, including amino acid transport and metabolism and energy production and conversion, and there was an enrichment of fungal functional features, including undefined saprotrophs, plant pathogens and soils aprotrophs. Conclusions Unique distributions of bacterial and fungal communities were observed in soils under organic mulching. Thus, we believe that the organic mulching has a positive regulatory effect on the soil bacterial and fungal communities and ecosystem functions, and so, is more suitable for tea plantation.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Cow manure is not only an agricultural waste, but also an organic fertilizer resource. The application of organic fertilizer is a feasible practice to mitigate the soil degradation caused by overuse of chemical fertilizers, which can affect the bacterial diversity and community composition in soils. However, to our knowledge, the information about the soil bacterial diversity and composition in tea plantation applied with cow manure fertilization was limited. In this study, we performed one field trial to research the response of the soil bacterial community to cow manure fertilization compared with urea fertilization using the high-throughput sequencing technique of 16S rRNA genes, and analyzed the relationship between the soil bacterial community and soil characteristics during different tea-picking seasons using the Spearman's rank correlation analysis. Results: The results showed that the soil bacterial communities were dominated by Proteobacteria, Bacteroidetes, Acidobacteria and Actinobacteria across all tea-picking seasons. Therein, there were significant differences of bacterial communities in soils with cow manure fertilization (CMF) and urea fertilization (UF) in three seasons: the relative abundance of Bacteroidetes in CMF was significantly higher than that in UF and CK in spring, and the relative abundance of Proteobacteria and Bacteroidetes in CMF was significantly higher than that in UF and CK in autumn. So, the distribution of the dominant phyla was mainly affected by cow manure fertilization. The diversity of bacterial communities in soils with cow manure fertilization was higher than that in soils with urea fertilization, and was the highest in summer. Moreover, soil pH, OM and AK were important environmental properties affecting the soil bacterial community structure in tea plantation. Conclusions: Although different fertilizers and seasons affect the diversity and structure of soil microorganisms, the application of cow manure can not only improve the diversity of soil bacteria, but also effectively regulate the structure of soil bacterial community in tea plantation. So, cow manure fertilization is more suitable for tea plantation. [ABSTRACT FROM AUTHOR]

Background: Different mulches have variable effects on soil physicochemical characteristics, bacterial and fungal communities and ecosystem functions. However, the information about soil microbial diversity, community structure and ecosystem function in tea plantation under different mulching patterns was limited. In this study, we investigated bacterial and fungal communities of tea plantation soils under polyethylene film and peanut hull mulching using high-throughput 16S rRNA and ITS rDNA gene Illumina sequencing. Results: The results showed that the dominant bacterial phyla were Proteobacteria, Actinobacteria, Acidobacteria and Chloroflexi, and the dominant fungal phyla were Ascomycota, Mortierellomycota and Basidiomycota in all samples, but different mulching patterns affected the distribution of microbial communities. At the phylum level, the relative abundance of Nitrospirae in peanut hull mulching soils (3.24%) was significantly higher than that in polyethylene film mulching soils (1.21%) in bacterial communities, and the relative abundances of Mortierellomycota and Basidiomycota in peanut hull mulching soils (33.72, 21.93%) was significantly higher than that in polyethylene film mulching soils (14.88, 6.53%) in fungal communities. Peanut hull mulching increased the diversity of fungal communities in 0–20 cm soils and the diversity of bacterial communities in 20–40 cm soils. At the microbial functional level, there was an enrichment of bacterial functional features, including amino acid transport and metabolism and energy production and conversion, and there was an enrichment of fungal functional features, including undefined saprotrophs, plant pathogens and soils aprotrophs. Conclusions: Unique distributions of bacterial and fungal communities were observed in soils under organic mulching. Thus, we believe that the organic mulching has a positive regulatory effect on the soil bacterial and fungal communities and ecosystem functions, and so, is more suitable for tea plantation. [ABSTRACT FROM AUTHOR]

In order to characterize the nitrification activities of tea plantation soils in different areas, totally 30 typical soil samples from 12 provinces were collected. The soil nitrification potential was determined by using the shaken-soil-slurry method. The multiple regression analysis and partial least squares regression (PLS) were carried out to characterize the main impact factors. The nitrification potential in tea plantation soils ranged from 0.24 to 5.31 mg⋅kg-1⋅h-1, and the abundance of AOA in soil was significantly higher than that of AOB. Both AOA and AOB showed significantly positive correlation with soil nitrification potential. Abundance of ammonia oxidation microbes, C/N, nitrate, ammonium, total nitrogen and organic carbon contents were the significant important factors influencing nitrification potential, with a descending order of importance according to PLS. These results reveal that nitrification potential is still high in tea plantation soil, since AOA dominate the ammonia oxidation process. The difference of ammonia-oxidizing microorganisms, availability of soil carbon, nitrogen caused by climate, soil conditions and fertilization regimes are likely to be the main factors for the variation of the nitrification potential in tea plantation soils. [ABSTRACT FROM AUTHOR]

Abstract Substitution of chemical nitrogen (N) with organic fertilizers in agricultural ecosystems has been promoted to sustain crop yield and soil quality. Soil microbes play key roles in soil nutrient cycling after organic matter addition. However, there is limited information about the effect of the organic substitution ratio (OSR) on soil bacterial communities, which are considered as a good indicator of soil quality in a tea plantation. In this study, a long-term field experiment with six treatments was established to study the effect of different OSRs of N, from pure synthetic fertilization (NPK) to 100% N substituted with organic fertilizer (OM100), on tea yield and soil bacterial communities. The soil bacterial community composition was measured using a high-throughput sequencing technique. The results showed that as the OSR increased, the soil bacterial diversity increased and the community structure shifted significantly. However, 25% N substituted with organic fertilizer (OM25) produced the highest yield. Additionally, the soil pH and organic carbon (SOC) were the predominant soil characteristics that accounted for the soil bacterial community structural change. With more chemical N being substituted with organic fertilizer, the soil pH, available potassium, SOC, total N, and microbial biomass C and N, were elevated; however, the yield of fresh tea leaves decreased. These results indicated the trade-off effect between tea yield and soil bacterial diversity under different OSRs, which could also alter the soil bacterial communities by changing soil characteristics. [ABSTRACT FROM AUTHOR]

Soil microbes are important drivers of nutrient cycling that regulate plant growth and productivity. Yet, a holistic understanding of the effect of magnesium (Mg) fertilizer on the soil microbial community is still poorly understood. Here, a four-year field experiment was conducted to investigate the impact of different rates of Mg application, including 0, 17.5, 35, 52.5, and 70 kg of MgO ha−1, on soil bacterial and fungal communities (Illumina 16S and ITS amplicon sequencing) associated with tea plantations. Results showed that Mg application significantly increased the soil pH and improved the soil acidity, carbon, and available nitrogen, calcium, and Mg contents. Hence, Mg application also significantly increased soil bacterial diversity but did not affectfungal diversity. Moreover, Mg fertilization increased the relative abundance of beneficial bacterial genera belonging to nitrogen fixation and phosphorus mineralizing groups, such as Gemmatimonas , Rhizomicrobium and Sphingomonas. In addition, the Mg fertilization decreased the relative abundance of some pathogen fungi, such as Pestalotiopsis, Chaetomium, and Coniosporium. Network analysis indicated that the Mg application increased the complexity of the bacterial network by enhancing node numbers and connectivity links, while for fungal networks, the low rate of Mg fertilizer increased total nodes and edges. However, the higher amount of Mg fertilizer decreased the complexity of the fungal network. Correlation analysis between soil properties and microbial communities showed that pH, total carbon and nitrogen, available carbon, and exchangeable Mg were the key soil factors that significantly influenced the microbial community structure. These findings suggest that Mg fertilization could increase soil microbial diversity, alter the microbial structure and improve the microbial network structure of the tea plantation soils. These findings could help to improve soil health, sustainability, and crop productivity. Therefore, Mg fertilization can be considered a viable strategy for improving the health and productivity of tea plantation soils. • The effects of Mg fertilization on soil microbial communities were examined in tea plantation soils. • Mg fertilization significantly increased bacterial diversity but did not affect fungal diversity. • Mg altered both bacteria and fungi composition at genus level. • Mg enhanced the complexity of bacterial but reduced fungal co-occurrence networks. • Soil pH, total C, N and exchangeable Mg were vital in structuring microbial communities. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nitrogen (N) fertilization is an important field management practice in tea (Camellia sinensis L.) plantations. Although the supply of N fertilizer plays a vital role in the growth and quality of tea plants, the optimal N application rate and the effects of different N application regimens on tea yield and quality still remain unclear. In this study, we conducted an eleven-year field experiment to investigate the impact of N application on tea yield and quality, as well as soil bacterial characteristics. We found that N fertilization quadratically increased the yield and amino acid (AA) content of tea, but quadratically decreased total polyphenol (TP) content. Increasing N rates resulted in significant changes in soil community characteristics, including decreased diversity, weakened community function and lower community stability. Additionally, higher taxonomic levels and low-abundance taxa were affected most significantly by N fertilization. Based on PERMANOVA results, the variation of bacterial community composition can be largely explained (~50%) by the soil properties of pH, exchangeable magnesium (Exch-Mg), exchangeable potassium (Exch-K) and exchangeable hydrogen (Exch-H). Partial least squares regression (PLSR) and path modeling (PLS-PM) illustrated that N fertilization indirectly affected tea yield and quality mainly by causing changes in soil properties of Exch-Al and pH, respectively. Soil bacterial characteristics, on the other hand, contributed relatively little to the changes in tea yield and quality. Overall, excessive N application had an adverse effect on soil quality, despite mostly positive effects on tea growth and quality. N application rates of 119–285 kg N ha−1 yr−1 were the most optimal for high tea growth and quality. Understanding the response of above- and belowground plant characteristics to N application rates should help to guide field fertilization and achieve a higher N-use efficiency in agricultural systems. [Display omitted] • Supply of nitrogen (N) fertilizer quadratically improves tea yield and quality. • N rates decrease diversity, stability and function of soil bacterial communities. • Bacterial communities could be largely explained by pH, Exch-Mg, Exch-K and Exch-H. • N indirectly affects tea yield and quality mainly by changing Exch-Al and pH. [ABSTRACT FROM AUTHOR]

The collaborative assessment and health risk evaluation of heavy metals (HMs) enrichment in soils and tea leaves are crucial to guarantee consumer safety. However, in high soil HM geochemical background areas superimposed by human activities, the health risk associated with HMs in soil-tea systems is not clear. This study assessed the HMs concentration (i.e., chromium (Cr), cadmium (Cd), arsenic (As), and lead (Pb)) in tea leaves and their relationship with soil amounts in the southwest region of China to evaluate the associated health risk in adults. The results revealed that the average soil concentration of Cr was the highest (79.06 mg kg -1 ), followed by Pb (29.27 mg kg -1 ), As (14.87 mg kg -1 ), and Cd (0.18 mg kg -1 ). Approximately 0.71, 4.99, 7.36, and 10.21% of soil samples exceeded the threshold values (NY/T 853-2004) for Pb, Cr, As, and Cd, respectively. Furthermore, the average concentration of Pb, As, and Cd in tea leaves was below the corresponding residue limits, but Cr was above the allowed limits. Correlation analysis revealed that the Pb, Cr, As, and Cd amounts in tea leaves were positively correlated to their soil amounts ( p < 0.01) with an R 2 of 0.203 **, 0.074 **, 0.036 **, and 0.090 **, respectively. Additionally, approximately 40.38% of the samples were found to be contaminated. Furthermore, spatial distribution statistical analysis revealed that Lancang was moderately contaminated, while Yingjiang, Zhenkang, Yongde, Zhenyuan, Lüchun, Jingdong, Ximeng, and Menglian were slightly contaminated areas. The target hazard quotients (THQ; health risk assessment) of Pb, Cr, As, and Cd and the hazard index ( HI ) of all the counties were below unity, suggesting unlikely health risks from tea consumption.