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

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.

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

Applied and Environmental Microbiology ◽

10.1128/aem.64.3.970-975.1998 ◽

1998 ◽

Vol 64 (3) ◽

pp. 970-975 ◽

Cited By ~ 29

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.

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

Canadian Journal of Soil Science ◽

10.4141/s02-056 ◽

2003 ◽

Vol 83 (2) ◽

pp. 155-165 ◽

Cited By ~ 94

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

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Effects of reclamation years on composition and diversity of soil bacterial communities in Northwest China

Canadian Journal of Microbiology ◽

10.1139/cjm-2017-0362 ◽

2018 ◽

Vol 64 (1) ◽

pp. 28-40 ◽

Cited By ~ 9

Author(s):

Zhibo Cheng ◽

Fenghua Zhang ◽

William Jeffrey Gale ◽

Weichao Wang ◽

Wen Sang ◽

...

Keyword(s):

Bacterial Communities ◽

Phylogenetic Diversity ◽

Aggregate Size ◽

Soil Aggregate ◽

Soil Electrical Conductivity ◽

Soil Organic C ◽

Organic C ◽

Size Classes ◽

Soil Bacterial Communities ◽

Soil Bacterial

The objective of this study was to evaluate bacterial community structure and diversity in soil aggregate fractions when salinized farmland was reclaimed after >27 years of abandonment and then farmed again for 1, 5, 10, and 15 years. Illumina MiSeq high-throughput sequencing was performed to characterize the soil bacterial communities in 5 aggregate size classes in each treatment. The results indicated that reclamation significantly increased macro-aggregation (>0.25 mm), as well as soil organic C, available N, and available P. The 10-year field had the largest proportion (93.9%) of soil in the macro-aggregate size classes (i.e., >0.25 mm) and the highest soil electrical conductivity. The 5 most dominant phyla in the soil samples were Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria, and Bacteroidetes. The phylogenetic diversity, Chao1, and Shannon indices increased after the abandoned land was reclaimed for farming, reaching maximums in the 15-year field. Among aggregate size classes, the 1–0.25 mm aggregates generally had the highest phylogenetic diversity, Chao1, and Shannon indices. Soil organic C and soil electrical conductivity were the main environmental factors affecting the soil bacterial communities. The composition and structure of the bacterial communities also varied significantly depending on soil aggregate size and time since reclamation.

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Cultivation effects on dispersible clay of soil aggregates

Canadian Journal of Soil Science ◽

10.4141/cjss95-013 ◽

1995 ◽

Vol 75 (1) ◽

pp. 101-107 ◽

Cited By ~ 18

Author(s):

L. G. Fuller ◽

Tee Boon Goh ◽

D. W. Oscarson

Keyword(s):

Soil Aggregates ◽

Aggregate Size ◽

Exchange Capacity ◽

Exchangeable Cations ◽

Organic C ◽

Size Fractions ◽

Clay Dispersion ◽

Native Prairie ◽

Exchangeable Ca

The objective of this study was to examine the effect of long-term cultivation on clay dispersibility of four aggregate size fractions (2.0–9.5 mm, 0.85–2.0 mm, 0.25–0.85 mm, and < 0.25 mm) obtained from a Chernozemic soil by comparing two cultivated sites with an adjacent native prairie site. Aggregate size fractions (ASF) were subjected to increasing levels of ultrasonic energy and the amount of clay dispersed at each energy level was determined. Organic carbon, hexose carbon, soluble hexose C, total clay, cation exchange capacity (CEC), and exchangeable cations were measured for each ASF. Clay contained within prairie aggregates was held much more strongly within the aggregate and therefore showed greater stability towards dispersion by ultrasonic vibration. More energy was required to disperse one-half of the ASF clay under prairie than under cultivated soils (228–425, and 95–229 kJ L−1 for prairie and cultivated macroaggregates, respectively; 370–433, and 249–334 kJ L−1 for prairie and cultivated microaggregates, respectively). Clay dispersibility was significantly correlated with organic C, hexose C, soluble hexose C, non-hexose C, CEC, and exchangeable Ca and Mg but was not correlated with total ASF clay. Long-term cultivation of this soil resulted in a decrease in the energy required to disperse an equivalent proportion of clay from aggregates relative to that of the grassland soil. Thus, cultivation of these soils has resulted in aggregates which are more susceptible to clay dispersion and therefore prone to water erosion and surface crusting. Key words: Clay dispersion, aggregation, carbohydrate

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

Soil Systems ◽

10.3390/soilsystems5030043 ◽

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.

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

10.5194/egusphere-egu2020-13644 ◽

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

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 &#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 cm3) at two depths in the topsoil (1-5 cm and 16-20 cm). Samples were wet sieved into four aggregate size classes of <63 &#181;m, 63-200 &#181;m, 200-630 &#181;m and 630-2000 &#181;m. Each aggregate size class was characterized by organic carbon (OC), total nitrogen (TN) and CaCO3 concentration. The chemical composition of the SOM of selected samples was characterized using solid-state 13C NMR spectroscopy.Wet sieving into aggregate size classes showed different trends along the chronosequence. Contradicting relation between CaCO3 and OC contribution to aggregate size classes display two different mechanisms on soil aggregate formation in young loess derived soils. CaCO3 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 CaCO3 role on stabilizing aggregates is not equally distributed and is aggregate size class dependent.

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Soil degradation under cropping and its influence on wheat yield on a weakly structured New Zealand silt loam

Soil Research ◽

10.1071/sr00024 ◽

2001 ◽

Vol 39 (2) ◽

pp. 291 ◽

Cited By ~ 17

Author(s):

G. S. Francis ◽

F. J. Tabley ◽

K. M. White

Keyword(s):

New Zealand ◽

N Uptake ◽

Wheat Yield ◽

Wheat Crop ◽

Soil Conditions ◽

Silt Loam ◽

Total N ◽

Organic C ◽

N Fertility

Results from the first phase of a long-term experiment showed that, after 6 years under pasture, several soil quality attributes had improved compared with soil cropped annually. The objectives of this study were to quantify the effects of pasture-induced increases in structural stability and organic matter (N fertility) on wheat grown in 3 successive seasons following pasture cultivation. Growing winter wheat after the ploughing of land that had previously grown perennial grass resulted in gradual reductions in soil organic C and total N. Reductions in soil microbial biomass C and earthworm populations were much more rapid. Soil aggregate stability declined rapidly in the first year after ploughing, but more slowly after that. Soil macroporosity increased after ploughing, mainly due to the relief of compaction caused by sheep treading during grazing. The contrasting soil conditions that existed at the end of the first experimental phase significantly affected the harvest yield of the first and second wheat crops, with yields 2—3 t/ha greater after perennial grasses than after annual crops. Variations in harvest yield and N uptake were explained by differences in soil N fertility and soil structural conditions. Treatment effects on yield were not detected in the third wheat crop. For the structural condition and N fertility of this soil, the extent of improvement during 3 years under perennial pasture was similar to the extent of decline under 3 years of cropping. This suggests that similar lengths of pastoral and arable cropping are needed in crop rotations for the long-term maintenance of these properties in weakly structured silt loam soils in New Zealand.

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Responses of soil labile organic carbon and water-stable aggregates to reforestation in southern subtropical China

Journal of Plant Ecology ◽

10.1093/jpe/rtaa087 ◽

2020 ◽

Author(s):

Yuanqi Chen ◽

Yu Zhang ◽

Shiqin Yu ◽

Feng Li ◽

Suping Liu ◽

...

Keyword(s):

Forest Type ◽

Aggregate Size ◽

Species Selection ◽

Subtropical China ◽

Organic C ◽

Soil Layers ◽

Soil C ◽

Size Classes ◽

Water Stable Aggregates ◽

Doc Concentration

Abstract Aims Reforestation can enhance soil carbon (C) stability and promote soil C accumulation. Experimental results are, however, highly variable, and the efficacy of reforestation in enhancing soil C stability is still in debate. Consequently, it remains unclear how the different soil C pools respond to reforestation in forest ecosystems. Methods The response of different soil C fractions to reforestation was examined in five subtropical forests, including the plantations of Eucalyptus urophylla (EU), Acacia crassicapa (AC), Castanopsis hystrix (CH), and 10-species mixed (MX), and a naturally recovered shrubland (NS). Soil labile C fractions (readily oxidized organic C by KMnO4: ROC; dissolved organic C: DOC), distribution of aggregate-size classes and aggregate-associated C from different soil layers (0-10, 10-20, 20-40 and 40-60 cm) were evaluated. Important Findings We found that reforestation and forest type did not affect ROC concentration, yet the highest DOC concentration was detected in NS at four soil layers. Aggregate C concentration was the highest in all aggregate-size classes of CH at 0-10 cm depth. In addition, forest type did not alter the proportion of soil water-stable aggregates at four soil layers. However, soil depths significantly affected the distribution of soil aggregates with >0.25 mm aggregates dominating in the top soils (0-20 cm), but 0.053-2 mm aggregates being dominant in the deep soils (20-60 cm). These results indicate that reforestation and forest type affectes soil DOC (0-60 cm) and aggregate C (0-10 cm). Furthermore, soil DOC and aggregate C were more susceptive to reforestation than ROC. The findings suggest that plantations reduce soil DOC concentration, highlighting that C leaching loss may decrease compared with natural recovery. Moreover, C. hystrix plantation may enhance soil C stability by physical protection in topsoil. This study provides valuable information on tree species selection for reforestation concerning soil C sequestration in southern subtropical China.

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Redox-driven changes in the distribution of Fe minerals between aggregate-size classes in illuvial and elluvial horizons of a hydromorphic soil

10.5194/egusphere-egu21-14354 ◽

2021 ◽

Author(s):

Beatrice Giannetta ◽

Danilo Oliveira De Souza ◽

Giuliana Aquilanti ◽

Daniel Said Pullicino

Keyword(s):

Particle Size ◽

Clay Fraction ◽

Aggregate Size ◽

Redox Cycling ◽

Paddy Soils ◽

Organic C ◽

X Ray ◽

Size Classes ◽

Particle Size Classes

<div> Paddy soils experience long-term redox alternations affecting the interactions between the biogeochemical cycling of iron (Fe) and carbon (C). Although the higher soil organic matter (SOM) accumulation rates in paddy topsoils with respect to non-paddy soils is generally assumed to be due to limited mineralization under anoxic soil conditions resulting from frequent field flooding, there is growing evidence questioning this assumption. Moreover, differences in particle aggregation and SOM turnover are likely to both affect and be affected by the trajectory of Fe mineral evolution/crystallinity with redox fluctuations. We hypothesized that redox cycling in paddy soils will affect the particle aggregation, the distribution and mineralogy Fe (hydr)oxides between aggregate size fractions, and consequently the mechanisms of SOM stabilization. In particular, we expect finer aggregate and particle size classes to have a higher proportion of short-range ordered (SRO) Fe oxides with respect to larger aggregates under paddy management, compared to non-paddy management, and that paddy management can result in lower amounts of Fe(hydr)oxides in the topsoil with respect to non-paddy soils. &#160; </div><div> We tested these hypotheses by evaluating mineralogical changes, and the distribution of Fe species and organic C between different aggregate and particle-size fractions in topsoil (eluvial) and subsoil (illuvial) horizons of soils under long-term paddy (P) horizons (Arp1, Arp2, Arpd, Brd1, Brd2) and non-paddy (NP) horizons (Ap1, Ap2, Bgw) in NW Italy. Soil aggregates (microaggregates: <200&#160;&#956;m, free silt: (53-2 &#956;m), free clay: <2 &#956;m, and, after sonication, fine sand, silt and clay within microaggregates) have been obtained frombulk soils using an aggregate and particle size physical fractionation method. After fractionation, Fe phases were evaluated by selective extraction procedures, X-ray diffraction (XRD) and Fe K-edge extended X-ray fine structure (Fe EXAFS) spectroscopy (Elettra XAFS beamline). </div><div> Our results indicate: (1) a depletion in the contents of ferrihydrite in the P topsoil horizons with respect to NP, though redox cycling favoured an increase in ferrihydrite in the P subsoil, possibly due to Fe(II) translocation from topsoil to subsoil, with consequent ferrihydrite precipitation and aggregates formation; (2) more crystalline Fe mineral phases were associated with intra-aggregate clay fraction in the P topsoil. In the clay fraction in the Brd2 subsoil horizon magnetite was observed. In the NP soil the illuvial horizons were not characterized by a significant increase in ferrihydrite. Our hypothesis that finer aggregate and particle size classes have a higher proportion of SRO Fe oxides with respect to larger aggregates under P management, with respect to NP management,&#160;was confirmed; (3) more organic C was associated with the fine fraction in P with respect to NP suggesting that redox cycling enhances the chemical stabilization of mineral-associated SOM. </div><div> These findings focused on localized Fe dynamics and biogeochemical coupling with SOM, suggesting that redox-driven changes in aggregate-size classes distribution were also linked to the differences in organic C and Fe stocks in these two agro-ecosystems. </div>

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