Rapid changes in microbial biomass and aggregate size distribution in response to changes in organic matter management in grass pasture

Geoderma ◽  
2013 ◽  
Vol 193-194 ◽  
pp. 68-75 ◽  
Author(s):  
Tunsisa T. Hurisso ◽  
Jessica G. Davis ◽  
Joe E. Brummer ◽  
Mary E. Stromberger ◽  
Maysoon M. Mikha ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Size Distribution ◽  
Aggregate Size ◽  
Aggregate Size Distribution ◽  
Organic Matter Management ◽  
Rapid Changes

Effects of heating on some soil physical properties related to its hydrological behaviour in two north-western Spanish soils

2004 ◽  
Vol 13 (2) ◽  
pp. 195 ◽  
Author(s):  
R. García-Corona ◽  
E. Benito ◽  
E. de Blas ◽  
M. E. Varela
Keyword(s):  
Organic Matter ◽  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Size Distribution ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Total Porosity ◽  
Water Repellency ◽  
Aggregate Size Distribution ◽  
Distribution Water

Two forest soils rich in organic matter but differing in texture (sandy loam and silty loam) were heated under controlled laboratory conditions in order to examine the consequences of the heating effect that accompanies the passage of a fire on the physical properties of soil. Three samples of both soils were heated for 30 min in a muffle furnace at temperatures of 25, 170, 220, 380 and 460°C. At each temperature, the following parameters were determined: dry aggregate size distribution, water aggregate stability, total porosity, pore size distribution, water repellency and hydraulic conductivity. Heating the soils at 170 and 220°C caused no significant changes in aggregate size distribution or total porosity but increased water aggregate stability and the volume of pores 0.2–30 μm. Also, increased water repellency and strongly decreased the hydraulic conductivity. All parameters underwent much more dramatic changes at 380 and 460°C that can be ascribed to the combustion of organic matter. At such temperatures, water repellency was destroyed and the low hydraulic conductivity can be attributed to the aggregate breakdown observed under dry and wet conditions.

scholarly journals Study of soil aggregate breakdown dynamics under low dispersive ultrasonic energies with sedimentation and X-ray attenuation

2015 ◽  
Vol 29 (4) ◽  
pp. 501-508 ◽  
Author(s):  
Jasmin Schomakers ◽  
Franz Zehetner ◽  
Axel Mentler ◽  
Franz Ottner ◽  
Herwig Mayer
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Size Distribution ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
X Ray ◽  
Aggregate Size Distribution ◽  
Aggregate Breakdown ◽  
Wet Sieving

Abstract It has been increasingly recognized that soil organic matter stabilization is strongly controlled by physical binding within soil aggregates. It is therefore essential to measure soil aggregate stability reliably over a wide range of disruptive energies and different aggregate sizes. To this end, we tested highaccuracy ultrasonic dispersion in combination with subsequent sedimentation and X-ray attenuation. Three arable topsoils (notillage) from Central Europe were subjected to ultrasound at four different specific energy levels: 0.5, 6.7, 100 and 500 J cm-3, and the resulting suspensions were analyzed for aggregate size distribution by wet sieving (2 000-63 μm) and sedimentation/X-ray attenuation (63-2 μm). The combination of wet sieving and sedimentation technique allowed for a continuous analysis, at high resolution, of soil aggregate breakdown dynamics after defined energy inputs. Our results show that aggregate size distribution strongly varied with sonication energy input and soil type. The strongest effects were observed in the range of low specific energies (< 10 J cm-3), which previous studies have largely neglected. This shows that low ultrasonic energies are required to capture the full range of aggregate stability and release of soil organic matter upon aggregate breakdown.

Measurement of soil dry aggregate size distribution using the laser diffraction method

2021 ◽  
Vol 211 ◽  
pp. 105023
Author(s):  
C. Polakowski ◽  
A. Sochan ◽  
M. Ryżak ◽  
M. Beczek ◽  
R. Mazur ◽  
...  
Keyword(s):  
Size Distribution ◽  
Diffraction Method ◽  
Aggregate Size ◽  
Laser Diffraction ◽  
Aggregate Size Distribution

Aggregate size distribution and stability of an oxisol under legume-based and pure grass pastures in the eastern Colombian savannas

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 153 ◽  
Author(s):  
AJ Gijsman ◽  
RJ Thomas
Keyword(s):  
Size Distribution ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Hot Water ◽  
Aggregate Size Distribution ◽  
Carbohydrate Concentration ◽  
Stability Measurement ◽  
Water Extractable

This study evaluated soil aggregate size distribution and stability of an Oxisol under improved grass-only or grass-legume pastures, established in previously native savanna. Three grass-legume combinations were included at various stocking rates. In all treatments and soil layers, soils were well aggregated, having more than 90% of their weight in macroaggregates (>250 �m). The addition of legumes to pastures did not affect the soil aggregate size distribution, although aggregates showed somewhat more stability against slaking. An increase in stocking rate negatively affected both average aggregate size and aggregate stability. Aggregates showed little or no dispersion of clay particles in any treatment. A positive correlation was found between wet aggregate stability and hot-water extractable carbohydrate concentration, supporting the hypothesis that these carbohydrates equate with plant-derived or microbial polysaccharides which glue soil aggregates together. It is suggested that determination of hot-water extractable carbohydrates may serve as a useful indicator of small differences in aggregate stability, even when these differences are not evident in the stability measurement itself.

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