Preservation of soil samples for assay of urease activity

doi:10.1016/0038-0717(75)90070-X

Soil Biology and Biochemistry

Volume 7, Issues 4–5, July 1975, Pages 297-299

https://doi.org/10.1016/0038-0717(75)90070-X Get rights and content

Abstract

Studies with 10 soils selected to obtain a wide range in properties indicated that several drying and storage treatments are satisfactory for preserving soil samples for assay of urease activity. The following treatments of field-moist soils had no effect on the values obtained in assay of urease activity: freeze-drying (−60°C) for 60 h; air-drying (22°C) for 48 h; oven-drying (55°C) for 24 h; storage at 20, 5, −10 or −20°C for times ranging from 1 day to 3 months. No change in urease activity occurred when air-dried soils were stored at 21–23°C for times ranging from 1 week to 1 year.

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With the utilization of pesticides and fertilizers (e.g. urea), the presence of nitrogen and heavy metals (e.g. copper) can enter and pollute the environment. Biofertilizers can be used to replace chemical fertilizers to increase crop yields and reduce environmental stress. The utilization of hydrogen-oxidizing bacteria (HOB) to be biofertilizers has recently attracted more attention. However, the enrichment of HOB on urea and the effect of copper are undetermined. HOB were successfully enriched using urea in this investigation. The average urea conversion rate (AUCR) was 180.08 mgN/L/d with a hydraulic retention time of 10 h. Microbial community (R₁) was dominated by Hydrogenophaga (83.92%), a biofertilizer-type HOB. After addition of 5.47 mg/L Cu²⁺, the AUCR was decreased by 16%–151.18 mgN/L/d, and the growth of HOB was inhibited by 48%. Meanwhile, inhibition was also reflected by the increase of polysaccharide content (20.27 ± 0.57 to 33.45 ± 2.53 mg/gVSS) and protein content (106.19 ± 19.39 to 125.14 ± 24.73 mg/gVSS) of extracellular polymeric substances in the HOB. The resulting microbial community (R₂) was changed to Azospiralium-dominated flora (91.33%). Both enriched microbial communities (R₁ and R₂) exhibited the abilities of ACC degradation and phosphate solubilization. This study demonstrates that employing urea can directly enrich biofertilizer-type HOB and copper-tolerant HOB can be obtained in a 5.47 mg/L Cu²⁺ environment. The results provide potential methods to obtain biofertilizer from copper-containing urea wastewater via HOB.
Effects of resin tapping on ectomycorrhizal fungal community composition and structure of Pinus massoniana in subtropical mountain forest ecosystems in southwestern China
2023, Forest Ecology and Management
Although resin tapping is an important management practice in Pinus massoniana plantation, our understanding of its influence on symbiotic ectomycorrhizal fungal (EMF) communities associated with P. massoniana remains limited. To determine the effect of resin tapping on the EMF community, this study observed the EMF community in resin-tapped (RT) and resin-untapped (NRT) P. massoniana plantation using community surveys, soil property analysis, and mycorrhizal identification. A total of 49 operational taxonomic units (OTUs), belonging to 15 families and 18 genera, were identified. At the phylum level, the relative abundance of Basidiomycota and Ascomycota accounted for 82.46% and 17.54% of the total population, respectively. Resin tapping significantly altered the composition and structure of the EMF community of P. massoniana, and the number of endemic OTUs was higher than that of the shared OTUs. Lactarius and Tomentella were dominant in RT plantation, and Russula and Tomentella were dominant in NRT plantations. There was no significant difference in the alpha diversity of EMF communities between RT and NRT Plantation. Principal coordinates analysis revealed marked differences in the composition of EMF communities between R and NR plantation. Canonical correspondence analysis showed that available K, total N, and urease were important factors influencing the EMF community of P massoniana. In conclusion, resin tapping affects the composition and structure of EMF communities associated with P. massoniana plantation in subtropical mountain ecosystems.
Over two years study: Peanut biochar promoted potassium availability by mediating the relationship between bacterial community and soil properties
2022, Applied Soil Ecology
Citation Excerpt :
All K forms were determined by a flame photometer (AP-1200, Shanghai Precision Instrument Co., China). The activities of soil urease and dehydrogenase were determined by a soil kit (Jiangsu Meibiao Biotechnology Co., Ltd) (Zantua and Bremner, 1975). Specifically, 9 mL of neutral phosphate buffer were mixed with 1 g of randomly selected fresh soil and incubated at 4 °C for 20 min at a speed of 2500 r/min before collecting the supernatant for enzyme activities using soil enzyme kits (Jiangsu Meibiao Biotechnology Co., Ltd).
In acidic soil, potassium (K) deficiency is a main limiting factor that restricts the growth of fruit trees. Biochar has been used as a soil amendment to increase pH and nutrients. However, studies on the effect of biochar on the bacterial community and soil properties in potted experiments are limited. Therefore, we used peanut shell biochar to investigate the effect of biochar on the structure and function of bacterial communities by high-throughput sequencing, soil enzymes (urease, dehydrogenase, and extracellular enzymes), and gene function prediction in response to K deficiency in acidic soil. The results indicated that soil pH, enzyme activity, and available nutrients were improved by biochar. In particular, biochar still had a beneficial effect on improving soil and plant K levels after thirty months of application. In addition, biochar promoted the growth of K-dissolving bacteria and relative abundance of bacteria (p_actinomycetes, p_chloroflexi, p_proteobacteria, p_acidobacteriota, and p_firmicutes). Based on the above results, we assumed that biochar application can effectively improve soil K levels and bacterial functions. Such as: K-dissolving, soil organic matter decomposition and the conversion of nutrients. Our findings encourage and support the use of biochar as an amendment in acidic soil.
The combination of biochar and plant roots improves soil bacterial adaptation to PAH stress: Insights from soil enzymes, microbiome, and metabolome
2020, Journal of Hazardous Materials
Citation Excerpt :
The soil samples for biological analysis were stored at −80 °C. Soils were air-dried prior to determination of the activities of the two soil enzymes, dehydrogenase and urease (Zantua and Bremner, 1975). To measure dehydrogenase activity, the soil dehydrogenase (S-DHA) kit was used.
Polycyclic aromatic hydrocarbon (PAH) contamination in agricultural soils poses serious stress to the soil microbiome. With the broad application of biochar, however, the co-effects of biochar and plant roots on the bacterial responses to PAH stress remain unclear. Here, the effects of biochar and the rhizosphere on bacterial community structure and functions were analyzed by coupling enzyme activity tests, high-throughput sequencing, and soil metabolomics. The contents of available nutrients and dissolved organic carbon, enzyme activities, and carbon metabolism functions were improved by biochar and plant roots. With the combined effects of biochar and plant roots, sucrose and starch metabolism was mainly impacted, and the soil metabolite diversity decreased. There was a strong co-occurrence network among soil properties, bacterial members, and metabolites in the biochar-amended and rhizosphere soils, favoring bacterial resistance to PAH stress, and consequently, PAH removal. In light of the above results, we suggest that biochar application can efficiently improve bacterial functions in rhizosphere soil, and our results facilitate the development of in situ remediation programs in soil contaminated with PAHs.
Factors controlling accumulation of soil organic carbon along vegetation succession in a typical karst region in Southwest China
2015, Science of the Total Environment
Citation Excerpt :
Urease activity was the most important enzyme type that affected SOC in the early stages (grassland and shrubland), both SAC and urease activity played a significant role in the secondary forest stage, and only SAC played a significant role in the primary forest stage. Urease is an important enzyme involved in the process of nitrogen supply, by transforming organic nitrogen to ammonium nitrogen (Zantua and Bremner, 1975; Zhou et al., 1983). Urease-producing bacteria release abundant URE to accelerate the N mineralization rate to meet their mineral N needs in N-poor soils.
Vegetation succession enhances the accumulation of carbon in the soil. However, little is known about the mechanisms underlying soil organic carbon (SOC) accumulation in different vegetation types in the karst region of Southwest China. The goal of this study was to identify and prioritize the effects of environmental parameters, including soil physico-chemical properties, microbial biomass, enzyme activities, and litter characteristics, on SOC accumulation along a vegetation succession sere (grassland, shrubland, secondary forest, and primary forest) in the karst landscape of Southwest China. Relationships between these parameters and SOC were evaluated by redundancy analysis. The results showed that SOC accumulation was significantly different among vegetation types (P < 0.01) and increased with vegetation succession (from 29.10 g·kg^− 1 in grassland to 73.92 g·kg^− 1 in primary forest). Soil biochemistry and physical characteristics significantly affected the accumulation of SOC. Soil microbial biomass showed a predominant effect on SOC in each of the four vegetation types. In addition, the soil physical property (especially the silt content) was another controlling factor in the early stages (grassland), and urease activity and saccharase activity were important controlling factors in the early-middle and middle-late stages, respectively. Litter characteristics only showed mild effects on SOC accumulation. Variation partitioning analysis showed that the contribution of sole main factors to SOC variation decreased, while the interaction effect among parameters increased along the succession gradient.
Spatial variability of phosphatase, urease, protease, organic carbon and total nitrogen in soil
1991, Soil Biology and Biochemistry
The spatial variability or urcase, phosphatase, casein-hydrolysing activities, organic C and total N was evaluated in a 5 yr old grass-legume association.
Twenty four soil samples from the superficial layer (0–20 cm) were collected from a 15 x 40 m meadow. Samples were air-dried, sievedand then stored at room temperature for I yr before being analysed. The enzymatic activities found after this time period are considered to be mainly due to enzymes protected and stabilized by their associaton or entrapment with clay minerals and humic molecules.
Four different procedures of statistical analysis were carried out: Analysis of Variance, statistical comparison of Coefficients of Variation. Principal Components Analysis and Proximities Analysis.
With euch procedure, urcase activity was the most variable parameter and total N the least variable parameter. Phosphatase and casein-hydrolysing activities showed a similar variability. Organic C was the least variable property when a comparison among the coefficients of variation of the means was carried out. hut it was the most variable property when using the analysis of variance test. These contrasting results can be explained by the fact that organic C analytical variability is so low as to make its effective spatial variability very important.
Phosphalase was correlated with protcasc and total N (P < 0.001) and with organic C (P < 0.005). Protease was correlated with organic C (P < 0.005) and total N (P <0.01). Total N was correlated with organic C (P < 0.05). The sign of all these correlations was positive.
Newman Keuls multiple range test and Principal Components analysis gave complex patterns of between sample differences.

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Preservation of soil samples for assay of urease activity

Abstract

Soil Biol. Biochem.

Soil Biol. Biochem.

Factors affecting urea hydrolysis in several Alberta soils

Pl. Soil

A survey of urease activity in soils of northern New South Wales

Pl. Soil

Effect of storage conditions on activities of urease, invertase, amylase, and dehydrogenase in soil