Upper North Shore Sydney Australia

Testing the microbial ‘aliveness’ of your topsoil

Using a jug of water and a small stainless steel strainer

Place the soil sample in the sieve and rest the sieve across the neck of your jug lowering the soil into the water.  Soil Sample

Healthy soils rich in soil biota will hold together while soils devoid of soil life fall apart and form a layer of sediment in the bottom of a jug of water.

 

 Wetted Soil

 Disturbed soil

Taking soil from a continuously tilled garden, a construction site, or from several inches below the surface will generally fall apart (disperse) into individual soil particles when immersed in water.

The loose soil will make the water cloudy, and when it settles it will form a layer of sediment in the bottom of the jug. A soil that is both disturbed and contains a lot of silt and clay will, if placed in a jug of water,

generally result in cloudy water that will take a while to clear. Tilled soils have a more open, crumbly, texture than cloddy soils. Their many pores and channels allow air and water to move into the soil quickly

and then are susceptible to erosion.

Undisturbed soil

Taking a soil sample from the surface layer of a lawn, an orchard, or a field that has not been disturbed or tilled for a couple of years will hold together when immersed in water.

The less disturbed the soil, the clearer the water, and the more stable the soil will be. Undisturbed soils have a dense, cloddy texture.

After the test this soil will have more pores and channels in it because the soil ‘glue’ held the various soil particles and did not collapse and fill them in.

The soil that holds together the best is the soil that can resist erosion the best.

Sometimes soils with high clay content are bound together chemically as opposed to physically. Humic acid increases clay’s plasticity if the soil is held together chemically it may not fall apart during this water jug test.

A second exception is exhibited by thick, dark soils where the mineral particles are clumped together by aged organic matter that has been created over a long time.

This dead organic matter is resistant to decomposition. If these soils are cultivated, the soil clods will fall apart very fast as sand-sized bits.

If placed in a jug of water the water will remain clear after the sand-sized aggregates settle to the bottom of the jug.

Happy testing!

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