Soil Microbiological Indicators Research Articles

Farm-Scale Mapping of Soil Microbiological Indicators Using Geostatistical Technique

Soil microbiological properties viz. soil microbial biomass carbon (MBC) and dehydrogenase activity (DHA) are sensitive soil quality indicators. Spatial modeling and prediction map of soil MBC and DHA were generated for a semiarid agricultural farm, New Delhi, India from 288 geo-referenced grid samples spaced 100 m × 100 m distance using geospatial techniques and geo-statistics. Soil microbial biomass carbon (MBC) ranged from 19.7 to 519.7 µg g-1 with standard deviation of 84.1 and soil DHA varied from 1.2 to 17.2 µg TPF g-1 dry soil hr-1 with sample variance of 10.89. Soil MBC and DHA had high data viability with coefficient of variation (CV) of 42.5 % and 53.2%, respectively. The best fit semivariogram for both soil MBC and DHA was exponential model and had practical spatial range of 1500 m and 1473 m respectively. Environmental disturbances or extrinsic factors dominantly influenced the spatial variability of soil MBC, expressing its weak spatial dependency. Besides, both soil structural/internal factors and extrinsic factors controlled soil DHA variability with moderate level of spatial dependency. Spatial variability map of soil MBC and DHA, prepared with good accuracy through ordinary kriging in GIS software, showed that major area of the farm had soil MBC ranging from 150 to 250 mg kg-1 and had DHA from 1.2 to 10 µg TPF g-1 dry soil hr-1.

Soil microbiological indicators in Coffea arabica crops under different weed management strategies

Soil microbiological indicators in Coffea arabica crops under different weed management strategies

Soybean response to organic fertilizer based on bird manure

Organic fertilizers based on chicken manure have a diverse composition of basic nutrients and microelements, which is their advantage over mineral fertilizers. The introduction of organic fertilizers obtained based on chicken manure improves the biological activity of the soil. The study aims to determine the effectiveness of using bird droppings as an organic fertilizer to conserve soil bioresources and increase soybean productivity. In the course of the work, the authors tested new organic fertilizers based on chicken manure obtained using a cavitationvortex heat generator by processing semi-dry manure. Their influence on soil microbiological indicators, growth, development, and biometric characteristics of soybean plants, phytosanitary condition of crops, productivity, and product quality was revealed. The authors also found that fertilizers based on chicken manure help to improve the microbiological characteristics of the soil, which increases the availability of nutrients for plants. The authors note a change in the number of mycomycetes at the beginning of the growing season: a decrease of 68% with the use of Preparation 1 and an increase of 35.6% with the use of nitrogen fertilizers. Pre-sowing introduction of preparations into the soil and processing during the growing season activate the vegetative development of plants and contribute to an increase in the yield of green mass and grain. The greatest effect was obtained when preparation 2 was applied under soybean. The increase in soybean grain yield was 0.2–0.3 t/ha or 8–14% of the control. The authors also found that treatment with drugs improves the structural parameters of soybean plants: the number of beans per plant increases by 6–8%; by 18–23% - the mass of grains from one plant; the safety of plants for harvesting increases by 2–4%.

Food and agricultural wastes-derived biochars in combination with mineral fertilizer as sustainable soil amendments to enhance soil microbiological activity, nutrient cycling and crop production

The ever-increasing human population associated with high rate of waste generation may pose serious threats to soil ecosystem. Nevertheless, conversion of agricultural and food wastes to biochar has been shown as a beneficial approach in sustainable soil management. However, our understanding on how integration of biochar obtained from different wastes and mineral fertilizers impact soil microbiological indicators is limited. Therefore, in the present study the effects of agricultural (AB) and food waste derived (FWB) biochars with and without mineral fertilizer (MF) on crop growth and soil health indicators were compared in a pot experiment. In particular, the impacts of applied amendments on soil microbiological health indicators those related to microbial extracellular (C, N and P acquiring) enzymes, soil basal as well as different substrate induced respirations along with crop’s agronomic performance were explored. The results showed that compared to the control, the amendment with AB combined with MF enhanced the crop growth as revealed by higher above and below ground biomass accumulation. Moreover, both the biochars (FWB and AB) modified soil chemical properties (pH and electric conductivity) in the presence or absence of MF as compared to control. However, with the sole application of MF was most influential strategy to improve soil basal and arginin-induced respiration as well as most of the soil extracellular enzymes, those related to C, N and P cycling. Use of FWB resulted in enhanced urease activity. This suggested the role of MF and FWB in nutrient cycling and plant nutrition. Thus, integration of biochar and mineral fertilizers is recommended as an efficient and climate smart package for sustainable soil management and crop production.

Microplastics persist in an arable soil but do not affect soil microbial biomass, enzyme activities, and crop yield

AbstractBackgroundMicroplastics (MP, plastic particles <5 mm) are ubiquitous in arable soils due to significant inputs via organic fertilizers, sewage sludges, and plastic mulches. However, knowledge of typical MP loadings, their fate, and ecological impacts on arable soils is limited.AimsWe studied (1) MP background concentrations, (2) the fate of added conventional and biodegradable MP, and (3) effects of MP in combination with organic fertilizers on microbial abundance and activity associated with carbon (C) cycling, and crop yields in an arable soil.MethodsOn a conventionally managed soil (Luvisol, silt loam), we arranged plots in a randomized complete block design with the following MP treatments (none, low‐density polyethylene [LDPE], a blend of poly(lactic acid) and poly(butylene adipate‐co‐terephthalate) [PLA/PBAT]) and organic fertilizers (none, compost, digestate). We added 20 kg MP ha–1 and 10 t organic fertilizers ha–1. We measured concentrations of MP in the soil, microbiological indicators of C cycling (microbial biomass and enzyme activities), and crop yields over 1.5 years.ResultsBackground concentration of MP in the top 10 cm was 296 ± 110 (mean ± standard error) particles <0.5 mm per kg soil, with polypropylene, polystyrene, and polyethylene as the main polymers. Added LDPE and PLA/PBAT particles showed no changes in number and particle size over time. MP did not affect the soil microbiological indicators of C cycling or crop yields.ConclusionsNumerous MP occur in arable soils, suggesting diffuse MP entry into soils. In addition to conventional MP, biodegradable MP may persist under field conditions. However, MP at current concentrations are not expected to affect C turnover and crop yield.

Microbiological Attributes and Performance of the Bacterial Community in Brazilian Cerrado Soil with Different Cover Crops

Soil microbiological indicators are essential tools to understand how the management with cover crops interferes in the activity and the soil microbial community. Thus, the objective of the study was to evaluate microbiological attributes and performance of the bacterial community in the soil of the Brazilian Cerrado with different cover crops. The experiment was performed in a randomized block design, evaluating seven cover crops, Sorghum bicolor, Crotalaria ochroleuca, Pennisetum americanum, Panicum miliaceum, Raphanus sativus, Urochloa brizantha, Urochloa ruziziensis, and a fallow area. Cover aerial biomass dry weight (CB), microbial biomass carbon (MBC), basal soil respiration (BR), metabolic quotient (qCO2), and abundance and structure of bacterial community based on the rrs 16S rRNA gene were evaluated. In the soil cultivated with S. bicolor there was the highest CB and MBC at the same time as there was less microbial activity (lower BR and qCO2). The structure of the bacterial community was more differentiated in soils cultivated with S. bicolor, P. americanum, and C. ochroleuca. The MBC was more associated with cover crops of the Urochloa genus, while BR was positively correlated with S. bicolor. Bacterial abundance was positively correlated with P. miliaceum.

Soil biological attributes in monoculture and integrated systems in the Cerrado region of Piauí State, Brazil

The implementation of integrated agricultural production systems is considered a promising strategy for sustainable agricultural intensification in Brazil. This study aimed to evaluate the effects of different monoculture and integrated production systems on the microbiological attributes and organic carbon of soil from the Cerrado region in Piauí, Brazil. Soil samples were collected from the 0.0-0.10-m layer in the following systems: no-tillage (PD), pasture (PAS), exclusive eucalyptus cultivation (CEE), integrated livestock-forest system (IPF) and a native Cerrado (CN) area, which was used as reference. Total organic carbon (TOC) and nitrogen (NT) contents, microbial biomass carbon (CMIC), microbial respiration (MR), microbial quotient (qMIC), metabolic quotient (qCO2), as well as the activities of the hydrolysis of fluorescein diacetate (FDA), acid phosphatase, β-glucosidase and urease enzymes were evaluated. High TOC contents were found in the CEE, IPF and PAS systems, and high CMIC and qMIC values were found in the CN and CEE systems. The variables MR, qCO2 and enzymatic activity varied as a function of the management systems. The IPF and CEE systems caused improvements in the soil attributes, with increases in organic carbon and microbial biomass. The IPF integrated production system promoted improvements in the microbiological indicators of soil quality and was considered an environmentally sustainable agricultural production system. The transition from CN to agricultural areas caused changes in the soil microbiological indicators, which were perceived several years after anthropogenic intervention, indicating that even with the adoption of conservation systems, it was not possible to reestablish the soil microbial biomass.

SOIL-MICROBIOLOGICAL METHODS IN MONITORING OF NEAR-LAKE ECOSYSTEMS OF THE WESTERN BAIKAL REGION

The article analyzes the main characteristics of the state and metabolic activity of the biomass of soil microorganisms in the ecosystems of the near-lake salt meadows and dry steppes of the Western Baikal region. It is shown that during the transition from semi-hydromorphic soils (lake salonchak) to automorphic soils (chestnut soils of dry steppes), the levels of moisture and salinity decrease. Changes in soil properties lead to a significant transformation of the soil microbiocenosis. The study demonstrated that such soil-microbiological indicators as the carbon content in the biomass of soil microorganisms, basal respiration and specific metabolic activity, estimated by the value of the metabolic coefficient, can be successfully used in the practice of environmental monitoring of the near lake areas of the Tazheran steppe.

Microbiological indicators of soil quality are related to greater coffee yield in the Brazilian Cerrado region

Abstract One of the main challenges faced by the rapidly growing human population is to increase agricultural sustainability. Soil quality is an essential aspect of agricultural sustainability, but farmers have generally assessed this based on conventional chemical and physical indicators, with little application of indicators of soil functions, such as soil microbiological attributes. These indicators may respond faster to changes in soil conditions and thus they could correlate better with the growth/yield of crops such as coffee. The aim of this study was to investigate the potential of soil microbiological indicators in assessment of soil quality for sustained coffee production, compared to or combined with conventional soil physical and chemical indicators. To accomplish that, two observational studies were performed by measuring soil microbiological, physical, and chemical attributes in coffee field areas with contrasting records of coffee yield but under similar edaphic and climatic conditions in the Cerrado (Brazilian tropical savanna) region of Minas Gerais, Brazil. In the first study, two neighboring field areas with contrasting yield were selected for each of the following three cultivars: Catuai Vermelho IAC 99, Catuai Vermelho IAC 144, and Rubi MG 1192. Samples were taken in two seasons (dry and rainy) of the year. In the second study, four neighboring field areas cropped with the cultivar Catuai Vermelho IAC 144 were chosen based on their contrasting yield records. In both studies, the experimental procedure consisted of collecting four composite soil samples (each composed of four subsamples) taken at a depth of 0–10 cm from each field area within the area of canopy projection of the coffee plant. The microbiological attributes evaluated were microbial biomass carbon; microbial basal respiration; metabolic quotient; urease, β-glucosidase, and arylsulfatase enzyme activities; and fluorescein diacetate hydrolysis. The physical and chemical attributes evaluated were texture, pH, organic matter content, and fertility. Climatic conditions affected the responses and must be considered in evaluation and elaboration of soil quality indexes. The physical and chemical attributes that were most closely related to higher coffee yields were Ca contents, organic matter content, effective cation exchange capacity, and base saturation in both studies in the rainy season. Microbial biomass carbon, metabolic quotient, and β-glucosidase and urease activities were positively related to higher coffee yields, and these attributes exhibited greater ability to discriminate the production potential of the soil than chemical and physical attributes did, in both seasons and studies.

Визначення мікроелементного складу ґрунту за його мікробіологічними та біохімічними показниками трансформації сполук циклу нітрогену

By results of information and analytical researches it was established high informational content of soil microbiological indicators, the reflecting direction and intensity of microbiological processes of nitrogen-containing compounds; the predictive value of indicators of soils integrated biochemical processes that are associated with transformation of soil nitrogen compounds; the effectiveness of using the established informativeness and predictive value of microbiological and biochemical indicators in the various types of soils nitrogen-containing compounds transformation for forecasting of the microelement status and simultaneous account the functional diversity of soil processes. The new method of different genesis soils microelement composition determination is grounded taking into account the orientation of microbiological transformation processes of nitrogen-containing substances, interaction of microbiological and biochemical components of nitrogen compounds of soils. The elaborated algorithm of the method includes: sampling, analysis and data acquisition; determination of soils microelement composition, their microbiological (indicators of the number of basic ecological-trophic microorganisms groups) and biochemical (integral biochemical parameters – non-symbiotic nitrogen fixation, ammonification and nitrification of soil) of the components of nitrogen compounds obtained by known methods; prediction of the soils elemental composition by regression equations, followed by the extension of the metod algorithm to the basic trace elements / heavy metals and soils of different types of a certain natural-climatic zone in the conditions of technogenic pollution and technological load. Due to the use of mathematical and statistical analysis, the establishing of new quantitative relationships of diagnostic indicators of the chemical and biological state of soils provides universality, increase informativeness, accuracy, expressiveness of the method in the background (natural) conditions, the impact of technological load, risk and the presence of technogenic pollution for soils quality management based on microelement composition and soil biogenicity. The patent protection method (patent for utility model № 124819 UA, 2018) provides the expressiveness of prediction of the soils microelement status and biogenicity; increase of accuracy and predictability of the soils qualitative state for the microelement composition.

Evaluation of optimal straw incorporation characteristics based on quadratic orthogonal rotation combination design

AbstractFor straw incorporation, three crucial factors affect the soil microbial community and various enzyme activities: straw length, amount and burial depth. To analyse the individual and interactive effects of these three factors on the soil microbial community and various enzyme activities, 23 treatments with five levels of the three variables (straw length, amount and burial depth) were applied in a quadratic orthogonal rotation combination design. A comprehensive indicator was constructed that could represent soil microbial functional diversity and enzyme activity by determining the weights of measured indicators and using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The results indicated that the soil microbiological indicators have a higher criteria weight than soil enzyme activity indicators. The final weight orders of indicators were as follows: Shannon–Weaver > invertase > Shannon evenness > urease > catalase > McIntosh index > Simpson diversity > phosphatase. The soil comprehensive values constructed by the TOPSIS method are reliable. The optimal combination for the improvement of soil microbial functional diversity and enzyme activity was a straw length of 13–24 cm, burial depth of 10–17 cm and straw amount of 370–650 g/m2.

Soil micro-biological indicators separated land use practices in contrast to abiotic soil properties at the 50 km scale under summer warm Mediterranean climate in northern Italy

Soil abiotic properties represent important framing conditions of ecosystems and soil microbiological biomass and microbial activity are the biological driving forces that respond sensitive to environmental impacts. In environmental research and monitoring programmes, approaches for spatial classification were elaborated poorly. Therefore, soil abiotic and microbiological indicators were clustered for a 2965km2 region in northern Italy with the aim to identify the key spatial characteristics. Forty one sampling points for 30cm soil depth were selected at the European Grid of the Land Use Cover Area frame Statistical survey (LUCAS). Soil abiotic indicators included physical (clay content and soil bulk density) and chemical (Cd, Pb and Hg content, organic carbon and total nitrogen) properties. The values varied between 3–47g clay 100g−1 soil, 1.27–1.62Mgm−3, 0.69–3.47g organic C 100g−1 soil and 0.07–0.31g total N 100g−1 soil. Our cluster analysis with the abiotic characteristics separated two core classes derived from four clusters. In contrast, soil microbiological indicators including microbial carbon, respiration values and microbial energetic quotients, separated three well-defined core classes derived from five clusters. The microbial properties values ranged between 24–431μg microbial Cg−1 soil and 0.08–1.82μgCO2-Cg−1soilh−1 and corresponded to those in other European agricultural soils. The three soil microbiological classes separated low, typical and high ranges for soil microbial biomass (values <120, 50–250 and >320μg microbial Cg−1 soil), for soil respiration rates (values <0.4, 0.4–0.7, and >1.4μgCO2-Cg−1soilh−1) for metabolic quotient (values <3.5, 3.5–5.0, >5.0, mg CO2-Cg−1Cmich−1) and for microbial C to organic C ratio (values <0.7, 0.5–1.7 and >1.0%). The soil microbiological indicators responded more evidently to land cover and soil management practices while soil abiotic indicators that referred mainly to the framing conditions such as geology and climatic conditions.

A comparison of indexing methods to evaluate quality of horticultural soils. Part II. sensitivity of soil microbiological indicators

Soil is a non-renewable natural resource, considered as the basis for food production. Changes in soil properties may indicate potentially beneficial or degradative effects of a given management practice, so it is important to select the most sensitive soil properties to act as quality indicators. This research evaluated different approaches to selecting soil quality indicators in the construction of soil quality indices (SQIs). The sensitivity of integrative SQIs, constructed by considering diverse chemical, physical, and biological properties, was compared with biological SQIs, using only biochemical and microbiological indicators, to assess soil quality in an intensive horticultural production system under short- and long-term organic and conventional management. The results provided by the SQIs showed that plots under organic management had increase soil quality compared with the conventionally managed plots, independent of the number of years under production. The SQIs integrated by physical, chemical and biological indicators were more sensitive than indices composed only of biological indicators, as they did not reflect the physical properties of the studied plots. The organic amendments had a great influence on the microbial community; therefore, microbiological indices could not provide reliable information on soil quality in production systems with high inputs of organic materials.

Soil microbiological indicators of soil quality in four rice rotations systems

Rice may have negative effects on the soil due to intensive levelling tasks required for flood irrigation. Therefore, rotations including rice influence soil physical, chemical and biological properties differently. In our study, the effects of rotations with rice on biological properties were evaluated and associated with the capacity of the soil to supply N to crops. Furthermore, the relationships among the variables were studied and those most sensitive to detect the resulting changes were determined. The study was conducted on four crop sequences over a 4-year period: rice monoculture (RR), rice–soybean (RS), rice–soybean–maize–soybean (RSMS) and rice–pasture (RP). The four rotations evaluated had a strong effect on soil properties. Principal components analysis showed that RR and the RP rotation were discriminated clearly, while RSMS and RS were in the middle of the biplot, forming two different groups. Microbial biomass N (MBN), potential of N mineralization measured by anaerobic incubations (PMN-AI) and the microbial biomass C to N ratio were the variables that differed most the studied rotations. The PMN-AI variable was positively associated with MBN, microbial biomass C, organic C, total N, urease, and fluorescein diacetate hydrolysis (FDA) variables. The potential of N mineralization measured with hot KCl neither evidenced differences among the evaluated situations nor was associated to the other variables. This is why it is assumed this is not a good soil quality indicator. The differences found in microbial analysis indicate that microbiological variables (MBC, MBN), nitrogen availability index (PNM-AI), and biochemical variables (FDA) were sensitive variables to evaluate soil rotations’ effects and they might be used as good soil quality indicators once their critical values have been determined for different conditions.