Apparatur zur Bestimmung der Krümelstabilität

Koepf, H.

doi:10.1002/jpln.19560740207

Cited by 6 publications

(2 citation statements)

References 2 publications

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“…The generated drops fall directly and at a constant rate (2 Hz) onto the aggregate until it has been rinsed through the sieve. For each biocrust, 20 repetitions were measured due to high variability of individual values ( Koepf, 1956 ). The fall height of the droplets was 1 m, and their diameter 4 mm.…”

Section: Methodsmentioning

confidence: 99%

Biological soil crusts decrease infiltration but increase erosion resistance in a human-disturbed tropical dry forest

et al. 2023

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Under continuous human disturbance, regeneration is the basis for biodiversity persistence and ecosystem service provision. In tropical dry forests, edaphic ecosystem engineering by biological soil crusts (biocrusts) could impact regeneration by influencing erosion control and soil water and nutrient fluxes, which impact landscape hydrology, geomorphology, and ecosystem functioning. This study investigated the effect of cyanobacteria-dominated biocrusts on water infiltration and aggregate stability in a human-modified landscape of the Caatinga dry forest (NE Brazil), a system characterized by high levels of forest degradation and increasing aridity. By trapping dust and swelling of cyanobacterial filaments, biocrusts can seal soil surfaces and slow down infiltration, which potentially induces erosion. To quantify hydraulic properties and erosion control, we used minidisc-infiltrometry, raindrop-simulation, and wet sieving at two sites with contrasting disturbance levels: an active cashew plantation and an abandoned field experiencing forest regeneration, both characterized by sandy soils. Under disturbance, biocrusts had a stronger negative impact on infiltration (reduction by 42% vs. 37% during regeneration), although biocrusts under regenerating conditions had the lowest absolute sorptivity (0.042 ± 0.02 cm s−1/2) and unsaturated hydraulic conductivity (0.0015 ± 0.0008 cm s−1), with a doubled water repellency. Biocrusts provided high soil aggregate stability although stability increased considerably with progression of biocrust succession (raindrop simulation disturbed: 0.19 ± 0.22 J vs. regenerating: 0.54 ± 0.22 J). The formation of stable aggregates by early successional biocrusts on sandy soils suggests protection of dry forest soils even on the worst land use/soil degradation scenario with a high soil erosion risk. Our results confirm that biocrusts covering bare interspaces between vascular plants in human-modified landscapes play an important role in surface water availability and erosion control. Biocrusts have the potential to reduce land degradation, but their associated ecosystem services like erosion protection, can be impaired by disturbance. Considering an average biocrust coverage of 8.1% of the Caatinga landscapes, further research should aim to quantify the contribution of biocrusts to forest recovery to fully understand the role they play in the functioning of this poorly explored ecosystem.

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Section: Methodsmentioning

confidence: 99%

Biological soil crusts decrease infiltration but increase erosion resistance in a human-disturbed tropical dry forest

et al. 2023

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“…An apparatus for analyzing a larger amount of soil aggregates has been developed e.g. by Sekera and Brunner (1943), Koepf (1956), Njos (1959) and Rose (1960). Birecki et al (1968) have introduced in their method book an apparatus for analyzing a large series of soil aggregates.…”

Section: Effect Of Freezing On Water Retention Of Fine Ground Soilsmentioning

confidence: 99%

Effect of moisture and freezing on some physical properties of clay soils from plough layer

Kivisaari

1979

AFSci

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The aim of this study was to elucidate the effects of freezing on some structural properties of clay soils. The laboratory analyses were based on field observations including measurements of soil temperature and frost depth. The daily temperatures showed remarkable variations on the very soil surface both in the autumn and spring, ranging from below zero at night-time to above 10°C at daytime. The depth of soil frost was deepest in the ploughed field, whilst the straw cowers on the soil surface not only strongly reduced its depth, but also slowed up the thawing. Eight clay soil samples were analyzed in the laboratory. At the potentials of —0.001 to —0.1 bar the water retention capability of soil was reduced by freezing. Disruption of the 5 —10 mm aggregates by freezing, analyzed with wet and dry sievings and waterdrop analysis was strongly dependent on the water potential, the Water potential of 1.0 bar or lower having in general no effect. The total pore volume of aggregates Was dependent on the water potential when it exceeded —15.0 bar. Freezing had a minor effect on the pore volume of the aggregates, if they were let to thaw before drying. The freeze-dried aggregates showed a clear increase of pore volume when the water potential at freezing exceeded —1.0 bar. The movement of water due to ice formation was studied with small and big soil cylinders. It showed a great effect on the structure, if total pore volume, determined with a mercury method, is considered the standard of judgement. Thus it was concluded that the water movement even at a short freezing period is one of the most essential factors determining the structural formation of ploughed clay soil.

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Untersuchungen über Krümelstabilität an einem Kalkversuch

Czeratzki

1957

Z. Pflanzenernaehr. Dueng. Bodenk.

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Apparatur zur Bestimmung der Krümelstabilität

Cited by 6 publications

References 2 publications

Biological soil crusts decrease infiltration but increase erosion resistance in a human-disturbed tropical dry forest

Biological soil crusts decrease infiltration but increase erosion resistance in a human-disturbed tropical dry forest

Effect of moisture and freezing on some physical properties of clay soils from plough layer

Untersuchungen über Krümelstabilität an einem Kalkversuch

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