Prideaux Walled Garden: Optimising compost management for bindweed control and soil health

Intro

It is widely accepted that compost can help capture carbon, retain nutrients, and reduce the dependence on bought-in fertiliser by improving the soil structure and biology. But how can you get the best out of your compost? And what benefits can you expect?

Five growers in Cornwall wanted to explore how management techniques, such as covering and turning compost, affect compost quality and crop yield. They took part in the project Farm Net Zero, where Cornish farmers and growers are uncovering how agriculture can contribute to Net Zero targets. One of the growers, Emma, had a particular interest in whether good quality compost helps control bindweed. She teamed up with experts through an Innovative Farmers field lab to put her ideas to the test.

The Challenge

Bindweed is thought to thrive in compacted soils with low organic matter.
Traditional methods for bindweed control may be labour-intensive or rely on chemical solutions.
Composting is potential solution to weed control, but creating high quality compost can feel overwhelming with a wide array of potential methods and techniques.

The Solution

Emma’s trial explored the combination of soil aeration with broad forking and compost application to improve soil health. She utilised a variety of materials for nutrient-rich compost, including wood chips, leaves, coffee grounds, and leaf mould, and is exploring biochar. She had also been experimenting with various homemade microbial supplements and was curious to test their impact on the presence of bindweed.

Image

The Trial

Two types of soil strips were tested: one aerated with a broad fork, and one not.
The goal was to see if soil aeration, combined with compost, could improve soil health and control bindweed.
Different microbial supplements were tested to see their impact on bindweed presence.
The trial also included the use of anthelmintic cover crops and land sheeting to reduce bindweed growth.

The Results

Early results suggest that compost and reducing compaction with broad forking can effectively control bindweed.
High-quality, microbially-rich compost and soil aeration significantly reduced bindweed infestation in just four months. Increasing organic matter and aeration allows soils to function better and make full use of the organic matter.
The application of a homemade, microbially rich compost significantly reduced the presence of bindweed.
Microbial supplements had little impact on bindweed presence.

The Impact

Emma's learnings and tips:

Produce a high quantity of compost to significantly reduce the presence of bindweed.
Use a wide variety of materials for nutrient-rich compost.
It is important to maintain the right moisture levels in the compost.
Frequent turning of compost heaps is essential for maintaining aerobic conditions; it regulates temperature and ensures even decomposition. Around 60°C is ideal for killing weed seeds without harming beneficial bacteria. Turn when it gets too hot or smells sulphuric.
Emma uses Bokashi to speed up decomposition of tougher materials and has experimented with other microbial brews.

Farmer Insights

“It was just amazing. I realised how much more compost I need to make, because a really good application of homemade, microbially rich compost significantly reduced the presence of bindweed. I want to replicate my composting success across the whole garden”. Emma Restorick, Prideaux Walled Garden