Soil Nutrient Content Research Articles

Nutrient Distribution in the Soil Profile Under Different Tillage Practices During a Long-Term Field Trial

Conservation tillage practices are increasingly used in agricultural systems. However, these practices require a complex approach regarding soil nutrition. Adequate nutrient content in soils is important for crop production, as reduced and no-tillage practices change the distribution of nutrient contents (P, K, Mg, and Ca) in the soil profile, necessitating new approaches for agronomists in crop nutrition. Little is known about the time changes in nutrient distribution in the soil profile under conservation tillage practices. Long-term field experiments with conventional (CT—plowing to 20–22 cm), reduced (RT—chiseling to 8–10 cm), and no-tillage (NT) practices were established in Prague–Ruzyně (Czech Republic) in 1995. This four-year crop rotation consisted of winter wheat changing with oilseed rape or pea. The soil nutrient contents have been determined since 2009 using the Mehlich 3 method and through extraction in 0.5 M ammonium acetate. The obtained results showed that P, K, and, to a lesser extent, Mg contents increased in the soil surface layer (0–10 cm) under the reduced and no-tillage practices, whereas Ca and pH values showed an opposite trend. We found an unbalanced ratio of nutrients in the upper soil layer in RT and NT caused by a high concentration of the monovalent cation K+ and the leaching of the divalent cations Ca2+ and Mg2+ into the deeper soil layers. In conventional practices, the ion contents are equalized throughout the topsoil due to the soil inverting during plowing. The determination of nutrient contents in deeper soil layers revealed that, over time, calcium, magnesium, and potassium were transported to deeper parts of the soil profile under RT and especially NT. Low nutrient ratios were found in the surface layer under RT and NT, negatively affecting the quality of the soil surface layer, including its structure. Fertilizer management and nutrient ratios in soils under RT and NT should be considered to maintain and possibly improve sustainable agricultural practices in fields with reduced or no-tillage practices. Furthermore, nutrient contents and their mutual ratios should be evaluated in more soil layers under these systems, enabling the detection of eventual problems in the upper layer that must be addressed by changing fertilization.

Effects of pepper–maize intercropping on the physicochemical properties, microbial communities, and metabolites of rhizosphere and bulk soils

BackgroundIntercropping increases land use efficiency and farmland ecological diversity. However, little is understood about whether and how soil biota, metabolites, and nutrients change under interspecific competition among plants. Thus, this study aimed to explore the changes in the physicochemical properties, microbial communities, and metabolites of rhizosphere and bulk soils of pepper monocropping and pepper–maize intercropping systems.ResultsIntercropping significantly increased the contents of available phosphorus (AP) and available potassium (AK), and decreased the pH value, whereas it had little effect on the total nitrogen (TN) and organic matter (OM) in the rhizosphere and bulk soils, compared with those in monocropping pepper. Moreover, the OM content was higher in rhizosphere soil than in bulk soil. The microbial community structures and metabolite profiles also differed between the two systems. The diversity of bacteria and fungi increased in intercropped pepper. The relative abundances of Actinobacteria, Chloroflexi, Cyanobacteria, and Ascomycota were higher while those of Proteobacteria, Planctomycetes, Mucoromycota, and Basidiomycota were significantly lower in the rhizosphere and bulk soils from the intercropping system than in those from the monocropping system. Linear discriminant analysis revealed that the predominant bacteria and fungi in the rhizosphere soil from the intercropping system belonged to the order Sphingomonadales and genera Nitrospira, Phycicoccus and Auricularia, whereas those in the bulk soil from the intercropping system belonged to the phylum Acidobacteria and genera Calocera, Pseudogymnoascus, and Trichosporon. Intercropping promoted the secretion of flavonoids, alkaloids, and nucleotides and their derivatives in the rhizosphere soil and significantly increased the contents of organoheterocyclic compounds in the bulk soil. Furthermore, the AP and AK contents, and pH value had strong positive correlations with bacteria. In addition, co-occurrence network analysis also showed that asebogenin, trachelanthamidine, 5-methyldeoxycytidine, and soil pH were the key factors mediating root-soil-microbe interactions.ConclusionIntercropping can alter microbial community structures and soil metabolite composition in rhizosphere and bulk soils, enhancing soil nutrient contents, enriching soil beneficial microbes and secondary metabolites (flavonoids and alkaloids) of intercropped pepper, and provided a scientific basis for sustainable development in the pepper-maize intercropping system.

Assessment of Water and Soil Contamination and Land Cover Changes in the Spring Creek Bayou Watershed in Houston, Texas

Stormwater runoff and nutrient pollution are significant sources of water contamination that continue to grow in rural and suburban watersheds. The goal of this research is to analyze and evaluate the impact of urbanization and industrialization on suburban watersheds in southeast Texas. The objectives are to: (1) determine nutrient and heavy metal concentrations in soil and water samples along Spring Creek Bayou (SC), (2) analyze land cover changes over the last 30 years and (3) assess and evaluate socio-economic data within the watershed. The soil and water samples were collected from upstream, midstream and downstream locations in triplicate during the spring and fall seasons along the bayou. The samples were analyzed to determine chemical concentrations and Landsat 5, and eight imageries were used to derive thematic land cover maps. The soil and water chemical concentrations were interpolated to spatial maps for distribution analysis. The chemical analysis of water samples collected from SC Bayou revealed that N and P concentrations were at elevated levels that can pose a threat to water quality and aquatic organisms. Heavy metal concentrations of Zn were at elevated levels in water samples from the SC Bayou watershed. Land cover change patterns showed that high-vegetation surfaces decreased while low-vegetation surfaces increased slightly over the past three decades. The watershed experienced an increase in total population from 129,629 residents in 1990 to 389,977 residents in 2020. This research is important in improving our understanding on the impact of natural and human activities on suburban watersheds in the Greater Houston metropolitan region.

Soil Nutrient Changes in Black Soil of Northeastern China Under Long-Term Cultivation with Different Fertilizer Applications and Tillage Patterns: A Meta-Analysis

ABSTRACT As one of the four major black soil distribution areas in the world, the black soil region in northeastern China has shown a trend of nutrient degradation under excessive development. Understanding its nutrient changes and the factors affecting them is of great significance to the sustainable development of black soil. Soil nutrient profiles are influenced by several anthropogenic management patterns, including fertilizer application methods and tillage practices. A comprehensive analysis of the influencing factors can help to understand the mechanisms of nutrient changes in black soil cropland. Therefore, using soil organic carbon (SOC) as a proxy for nutrients, this study applied a meta-analysis based on 1138 observations from 60 papers to reveal the effects of anthropogenic management practices (application of organic fertilizers (OF), straw back (SB), application of chemical fertilizers (CF) and conservational tillage (CT)) on soil nutrients. The results showed that the most of soil nutrients increased significantly under management model. The application of chemical fertilizers decreased soil pH by 4.55% and increased soil available phosphorus (AP) content by 112.14%. Compared to the conventional model, application of organic fertilizers significantly increased SOC content, total nitrogen (TN) content and microbial biomass carbon (MBC) content by, 16.75%, 20.10% and 31.15% (p < .05), respectively. The effect values of SOC content were positively correlated with those of most soil nutrient contents under different anthropogenic management. This study helps to understand the response of nutrient content of northeastern black soils to different anthropogenic management models and provides reasonable references for sustainable farming patterns.

Response and Assembly Process of Soil Microbial Communities Under Different Reclamation Measures

Reclamation is essential for restoring the ecological function of soil in mining areas. However, the microbiological mechanism of soil ecological function reconstruction under different reclamation measures still needs to be clarified. Clarifying the characteristics of soil bacterial and fungal communities, assembly mechanisms, and their relationship with physicochemical properties under different reclamation measures is crucial for reshaping the ecological stability of soil in mining areas. Metagenomic sequencing technology was combined with the null model and neutral model to analyze the differences in soil microbial diversity, community composition, network structure, and community assembly process between the reclaimed natural recovery area （LH） and the reclamation fertilization area （MM）. The results suggested that： ① Compared with that in the LH treatment, the MM treatment significantly increased the soil nutrient content, and the total nitrogen （TN）, total phosphorus （TP）, available phosphorus （AP）, and available potassium （AK） contents increased by 34.70%, 72.72%, 468.98%, and 45.74%, respectively （P&lt;0.05）. ② The dominant bacterial and fungal communities did not change under the LH and MM treatments； however, the abundance of bacterial communities changed significantly. Compared with that in the LH treatment, the relative abundance of Acidobacteria increased significantly by 5.4% in the MM treatment, while the relative abundance of Candidatus Rokubacteria decreased significantly by 235.72% （P&lt;0.05）. Under different reclamation measures, the indicator microorganisms of bacterial and fungal communities changed. ③ Compared with that in the LH treatment, the MM treatment increased the complexity of bacterial networks, decreased the complexity of fungal networks, and increased the number of soil bacterial nodes and links. The reclamation measures transformed the key bacterial groups from Proteobacteria to Candidatus Rokubacteria and Planctomycetes. The key group of fungi was Ascomycota. 4.） The deterministic process dominated the assembly of bacterial and fungal communities. Homogeneous selection contributed the most to the bacterial community assembly in the LH treatment, and heterogeneous selection contributed the most to the MM treatment. The fungal communities were all dominated by heterogeneous selection. These results provide new insights into the soil microbial community structure and ecological function restoration in coal mining subsidence reclamation areas.

Biochar Influences Polyethylene Microplastic-Contaminated Soil Properties and Enzyme Activities

Microplastics (MPs) have emerged as a significant pollutant, threatening agricultural ecosystem sustainability and global food security. However, relatively few studies have investigated biochar remedial effects on plant growth and biochemical properties in soils contaminated with MPs. In polyethylene microplastic (PE-MP)-contaminated soil, we investigated corn stover biochar effects on soybean growth, soil nutrient content, enzyme activity, and microbial biomass and assessed its impact on soil microbial resource limitations. The addition of MPs inhibited soybean growth in various forms across four stages. Conversely, the addition of biochar to MPs improved soybean growth to some extent, where above-ground biomass increased by 5.82% after adding biochar to soils containing microplastics. In soil treated with MPs and biochar, nitrate nitrogen (N), available phosphorus (P), and available potassium (K) increased by 20.1, 27.4, and 57.2%, respectively, while available nitrogen significantly decreased to 128.3 mg kg−1 compared to the MP-only treatment. PE-MPs alone significantly reduced soil carbon (C), N, and P enzyme activities, as well as microbial biomass, with β-glucosidase, leucine aminopeptidase, and acid phosphatase activities decreasing by 29.9, 27.8, and 25.5%, respectively. Interestingly, biochar addition to MPs significantly alleviated these detrimental effects. Microbial biomass C, N, and P increased by up to 56.0, 22.5, and 96.6%, respectively, following biochar addition to soils containing MPs. Analysis of vector lengths, vector angles, and scatter plots indicated that the presence of MPs reduced soil N and P availability. Overall, while MPs inhibited soybean development, biochar addition alleviated this effect to some extent. Furthermore, partial least-squares path modeling revealed that MPs negatively affected soil chemical properties, microbial biomass, and enzyme activities, whereas biochar positively influenced soil enzyme activities.

Impacts of phosphate-solubilizing bacterium strain MWP-1 on vegetation growth, soil characteristics, and microbial communities in the Muli coal mining area, China

Due to the cold climate and low soil nutrient content, high-altitude mining areas are challenging to restore ecologically. Their poor nutrient content may be ameliorated by introducing specific microorganisms into the soil. This study aims to evaluate the effects of a highly efficient phosphate solubilizing bacterium MWP-1, Pseudomonas poae, on plant growth, soil nutrients in remedying the soil of the high-altitude Muli mining area in Qinghai Province, and analyze its impact on microbial communities through high-throughput sequencing soil microbial communities. The results showed that MWP-1 significantly increased the content of soil available phosphorus by &amp;gt;50%, soil organic matter and total nitrogen by &amp;gt;10%, and significantly increased the height, coverage, and aboveground biomass of vegetation by &amp;gt;40% in comparison with the control (p &amp;lt; 0.05). MWP-1 mainly affected the composition of the soil bacterial communities at the taxonomic level below the phylum. Its impact on soil fungal communities occurred at the phylum and below taxonomic levels. In addition, MWP-1 also significantly improved the diversity of soil bacterial and fungal communities (p &amp;lt; 0.05), and changed their functions. It also significantly altered the relative abundance of genes regulating phosphorus absorption and transport, inorganic phosphorus dissolution and organic phosphorus mineralization in the bacterial community (p &amp;lt; 0.05). It caused a significant increase in the relative abundance of the genes regulating nitrogen fixation and nitrification in nitrogen cycling (p &amp;lt; 0.05), but a significant decrease in the genes regulating phospholipase (p &amp;lt; 0.05). Although sequencing results indicated that Pseudomonas poae did not become the dominant species, its dissolved phosphorus elements can promote plant growth and development, enrich soil nutrient content, and affect the succession of microbial communities, enhance ecosystem stability, with an overall positive effect on soil remediation in the mining area.

Physicochemical properties of acid sulphate soil profoundly influence the composition of rhizobacterial community of rice (Oryza sativa L.)

The soils of kari lands of Kuttanad, the ‘Rice bowl’ of Kerala, India are characterized as acid sulphate as they comprise of pyrite deposits. Productivity in these soils is at stake due to several constraints like high acidity and salinity, metal toxicity, nutrient unavailability, redox fluctuations, besides seasonal flooding. Sustainable management of acid sulphate soil is a critical priority to improve the rice output from these areas. Such soils would harbor unique innate microbial communities with definite abilities which could be exploited further for their sustainable amelioration. Development of inoculant technology with soil and crop specific beneficial microbial agents is expected to boost the production potential of kari soils. However, the soil parameters would impose a great influence on the rhizobacterial community development in these geologically distinct soils. We studied the rhizobacterial communities (at the family level), associated with rice grown in five acid sulphate (Purakkad, Vaikom, Ambalappuzha, Thakazhi and Kallara) as well as one non-acid sulphate (Muhamma) soil series of geographically unique Kuttanad region. We also examined the effects of soil physicochemical attributes on shaping the rhizosphere bacterial community assemblage. The soil physicochemical attributes were analyzed using standard procedures and correlations existing amongst them were also determined. A metagenomic approach was adopted to study the rhizobacterial communities (family level) and were correlated with soil parameters using canonical correspondence analysis (CCA). Compared to other acid sulphate regions, Thakazhi and Kallara soils indicated higher electrical conductivity, available nitrogen, potassium, organic carbon, aluminium as well as iron and lowest pH and available phosphorus. Intense significant relationships were exhibited amongst the acid sulphate properties and soil nutrient contents. The taxa summary after the Illumina MiSeq sequencing revealed the abundant rhizobacterial families in the soil samples as Anaerolineaceae, Ktedonobacteriaceae, Acidothermaceae, Acidimicrobiaceae, Clostridiaceae, Nocardioidaceae, Xanthobacteraceae, Methanobacteriaceae, Sphingomonadaceae and Peptostreptococcaceae. Acidothermaceae (14%) and Acidimicrobiaceae (12%) were found abundant exclusively in highly acid sulphate soil samples. Moreover, only a few shared taxa were observed between the soil samples, which denoted the uniqueness of each sample in terms of rhizobacterial communities. The shared taxa between highly acidic sampling areas include members of Acidothermaceae, Ktedonobacteraceae, Acidimicrobiaceae, Micrococcaceae, Stellaceae and Anaerolineaceae. CCA showed that pH, EC and Al content were the soil properties governing the bacterial assembly in the rhizosphere of actively tillering rice grown in acid sulphate soil followed by P and K. The data generated in the present study are considered to be of use in developing consortia of kari soil specific rice rhizosphere microbial agents which could be used as inoculants in future.

Coupling Relationship Between Soil Properties and Plant Diversity Under Different Ecological Restoration Patterns in the Abandoned Coal Mine Area of Southern China.

Understanding the effects of ecological restoration in abandoned coal mines on soil and plant is important to improve the knowledge of ecosystems evolution and facilitate taking appropriate ecological restoration management practices. This study aims to evaluate the coupling relationship between plant diversity and soil properties after ecological restoration in abandoned coal mine area. The plant diversity such as Margalef index (M), Simpson index (H), Shannon-Wiener index (D), and Pielou index (J), and soil properties such as soil pH, soil water content (SWC), soil bulk density (SBD), soil organic matter (SOM), available nitrogen (AN), and microbial biomass carbon (MBC) were investigated in four sites of different ecological restoration patterns, Tand study the coupling relationship between them. The results indicated that: (1) the Pinus massoniana and Schima superba gardner and champ restoration (PSR) site had higher Shannon-Wiener index and Simpson index values than Pinus massoniana restoration (PR) site, and in herb layer, the plant diversity was significantly higher than in other layers; (2) in the PSR site, the soil properties were improved more notably than that of PR and nature restoration (NR) sites, and the plant diversity were also higher than PR site; (3) Clay, SOM, and MBC made a great contribution to the plant diversity. It was concluded that ecological restoration patterns had significant effects on soil nutrient content and plant diversity, and there exists evident coupling relationship between plant diversity and soil properties. This study has important effects of ecological restoration and management in abandoned coal mine area.

Soil multifunctionality and nutrient cycling-related genes in Cunninghamia lanceolata plantations: metagenomic perspective insights into ecological restoration

The widespread cultivation of Cunninghamia lanceolata in China has led to soil degradation and decline in microbial diversity, which have a significant impact on supporting forest ecological services. However, little is known about the long-term consequences from forest management practices on the bacterial functional genes associated with soil nutrient cycling. Here, metagenomic sequencing was used to investigate the soil bacterial functional genes involved in carbon (C), nitrogen (N), and phosphorus (P) cycling in a 16-year pair experiment of pure (C. lanceolata) and mixed plantations (C. lanceolata + Betula luminifera). The results showed that the mixed plantations had much higher soil nutrient content as well as enzyme activity, thereby improving soil multifunctionality (SMF). Forest management practices resulted in differences in the structural and functional composition of soil bacterial communities, such as Chloroflexi, Firmicutes and acid metabolism were enriched in pure plantations, while Acidobacteria, Planctomycetes and amino acid metabolism were enriched in mixed plantations. Compared with monocultures, mixed plantations had higher abundance of genes participated in C degradation, C fixation, methanogenesis, N cycling and P solubilization. The CNP cycling genes also varied with taxon-specific responses to forest management. Forty-seven nearly entire bacterial metagenome-assembled genomes (MAGs) were obtained, in which MAGs enriched in mixed plantations had more functional genes involved in CNP cycling. Notably, acidophilic Acidobacteria played important roles in reduction of Fe(III) and the subsequent release of organic P. In all, our results demonstrated that the use of mixed plantations enhances a number of soil functions via its influence on the abundances of keystone taxa and functional genes, providing a foundation for developing forest management strategies in subtropical regions. In future researches, attention should be paid to the effects of mixed plantations on soil microbial diversity and nutrient cycling across various seasons.

Comparison of Automated Controller Settings for Irrigation and Fertilizer Needs of Potted Geranium

The future of agricultural water availability is threatened by climate change, population growth, and environmental regulations. Most of the global water is being used for crop irrigation. The objective of this research was to determine optimum timer-based controller settings and controlled-released fertilizer rates for ‘American Red’ (Pelargoium ×hortorum) potted geranium plants. Fertilizer was top-dressed at 3, 6, or 9 g. Plants were irrigated by a timer-based controller set to water at 11:00 AM every other day for 2 minutes, 9:00 AM and 2:00 PM for 1 minute per day, 11:00 AM for 1 minute per day, 11:00 AM for 2 minutes per day, and a control of manual hand watering. Data regarding plant growth, soil and leaf nutrients, and water use were collected. For geranium growth factors, the total flowers per plant was greatest for irrigation at 11:00 AM for 1 minute with 6 g fertilizer. Plant height and shoot dry weight were greatest for 6 and 9 g fertilizer. The number of umbels and soil plant analysis development (SPAD) chlorophyll meter readings were greatest for 9 g fertilizer. For geranium soil nutrient content, the pH was greatest for 3 g fertilizer, whereas the electrical conductivity, potassium, nitrate, sulfate, and boron were greatest for 6 and 9 g fertilizer. Regarding the nutrient content of the leaves, total nitrogen, boron, iron, and copper were greatest for 9 g fertilizer. Water use efficiency was greatest with 6 and 9 g fertilizer and irrigation 1 minute per day at 11:00 AM. The findings indicated that using timer-based controlled irrigation systems programmed to water for 1 minute during the morning with 6 g fertilizer resulted in plants that not only reduced water consumption but also enhanced water use efficiency and overall plant quality.

Land-use change from native forest to avocado orchards: Effects on soil nutrient transformation and microbial communities

Land-use change is known to alter soil microbial communities and the processes they carry out. However, there is meager information about how conversion of natural forests to agricultural land for avocado production affects soil nutrient concentration and microbial activity and diversity. Total soil nutrients (C, N and P), microbial ecoenzymatic activity, and microbial diversity were studied in avocado orchards and contiguous forest fragments in Michoacán state, México. Within orchards, samples were taken from fertilized areas beneath avocado trees as well as from unfertilized areas. Results showed that (i) total phosphorus concentration was higher in avocado orchards compared to native forests soils; (ii) transformation of native forests to avocado orchards decreased the ecoenzymatic activity necessary for degradation of lignified compounds and phosphate monoesters; (iii) bacterial diversity was higher in avocado orchard soils compared to native forest soils while fungal diversity was higher in avocado unfertilized soils; (v) transformation of native forests to avocado orchards increased the evenness of bacterial and fungal communities; (vi) transformation of native forest to avocado orchards caused significant changes in the composition of soil microbial communities; however, this was clearer for fungal communities than for bacterial communities; (vii) abundance of ectomycorrhizal fungi and antagonists of plant pathogens decreased in avocado orchards while pathogenic and saprotrophic fungal guilds increased. Our results suggest that land use change from native forest to avocado orchards generates important changes in the dynamics of soil organic carbon and soil organic phosphorus in avocado orchard soils, probably due to the predominant conventional management model in the avocado belt. Furthermore, this type of land use change results in the increased abundance of important microbial groups identified as phytopathogens and the decrease of beneficial microbial groups. These changes should be taken into account to formulate forest and soil conservation polices and of more sustainable agricultural management models that consider soil microbial communities and their functions.

Extreme summer drought increased soil detachment capacity of biocrusts in subtropical China

Biological soil crusts (Biocrusts) are considered to have significant effects on soil detachment processes. Increasing extreme droughts are expected to affect the structure and functioning of biocrust ecosystems. However, understanding how biocrust ecosystems will respond to drought requires further investigation in the subtropical region. This study conducted continuously monitoring of understory biocrusts in subtropical China from May to November 2022, analyzed the monthly variation of near-surface characteristics of biocrusts and performed scouring experiments with six flow shear stresses (7.61–21.08 Pa) to assess the monthly variation of soil detachment capacity (Dc) of biocrusts. Finally, we elucidated the complex effects of summer drought (August-September) on Dc of biocrusts. Results showed that summer drought led to significant reductions in biocrust coverage (BC) and biocrust thickness (BT) (P<0.05), as well as notable declines in soil stability (including soil cohesion and Mean weight diameter) and soil nutrient content (including soil organic matter, total Nitrogen, total Phosphorus) (P<0.05), except for a non-significant increase in bulk density (P>0.05). Furthermore, Dc of biocrusts significantly increased by 172.2 % during the summer drought compared to the previous months (P<0.05). These changes of biocrusts are mainly affected by moisture stress more than heat stress. Partial least squares path modeling (PLS-PM) revealed that reduced rain and lower soil moisture increased Dc mainly by diminishing the BC and BT, followed by reducing soil cohesion and soil aggregate stability. The results provide empirical evidence for the cumulatively detrimental effects of future climate on biocrusts and contribute to more comprehensive understanding of biocrusts multifunctionality.

Assessing the health of climate-sensitive trees in a subalpine ecosystem through microbial community dynamics

Climate change has significantly affected the subalpine ecosystems, leading to mass die-offs of the Korean fir tree, a key climate-sensitive species in these environments. Proactive analysis of the phenotypic responses of these trees to climate change or the establishment of preemptive strategies for trees to adapt to these environmental changes remains a challenge. The current study aimed to investigate the impact of climate change on the health of Korean fir (Abies koreana) in the subalpine ecosystem of Jirisan Mountain, South Korea. We integrated soil physicochemical analyses, microbial community dynamics, neutral community model, and network analyses to examine the relationships between tree health and microbial communities. Our findings revealed significant changes in soil chemical properties, including pH and nutrient concentrations, across the various health statuses of trees. Microbial community analysis demonstrated shifts in bacterial and fungal communities corresponding to the health continuum of the trees, with decreased diversity and altered composition in the declining trees. A remarkable increase in modularity of the microbial network and a clear transition from stochastic to deterministic microbial community assembly processes were observed as the trees progressed from a healthy to a dead stage. Two bacterial genera, Bradyrhizobium and Burkholderia, along with an unclassified fungal group from Basidiomycota, were identified as key microbial indicators of good tree health. This study highlighted the importance of microbial communities as bioindicators for assessing the health of subalpine ecosystem and its resilience to climate change, offering valuable insights into the conservation and management strategies for subalpine ecosystems.

Enhancing Regional Topsoil Total Nitrogen Mapping Through Differentiated Fusion of Ground Hyperspectral Data and Satellite Images Under Low Vegetation Cover

Total nitrogen in soil (STN) serves as a crucial indicator of soil nutrient content and provides an essential nitrogen source necessary for crop growth. Precisely inversion of STN content is crucial for the sustainable management of soil resources and the advancement of agricultural development, particularly to achieve efficient fertilization—reduction in fertilizer usage without compromising yield or increase in yield while maintaining the total fertilization amount. Spectroscopy technology is regarded as an ideal non-destructive method for nutrient detection. However, due to the weak spectral signals of STN and its spatial heterogeneity, hyperspectral imaging technology presents significant potential for high-resolution measurements and precise characterization of STN heterogeneity. In this paper, the STN content was selected as the study subject, and three aspects of soil spectral feature enhancement, multi-source remote sensing data differentiated fusion, and STN content inversion model construction were studied. Therefore, a differentiated fusion of enhanced multispectral image bands (DFE_MSIBs) method combined with Random Forest (RF) algorithms was developed for spectral inversion of STN content. The findings demonstrate the following: 1. The enhanced spectral characteristics and differentiated fusion method not only strengthen the relationship between STN and Sentinel-2A MSI data but also enhance the precision of regional STN inversion models. 2. For the differentiated fusion of enhanced multispectral image bands (DFE_MSIBs) method combined with Random Forest (RF) algorithms, the R2 was 0.95, RMSE was 0.10 g/kg, and LCCC was 0.89. 3. Compared to the unfused model, the average R2 value was increased by 0.02, the average RMSE was decreased by 0.01 g/kg, and the average LCCC was increased by 0.03. These findings hold practical significance for utilizing multi-source remote sensing data in STN mapping and precision fertilization in agricultural fields.

Changes of Soil Microbial Characteristics and Nutrient Content in Sandy Soil Under Drip Irrigation System

Changes of Soil Microbial Characteristics and Nutrient Content in Sandy Soil Under Drip Irrigation System

Influence of Soil Extractable Plant Nutrients on the Walnut Kernel Ionome in Southern Kyrgyzstan at Different Elevations

Abstract Background and Aims Climate change causes altered precipitation patterns and temperature increases, which may affect food quantity and quality. In Kyrgyzstan anticipated temperature changes are expected to influence the physiology of walnuts (Juglans regia L.) and soil properties relevant to plant nutrition, thereby impacting walnut fruit quality. This study explores the relationship between plant available nutrients in soil and walnut fruit nutrient content as affected by future temperature changes. Methods The soil samples were collected in the walnut forests of Southern Kyrgyzstan from top- and subsoils at three elevation levels (1000, 1300, and 1600 m above sea level). The walnut samples were collected from the same sampling sites and both soil Mehlich-3 extracts and acid digests of walnut fruits analyzed by ICP-OES. Results The results revealed no consistent relationship between Mehlich-3 extractable elements and walnut extractable elements, except for a weak negative correlation with zinc (Zn). Stronger relationships were observed among soil elements, but no clear associations with elevation levels were found. The walnut kernel ionome exhibited differences, particularly in calcium (Ca) and potassium (K) concentrations, with the low elevation site showing higher Ca and lower K concentrations compared to the high elevation site. Conclusions Differences in average temperature as caused by elevation did not affect available plant nutrients in the soil but altered the walnut kernel ionome and thus affected the walnut quality in the investigated forest systems. Future investigations should focus on climate change effects, such as altered precipitation patterns and drought, which may impact walnut fruit development and kernel properties.

Microplastics influence nutrient content and quality of salt-affected agricultural soil under plastic mulch

Northeast China is an important food production base and plays a crucial role in national food security. However, the increase in salt-affected soils poses a challenge to agricultural production in this region. Plastic mulching is an effective technique for saline cropland improvement, and although it has increased crop yields in the short term, its long-term application may have introduced the problem of contamination by microplastics (MPs). The distribution of MPs in salt-affected cropland, along with the effects on soil nutrients, remains largely unknown. Accordingly, the presented research selected salt-affected cropland as the research object, after which MPs were quantified from 46 soil samples from currently mulched and unmulched fields. MPs abundance in the sampled soils ranging from 4.10 × 103∼1.50 × 104 particles per kilogram of dry soil. The detected MP polymers were mainly high-density polyethylene (46%), polypropylene (22%) and polyvinyl chloride (20%). The MP particles most commonly fell under the size ranges of 50∼100 μm (35%) and 100–200 μm (28%), both of which are small particle sizes. The most commonly detected MP shapes were film (34%) and fragment (31%). The mulched samples from salt-affected cropland generally showed higher soil nutrient contents than the unmulched samples. Moreover, MP abundance, type, size, and shape all demonstrated strong correlations with soil organic carbon and total nitrogen. MP type is a major factor determining soil nutrient content. Plastic mulching serves as an important source of MPs in salt-affected cropland, with these contaminants affecting nutrient content. Future research should be broader in scope and include ecological benefits and policy implications, with a view to optimizing the problem of MPs contamination due to mulching.

Impact of long-term integrated nutrient management on productivity, profitability, soil microbial activity and nutrient content ofrice (Oryza sativa) in Assam

A study was carried out during 2021 to 2022 at Assam Agricultural University, Jorhat, Assam to study the effect of long-term integrated nutrient management on productivity, profitability, soil microbial activity and nutrient content of rice (Oryza sativa L.) in Assam. The experiment was conducted in a randomized block design (RBD) comprised of 5 nutrient management practices, viz. T1, Absolute control; T2, 100% recommended dose (RD) through chemical fertilizers (CF); T3, 50% RD through CF + liquid biofertilizers; T4, 50% RD through CF + solid biofertilizers; and T5, 50% RD through CF + enriched compost (EC) (@1 t/ha), with 4 replications. The results showed higher grain yield and profitability in treatment T2 (5.23 t/ha and $1472.29/ha) followed by T5 (5.23 t/ha and $1446.29/ha), T3 (4.90 t/ha and $1362.29/ha), T4 (4.87 t/ha and $1346.69/ha), and the lowest in T1 (3.21 t/ha and $897.85/ha). Notably, treatment T5 delivered comparable yield and returns to T2. However, treatment T5 significantly increased the essential nutrients (N, P, K, Zn, Cu, Mn, Fe) in grain compared to T2 or T3/T4. In addition, soil microbial activity such as dehydrogenase activity, phospho-monoesterase activity, microbial biomass carbon, fluorescein diacetate hydrolase, and arylsulphatase activity were significantly higher under treatment T5. These findings highlight that treatment T5 i.e. 50% CF + EC (@1 t/ha) not only matches conventional 100% fertilizer application in yield and returns but also enhances soil microbial activity. Study highlights the potential of integrated nutrient management practices with 50% RD through CF + enriched compost (EC) (@1 t/ha) to address micronutrient deficiencies, improve crop productivity, profitability, and promote sustainable agriculture in the region.

A Systematic Review and Meta-Analysis of the Sustainable Impact of Sewage Sludge Application on Soil Organic Matter and Nutrient Content

The increasing scarcity of natural resources makes the linear production model unsustainable, highlighting the need for more sustainable practices under the umbrella of circular economic principles. Sewage sludge emerges as a promising solution to provide soil organic matter (SOM) and nutrients. This meta-analysis evaluated the impacts of three levels of sludge application (low, medium, and high) on organic matter (OM), nitrogen (N), phosphorus (P), copper (Cu), and zinc (Zn) contents, considering different areas and experimental conditions worldwide. The analysis included 37 studies and 355 comparisons, after screening 7625 records, following the 2020 PRISMA protocol. The effects of sludge concentrations, continents, and types of experiment (field or greenhouse) were evaluated. Sewage sludge application significantly increased OM, N, Cu, and Zn levels, mainly at medium and high rates. The largest effects were observed in greenhouses, suggesting variation by location and environment. Moderators explained a part of the variation in the results, but the residual heterogeneity test revealed that there is still unexplained variability.