Conservation, Land, Plant Systems, Podcasts, Rehabilitation, Seeds, Soil Conservation, Structure, Water Harvesting — by Craig Mackintosh PRI Editor September 19, 2012
With the U.S. and other countries caught in unprecedented droughts, and arid areas of the world growing in tandem, this simple method for speeding revegetation at scale offers a lot of promise.
The barren, arid landscapes of the world are notoriously hard to revegetate. Indeed, the earth in these regions is usually very hard to describe as ’soil’. As vegetation dies off, the soil gets exposed to intense heat and evaporation, and any seeds that are present, or applied, are then unable to get the moisture they need to germinate and survive. With plant roots, organic matter and microorganisms no longer present in the soil, it rapidly loses any of the structure it once possessed. Soil erosion from rain events and harsh winds then easily undermine nature’s attempts at natural, progressive restoration, by sending any accumulated soil particles elsewhere, or out into the ocean.
Human intervention has been, in many cases, the driving force in starting this destructive cycle, and, as evidenced by the rapid advancement of desertification worldwide, it’s also clear that it will only be through human intervention that we can reverse it.
1 year after
Dr. Robert Dixon has been experimenting and having great success with a simple way to fast-track the revegetation of barren lands since 1976 — with a technique called ‘imprinting’. Found in a forgotten Internet 1.0 styled corner of the interweb, and forwarded to me by Geoff Lawton, this method immediately struck a chord with my biologically minded self, as I’m sure it will for all of you soil afficionados.
Imprinting is a method for instantly adding what permaculturists call the ‘edge effect’ to soils, utilising a heavy and dimpled/wedged roller to ‘imprint’ soils with patterned depressions. The bottom of these depressions then become collection points for all the crucial elements needed for seed germination and soil building: seeds themselves, water, organic matter (including plant debris and animal manure) and wind-blown silt and clay particles.
Four months after
Instead of rain running off the land, taking precious organic matter and soil particles along with it, an imprinted surface soaks and sinks the water instead. The lucky seed that finds itself at the bottom of one of these dimples also gets shaded from the harsh sun during the early morning and late afternoon parts of the day.
Bill Mollison actually featured the imprinting technique in the Global Gardener video series. Watch from 23:45 of the Drylands episode of the series to see Bill and Bob taking a look at the machine, how it works, and the amazing results. It’s stunning to watch as the cameraman films the two men walking through a degraded section of land — which had little to no hope of revegetating naturally — before turning 180 degrees as they enter another section of the same land, but which had had the imprinting applied. The scene goes from a bare sandy soil with a few scattered bushes to one of quite dense grassland. This metamorphosis begins a new and positive cycle, where the soil is now protected by plants — from sun, wind and rain and flood events — and so moisture and organic matter can once again begin to accumulate on and in the soil. In this scene you can clearly see that a natural cycle of succession has been kick started into life!
The no-till method for seeding of plants called land imprinting has been under development in Tucson, Arizona since 1976. Through ecological weed control, land imprinting has restored perennial grasses to 20,000 hectares of degraded rangeland in southern Arizona since 1980. — imprinting.org
Most of the arid regions of the world get a reasonable dump of rainfall at least once or twice per year. Can you imagine the potential found in imprinting large areas of arid land just before the Spring rains? I can envision these areas being simultaneously imprinted and seeded — and seeded with a diverse mix of hardy, climate-appropriate pioneer grasses, legumes and other plants, which can themselves be just the beginning of nature’s own series of subsequent successions.
Well-formed imprints in the foreground efficiently establish vegetation on severely
degraded land. The ripping shanks at the rear of the tractor loosen hard soil
spots enough to imprint them.
These transformations, once begun in the uninhabited and uninhabitable areas of our world, can then be left to themselves, to progress on their own. Regeneration can thus still occur at scale in the interim, even while we’re yet figuring out how to transition the intensely farmed, more inhabited parts of our landscapes into a similar, more regenerative cycle.
Indeed, I can also envision a version of the imprinting roller designed to be pulled by beasts of burden, or even by a few people, in order to better establish gardens and perennial grasslands for humans, livestock and wildlife in inhabited rural areas.
Dr. Dixon has experimented and fine-tuned various imprinting roller types, and for different situations (i.e. flat lands, slopes, etc.). He has, in point of fact, made quite a science out of it. Readers wanting to find out more should thoroughly check out www.imprinting.org, and the following article in particular:
- Land Imprinting for Low-Cost Revegetation of Degraded Land in the Desert Southwest: Updated/Expanded Version
As permaculturists well know, nature always seeks to restore herself, and often will, if left in peace, to her own devices. But we also know that once certain feedback loops have kicked into gear, like desertification, even nature itself is unable to restore itself. In these cases, humans armed with determination and an holistic understanding of the integrated sciences of biology, soil science and hydrology, etc., can give nature a helping hand, and speed her on her way.
If we can do this, then, as John Liu astutely put it, why don’t we?
Imprinting soils may offer an easy, efficient and cost-effective way to stabilise desert soils and create new rangelands (and ultimately perhaps even carefully managed croplands), by putting arid lands and degraded ’set asides’ back to work — pulling untold tons of CO2 out of the atmosphere, where it currently works to grow deserts, and putting it back into our soils where it builds fertility and climate stability instead.
For good measure, and to hear the man himself, take a listen to this podcast interview with Dr. Robert Dixon, courtesy of agroinnovations.com:
Click play to hear the interview!Interview with Robert Dixon Comments (10)