Careful cultivation the key to avoiding trouble
Published 24/08/2010 | 05:00
THE processes of wetting and drying, freezing, thawing, root growth, soil organisms and soil cultivations all contribute to the development of soil structure.
The wetting and drying cycle can affect the entire rooting depth. In heavier soils cracks open as the clay shrinks and roots can then grow through these cracks further loosening the soil.
In soils with low clay content, root growth is vital to maintaining an open structure. The exploring roots probe the soil and as they die, they leave channels for other roots to follow.
Fine crumb structures are developed in grassland by the fibrous roots of grasses. This can be seen when you shake out a tuft of grassland soil compared to a dug up section of bare soil.
Freezing and thawing also play an important role in developing soil structure by shattering clods in the surface layer. This process is vitally important in clay soils.
Earthworms and other soil organisms loosen the soil and provide drainage channels. They also produce binding agents which stabilise the overall structure.
Cultivation is required to produce a suitable rooting environment for crops, but cultivation can lead to compaction which is characterised by the lack of vertical cracks, making it difficult for the movement of roots and water. The larger pores are lost and this can lead to poor drainage.
Regular application of lime, farmyard manure and other organic materials are beneficial for both aggregation formation and stability since they promote the activity of soil fauna and soil micro organisms.