PHOSPHORUS FRACTIONS AND DYNAMICS AMONG SOIL AGGREGATE SIZE CLASSES OF ORGANIC AND CONVENTIONAL CROPPING SYSTEMS

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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Distribution of microbial biomass and its activity in different soil aggregate size classes as affected by cultivation

Soil Biology and Biochemistry ◽

10.1016/0038-0717(88)90082-x ◽

1988 ◽

Vol 20 (6) ◽

pp. 777-786 ◽

Cited By ~ 401

Author(s):

V.V.S.R. Gupta ◽

J.J. Germida

Keyword(s):

Microbial Biomass ◽

Aggregate Size ◽

Soil Aggregate ◽

Size Classes

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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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Carbon and nitrogen mineralization and enzyme activities in soil aggregate-size classes: Effects of biochar, oyster shells, and polymers

Chemosphere ◽

10.1016/j.chemosphere.2018.01.034 ◽

2018 ◽

Vol 198 ◽

pp. 40-48 ◽

Cited By ~ 23

Author(s):

Yasser Mahmoud Awad ◽

Sang Soo Lee ◽

Ki-Hyun Kim ◽

Yong Sik Ok ◽

Yakov Kuzyakov

Keyword(s):

Nitrogen Mineralization ◽

Enzyme Activities ◽

Aggregate Size ◽

Soil Aggregate ◽

Carbon And Nitrogen ◽

Size Classes

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Differences in SOM Decomposition and Temperature Sensitivity among Soil Aggregate Size Classes in a Temperate Grasslands

PLoS ONE ◽

10.1371/journal.pone.0117033 ◽

2015 ◽

Vol 10 (2) ◽

pp. e0117033 ◽

Cited By ~ 13

Author(s):

Qing Wang ◽

Dan Wang ◽

Xuefa Wen ◽

Guirui Yu ◽

Nianpeng He ◽

...

Keyword(s):

Temperature Sensitivity ◽

Aggregate Size ◽

Soil Aggregate ◽

Temperate Grasslands ◽

Size Classes ◽

Som Decomposition

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Carbon in aggregate size classes in a Rhodic Eutrudox under different cropping systems

Semina Ciências Agrárias ◽

10.5433/1679-0359.2019v40n4p1709 ◽

2019 ◽

Vol 40 (4) ◽

pp. 1709

Author(s):

Wesley Machado ◽

Thadeu Rodrigues de Melo ◽

Alex Figueiredo ◽

José Victor de Freitas dos Santos ◽

Felipe Gasparello Luccas ◽

...

Keyword(s):

Crop Rotation ◽

Production Systems ◽

Cropping Systems ◽

Lupinus Albus ◽

Aggregate Size ◽

Soil Disturbance ◽

Productive Capacity ◽

No Tillage ◽

Size Classes ◽

Crop Succession

Soil productive capacity is related to levels of carbon (C) in aggregates of different sizes. The aim of this study was to assess total organic carbon levels in different size classes of water-stable aggregates in a Rhodic Eutrudox under different production systems. The cropping systems assessed were no-tillage (NT); no-tillage scarified every three years (NTS); disk plowing (DP) and heavy disking (HD). All systems were subjected to crop succession (S) (soybean - Glycine max / wheat - Triticum aestivum) and rotation (R) (soybean, maize (Zea mays), wheat) and cover and green manure (Lupinus albus, Raphanus sativus and Avena strigosa). Intact soil samples were collected in trenches at depths of 0–0.10; 0.10-0.20; 0.20–0.30 and 0.30-0.40 m. The highest levels of carbon were found under no-tillage, irrespective of the aggregate size class. In all treatments, the top layer (0.0–0,10 m) under crop succession showed the highest carbon content for all aggregate size classes. However, at depths below 0.10 m, crop rotation exhibited the highest carbon levels (between 12 and 20 g kg-1). After 29 years of trials, cropping systems with the lowest soil disturbance combined with crop rotation were found to contribute to raising the level of carbon in the soil and maintaining stable aggregates.

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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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