Learning from Weeds on Permaculture Farms

Observation is an important part of Permaculture practice, and here are a few things it has taught me about weeds on our property this spring.

Have a close look at this photo. It shows a tree on a property adjacent to our own. The purple stuff is the weed “Paterson’s Curse” (PC). Do you notice that there is no PC under the tree? When you look closely you will see that this has nothing at all to do with sunlight – the ground is PC-free not just in the shady area under the tree, but within its entire dripline.

What is that telling us? What is different about the soil under the tree?

That tree is probably about 200 years old, so you’d have 200 years accumulation of feces from insects, reptiles and birds under it. So first clue about PC – it doesn’t grow where the fertility is high, favoring low fertility soils.

Here’s another photo showing either side of a fence on our property.

Both areas have been fertilized using organic materials according to Albrecht soil test results.

On the left is grazed land inside a paddock, on the right of the fence is the verge of our driveway that is not grazed but slashed each year.

After only 3 years of different treatment the contrast in amount of PC is astounding. What I am reading in this is that (over) grazing favors PC and slashing deters it.

Again we are probably talking about fertility – grazing removes some of the protective mulch from the soil surface, drying it out and retarding biological activity. Slashing has the opposite effect.

The top right of the photo shows a neighbor’s property thick with PC. It has been neither fertilized nor grazed (except by kangaroos). To me that suggests that prescriptive fertilization is the single biggest step you can take to favor the growth of useful pastures over weeds on your property.

Here’s another one that underlines this:

Both sides of this fence are grazed paddocks on our property. The only difference between them is in the amount of grazing pressure: the paddock on the left is properly fenced so has been grazed harder than the one on the right which has only temporary electric fencing that kept our ram in briefly …until the grass elsewhere started looking greener (we have since eaten the bugger which certainly taught him a lesson!). Neither side was ever slashed, so slashing is not absolutely necessary to deter PC.

What do all these things add up to? To me, they are saying that this weed (like many) appears where it is needed to restore fertility. If a combination of improvements are made to the health of the soil – such as adding strategic fertility amendments, and ensuring adequate pasture cover by not overgrazing – the weed disappears, making way for higher quality pasture plants. Conversely, damage the soil in any way, such as by overgrazing in our case, and the weed is there to repair the damage. In soils lacking in some essential nutrients, the weed that flourishes very often is able to harvest the lacking nutrients from very deep in the soil profile (and, some would argue, by less understood pathways), concentrating them in the tissues of the weed.

Australian farmer Peter Andrews made use of these valuable functions of weeds to bring the denuded landscape of his farm “back from the brink”. He explains how he did it in his book by the same name.