scholarly journals Distribution of a Population of Rhizobium leguminosarum bv. trifolii among Different Size Classes of Soil Aggregates

1998 ◽  
Vol 64 (3) ◽  
pp. 970-975 ◽  
Author(s):  
Ieda C. Mendes ◽  
Peter J. Bottomley
Keyword(s):  
Cover Crop ◽  
Rhizobium Leguminosarum ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Red Clover ◽  
Size Class ◽  
Most Probable Number ◽  
Probable Number ◽  
Size Classes ◽  
Soil Population

ABSTRACT A combination of the plant infection-soil dilution technique (most-probable-number [MPN] technique) and immunofluorescence direct count (IFDC) microscopy was used to examine the effects of three winter cover crop treatments on the distribution of a soil population ofRhizobium leguminosarum bv. trifolii across different size classes of soil aggregates (<0.25, 0.25 to 0.5, 0.5 to 1.0, 1.0 to 2.0, and 2.0 to 5.0 mm). The aggregates were prepared from a Willamette silt loam soil immediately after harvest of broccoli (September 1995) and before planting and after harvest of sweet corn (June and September 1996, respectively). The summer crops were grown in soil that had been either fallowed or planted with a cover crop of red clover (legume) or triticale (cereal) from September to April. The Rhizobiumsoil population was heterogeneously distributed across the different size classes of soil aggregates, and the distribution was influenced by cover crop treatment and sampling time. On both September samplings, the smallest size class of aggregates (<0.25 mm) recovered from the red clover plots carried between 30 and 70% of the total nodulatingR. leguminosarum population, as estimated by the MPN procedure, while the same aggregate size class from the June sampling carried only ∼6% of the population. In June, IDFC microscopy revealed that the 1.0- to 2.0-mm size class of aggregates from the red clover treatment carried a significantly greater population density of the successful nodule-occupying serotype, AR18, than did the aggregate size classes of <0.5 mm, and 2 to 5 mm. In September, however, the population profile of AR18 had shifted such that the density was significantly greater in the 0.25- to 0.5-mm size class than in aggregates of <0.25 mm and >1.0 mm. The populations of two otherRhizobium serotypes (AR6 and AS36) followed the same trends of distribution in the June and September samplings. These data indicate the existence of structural microsites that vary in their suitabilities to support growth and protection of bacteria and that are influenced by the presence and type of plant grown in the soil.

Quality of soil from the nickel mining area of Southeast Sulawesi, Indonesia, engineered using earthworms (Pheretima sp.)

2021 ◽  
Vol 8 (4) ◽  
pp. 2995-3005
Author(s):  
Hasbullah Syaf ◽  
Muhammad Albar Pattah ◽  
Laode Muhammad Harjoni Kilowasid
Keyword(s):  
Tap Water ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Mining Area ◽  
Size Class ◽  
Soil Conditions ◽  
Total N ◽  
Organic C ◽  
Size Classes ◽  
Nickel Mining

Earthworms (Pheretima sp.) could survive under abiotic stress soil conditions. Furthermore, their activities as ecosystem engineers allow for the creation of soil biostructures with new characteristics. Therefore, this study aimed to investigate the effect of the abundance of Pheretima sp. on the aggregate size, physicochemistry, and biology of the topsoil from the nickel mining area of Southeast Sulawesi, Indonesia. It was carried out by first grouping their abundance into zero, two, four, six, and eight individuals per pot and then carrying out tests. The Pheretima sp. were then released onto the surface of the topsoil and mixed with biochar that was saturated with tap water in the pot overnight. The results showed that the abundance of the species had a significant effect on the size class distribution, and aggregate stability of the soil. Furthermore, the size of the soil aggregates formed was dominated by the size class 2.83 - 4.75 mm under both dry and wet conditions. Under dry conditions, three size classes were found, while under wet conditions, there were five size classes. The results also showed that the highest and lowest stability indexes occurred with zero and eight Pheretima sp., respectively. Furthermore, the abundance had a significant effect on pH, organic C, total N, CEC, and total nematodes. However, it had no significant effect on the total P, C/N ratio, total AMF spores, and flagellate. The highest soil pH occurred with zero Pheretima sp., while with six and two members of the species, the total nematode was at its highest and lowest populations, respectively. Therefore, it could be concluded that the species was able to create novel conditions in the topsoils at the nickel mining area that were suitable for various soil biota.

scholarly journals Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates

Soil Systems ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Daphne Topps ◽  
Md Imam ul Khabir ◽  
Hagir Abdelmagid ◽  
Todd Jackson ◽  
Javed Iqbal ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Cover Crop ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Control Treatment ◽  
Hairy Vetch ◽  
Vicia Villosa ◽  
Size Classes ◽  
Oilseed Radish

Cover crops are considered an integral component of agroecosystems because of their positive impacts on biotic and abiotic indicators of soil health. At present, we know little about the impact of cover crop types and diversity on the organic carbon (OC) contents of different soil aggregate-size classes. In this study, we investigated the effect of cover plant diversity on OC contents of different soil aggregates, such as macro- (<2000–500 μm), meso- (<500–250 μm), and micro-aggregates (<250 μm). Our experiment included a total of 12 experimental treatments in triplicate; six different monoculture treatments such as chickling vetch (Vicia villosa), crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), field peas (Pisum sativum), oilseed radish (Raphanus sativus), and mighty mustard (Brassica juncea), and their three- and six-species mixture treatments, including one unplanted control treatment. We performed this experiment usingdeep pots that contained soil collected from a corn-soybean rotation field. At vegetative maturity of cover plants (about 70 days), we took soil samples, and the soil aggregate-size classes were separated by the dry sieving. We hypothesized that cover crop type and diversity will improve OC contents of different soil aggregate-size classes. We found that cover plant species richness weakly positively increased OC contents of soil macro-aggregates (p = 0.056), whereas other aggregate-size classes did not respond to cover crop diversity gradient. Similarly, the OC contents of macroaggregates varied significantly (p = 0.013) under cover crop treatments, though neither monoculture nor mixture treatments showed significantly higher OC contents than the control treatment in this short-term experiment. Interestingly, the inclusion of hairy vetch and oilseed radish increased and decreased the OC contents of macro- and micro-aggregates, respectively. Moreover, we found a positive correlation between shoot biomass and OC contents of macroaggregates. Overall, our results suggest that species-rich rather than -poor communities may improve OC contents of soil macroaggregates, which constitute a major portion of soil systems, and are also considered as important indicators of soil functions.

Diversity and symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii isolates from pasture soils in south-western Australia

Soil Research ◽  
2002 ◽  
Vol 40 (8) ◽  
pp. 1319 ◽  
Author(s):  
M. T. Collins ◽  
J. E. Thies ◽  
L. K. Abbott
Keyword(s):  
Western Australia ◽  
Rhizobium Leguminosarum ◽  
Subterranean Clover ◽  
Most Probable Number ◽  
Enzyme Linked Immunosorbent Assay ◽  
Symbiotic Effectiveness ◽  
Probable Number ◽  
Pcr Fingerprinting ◽  
Rapd Pcr ◽  
Inoculant Strain

The abundance of the Australian inoculant strain of Rhizobium leguminosarum bv. trifolii for subterraneum clover (WU95) and the diversity of naturalised rhizobia were assessed in 3 subterranean clover pastures in the Albany region of south-western Western Australia. Most probable number, enzyme linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) techniques were used. A putative strain similar to inoculant strain WU96 was uncommon at one site (South Stirling) and not isolated at 2 other sites. Randomly amplified polymorphic DNA (RAPD) PCR fingerprinting using the RPO1 primer identified 45 different profiles amongst the 208 isolates examined. RAPD-PCR fingerprinting using the primers RPO4 and RPO5 confirmed most groupings based on RPO1 fingerprint patterns and revealed further genetic diversity within some groups. Overall, 54 putative strains were defined by RAPD-PCR fingerprint profiles across the 3 sites. Subterranean clover rhizobia at the Manypeaks and Mount Shadforth sites were dominated by isolates with 1 or 2 RPO1 RAPD profiles at 2 sampling times, while the population at South Stirling was much more diverse. The symbiotic effectiveness of 11 rhizobial isolates, representing the major RPO1 RAPD profile groups within naturalised rhizobial populations, were compared in pot culture with those of the 2 commercial inoculant strains for subterranean clover, WU95 and TA1, on 3 cultivars. Differences in effectiveness among 3 of the 11 isolates were observed in comparison to both the commercial strains and other naturalised isolates. The nitrogen fixing effectiveness of 8 isolates representing different subgroups from one RP01 group was not the same. The use of all 3 primers increased the precision in defining putative strains of Rhizobium leguminosarum bv. trifolii, and although naturalised rhizobia from these pastures are saprophytically competent, their dominance in nodules does not appear to be linked to symbiotic effectiveness.

Agronomic and environmental drivers of population size and symbiotic performance of Rhizobium leguminosarum bv. viciae in Mediterranean-type environments

2012 ◽  
Vol 63 (5) ◽  
pp. 467 ◽  
Author(s):  
E. A. Drew ◽  
M. D. Denton ◽  
V. O. Sadras ◽  
R. A. Ballard
Keyword(s):  
Population Size ◽  
Dry Matter ◽  
Rhizobium Leguminosarum ◽  
Field Pea ◽  
Environmental Drivers ◽  
Annual Rainfall ◽  
Maximum Temperature ◽  
Most Probable Number ◽  
Probable Number ◽  
Commercial Strain

The population size and symbiotic performance (ability to fix N2) of rhizobia (Rhizobium leguminosarum bv. viciae) capable of nodulating field pea (Pisum sativum) were assessed in 114 soils from Mediterranean-type environments of southern Australia. All soils were collected in autumn, before the growing season, and had a history of crop legumes including field pea, faba bean, lentil, or vetch. The most probable number (MPN) technique, with vetch as a trap plant, was used to estimate the numbers of pea rhizobia in soils. Of the soils tested, 29% had low numbers of pea rhizobia (<100 rhizobia/g), 38% had moderate numbers (100–1000/g), and the remaining 33% had >1000/g. Soil pH, the frequency of a host crop in the rotation, and the number of summer days with a maximum temperature >35°C were strongly correlated with the pea rhizobia population size. Symbiotic performance (SP) of pea rhizobia in soils was assessed for soils with a MPN >100 rhizobia/g. An extract of the soils was used to inoculate two field pea cultivars growing in a nitrogen-deficient potting media in the greenhouse. Plants were grown for 5 weeks after inoculation and shoot dry matter was expressed as a percentage of the dry matter of plants grown with a commercial strain R. leguminosarum bv. viciae, SU303. Symbiotic performance ranged from 25 to 125%. One-quarter of the soils assessed had suboptimal SP (i.e. <70%). Soil and climatic variables were weakly associated with SP, with pH and average annual rainfall accounting for 17% of the variance. This research highlights the complexity of factors influencing population size and symbiotic performance of pea rhizobia in soils. Options for the improved management of populations of pea rhizobia in Mediterranean environments are discussed. Specifically, our data indicate that inoculation of pea crops is likely to be beneficial where pH(H2O) <6.6, particularly when summers have been hot and dry and when a host has been absent for ≥5 years, as numbers of rhizobia are likely to be below the thresholds needed to optimise nodulation and crop growth. New inoculation technologies and plant breeding will be required to overcome large populations of pea rhizobia with suboptimal SP.

Populations of Rhizobium leguminosarum biovars phaseoli and viceae in fields after bean or pea in rotation with nonlegumes

1989 ◽  
Vol 35 (6) ◽  
pp. 661-667 ◽  
Author(s):  
R. M. N. Kucey ◽  
M. F. Hynes
Keyword(s):  
Rhizobium Leguminosarum ◽  
Most Probable Number ◽  
Inoculum Potential ◽  
Phaseolus Vulgaris L ◽  
Probable Number ◽  
Pisum Sativum L ◽  
Plasmid Profiles ◽  
Southern Alberta ◽  
Rhizobium Competition ◽  
Legume Inoculants

Populations of Rhizobium leguminosarum bv. phaesoli and bv. viceae in southern Alberta soils were measured over a period of 4 years using a most probable number method. Five fields cropped to bean (Phaseolus vulgaris L.), five fields cropped to pea (Pisum sativum L.), and two fields cropped to wheat were used as test sites. Legume crops had received appropriate legume inoculants. Fields were sampled in the fall of the crop year and in the spring of the following 3 years during which fields were cropped to nonlegumes or left fallow. Numbers of R. leguminosarum bv. phaseoli were 100 to 1000 times higher in fields that had been planted to bean than in fields that had been planted to pea or wheat. Fields that had been planted to pea maintained populations of R. leguminosarum bv. viceae 10 to 100 times higher than fields that had been planted to bean or wheat. Wheat fields, which had never had legumes grown in them, contained between 1 and 100 rhizobia per gram of soil of both biovars of R. leguminosarum, indicating that both biovars are native to southern Alberta soils. The numbers of rhizobia did not decrease in proportion to the population of other bacteria in the soil over the duration of the experiment. Plasmid profiles of soil Rhizobium isolates obtained in the last year of the experiment showed that none of the isolates had plasmid profiles similar to those of strains added as inoculants in the 1st year of the experiment. These results show that fields cropped to legumes and receiving rhizobial inoculants in this study maintained high populations of rhizobia for several years after harvest of the legume crop.Key words: Rhizobium leguminosarum bv. phaseoli, Rhizobium leguminosarum bv. viceae, nodule, plasmid profiles, inoculum potential, rhizobium competition.

Evaluation of selected factors influencing aggregate fragmentation using fractal theory

1992 ◽  
Vol 72 (2) ◽  
pp. 97-106 ◽  
Author(s):  
V. Rasiah ◽  
B. D. Kay ◽  
E. Perfect
Keyword(s):  
Fractal Dimension ◽  
Probability Model ◽  
Soil Aggregates ◽  
Fractal Theory ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Red Clover ◽  
Probability Of Failure ◽  
Continuous Corn ◽  
Wet Sieving

Two fractal parameters, probability of failure (P) and fractal dimension (D), were used to evaluate the influence of cropping and wetting treatments, and aggregate size on fragmentation of soil aggregates during wet sieving. Five different sizes of aggregates (4–10, 2–4, 1–2, 0.5–1 and 0.25–0.5 mm) from five cropping treatments [conventionally cultivated continuous corn (CCC), CCC underseeded to red clover (CCR), minimally tilled continuous corn underseeded to red clover (CCRM), alfalfa (AL), and bromegrass (BR)] were subjected to two wetting treatments (rapid and slow) before being wet sieved. P increased nonlinearly with increasing aggregate size. The P of the slowly wetted agggregates was always less than that of the rapidly wetted aggregates. The P of larger aggregates, 2–4 and 4–10 mm, increased in the following order of cropping: BR = AL < CCRM < CCR = CCC. The D for the size distribution of 4- to 10-mm aggregates increased in the same order of cropping as that given previously. The D for the rapidly wetted aggregates was higher than that of the slowly wetted aggregates for all cropping treatments except CCC. The values of P predicted from a fractal probability model correlated well with the observed values. The results show that P and D of soil aggregates are strongly influenced by cropping and wetting treatments and aggregate size. Key words: Probability of failure, fractal dimension, wet sieving, wet aggregate stability, prewetting

Cover crops and nitrogen fertilization effects on soil aggregation and carbon and nitrogen pools

2003 ◽  
Vol 83 (2) ◽  
pp. 155-165 ◽  
Author(s):  
U. M. Sainju ◽  
W. F. Whitehead ◽  
B. P. Singh
Keyword(s):  
Cover Crops ◽  
Nitrogen Fertilization ◽  
Cover Crop ◽  
N Fertilization ◽  
Size Class ◽  
Soil Aggregation ◽  
Total N ◽  
Organic C ◽  
Size Classes ◽  
C And N

Cover crops and N fertilization rates may influence soil aggregation and associated C and N pools, thereby affecting soil quality and productivity. We compared the effects of legume [hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnatum L.)] and nonlegume [rye (Secale cereale L.)] cover crops and N fertilization rates {half N rate [HN: 90 kg N ha-1 yr-1 for 3 yr of tomato (Lycopersicon esculentum Mill.) followed by 80 kg N ha-1 yr-1 for eggplant (Solanum melogena L.)]} and full N rate [FN: 180 kg N ha-1 yr-1 for 3 yr of tomato followed by 160 kg N ha-1 yr-1 for eggplant]} on soil aggregation and C and N pools in whole-soil and aggregates. The pools were organic C, total N, potential C mineralization and potential N mineralization (PCM and PNM), microbial biomass C and microbial biomass N (MBC and MBN), and particulate organic C and particulate organic N (POC and PON). Field experiment was conducted in a Greenville fine sandy loam (fine-loamy, kaolinitic, thermic, Rhodic Kandiudults) from 1995 to 2000 in Fort Valley, Georgia, USA. While the amount of soil present in aggregates decreased with decreasing size class, the amount was greater with nonlegume and FN than with HN and legume cover crops in the 2.00- to 0.85-mm size class. Organic C, PCM, and MBC contents in whole-soil were greater with nonlegume, but MBN and PON were greater with legumes than in the control with no cover crop or N fertilization. Organic C and total N concentrations in aggregates were greater in 2.00- to 0.50-mm than in 4.75- to 2.00-mm, <0.25-mm, or <4.75-mm (whole-soil) size classes, but PNM and MBN were greater in <0.50- or <4.75-mm than in 4.75- to 2.00-mm size classes. As POC and PON decreased with decreasing aggregate-size class, POC in the <0.85-mm size class was greater with nonlegume and PON in the 2.00- to 0.85-mm size classes was greater with legumes than with the control and N rates. Nonlegume may increase soil aggregation, microbial activities, and C sequestration, but legumes may increase N mineralization in the soil compared with no cover crop. Nitrogen fertilization also may improve soil aggregation. Nitrogen mineralization and C and N sequestration may be greater in aggregates <2.00 mm diameter. Cover crops and N fertilization may improve soil quality and productivity, particularly in intermediate and small size (<2.00 mm) aggregates. Key words: Cover crop, nitrogen fertilization, soil aggregation, soil carbon, soil nitrogen

scholarly journals The role of SOM and CaCO3 on soil aggregate development in reclaimed soils

2020 ◽  
Author(s):  
Evelin Pihlap ◽  
Markus Steffens ◽  
Ingrid Kögel-Knabner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Extracellular Polymeric Substances ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Parent Material ◽  
Size Class ◽  
Aggregate Formation ◽  
Structural Formation ◽  
Size Classes

&lt;p&gt;Soil organic matter (SOM) and extracellular polymeric substances (EPS) from biological processes are considered to be major contributors in aggregate formation. But there is limited knowledge on soil structural formation after reclamation &amp;#8211; the step when SOM content is low and soil properties are mostly controlled by the parent material. In our study we used a chronosequence approach in the reclaimed open-cast mining area near Cologne, Germany to elucidate the development of soil structure and soil organic matter during initial soil formation in a loess material. We selected six plots with different ages of agricultural management after reclamation (0, 1, 3, 6, 12, and 24 years after first seeding). In each reclaimed field 12 spatially independent locations were sampled with stainless steel cylinders (100 cm&lt;sup&gt;3&lt;/sup&gt;) at two depths in the topsoil (1-5 cm and 16-20 cm). Samples were wet sieved into four aggregate size classes of &lt;63 &amp;#181;m, 63-200 &amp;#181;m, 200-630 &amp;#181;m and 630-2000 &amp;#181;m. Each aggregate size class was characterized by organic carbon (OC), total nitrogen (TN) and CaCO&lt;sub&gt;3&lt;/sub&gt; concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.&lt;/p&gt;&lt;p&gt;Wet sieving into aggregate size classes showed different trends along the chronosequence. Contradicting relation between CaCO&lt;sub&gt;3&lt;/sub&gt; and OC contribution to aggregate size classes display two different mechanisms on soil aggregate formation in young loess derived soils. CaCO&lt;sub&gt;3&lt;/sub&gt; influenced aggregation predominantly in finer aggregate size classes, where the highest concentration and contribution was measured. SOM, on the other hand, played an important role on formation of large macro-aggregates after organic manure application in year 4. Furthermore, the loss of total OC after year 12 was connected with the loss of OC contributing to the largest aggregate size class. Our findings reveal that SOM and CaCO&lt;sub&gt;3&lt;/sub&gt; role on stabilizing aggregates is not equally distributed and is aggregate size class dependent.&lt;/p&gt;

scholarly journals Effects of Heavy Metal from Polluted Soils on the Rhizobium Diversity

2011 ◽  
Vol 39 (1) ◽  
pp. 88 ◽  
Author(s):  
Vasilica STAN ◽  
Eugenia GAMENT ◽  
Călina Petruţa CORNEA ◽  
Cătălina VOAIDEŞ ◽  
Mirela DUŞA ◽  
...  
Keyword(s):  
Trifolium Pratense ◽  
Red Clover ◽  
Bromothymol Blue ◽  
Most Probable Number ◽  
Ph Change ◽  
Polluted Soils ◽  
Probable Number ◽  
Trifolium Pratense L ◽  
Soil Zn ◽  
Technology Type

Heavy metals adversely influence microorganisms, affecting their growth, abundance, genetic diversity, nodulation ability and efficacy. The aim of this study was to isolate and characterize free-leaving Rhizobium from soil which were artificially polluted with Cu (100, 250, and 500 mg kg-1 soil), Zn (300, 700, and 1500 mg kg-1 soil) and Pb (50, 250, and 1000 mg kg-1 soil), but also with a mixture of all these metals, and cultivated with red clover (Trifolium pratense L.), and to compare them with bacteria isolated from similar type of soil, but unpolluted. Rhizobia from soil were isolated on YMA medium with or without bromothymol blue (0.00125%) as a pH-change indicator and the morpho-physiological characteristics of the colonies were examined. The number of Rhizobium was estimated using the most probable number method. Compared to the control, a decrease of rhizobia number and an increase of the metal concentration were observed. Several decameric primers (Operon Technology type) were used and a reduced polymorphism among isolated bacteria was observed. Moreover, significant differences were observed among these strains and the collection strains used as reference. Also, when primers nodCF/nodCI for detection of nod genes were used, several amplicons were obtained, different from the results obtained with similar strains isolated from unpolluted soil. These results suggest that the survival „price” of the Rhizobium in such polluted area was the alteration of some genes, including those involved in symbiosis and, probably, in nitrogen fixation.

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