Keep a close eye on soil structure
Best is granular, but 'loams' are typical
Published 24/08/2010 | 05:00
FOR farmers using min-till on a continuous basis, keeping a close eye on soil structure is essential. The best soil structure is granular. This is where the soil breaks up like breadcrumbs in your hands. Typical soils would be sandy loams or silty loams. Crumb structure has large pore space ideal for drainage and root growth.
At the other end of the spectrum is platy; this peels away in layers in your hands and there are very few pore spaces. Hence, water movement is very poor.
Soil particles can be made up of sand, silt, clay and organic matter, and are clumped together to form larger aggregates called peds.
A clod is not a ped, as it is formed artificially by the compression of a wet soil.
The diagrams, right, show different soil structures.
A practical test to check out the structure of the soil in a particular field is to take a section of soil approximately one foot square, the depth of your spade and then drop it on to the ground from a height of two or three feet.
If it breaks up easily and falls away it has a good structure. If it stays in a solid mass it has a poor structure that is very compacted.