Weeding takes up too much of our time. It is expensive if we need to employ people to do the job, and it is not necessarily the best thing to do. Here’s a radical, but remarkably practical solution to weeding – using instead of removing weeds!
Hold on, wait a moment… before you head off somewhere else – using weeds is not such a ridiculous idea. The reason – growing weeds is much better for our soil than growing no plants at all. And here’s why:
|Produce mulch right where you need it||No protective soil cover|
Supply root exudates
|No root exudates|
|Supply organic matter||Declining levels of organic matter|
|Roots help de-compact the soil||Compacted soil|
|Provide a living ground cover reducing runnoff||High rate of runoff|
|Plant cover produced shade reducing water loss from evaporation||Increased water loss from evaporation|
|Increase water infiltration into soil||Reduced water infiltration into soil|
|Reduce temperate fluctuations in soil||High-temperature fluctuations in soil|
|Supply ecological support services||Zero ecological services|
|Increase plant diversity||Zero plant diversity|
|Provide food and habitat for insects, birds and other living organisms||Provide habitat for few species|
Benefits of using this practical solution to weeding
Crucially, weeds supply organic matter and root exudates.
When soil organisms get a regular, generous and varied diet of both they work 24/7 building soil structure and recycling nutrients for plants to reuse. Soil organisms are the experts at building soil structure, recycling nutrients and making nutrients available to our plants when and where they need them.
Root exudates are sugars and proteins plants release from their roots, usually 20 to 30% of the plant’s total sugar and protein production. Using the sugars and proteins in these secretions, mycorrhizal fungi and bacteria build soil aggregates, construct glomalin and humus for long-term storage of carbon in soil, supply of water and nutrients to plants, and help protect roots from pathogens.
Weeds also supply free ecological support services.
How often have you tried to pull out a weed, only to find you can’t because it is deeply rooted in the ground? Letting it grow will help de-compact your soil and bring up leached nutrients. Many weeds are legumes or other types of plants with nitrogen fixing bacteria in their roots. Other weeds grow large solar panels to capture solar energy or provide generous supplies of pollen and nectar for the predators and parasites of your insect pests.
By supplying targeted ecological services, weeds add functional biodiversity to your production system or garden.
Weeds are obviously not the only plants providing these benefits.
Other plants can do the job as well. But there are good reasons why using weeds is the practical solution to weeding:
- Cheap seed!
- Adapted to our growing conditions – otherwise, they wouldn’t be growing!
- Save us time researching and trialing suitable plants to use instead
- Grow without help or intervention from us
That’s why weeds can be such a useful tool. Remember this when you get ready to go out weeding again…
Using weeds makes sense. It’s eco-logical!
While your soil may not show the usual indicators of soil degradation – salinity, erosion and compaction, it’s still likely to be degraded. Virtually all of our soils lack functional nutrient recycling systems and soil structures promoting root growth and healthy soil ecosystems. Sadly, working with dysfunctional soils has become the norm.
Many species we call ‘weeds’ are specialists in colonising and repairing bare and compacted soil. They are opportunistic species, producing masses of seed with excellent seed dispersal mechanisms. Their seed remains viable in the soil for years waiting for the right conditions to germinate. This means that they are ready, waiting, and keen to help you repair your soil.
If we can sound the retreat for a moment with the war on weeds, we begin to see that many of their annoying characteristics can actually be an asset.
They grow fast, protect soil, reduce temperature extremes and water loss through evaporation. They also quickly produce plant biomass which acts as a ‘starter pack’ of organic material and root exudates, providing food for your nutrient recyclers and soil structural engineers.
In natural areas, with no human intervention, soil conditions improve as other types of plants start to grow. Ecologists call this process succession. On the ground, the amount and variety of organic materials (growth forms, leaf shapes, roots, animals remains and faeces, and so on…) expands. The diversity and biomass of soil organisms increases as does the beneficial connections in the soil food web. Consequently, more nutrients are recycled and stored and fewer nutrients are lost through erosion and leaching.
In vegetable and arable production, we don’t usually allow this to happen. We maintain our production systems in an early stage of succession. Pivoting back and forth between the bare ground and a single layer of crops. This is why food growers using these types of production systems experience the most challenges with weeds and soil maintenance.
Some ideas for using weeds
‘Soil-wise’ market gardeners, vegetable and cereal producers understand the importance of growing a diverse and generous cover of plants.
They use cover crops in between their cropping cycles, grow mixtures of crops together, and interplant crops with ecological support plants (companion cropping).
Why not explore using weeds as part of your cover crop mix and companion planting?
Jumping the obstacles…
Am I making working with weeds sound too easy?
There are situations when encouraging weeds isn’t a good idea.
For example, if you end up growing a dense cover of problem weeds like Field Horsetail (Equisetium arvense) and Black grass (Alopecurus myosuroides) in Europe, Paterson’s curse (Echium plantagineum) and Sicklepod (Senna obtusifolia) in Australia. Some of these agricultural weeds are ‘notifiable’ meaning that we are required by law to control them. In some places, we also need to consider species that invade natural areas. Our nature reserves, waterways and National Parks need all the help they can get! Even vigorous and creeping grasses, like couch, and species that are difficult to terminate in large scale crop production can be an issue.
Selective removal of some weed species may be required if they:
- Overshadow your crop
- Competitively exclude useful companion plants
- Produce seed too early
If you hand weed this is easy to do. Removing a few undesirable plants is less time consuming than removing the whole ‘bloody’ lot! With mechanical weeding it is not so easy; timing and row spacing’s become crucial.
Don’t always be quick to judge.
Look first at the ecological services they provide.
On my farm in Australia, where there is bare ground masses of Sicklepod seedlings sprout. Friends advised me against buying the land. But I was lucky to have Hugh Lovel, a soil scientist visit the property and advise me otherwise.
“Look at the pasture grasses growing around that patch of sicklepod and tell me what you see,” he said. Sicklepod isn’t a legume, but it is deep-rooted and contains nitrogen-fixing bacteria. The benefits were clear to see. “Sicklepod isn’t a weed competing with your grasses. It’s improving your pasture.” It was a game-changing moment for me and never again would I be so ready to label plants weeds!
Sometimes the hardest obstacle to jump is change itself.
How we deal with the fear that what we intend to do might not work. “What will the neighbours think!” We can never be 100% certain about how things will turn out. Some risk is inevitable. But we can minimise this risk by doing our own on-farm trials and starting small.
Keep in mind that, as you repair your soil nutrient recycling system and soil structure, you will get fewer weeds and improve the capacity of your agro-ecosystem to weather the storms of change and take the lead in decision-making.
You’ll be learning from Nature. Working with the expertise Nature has developed over three billion years to create ecosystems that are self-maintaining and highly productive – using the energy and resources they have available. Ecosystems that quickly bounce back from extreme weather events. Everything we want for our farms!