Can you have too Much Organic Matter?

Recorded live at Groundswell 2023, we delve into the crucial topic of organic matter and its impact on soil health, productivity, and sustainability.

Why is it so important, what are we trying to achieve and how do we get there?

And how do we benchmark and measure our soil organic matter levels?

What Is Organic Matter and Why Is It Important?

Amy Watkins:
Organic matter consists of decomposed animal and plant residues in varying states. Humus represents the most decomposed element, while plant roots from the previous year’s stubble are less decomposed.

Organic matter is essential for:

• Water Retention: Helps retain water during dry periods and enhances infiltration during heavy rainfall, supporting nutrient movement through the soil profile.
• Nutrient Retention: Aids in holding nutrients, vital for crop growth.
• Climate Resilience: Enhances the soil's ability to offset emissions and mitigate climate change.
  
  
  

Farmer's Perspective: How does organic matter impact your farming operations?

Oliver Harris: It’s about building resilience and managing risk. We face unpredictable climates, and consistent yields are essential for financial stability. Organic matter strengthens the soil, making our business more robust and future-proof.

Measuring Organic Matter Effectively

How do we measure organic matter accurately?

Steve Corbett:
We’ve found that standard sampling techniques can miss the initial build-up of organic matter in the topsoil, especially with direct drilling. To improve accuracy, we’ve started photographing soil profiles and dissecting them into layers to pinpoint where organic matter is accumulating. This detailed assessment helps inform targeted actions to maintain or enhance soil health.

Managing Organic Matter Levels

What is the target for organic matter levels in soil, and how can these vary?

Amy Watkins:
The ideal level depends on soil type. Sandy soils may have lower organic matter levels but need it more for restructuring, whereas clay soils naturally support higher levels. An organic matter level of 3-5% is generally desirable, though regions with intensive arable farming may start lower but have significant potential for growth.

Oliver Harris:
We recently conducted comprehensive soil health assessments and found levels between 3-6% across our fields. One regret is not benchmarking earlier in our transition to track progress over time better.

The Challenges of High Organic Matter

What happens when there's too much organic matter in the soil?

Panel Insight:
High organic matter can lead to nutrient lock-up and challenges with herbicide effectiveness. Monitoring and maintaining balanced organic matter is crucial to avoid negative impacts on crop production.

Choosing the Right Machinery for Soil Management

What role does machinery play in managing soil and organic matter?

Simon Weaving:
The machinery choice must be tailored to each farm's soil type and goals. For example, transitioning from a heavy plow-based system to a low-disturbance method might require using a tine for minimal soil movement initially. Demonstrations at events like Groundswell help farmers see these options in action, guiding them toward the best fit for their unique needs.

Steve Corbett:
Flexibility is key. Weather extremes—whether heavy rainfall or dry conditions—necessitate adaptable machinery that allows farmers to adjust their approach to manage soil health and maintain productivity.

Final Thoughts: Building a Sustainable Future

Steve Corbett:
It’s not just about increasing organic matter but managing the entire ecosystem—from organic matter to water infiltration and crop yield. This approach ensures soil health and sustainability while maintaining profitability.

*Listen to the full podcast for a deeper exploration of soil organic matter and its impact on farming.