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Stabilization of Newly Formed Soil Aggregates 1
Author(s) -
Arya L. M.,
Blake G. R.
Publication year - 1972
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1972.00021962006400020015x
Subject(s) - soil water , shearing (physics) , water content , plough , sieve (category theory) , chemistry , soil science , environmental science , materials science , geology , agronomy , geotechnical engineering , composite material , mathematics , combinatorics , biology
The stabilization of newly formed soil aggregates was observed. Stabilization was postulated from previous research to be time dependent. Three kinds of newly formed aggregates were collected, aged at constant water content, and tested for changes in relative stability in water at frequent intervals after formation. Stability of 3‐ to 5‐mm diameter aggregates collected immediately after plow‐shearing on four soil types increased with time after plowing when water content was held constant. The rate of increase was high during initial aging times and decreased as aging progressed. Increases of about 0.17 for sandy soils and about 0.24 for finer‐textured soils were observed in 72 hours of aging. For all soils, stability increase after about 10 to 12 hours was small. Earthworm casts were simulated by extruding kneaded, moist soil through a sieve with 2‐mm round holes. Extrusions aged at four water contents showed considerable increases in relative stability in the 24‐hour period following formation. Stabilities determined shortly after extrusion varied with water content of the extrusions. The largest change in stability was from 0.68 to 0.98 at a water content of 0.36 g/g. Aggregates were also prepared by placing water drops on dry soil powder and collecting the individual coalesced portions. These aggregates were aged at two water contents. Initially, stabilities were near 0 but attained values ranging from 0.14 to 0.31 in about 120 hours. Stability differences due to water content were inconclusive. These facts raise important questions regarding timing of tillage operations following plowing. Soils in humid climates with a tendency to weakly developed aggregates may have better tilth if further tillage is delayed a few hours. The data suggest that an intense rain soon after plowing will puddle the soil to a greater extent than if it is delayed a few hours.