Ever wonder how our farming activities impact the soil beneath our feet? As part of Soil Health Week, Soil and Plant Nutrition Specialist, Dr. Veronica Nyhan and Luis Lopez-Sangil, Soil Quality Technologist, take a closer look at compaction and offer some guidance as to how to reduce its impact in tillage scenarios.

At the Oak Park Crops and Technology Open Day, held earlier this summer, visitors had the opportunity to explore our walk-in soil pit.

The pit was located on a Luvisol soil type, locally referred to as ‘difficult’, and positioned on the turning headland of a field parcel, intersecting a tramline near the field entrance.  As a result, the cumulative effects of repeated trafficking and tillage on soil structure were clearly visible.

One of the most noticeable features of soil compaction observed was a platy structure. This type of structure, characterised by horizontal, flat, plate-like aggregates, restricts both water infiltration and root growth.  While such structures are typically found deeper in the soil profile, at this site they were present near the surface, indicating significant compaction and poor soil health.

A distinct plough pan was also observed at approximately 25cm depth, formed by continuous cultivation at this level. In some areas above the plough pan, the soil appeared quite friable, with small, rounded aggregates and a well-developed root system. However, the presence of the plough pan hindered water drainage and limited plant access to deeper water reserves, thereby reducing the soil’s resilience to extreme weather conditions.

Addressing the issue

Enhancing soil organic matter is one approach to addressing these issues. Increasing organic matter can significantly improve soil structure, which in turn promotes better root growth, drainage, workability, and trafficability. It also boosts the soil’s water-holding capacity – particularly important in lighter soils – while supplying nutrients, enhancing nutrient retention, and supporting soil biology.  A richer and more diverse biological community further aids the development of stable soil structure.

Where organic manures are not available, cover crops can play a vital role in mitigating some of the adverse effects of arable farming on soil structure, as demonstrated in the soil pit at Oak Park.

While often promoted for their ability to capture excess nutrients, certain deep-rooted cover crops may also contribute to the remediation of sub-surface compaction in tillage systems.  Through the canopy they provide, and their stabilising living root system, cover crops protect the soil from degradation over the winter period, while also providing food for soil macro and micro fauna. The substantial biomass they are capable of producing, both above and below ground, contributes to pool of organic matter once incorporated into the soil the following spring.

However, to maximise their benefits, it is essential to choose the right cover crop species for the intended purpose, ensure it fits within the farm’s rotation plan and sow it at the appropriate time.

In the below video, recorded at the Teagasc Oak Park Open Day, Luis Lopez-Sangil talks us through the soil compaction impact of tramlines, illustrates an example of a plough pan and what impact it can have on crop growth and discusses the role cover crops play in soil health and adding organic matter back into the soil:

Soil Health Week

This week marks Soil Health Week, a dedicated weeklong initiative designed to support and inspire farmers, students and the general public with the latest insights, innovations, and practical guidance on soil health. From informative podcasts and live “Ask the Expert” webinar, to farm walks, expert-led lectures, and engaging talks, the week offers a packed schedule aimed at deepening understanding and sparking conversation around sustainable soil management.

Find out more about Soil Health Week here.

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