Bioindicators Of Soil Health Research Articles

Entomopathogenic Nematodes as Bioindicators of Soil Health

Entomopathogenic Nematodes as Bioindicators of Soil Health

Nematodes as bioindicators of soil health in different land uses in the São Francisco River Valley, Brazil

Summary Brazilian Caatinga is one of the most diverse, seasonally dry, tropical forests of the world and is threatened by strong land use pressure and poor protection. One way of understanding changes in the soil conditions caused by anthropogenic activities is using the nematode assemblages as potential bioindicators. This study analysed changes in nematode communities in three different types of land use (natural forest-CA, natural area with accumulation of salts-SS, and agricultural growing areas, such as cover crops-CC for cattle and fruit trees-IC) in the Caatinga, in the sub-median region of the São Francisco River Valley (SFRV), Pernambuco, northeastern Brazil. We recorded a total of 63 262 nematode individuals, representing 42 genera, belonging to 23 families. Nematode abundance, diversity and maturity indices were highest in the CC and lowest in the SS. Among the nematode trophic groups, bacterivores, omnivores + predators and plant parasites were significantly affected by type of land use. Different soil properties were related to the differences in taxonomic composition among the natural and agricultural areas, accounting for 26.6% of the total variation. In general, our results indicate that soil salinisation and desertification in the natural areas, as well as soils subjected to cover crops and fruit tree production, significantly influenced the composition of nematode communities in the São Francisco River Valley.

Theoretical study on the inhibition mechanisms of heavy metal ions on urease activity

Soil urease is highly sensitive to soil heavy metal pollution, and thus its activity can be used as bio-indicator of soil health. However, little is known about the inhibition mechanisms of heavy metals on urease. The effects of dimetallic substitution (i.e., Cd, Co, Cu, Hg, and Zn) on the binding of urea in the urease and its subsequent decomposition were studied using quantum chemical methodologies with a urease mimic (phthalazine-dinickel complex). The dimetallic substitution altered the structural features of the dimetal complexes and the M−O bond length between the dimetals and the carbonyl-O of coordinated urea molecules, weakening the binding energies of urea in dimetal complexes, which further affected the transformation of urea. In the urea decomposition via intra-molecular proton transfer, all dimetal complexes have a high activation barrier due to the weak binding of urea in complexes and hydrogen bonding within urea molecules, which are therefore difficult to occur spontaneously. In the urea decomposition via water-assisted inter-molecular proton transfer, the addition of water molecules decreased the energy barrier of urea decomposition. Regardless of the urea decomposition pathway, the dimetallic substitution altered the M−O bond length and hydrogen bond pattern of intermediates and transition states, and also affected the leave of the resulting NH3 from the dimetal complexes by regulating the C–N bond length within the decomposed urea molecule. Overall, the theoretical study provided insight into the molecular mechanisms of the inhibitory effects of heavy metals on urease activity.

Linking agricultural diversification practices, soil arthropod communities and soil health

Abstract Soil arthropods comprise a substantial portion of soil biodiversity and regulate processes in the soil ecosystem. Despite this, cropping system diversification designed to improve soil health for agriculture is rarely evaluated for its effects on soil arthropod biodiversity and community structure. As a result, soil arthropods are not usually considered in management decisions. To address this gap, we evaluated the effects of agricultural diversification through rotation on soil arthropods and soil properties using replicated large‐plot field studies representing two climatically distinct agroecological classes (AECs) in the dryland cereal‐growing region of the inland Pacific Northwest, USA. We investigated how different 3‐year annual crop rotations affected soil arthropod biodiversity and community structure. Treatments reflected ‘business‐as‐usual’ rotations in dryland systems and diversified rotations achieved by incorporating novel winter pea (WP) or forage crops (FORs). We also assessed relationships between the Soil Biological Quality index (QBS‐ar), which uses soil arthropods as bioindicators of soil health, and other biological and physiochemical soil health indicators. We collected 710 community samples with 82,509 arthropod specimens across 66 taxa. Novel crops in diversified rotations promoted soil arthropod abundance and biodiversity relative to crops they could replace in rotation. Crop type determined community composition. Most taxa driving differences in community structure were predators and detritivores associated with WP and FORs. In addition to effects on soil arthropods associated with specific crops, effects were also detected across rotations. Incorporating WP into rotations improved QBS‐ar across entire rotations, not just in the WP phases, in both AECs. Links between QBS‐ar and other soil health indicators were complex and varied by AEC. Synthesis and applications: Soil arthropods respond to agricultural diversification and can be used as bioindicators to assess the effects of diversification on soil health. Below‐ground arthropod communities are structured by crop type, suggesting that planting specific crops may promote soil arthropods and their services. We showed that incorporating winter pea and forage crops into dryland cereal rotations supported soil arthropod biodiversity and soil health. Results indicate that soil arthropod assessments can be included in the soil health framework to guide agricultural management decisions.

Using Trait-Based Approaches to Assess the Response of Epedaphic Collembola to Organic Matter Management Practices: A Case Study in a Rubber Plantation in South-Eastern Côte d'Ivoire.

Simple SummaryWhile studies based on the taxonomic facet of biodiversity have already proven their value in understanding soil functioning, studies focusing on the functional facet based on the traits of organisms are scarce in the Ivorian context. Among soil organisms, springtails play an important role in soil functioning and are a useful bioindicator for assessing the impact of land use change and agricultural practices on soil biodiversity. However, their taxonomy is very poorly known in Côte d’Ivoire. The functional trait approach is therefore a relevant alternative for assessing the response of springtails communities to organic matter management in tree plantations. The aim of this study was to determine how different input of organic matter in the form of logging residues and legumes influence the body size and functional diversity of springtails. Our results showed a high functional richness and body size of springtails in the practice with trunks and large branches (R2L1). Functional traits are useful to assess the effects of agricultural practices on springtails communities.We used trait-based approaches to reveal the functional responses of springtails communities to organic matter inputs in a rubber plantation in Côte d’Ivoire. Pitfall traps were used to sample springtails in each practice. The results showed that the total abundance of springtails increased significantly with the amount of organic matter (R0L0 < R2L1). Larger springtails (body length, furca and antennae) were observed in plots with high organic matter. Practices with logging residues and legume recorded the highest functional richness. The principal coordinate analysis showed different functional composition patterns between practices with logging residues (R1L1 and R2L1) and those without inputs (R0L0 and R0L1). This difference in functional composition (PERMANOVA analysis) was related to the effect of practices. These results highlight the pertinence of the functional trait approach in the characterization of springtail communities, a bioindicator of soil health, for organic matter management practice.

Soil protists: An untapped microbial resource of agriculture and environmental importance

Protists are essential components of soil biodiversity and ecosystem functioning. They play a vital role in the microbial food web as consumers of bacteria, fungi, and other small eukaryotes and are also involved in maintaining soil fertility and plant productivity. Protists also contribute to regulating and shaping the bacterial community in terrestrial ecosystems via specific prey spectra. They play a role in plant growth promotion and plant health improvement, mostly via nutrient cycling, grazing, and the activation of bacterial genes required for plant growth and phytopathogen suppression. Thus, protists may prove to be a useful inoculant as biofertilizer and biocontrol agent. They can also be applied as model organisms as bioindicators of soil health. Despite their usefulness and essentiality, they are often forgotten and under-researched components of the soil microbiome, as most of our research focuses on bacteria and fungi. In this review, we provide an overview of the role of protists in plant productivity and plant health management and in shifts in soil bacterial community composition, as well as their roles as bioindicator. We also discuss the perspectives of knowledge gaps and future prospects to further improve soil biology. More research in soil protistology will provide insights into sustainable agriculture and environmental health alongside the study of bacteria and fungi.

Positioning entomopathogenic nematodes for the future viticulture: exploring their use against biotic threats and as bioindicators of soil health

Vineyards face several biotic threats that compromise the grape quality and quantity. Among those that cause relevant economic impact and have worldwide distribution are the oomycete Plasmopara vitícola, the fungi Erysiphe necator and Botrytis cinerea, and the arthropods Lobesia botrana, Tetranychus urticae, and Phylaenus spumarius (principal vector of the bacterial disease Xylella fastidiosa in Europe). Their management relies primarily on agrochemicals with short persistence; widespread use of these chemicals causes environmental and human health problems. The challenge of sustainable viticulture is to provide ecologically sound alternatives. In this regard, the application of entomopathogenic nematodes (EPNs) and natural products derived from their symbionts can be an alternative. EPNs are well-known biocontrol agents for soil-dwelling insects. However, current research demonstrates the great potential of both EPN and their derivates as direct bio-tools against some of the key fungal and arthropods pests present aboveground. In addition, recent evidence shows that detecting EPN presence and activity and their relation with other soil organisms associated with them can help us to understand the impact of different agricultural practices on vineyard management. Altogether, this review illustrates the great potential of EPN to enhance pest and disease management in the next generation of viticulture.

Soil Nematode identification service and training in the new normal

Nematodes constitute one of the key components of soil ecosystems, and further studies are needed to explore the roles of each nematode taxon in soil ecosystems. Nematode communities can serve as bioindicator of soil health. However, the two points necessitate accurate identification of existing nematode taxa which in Indonesia is challenging due to the insufficient skill of workers and lack of identification service. The present study was aimed to explore the prospect of online nematode identification training and service as a solution to the above problem. A video conference with 38 participants was held during which still and video images of nematodes examined under a microscope were shared. The results showed that most participants reported clear images with minimum delay, although a smaller percentage had problems related to unstable internet connection. Therefore, the present study suggested the possibility of online nematode identification training and service. In this paper some procedures and setups are proposed for implementing such services, emphasizing on online activities during New Normal and beyond. Fully online or blended deliveries are proposed with increasing nematode handling skill development but also increasing need of access to laboratory facilities. The blended program is extensible to the post-pandemic state or new normal schemes of such activities have been proposed. The present paper also argues that Indonesia needs to build center(s) of nematode collection employing specialist taxonomists who can identify nematodes and are competent in providing identification services.

The abundance of soil invertebrates in young and mature palm oil plot in relations to soil physical properties: A preliminary study

The soil biota is considered the biological engine of the earth and is associated with most of the critical functions of the soil in terms of ecosystem services. The knowledge on the impact of land management and agricultural activities on the abundance and diversity of soil invertebrates is still understudied especially in Malaysia. This study was conducted to investigate the relation of the abundance and diversity of soil invertebrates with the soil physical parameters from two different palm oil plots. Sampling methods of soil invertebrates include pitfall trap and Burlese-Tullgren funnel. Invertebrate’s abundance and diversity were measured and invertebrates were identified according to their morphological characteristics under the dissecting microscope concerning taxonomic keys. A total of 621 individuals were documented from both sites with 408 collected in mature palm oil farms whereas 213 individuals were documented in young palm oil farms. Hymenoptera (67.31 %) is the most dominant invertebrate followed by Orthoptera (12.40 %) and Arachnida (10.14 %). Morphospecies diversity, evenness, and richness are highest in mature palm oil plot with Shannon; 1.54, Evenness; 0.32, and Menhinick; 0.67 respectively. Well-developed canopy, plenty of shelters, and reduced agricultural activities in mature palm oil mainly contributed to ideal soil physical parameters (bulk density; 1.23 (g/cm3) ± 0.02, porosity; 55.03 % ± 2.48, temperature; 35.65°C ± 0.30 and moisture; 34.05 % ± 0.60) produces a comparatively more balanced habitat for a diverse community of soil invertebrates. Because of the roles they play in soil biological processes, soil invertebrates may be used as bioindicators of soil health. This study can be used as a baseline for more extensive research that may be applied in future planning on land management in achieving the nation’s agricultural sustainability.

Sugarcane Leaf Litter as Soil Amendment to Stimulate Collembolan Diversity

The sugarcane leaf litter contains organic material and if it is returned to the soil, it will increase the diversity of Collembola. Collembola has an important role as a decomposer of soil organic matter and bioindicator of soil health. This study was conducted to determine the effect of sugarcane leaf litter on the diversity of Collembolan in sugarcane plantation at Kebonagung Sugar Factory, Malang. This study was conducted from March to June 2018. Transect method was used in sampling method. The pitfall traps were used to obtain Collembolan samples on the surface of the ground while the Berlese-Tullgren funnels were used to obtain Collembolan samples inside the soil. A total of 5,535 collembolan were collected. Five species were collected, including Brachystomella sp., Folsomides sp., Mesaphorura sp., Alloscopus sp., and Dicranocentrus sp. Applying sugarcane leaf litter to the soil has a positive effect on Collembolan diversity, as evidenced by the increasing value of diversity index on the soil surface from 0.53 to 1.11 and decreasing the value of dominance index on the soil surface from 0.76 to 0.43.

Herbicidal effect on the bio-indicators of soil health- A review

Soil microbial population, earth worms in soil, soil enzyme activity and organ carbon content in soil are considered as the bio indicators of soil health. They are used as indicators of soil health because of their active role in soil organic matter production, decomposition of xenobiotics and cycling of nutrients, ease of measurement and rapid response to changes in management practices. The assessment of soil health can be used to develop more sustainable crop production system. A number of herbicides have been introduced as pre and post emergence weed killer. The impact of herbicides on soil health depends on the soil type, type and concentration of herbicide used, sensitivity to non-target organisms and environmental conditions. The review elaborates the impact of herbicidal application on the biological indicators of soil health.

Options for Soil Health Measurement in Vineyards and Deciduous Fruit Orchards, with Special Reference to Nematodes

Soil is a non-renewable resource and supports all land-based forms of life. The sustainable production of crops is becoming progressively more critical as human populations increase and viable agricultural land decreases. Soil health plays an indispensable part in the sustainability of soil as a resource for future generations. For this very reason it is important to have suitable tools to measure the improvement or deterioration of soil health in vineyards and orchards. In this review, the use of different bio-indicators to indicate soil health will be discussed, with special emphasis on the use of nematode population structure and function as indicators of soil health. The use of nematodes as a bio-indicator of soil health can play a crucial role in the establishment of future sustainable production of grapes and fruit in the Western Cape. This paper provides a comprehensive review of soil health, the use of different biological indicators, and the potential of nematodes as suitable indicators thereof, aimed at vineyards and deciduous fruit orchards.

Free living soil Nematodes as Ecological Indicators

Free living Nematodes communities used as bioindicators of soil health because their composition well correlates with, two critical ecological processes i.e. nitrogen cycling and decomposition in soil . Nematodes indices withstand statistical rigor better than abundances, proportions, or ratios of trophic groups. Nematodes indices respond to a variety of land-management practices, based largely on life history characteristics of families.

26年长期施肥对土壤微生物量碳、氮及土壤呼吸的影响研究

Soil microbial properties play important roles in soil quality changes and nutrition cycling. The relationship between soil microbial properties and soil quality changes as a result of climate conditions,soil types,tillage and fertilizer.Lots of studies had been done; however,there are not too many reports on loessial soil. Loessial soil is one of the main types of soil on loess plateau. The study about loessial soil plays an important role in getting better soil environment and increasing productivity of dryland on loess plateau. In this paper,the relationship between soil quality and soil microbial properties such as soil microbial biomass carbon,soil microbial biomass nitrogen and soil basal respiration was studied in order to illustrate the function of soil microbial properties as bio-indicators of soil health. The long-term experiment was set up in1984 in Changwu county,Shaanxi province,China. We collected samples from the 0—20 cm soil zone of the long-term wheat cultivation and fertilization system. Nine treatments were carried out in this study: 1) fallow( F); 2) no fertilization as control( CK); 3) nitrogen( N); 4) phosphorus( P); 5) manure( M); 6) nitrogen + phosphorus( NP); 7)phosphorus + manure( PM); 8) nitrogen + manure( NM); 9) nitrogen + phosphorus + manure( NPM). The chemical properties such as p H,organic matter,total nitrogen,and total phosphorus content were analyzed in order to determine to the effects of long-term wheat cultivation and fertilization on soil nutrients. The soil microbial biomass carbon,soil microbial biomass nitrogen,basal respiration and the derivative indices of the arable soil in different long-term fertilization systems were also analyzed. The results showed that different fertilization on loessial soil in 26 years significantly affected soil chemical and microbial properties. Long-time combined application of organic and mineral fertilizers had more effect on soil organic matter,total nitrogen and total phosphorus content than mineral fertilizers alone. All these properties in treatment with fertilizers input NPM were the highest. In different fertilization treatments,the contents of soil microbial biomass carbon changed between 254.65 mg / kg and 745.26 mg / kg,and the contents of soil microbial biomass nitrogen changed from 31.70 mg / kg to 120.54 mg / kg. Long-term fertilization and planting increased the content of soil microbial biomass carbon and soil microbial biomass nitrogen. Especially, organic fertilizers can significantly enhance soil microbial biomass content.Compared with CK,the treatments with organic fertilizers input increased soil microbial biomass carbon,soil microbial biomass nitrogen and soil basal respiration. The soil basal respiration of treatments with organic fertilizer was increased by15.91% to 75.73%. In the meantime chemical fertilizer had no promotion on the soil basal respiration,and decreased the metabolic quotient. Some of soil microbial properties( Soil microbial biomass carbon,Soil microbial biomass nitrogen,Soil basal respiration) were significantly correlated with soil organic matter and soil total nitrogen contents. Soil basal respiration was also significantly correlated with soil total phosphorus content. The correlations between microbial quotient and soil nutrients,metabolic quotient and soil nutrients were not obvious. These results indicate that soil microbial properties reflect the changes of soil quality and thus can be used as biological indices in the evaluation of soil fertility.

Effect of tetraconazole application on the soil microbial community

Tetraconazole is one of the most commonly used triazole fungicides in agricultural practice, and its continuous application poses a potential risk for non-target soil microorganisms. Therefore, the objective of this study was to evaluate the effect of tetraconazole at the field rate (T1, 0.33 mgkg(-1) of soil), three times the field rate (T3, 1.00 mgkg(-1) of soil) and 10 times the field rate (T10, 3.33 mgkg(-1) of soil) on the soil microorganisms. To ascertain this effect, the tetraconazole concentration and the microbial properties with potential as bioindicators of soil health (i.e. microbial biomass C, basal respiration, substrate-induced respiration, structure diversity and functional community profiling) were determined. The results showed that the degradation half-lives of tetraconazole varied from 69 to 87 days, depending on the three application concentrations. The microbial biomass C, basal respiration and substrate-induced respiration were inhibited, but they tended to recover at the end of the incubation when tetraconazole was applied at the recommended field rate. The ratios of the gram-negative to gram-positive (GN to GP) bacteria decreased, and the fungi to bacteria ratio increased after a temporal decrease on the seventh day. A principal component analysis of the PLFAs showed that tetraconazole application significantly shifted the microbial community structure on day 7. Different functional community profiles were observed, depending on the tetraconazole application rates. It was concluded that tetraconazole application decreases the soil microbial biomass and activity and changes the structures of the soil microbial community.

Impact of sources of environmental degradation on microbial community dynamics in non-polluted and metal-polluted soils

Soils are currently being degraded at an alarming rate due to increasing pressure from different sources of environmental degradation. Consequently, we carried out a 4-month microcosm experiment to measure the impact of different sources of environmental degradation (biodiversity loss, nitrogen deposition and climate change) on soil health in a non-polluted (non-degraded) and a heavily metal-polluted (degraded) soil, and to compare their responses. To this aim, we determined a variety of soil microbial properties with potential as bioindicators of soil health: basal respiration; β-glucosaminidase and protease activities; abundance (Q-PCR) of bacterial, fungal and chitinase genes; richness (PCR-DGGE) of fungal and chitinase genes. Non-polluted and metal-polluted soils showed different response microbial dynamics when subjected to sources of environmental degradation. The non-polluted soil appeared resilient to “biodiversity loss” and “climate change” treatments. The metal-polluted soil was probably already too severely affected by the presence of high levels of toxic metals to respond to other sources of stress. Our data together suggests that soil microbial activity and biomass parameters are more sensitive to the applied sources of environmental degradation, showing immediate responses of greater magnitude, while soil microbial diversity parameters do not show such variations.

Tebuconazole application decreases soil microbial biomass and activity

A short-term mesocosm experiment was conducted to ascertain the impact of tebuconazole on soil microbial communities. Tebuconazole was applied to soil samples with no previous pesticide history at three rates: 5, 50 and 500 mg kg −1 DW soil. Soil sampling was carried out after 0, 7, 30, 60 and 90 days of incubation to determine tebuconazole concentration and microbial properties with potential as bioindicators of soil health [i.e., basal respiration, substrate-induced respiration, microbial biomass C, enzyme activities (urease, arylsulfatase, β-glucosidase, alkaline phosphatase, dehydrogenase), nitrification rate, and functional community profiling]. Tebuconazole degradation was accurately described by a bi-exponential model (degradation half-lives varied from 9 to 263 days depending on the concentration tested). Basal respiration, substrate-induced respiration, microbial biomass C and enzyme activities were inhibited by tebuconazole. Nitrification rate was also inhibited but only during the first 30 days. Different functional community profiles were observed depending on the tebuconazole concentration used. It was concluded that tebuconazole application decreases soil microbial biomass and activity.

Microbiological polyphasic approach for soil health evaluation in an Italian polluted site

The use of microorganisms as bioindicators of soil health is quite a new feature, rarely considered for the soil health evaluation in chronically-polluted industrial sites, and still suffering of the bias related to the technique applied. In this work we applied a microbiological polyphasic approach, relying on soil indigenous microorganisms as bioindicators and combining culture-dependent and -independent methods, in order to evaluate soil health of four sites (1a, 1b, 2a and 2b) inside a chemical factory with a centenary activity. Functional as well as structural aspects were comprehensively considered. Results were related to the kind of pollutants found in each site. Heavy metal pollution was recorded in sites 1b and 2b, while both organic and inorganic substances were detected in sites 1a and 2a. Based on the chemical and physical properties of the four soils, site 1b and 2b grouped together, while 1a and 2a were separated from the others. The density of the culturable bacteria was very low in site 2a, where only Gram-positive were found. According to the identification of culturable bacteria, site 2a showed the lowest similarity with the other sites. Microbial activity was detected only in sites 1b and 2b. PCR-DGGE (Denaturing Gradient Gel Electrophoresis), was performed on the culturable, total and active microbial communities. Consistently with the identification of culturable bacterial strains, the molecular profile of the culturable fraction of site 2a, was clearly separated from the molecular profiles of other sites in cluster analysis. Molecular fingerprintings of the whole and active bacterial communities differed among the sites, but clustered according to the pollutants present in each site. The presence of possible key species in each site has been discussed according to the whole and active species. Since the results obtained by microbiological analysis are consistent with the chemical data, we suggest that the use of this microbiological polyphasic approach and of microorganisms as intrinsic bioindicators, can be suitable for the evaluation of soil health.

Effects of Long-Term Combined Application of Organic and Mineral Fertilizers on Microbial Biomass, Soil Enzyme Activities and Soil Fertility

Soil health is important for the sustainable development of terrestrial ecosystem. In this paper, we studied the relationship between soil quality and soil microbial properties such as soil microbial biomass and soil enzyme activities in order to illustrate the function of soil microbial properties as bio-indicators of soil health. In this study, microbial biomass C and N contents (Cmic & Nmic). soil enzyme activities, and soil fertility with different fertilizer regimes were carried out based on a 15-year long-term fertilizer experiment in Drab Fluvo-aquic soil in Changping County, Beijing, China. At this site, 7 different treatments were established in 1991. They were in a wheat-maize rotation receiving either no fertilizer (CK). mineral fertilizers (NPK). mineral fertilizers with wheat straw incorporated (NPKW+), mineral fertilizers with incremental wheat straw incorporated (NPKW+), mineral fertilizers plus swine manure (NPKM), mineral fertilizers plus incremental swine manure (NPKM+) or mineral fertilizers with maize straw incorporated (NPKS). In different fertilization treatments Cmic changed from 96.49 to 500.12 mg kg −1, and Nmic changed from 35.89 to 101.82 mg kg −1. Compared with CK, the other treatments increased Cmic & Nmic, Cmic/Corg (organic C) ratios, Cmic/Nmic, urease activity, soil organic matter (SOM). soil total nitrogen (STN), and soil total phosphorus (STP). All these properties in treatment with fertilizers input NPKM+ were the highest. Meantime, long-term combined application of mineral fertilizers with organic manure or crop straw could significantly decrease the soil pH in Fluvo-aquic soil (the pH around 8.00 in this experimental soil). Some of soil microbial properties (Cmic/Nmic. urease activity) were positively correlated with soil nutrients. Cmic/Nmic was significantly correlated with SOM and STN contents. The correlation between catalase activity and soil nutrients was not significant. In addition, except of catalase activity, the soil pH in this experiment was negatively correlated with soil microbial properties. In conclusion, soil microbial properties reflect changes of soil quality and thus can be used as bio-indicators of soil health.

Soil microbial characteristics as bioindicators of soil health

Soil microbial characteristics as bioindicators of soil health