Getting to the root of soil structure

The soil is a key element for farmers seeking to reduce both the immediate and long-term effects of climate change.

“The more organic matter in the soil, the more the soil can act as a sink or sequester of carbon, the better it is able to cope with periods of wet or dry weather,” says Stephen Nortcliff at Reading University’s department of soil science.

Prof Nortcliff points to particular soil structure problems in East Anglia, where the land has been heavily farmed for decades. “Not enough organic material has been returned to the soil so its structure has been damaged.”

There are a number of benefits to a well-structured soil with a high organic content, argues Prof Nortcliff.

The first is that carbon within plant material is buried, preventing the negative effect of caused by emissions of carbon dioxide. Organic material within the soil can also absorb water or allow it to freely drain in times of heavy rainfall. The retention of water at times of excess means that crops within the soil are better able to endure periods of drought. High organic matter will also result in the release of valuable nutrients such as nitrogen.

“A well-structured soil will also be more robust, making machinery operations easier and more efficient,” adds Prof Nortcliff.

But improving soil structure by increasing organic matter poses problems for many growers. Mixed farmers with access to manure and with grass in rotations are at an advantage, according to Prof Nortcliff. But the options for arable growers are more limited.

“Incorporating straw and stubble will have the effect of an initial release in carbon, while the benefits of bringing in compost might be outweighed by the distance it has to travel.”

Other options include planting spring or leguminous crops, although perhaps the most beneficial might be a period of fallow. However, Prof Nortcliff acknowledges this might not be attractive to growers seeking to maximise production.

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