Deane Valley Farm Blog

Why subsoil?

Autumn days

Over the past few weeks, it has been a very busy planting season at Deane Farm. Peter and the team have spent long days and nights planting winter barley and wheat for harvest 2024. As part of Deane Farm’s increasingly regenerative initiatives, improving soil health is a key objective. One way to achieve this is using our new direct drill to minimise soil disturbance when planting . To build on this further and as a mitigation measure for the recent high rainfall, this year we are increasing the amount of subsoiling we carry out during our autumn cultivations.

What is subsoiling?

Subsoiling is a tillage practice that loosens the subsoil with minimum disturbance of the topsoil. The subsoiler is a tractor-mounted implement, similar to a plough but instead of turning the earth over, it has tines that are drawn through the soil. The technique is especially useful in fields where the ground has become compacted. This can be the result of a high volume of machinery travel or livestock (especially when conditions are too wet) or where regular ploughing has resulted in a compacted layer.

Close-up of the subsoiler tines

Why is soil compaction a problem?

Soil compaction compresses the naturally occurring spaces, channels and cracks in the soil. These are usually filled with either water or air depending on the soil’s water content. The resulting fewer number and reduced size of the soil pores mean roots cannot grow freely and the restriction of water can result in upper layer saturation, leading to oxygen deficiency for the roots below. This lack of aeration also means that availability of key plant nutrients such as nitrogen and manganese are restricted.

The financial impact of compaction can be considerable. Crop yields decrease by 10-15% when soil bulk density increases from 1.35t/cu m to 1.5t/cu m. These factors are estimated to result in a cost to UK farming of Β£1bn annually.

Behind the subsoiler

How does subsoiling help?

Subsoiling is a means of helping nature do its job of improving soil structure through physical interactions like drying, cracking, freezing and shrinking. The subsoiler creates vertical cracks so the roots can bore down into the soil. The resulting aerobic conditions assist biological activity such as worms, bacteria and fungi to stabilise the soil further and ultimately improve soil health. It is important to avoid cultivating at the same depth each year as this can create a weakness.

Deane Farm is predominantly a freely draining slightly acid loamy soil. Such soils that are high in silt or sand can have a lesser calcium content and be low in organic matter. This means they are one of the types to benefit most from subsoiling. The best time to subsoil is in the early autumn before the soil becomes too wet. Ahead of drilling is a good time and it aids crop establishment, especially for oilseed rape which has a less robust rooting habit and is particularly susceptible to the ill-effects of compaction.

Winter ahead

As we head towards November and the clocks going back at the weekend, winter really will very soon be upon us. Hopefully the subsoiling will stand us in good stead for the season ahead and aid plant establishment in the coming weeks. Don’t forget to check out our planting video on the Deane Valley Produce Facebook page!

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