Perennial crops; the future of food supply?

Within a generation scientists are aiming to have perennial crops supplying our food chain. Not only will this reduce the costs of farming, it will also bring huge environmental benefits.

Currently most food crops work on an annual cycle. New crops only come about by planting new seed. Up until now farmers have selected annual wheat for domestication because of its high grain yield. As a result the plant sacrificed other attributes to maximize the amount of seed.

The latest breeding programmes to find the magical perennial crop have been under way for some time, for ten years in the case of Washington State University. They hope to have a wheat breed that survives for up to five years. They and others are also looking at all the other crops ranging through sunflowers, sorghum to chickpeas.

Washington State University uses old-fashioned breeding techniques, such as crossing wheat with wild grass but, not genetic modification. This takes time and therefore means it will probably be the next generation that benefits.

Hugh benefits are foreseen. There is an urgency to this research that is driven by a number of factors, climate change and soil erosion being two of them. Once a crop stays in the ground there is less soil erosion because land isn’t lying fallow, with the winds whipping off the top soil. Perennials have larger roots which search out water deeper in the ground making them better crops for surviving the higher temperatures that come with climate change. On top of all this, with less plowing and planting, savings on fuel bills are estimated to be as high as 75%.

Perennial crops; think it, like it, want it. Because the world is going to need them. Let’s hope this approach to crop management adds up!

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19 Responses to Perennial crops; the future of food supply?

  1. Pete Smith says:

    Yes, this seems to be the latest thing in agricultural research. Some points to ponder …
    Wes Jackson and his people at The Land Institute have been doing research in this area for over 30 years.
    Permaculture, which dates back to the 1970s, promotes agricultural systems that mimic natural systems, incorporating perennial crops as a key component.
    Perennial crops are in widespread use in horticulture: fruit (tree and bush), nuts, herbs, green manures. Some crops, e.g. runner beans, can in fact be grown as perennials, but are commonly grown as annuals for convenience and for more efficient use of land.
    Perennials in one climate may only be able to be grown as annuals in another.
    The term ‘perennial’ is used loosely to describe a plant that lives for longer than 2 years, so ploughing and replanting may well still be needed but less frequently. Benefits from reduced soil management may be offset by the build up of pests and diseases due to the absence of crop rotation and the lack of pesticides suitable for perennial crops.
    It’s amusing that the development of higher-yielding cereals from native grasses apparently bred out the perennial gene, and now we’re desperate to put it back.

  2. matt says:

    > It’s amusing that the development of higher-yielding cereals from native grasses apparently bred out the perennial gene, and now we’re desperate to put it back.

    Yes, I do find this strange; land of the plenty once upon a time perhaps.

    I get the feeling there will be a lot of re-thinking going on in many areas of running our societies! Slimming things down, cutting off the excess fat and doing a re-fry … a whole new recipe in living. :)

  3. the Grit says:

    Hi Pete and Matt,

    Sorry, but it won’t work. The fundamental basis of modern farming is crop rotation. The original version of this is what allowed the industrial revolution to happen. The only difference between the original version and what we do today, is that we can apply artificial fertilizer instead of leaving a given field fallow one year in four.

    This is based on the facts that each different crop takes nutrients from the soil in different amounts, and on the fact that, if you grow the same crop on the same field too often, it encourages plant disease and crop pests in that area. Thus, if you plant corn one year, and cotton the next, the needs of each plant can be met with not much artificial help. You also have to work in, one year in three, a crop of nitrogen fixing plants, such as soy beans, which also gives the crop residue, the part of the previous crops not carried off, time to rot. Thus, if you have a perennial crop of wheat growing for 5 years, you will have to spray for insects and disease much more heavily and apply lots more fertilizer, and your soil will not have the benefit of yearly infusions of organic matter being worked into it. On top of that, the crust that forms between the plants will keep rain from seeping into the ground, increasing the need for irrigation. Besides, the point of winter wheat is to plant late, harvest early, and have time to get a second crop off the same land. Now, if they can come up with a wheat variety that fixes nitrogen, life will be good.

    the Grit

  4. matt says:

    Ouch! I was thinking along the lines of fertilizer too but you bring up a whole stream of issues there Grit. Enough for me to put a question mark next to the title of this post.

    The professor leading the research at Washington State University is Dr. Stephen Jones. His email is joness@wsu.edu . Do you want to contact him Grit with your thoughts or shall I?

    He’s been doing his research now for ten years (including other areas of work) so one would imagine he has some answers for you/us.

  5. Pete Smith says:

    Hi Grit,
    As you might guess from reading my first post, I agree with you about the rotation issues. This is a complex field (no pun intended) with many variables. As you mention, using legumes in your rotation reduces the need for nitrogen inputs.
    Some of the problems may be self-cancelling. For example, runoff due to panning may not require extra irrigation because the established plants’ root systems can extract water from deeper below the surface.
    The problems you describe are most significant if perennial strains are grown in large-scale monocultures as annual strains are now. The new strains could probably play an important role in a permaculture layered system or polyculture.
    Pete

  6. Pete Smith says:

    I also have reservations on cost grounds. Commercial development of perennial strains has been sidelined because it’s not in the seed companies’ interest. If these things are made available commercially, how much will the big corporations charge the farmer?

  7. the Grit says:

    Hi Matt,

    Not only am I a shy type, but my plate, and a couple of extras are full at the moment, so I will leave you to speak to the good Professor. Although, if he feels I could be of any real help, our email address is listed on our blog.

    Hi Pete,

    While this sort of thing won’t work on field crops, it would be great for hot house plants. A tomato or pea vine, even broccoli or squash, that continued to produce for several years in the protected environment of a greenhouse would be a marvelous development. It would, I expect, also lend itself to organic production. Considering the prices people are willing to pay for fresh organic vegetables in the middle of winter, if Dr. Jones comes up with something along these lines, please let me know so I can buy stock!

    the Grit

  8. Pete Smith says:

    Hi Grit,
    Like the runner bean which I mentioned earlier, the tomato is in fact a perennial, although grown as an annual. This doesn’t mean it will crop continuously, treat it as an herbaceous perennial. Cut the vines down to ground level and protect the crown from frost, you’ll get vigorous early growth next year.
    Pete

  9. Pete Smith says:

    It’s important to appreciate that, if and when perennial cereals are perfected, they will not be plug-compatible with annual strains. They will require a whole new approach to land management. The Land Institute is working on incorporating perennials into a system that mimics pre-agricultural prairie eco-systems.

  10. matt says:

    Eds note: Dr. Jones serves on the Advisory Board of the Land Institute in Salina, Kansas, and is a member of the Board of Directors of the Organic Seed Alliance.

  11. Pete Smith says:

    Interesting background article
    Good to see there’s still nothing new under the sun.

  12. the Grit says:

    Hi Pete,

    Allow me to echo Matt’s earlier ouch! I knew that about tomatoes, but the local growing methods pushed it out of my mind until you mentioned it.

    the Grit

  13. matt says:

    Pete,

    Yes, as the original post says,

    ‘Up until now farmers have selected annual wheat for domestication because of its high grain yield. As a result the plant sacrificed other attributes to maximize the amount of seed.’

    So, as your link talks about as well, annuals have been favoured for their yeild vs perennials advantages, but they are now looking at the later because of soil erosion and fuel costs etc.

    But yes, nothing is particularly new under the sun. It’s just the focus that’s different!

  14. Brian says:

    Cultivation of the same crop in the same field year after year – a practice called monoculture – has long been regarded as unsustainable because of declines in yields after about three years. The yield loss is generally attributed to soil-borne pathogens that are specialized in ability to infect the roots of that crop, but that die out while the field is planted to a different crop.

    However, research at Washington State University in the United States has documented a remarkable and apparently wide-spread microbiological control of a root disease in wheat and barley when these crops are grown continuously in the same location.

    “The root-associated microbes are responsible for the well-documented decline of the disease ‘take-all’ and a corresponding increase in yields following one or more outbreaks of the disease,” said R. James Cook, interim dean of WSU’s College of Agricultural, Human, and Natural Resource Sciences.

    Cook is a strong advocate for crop rotation for many reasons, but points out that crop monoculture also has advantages and can be achieved sustainably with the help of soil microbes.

    He reported at the Fourth Annual Crop Science Congress on research that he, David M. Weller and several colleagues have conducted over the past 25 years. Weller is a research plant pathologist with the Agricultural Research Service of the U.S. Department of Agriculture.

    Cook and Weller studied the pathogens responsible for four major root diseases of wheat and barley grown in the inland Pacific Northwest. “Breeding for host plant resistance has provided only useful tolerance for management of one of these, Fusarium crown rot, and no useful resistance or tolerance to take-all, Rhizoctinia root rot and Pythium root rot,” Cook said.

    “Considering the fact that the progenitors of modern wheat evolved as a virtual monoculture, the lack of genes for resistance to root diseases implies that some other defense mechanism exists. Such protection develops against take-all with wheat monoculture.”

    He said that wheat and barley selectively stimulate and support populations of antagonistic microorganisms in the rhizosphere, or root zone. “Often four to six consecutive crops are required before the onset of take-all decline, but the exact number of consecutive crops may vary.”

    Cook and Weller found that the disease suppression associated with take-all decline is transferable to non-treated conducive, fumigated or pasteurized soil. The decline in this disease is reduced when another crop is planted that is not susceptible to take-all.

    However, Cook noted that a field with a long history of take-all decline generally will regain suppressive traits with resumption of wheat or barley monoculture following a non-host break crop.

    He said that many different kinds of microorganisms are suppressive to take-all at different stages of the disease cycle, but only a very select and closely related group of root-associated bacteria are responsible for take-all decline. These bacteria team up with the roots of wheat and, through production of antibiotics inhibitory to the pathogen, provide the equivalent of host plant resistance to the disease.

    Cook said that the beneficial antibiotic-producing bacteria are members of a large and diverse taxonomic group of bacteria known scientifically as Psuedomonas fluorescens.

    Weller found that while the roots of different crops enrich for different subgroups of P. fluorescens, distinguished by DNA fingerprinting, most of all of the subgroups produce the same antibiotics regardless of their host preferences. The wheat-adapted subgroups responsible for take-all decline produce the antibiotic 2,4 diacetyphloroglucinol or DAPG.

    WSU research has focused on wheat monoculture soils from irrigated fields in central Washington and non-irrigated soils in southeast Washington. The soils were compared with nearby fields in crop rotation and soils covered by native vegetation.

    Population densities of the DPAG-producing wheat-adapted strains of Pseudomonas spp. were two and three orders of magnitude higher on roots of wheat seedlings grown in a glasshouse test in wheat-monoculture soils than on roots of wheat seedlings grown in the same test but in soils from fields rotated to different crops, according to Cook.

    Weller also quantified DAPG producers in paired soils samples from fields across the United States and found that DAPG producers were consistently more abundant in monocultured wheat fields than in the corresponding and typically nearby field rotated to different crops. Working with colleagues internationally, he has found that DAPG-producing fluorescent Pseudomonas spp to occur globally in agricultural soils, which can explain why take-all decline has been shown to occur in wheat-producing areas world wide.

    Since different crops appear to enrich for different strains of antibiotic-producing bacteria, the research team is now investigating whether other subgroups of P. fluorescens play a role in protection of other crops against root diseases in ways similar to but possibly more subtle than the conspicuous and near-universal take-all decline.

    While root and crown disease problems can be exacerbated in direct seeding systems which are being widely adopted around the world, Cook contends that yields can be maintained with crop monoculture provided that the soil-borne pathogens are controlled.

    “For field crops such as wheat and barley, control of soil-borne pathogens depends on integrated methods that make use of natural microbiological control, host plant resistance, plant nutrients made conveniently available to diseased roots, widening crop rows and timely elimination of volunteer and weed hosts to maximize the host-free period between harvest and planting.”

  15. Pete Smith says:

    Hi Brian,
    Thanks for your fascinating post. Am I right in thinking it is essentially the media release of Cook’s presentation at the 2004 Brisbane conference? For anyone interested in reading the full transcript, go to

    http://www.cropscience.org.au/icsc2004/symposia/2/1/1128_cookrj.htm

  16. matt says:

    So that’s saying monoculture is good and natural defences eventually take hold. To relate to my original post on perennials, this research you refer to could support the move back to perennials, all other factors and there are many, assumed to be controlled sufficiently.

  17. Brian says:

    Yes, it is an adaption of a media release. Please note that perennial does not mean monoculture–the two are not synonymous.

  18. Pete Smith says:

    “perennial does not mean monoculture”
    Yes, that seems to be a common misconception. I mentioned earlier the use of perennials in permaculture, and mixed pseudo-prairie ecosystems.
    Perennial doesn’t mean eternal either. I suppose people are tuned in to garden herbaceous perennials that seem to go on for ever. I think your guys at Washington State are aiming for a 5 year ‘shelf life’.

  19. Scott says:

    Pete,

    Could you tell me more about the method to grow tomatoes on as the perennials they are? Where can I find more information about that? I’m doing a pretty interesting experiment at the moment which is a polyculture that involves tomatoes and I’d like to try this.

    Plant for a future website is a good source of information on Perennials and is pro permacultutre http://www.pfaf.org/index.php. I think to understand the debate between perennials and monoculture or typical contemporary cultivation you need to A) know how wrong industrial agriculture has got it (soil loss etc..) and B) consider peek oil possibilities in the coming decades. Then extrapolate the economic implications/strategy and make a decision. Recommend reading Guns Germs and steal chapter: “to farm or not to farm”. Gives good insight to the origins of farming in the first place and how it was not accepted many societies at all, for good reason too! its hard work and it gets harder evidently.

    Regards

    Scott

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