The Use of Micro‐Aggregation or Dispersion Measurements for Following Changes in Soil Structure

An investigation was made of the time taken by a ley to change the physical state of an old arable soil ro that of an old grassland soil so that, for example, its physical condition on ploughing is the same as that of old grassland on ploughing. The process was found to be slow, taking possibly 50 years or more on some clay soils. On coarse sandy soils the process may be considerably faster, e.g. 5-10 years. I Old pasture and old grassland have been used synonymously.

mentioning

confidence: 96%

Improvements in the Structural State of Soils Under Leys

Low

1955

“…A method for measuring this proportion has been put forward by Middleton (1930). Somewhat similar methods were used by Kolodny and Neal (1941), Clarke and Marshall (1947), Puri and Keen (1925), and others. This is a very brief summary of some of the methods used in studying phenomena related to soil structure.…”

Section: Measurement Of the Probable Stability Of A Structurementioning

confidence: 99%

The Study of Soil Structure in the Field and the Laboratory

Low¹

1954

133

WITH FOUR PLATES Summary* It is not suggested that this 'ideal' condition is possible in practice. 60A. J. LOW * This work was done before the change to 2-and o.g-mm. sieves. 70A. J. LOW is used in addition. In Fig. 3 the percentage water-stable aggregates > 2 mm. and > 0-5 mm. are plotted. For the old pasture the two graphs are very similar. For the ley the slope is a little steeper on the 0.5-mm. graph. Nevertheless the difference is about the same between 2-mm. and o-s-mm. values at the last reading for both soils.

“…Allison (1968) has reviewed these problems and has emphasised the need to distinguish between factors causing formation of aggregates and those promoting stability. He asserts that natural aggregates may be formed chiefly by pressure and drying (Kolodny and Neal, 1941) 414 F. A. SKINNER which cause closer packing of the particles, but are stabilized mainly by microbial polysaccharides. The vigorous root and microbial activity in pasture soil may well explain the large proportion of highly stable aggregates usually found under grass.…”

Section: Introductionmentioning

confidence: 99%

Rothamsted Studies of Soil Structure Vii.

Skinner

1979

Natural aggregates 01' topsoil samples of six British soils (Handope, Ragdale, Evesham, Denchworth, Flint and Salop) were incubated with added nutrients and changes in their stability to wet sieving determined. Under anaerobic incubation the type of nutrient added had little effect on stability. Aerobic incubation with glucose gave a larger proportion of stable aggregates than with water. With peptone stability usually decreased, and occasionally increased, which may indicate differences in the binding mechanisms of the soil particles. Both sterile and unsterile aggregates incubated with water became more stable than controls; the rapidity of this change suggested a physical. rather than microbiological cause. Very stable grassland aggregates changed little on aerobic incubation with water, but b e c a m more stable with solutions of glucose or peptone. Artificial aggregates made from the Same soil developed considerable stability to water on aerobic incubation. but remained almost totally unstable when incubated anaerobically.