Sitting on a coach on the way home from London, I was eating a meal that
included roasted chestnuts. Opposite me were a couple of people eating sandwiches.
I started to think about the different foods we were eating. Nutritionally
they were somewhat similar, both chestnuts and wheat being good sources
of carbohydrate, though the chestnuts are rather lower in protein. I then
thought about the work involved in growing, harvesting and utilizing each
of these foods.
With the sweet chestnuts all you have to do (once the trees have been
planted and are old enough to bear fruit) is come along in the autumn
and harvest the seeds - the plants will continue to yield for possibly
hundreds of years without any help from you. With the wheat, however,
it is quite a different matter. Here the ground must be cultivated every
year in order to prepare a seed bed; the seed must then be sown; a method
found of controlling the weeds; fertilizers added in order to achieve
satisfactory yields; fungicides and insecticides applied in order to control
pests and diseases and then large machinery used in order to harvest the
crop.
This is all so much extra work, particularly when you consider that,
even with all this effort put into growing it, the yields of wheat will
still be less than the yields of chestnuts could be from the same area
of ground. It made me wonder why on earth people had fallen into the trap
of growing annual crops.
When you go on to consider the wider effects of growing annual crops
such as wheat compared with tree and other perennial crops then the issue
seems to move from the farcical to the totally ridiculous. Not only have
we given ourselves so much extra work for lower returns, we have also
devised a method of growing our food that is extremely damaging to our
environment and to all the plants and creatures that live in it (which
includes us of course).
Let me try and explain this in more detail and, as an example, let me
first look at a field of wheat and then compare this with a woodland.
Annual monoculture
Annual crops, grown in conventional systems, demand that the soil is cultivated.
The very act of cultivating the soil serves to destroy organic matter, kills
much of the soil fauna and leaves the soil at risk of erosion from wind
and rain. The soil structure is damaged and, with continued cultivation,
the sub-soil becomes very compacted and is unable to drain properly or allow
roots to penetrate and obtain their nutrients. When it rains soil is washed
away. Just go and stand in a country lane on a wet day and you will see
all the muddy water flowing along the sides of the lane. This is our valuable
top soil, being carried off to streams and thence to the sea.
In a field of wheat all the plants have the same nutritional requirements,
their roots occupy the same levels in the soil and will only be able to
obtain nutrients from this one level of the soil. Any nutrients that have
been washed lower down into the soil will be lost to the plants and will
eventually find their way into the water system either to be washed out
to sea or to pollute our drinking water. Genetically very similar, these
plants are all susceptible to the same pests and diseases and all have
similar climatic requirements. If one suffers, they all suffer. The system
is dependent on large inputs of fertilisers, herbicides, pesticides, fungicides
etc. The soil is little more than a medium to hold the plant up, and even
this it is becoming less able to do well as soil structure and depth are
destroyed. The Fenlands, for example, are losing 30 mm of topsoil every
year.
A field of wheat is like a desert to most of our wild animals and plants
- the intensive growing regime means that very few species of plants will
be able to grow in the field and thus there will be very few animals that
will be able to survive in and around the field. In the edition of The
Guardian newspaper dated 12/08/94 there was an article about the declining
population of some of our commonest species of birds. Apparently, in the
period between 1969 and 1991 tree sparrow populations declined by 85%,
corn bunting by 76%, grey partridge by 73%, turtle doves by 75% and skylarks
by 50%. The article went on to blame current agricultural practices that
have seen hedgerows destroyed, meadows ploughed up and fields harvested
before the birds had a chance to finish rearing their young. It said that
the dawn chorus, that enchanting time of the morning when the air is alive
to the sound of bird song, is heard no more in many parts of E. Anglia,
where an eerie silence now greets the dawn.
It can be argued that yields of wheat have increased dramatically in
the last 100 years, from around 1 ton per acre at the beginning of the
century to 3 tons or more now. But is this sustainable? No it is not!
In fact when you take into account all the energy that is expended in
making the farm machinery, in fuelling it, in making the fertilisers etc.
and all the other things that need to be done in order to produce the
food, far more energy is actually used up in growing the food than the
food itself yields in energy! This ridiculous state of affairs is only
possible due to the current abundance of fossil fuels, but how long are
they going to last?
Woodland systems
Let us now look at a native woodland. Who feeds this with artificial fertilisers?
Who sprays fungicides? Who applies the herbicides and why isn't everything
eaten up by insects? Year after year the woodland produces masses of plant
growth feeding a host of mammals, birds and insects. A wide range of plants
grow side by side, sometimes competing but more often occupying subtly different
niches in the woodland. For example, some plants will have deep root systems
and these will obtain many of their nutrients from deep down in the soil
in areas beyond the reach of other plants. When their leaves die in the
autumn many of these nutrients will be made available to other members of
the plant community. Other plants will have shallower root systems and these
will obtain their nutrients from nearer the soil surface. Similarly, there
will be gradations of height in the woodland, some of the plants will be
tall trees, some will be small trees or shrubs, there will be climbers making
their way up the trunks of the trees, smaller perennials able to grow in
the shade of the trees will be found on the woodland floor. Some of the
smaller plants will come into growth early in the year, before the trees
have leafed out, and will complete most of their life-cycle by early summer.
Thus there are different niches for plants to occupy in the soil, above
the ground and in time.
The canopy of trees creates a sheltered and more stable environment
inside the woodland. Temperature fluctuations are less extreme than in
an open field, there is less wind and frost and so plants are less subject
to the vagaries of our weather. Because of all the different available
habitats there is a wide range of creatures able to live in the woodland
and the more diverse the numbers of species that live in an eco-system,
the more stable it becomes. The force of the rain is broken by the trees
and the rich carpet of organic matter in a woodland absorbs the rain and
allows it to drain into the soil and enhance the water table instead of
running off into the rivers and thence to the sea, taking valuable soil
and nutrients with it.
There are various fungal and bacterial activities taking place on the
root systems of the woodland plants which increase the abilities of plants
to take up nutrients from the soil and also produce nutrients for all
the plants to utilise. Recent research has demonstrated that the greater
the diversity of plants growing in an area then the greater the total
amount of growth that takes place. Thus we see that a woodland is not
only self-sustaining and highly productive, it can also lead to a gradual
build-up of fertility, unlike annually cultivated soil which needs constant
inputs if it is to remain fertile.
The value of diversity.
By growing a number of different species together so that there isn't a
large planting of one single species, insects that seek out plants visually
may be confused by the different shapes of plants and be less able to find
the species that they are looking for. If you can imagine a few pest insects
arriving at a large wheat field, once they have landed on one wheat plant
no matter what way they move they cannot avoid moving on to the next wheat
plant simply because they are totally surrounded by them. Heaven on earth
for the insect and ideal breeding conditions for it. The result is a very
rapid population explosion usually only controlled by an expensive regime
of chemical sprays. If, on the other hand, the field contains a diversity
of plants, as is found in a native woodland, the insect is going to have
to work much harder to find the next host plant and it is also going to
be much more at risk from predation, both because it has got to move about
a lot more and also because this diversity of plants offers more places
for its predators to live in. The result is far less damage to the plants
and a more balanced population of pests and predators.
There was an article in the Spring 1994 edition of 'Kew' magazine. It
was talking about a group of chimpanzees that live in a small area of
forest, called Gombe, in Africa. The forest is a reserve and is surrounded
by cultivated land. The article continued:-
'Outside Gombe, the local people are struggling to live off
perhaps 30 different types of foods, mostly introduced species of plants
grown in drought conditions on easily eroded soils.... But the chimps
seem to be expert botanists, knowing exactly where and when the next crop
of fruit will be. There may be only six major plant foods each month but,
over the year, more than 150 species are used. Some of the fruits they
eat are delicious and they can certainly teach us a great deal about a
balanced diet and preventative health-care. But although a lot is known
about the chimps' social behaviour, our understanding of their botanical
knowledge and its significance to us is in its infancy. Few of their food
plants have been tested for nutrients or medicinal properties.'
It seems that the chimpanzees are more intelligent than we are!
Selecting the plants.
Of course, if you try to depend on a typical British woodland to provide
you with all your food for the year, then you are either going to die fairly
quickly of starvation, or you are going to have to learn to eat a lot of
rather unpleasant tasting foods such as acorns. It is quite probable that
neither of these possibilities appeal to you - but there is an alternative.
It is possible to plan out a woodland, using the guidelines that nature
has shown us, but using species that can provide us with tasty fruits, seeds,
leaves, roots and flowers. When well designed, such a system can:-
be far more productive than a field of annuals
produce a much wider range of foods
require far less work
require far less inputs such as fertilizers and pesticides
provide valuable habitats for wildlife
be very pleasing aesthetically.
It all comes down to selecting the right mixture of species .There are over
5,000 species of edible plants that can be grown outdoors in Britain and
about 2,100 of these can be grown in a woodland so there really is no lack
of variety to choose from.
The main difficulty is that people have been selectively breeding the
traditional annual crops over a period of thousands of years. In that
time the cultivated plants have often changed dramatically from the original
wild species (cauliflowers, brussel sprouts and cabbage all derive from
the same wild plant) whilst the taste and yield has also undergone great
changes. Thus the cultivated lettuce was derived from a bitter tasting
poisonous plant and the wild ancestor of carrots has a thin woody root
that really does not make very pleasant eating.
This selective breeding, however, has also had a number of disadvantages.
We might have ended up with a lettuce that has mild flavoured leaves that
go well in a salad, but we also have a plant that is very susceptible
to pests and diseases, whilst it also requires a lot of attention when
growing since it is unable to compete with most other plants. Thus if
anyone wants to eat lettuce all the year round they have to sow seed on
at least 10 occasions over the year - which means preparing the soil,
weeding, watering if the weather is dry, trying to prevent the plants
running to seed if the weather is hot and trying to prevent them rotting
if the weather is wet. We also have to supply nutrients and organic matter
to the soil if we are to produce a good quality plant. Even with all this
attention, we will produce a plant that is considerably lower in nutrients
than the wild plant it was bred from.
Most of the perennial plants that we recommend for woodland plantings
have never been selectively bred for yields, flavour etc. Thus the harvest
might be lower than you would expect from cultivated annuals, or it might
be more fiddly - but all the plants on the lists below produce very tasty
crops. Once established these plants will continue to yield their harvests
for many years with very little work on behalf of the grower. Not only
that, but they will tend to suffer far less from pests and diseases, will
not require much in the way of fertilising and will be far more resilient
to the vagaries of the weather. Since many different species will be able
to occupy the same area of land, overall yields can be much higher than
from annual plants. There is also a lot of scope for careful selective
breeding in order to produce more productive and easier to harvest cultivars.
Any selective breeding, however, should always take into account any potential
negative effects on the plants.
A woodland garden.
The first thing that you need is a woodland. If you are fortunate enough
to already have a few mature trees then you can begin straight away planting
out the other plants of the woodland. If you do not have some trees already,
then it is best to plant the trees first and allow them to grow for a few
years to become established before putting in the other plants. There are
a number of general points to remember when deciding whether or where to
grow a woodland garden.
It is possible to grow trees almost anywhere in Britain (97% of the
land used to be covered with trees before people started chopping them
down). What is important is to choose the correct trees for the site
- if planting right by the coast, for example, then you need to select
species that can tolerate the strong salt laden winds. Once the trees
are established they will provide shelter from the elements so that
other less tolerant plants can be grown amongst them.
You do not need large areas of land on which to grow your woodland.
By choosing small trees it is possible to have a mini-woodland even
in a small back yard.
Be clear in your mind what crops you want to grow and then choose
the appropriate species.
Plant the sun worshippers on the sunny side of the woodland - most
fruit-bearing species crop better when grown in full sun.
Taller trees should be towards the north side so that they do not
shade out the smaller species
Be aware of the vigour of each plant and plan accordingly. If, for
example, you plant a very strong-growing climbing plant into a small
tree then it is very likely that the tree will be smothered by the climber
and die.
There is no space in this leaflet to talk about the plants that can
be grown in this woodland system - if you would like more information
on these then please ask for our leaflet titled Woodland
Garden Plants. However, I would like to list just a few of the plants
that you could be growing to supply food all the year round.
Seeds
Araucaria araucana (Monkey puzzle); Caragana arborescens
(Siberian pea tree); Castanea sativa (Sweet chestnut); Cephalotaxus
drupacea harringtonii; Corylus species (Cobnuts and Filberts);
Juglans regia (Walnut) and Quercus ilex (Holm oak) all
bear well at least in parts of Britain.
Fruits
There is such a wide range here that I can only mention just a very
few of them. Actinidia deliciosa (Kiwi fruit); Amelanchier
alnifolia (Juneberry); Cornus species; Crataegus species;
Elaeagnus x ebbingei; Malus sylvestris domestica (Apple);
Prunus domestica (Plum); Pyrus communis (Pear); Ribes
species (Gooseberries and currants) and Rubus species (Raspberries
and blackberries) will provide a succession of fruit all year round.
Leaves
Allium ursinum (Wild garlic); Campanula
persicifolia (Harebell); Cryptotaenia japonica (Japanese
parsley); Fagopyrum dibotrys (Perennial buckwheat); Montia
sibirica (Miner's lettuce); Myrrhis odorata (Sweet Cicely);
Rumex acetosa (Sorrel); Tilia species (Lime trees); Urtica
dioica (Stinging nettles) and Viola odorata (Sweet violet)
are just a few of the species to choose from and between them you should
be able to pick fresh leaves all the year round.
Roots
Erythronium species (Dog's tooth violets); Lathyrus tuberosus;
Lilium lancifolium (Tiger lily); Medeola virginica (Cucumber
root) and Streptopus amplexifolius are some of the more interesting
root crops that you could grow.
Plants for a Future does not verify the accuracy of reader comments,
use at your own risk. In particular
Plants For A Future can not take any responsibility for any adverse effects from the use of plants.
You should always consult a professional before using plants medicinally.
Cryptotaenia japonica
Chris Brown
Fri, 14 May 1999 13:44:48
I recently obtained a
Cryptotaenia japonica plant from a local plant sale (Eugene,
Oregon); the grower said it was an edible, so that made it a very
appealing addition to my garden. As it was not in any of my horticultural
reference books, I decided to do an internet search to see what
kind of conditons it would flourish in. To my surprise, the North Carolina State University declared it a poisonous
plant!
I then discovered your page, which confirmed my original
information, which lists it as an edible plant. I don't know which source
is correct, yours or the University's, but I don't think I will be eating
it anytime soon!
Why Perennials
Fri Jan 19 18:47:02 2001
I am doing a science fair project at my school.My experiant is on if
talking to your plants helps them grow any better. I am using perennial
plants is this a good coice?
Cryptotaenia japonica
Shani
Sun Aug 26 21:55:18 2001
This is what the site has to say regarding edibility of this plant.
North Carolina State University website
(link - http://www.ces.ncsu.edu/depts/hort/consumer/poison/Cryptja.htm )
Poisonous Part
Leaves.
Symptoms
Severe skin irritation following repeated contact.
Edibility
EDIBLE PARTS: Cooked, starchy Oriental vegetable (root) or salad greens.
Toxic Principle
Unidentified.
Severity
TOXIC ONLY IF LARGE QUANTITIES EATEN.
Why Perennials
Jesse Chisholm
Tue Jul 8 02:25:34 2003
For a good answer to "why" so many annuals were "chosen" over history
for agriculture, read the book "Guns, Germs and Steel" by Jared Diamond.
This book has a section that talks about the domestication of plants
and animals and why some were chosen and others weren't.
There is a review at this site: http://dannyreviews.com/h/Guns_Germs_Steel.html
But perhaps the simplest reason for annuals is the number of years
that some perennials (for example fruit and nut trees) need to get
established before they produce. The annuals produce the very year
you plant them. If you need to migrate, you can plant in the new
location and have a crop that year.
All depends on whether you prefer being a hunter-gatherer or a food-cultivator.
-Jesse Chisholm
Why Perennials
Vicki Morrone
Thu Aug 21 16:20:46 2003
Regarding root depth of annual versus perennial. I don't beleive it is correct to say that roots of annuals explore all the same depth. I know of research that looks at differences in varieities of common bean roots that are able to explore different levels in the soil. The purpose of this research is for growing crops where the soil nutrients are limited and maximum root exploration is desirable. Have you ever dug a root profile for a tomato plant? You could go as deep as 11 feet! so the diagram needs qualifying and yes tomato is really a perennial but in North American we grow it as an annual due to our temperate climate.
Excellent Article!!
Aaron James Schnebly
Sun Nov 9 06:31:37 2003
I agree with much of this article, although I think annual crops and modern growing techniques are a blessing to a large extent. But, annual crops would be much better if they were broken up by swaths of woodland crops (i.e. fruit trees, nut trees, and berries) so that there wouldn?t be endless fields of a single crop. Crop rotation and companion planting should be much more common with field crops. This article illustrates these points beautifully, and brings up many other valid points. I have planned to create woodland garden to surround my home for a long time now. A woodland garden in Arizona would be different from an English woodland garden (irrigated for one), but this article nonetheless confirmed my ideas and gave me more material to work with. I think this system would be most valuable around homes and towns, where people were nearby to micro-harvest. Most of the desired annuals could be grown in gardens and small fields with minimal impact on the environment. I imagine that these woodlands would have a very pleasant and park-like atmosphere, granting relief from the city and/or endless fields of single crops. This would bring nature closer to the people and the people closer to nature. I see this as one step closer to recovering the Garden of Eden.
Why Perennials
Sun Nov 9 06:49:54 2003
I agree with much of this article, although I think annual crops and modern growing techniques are a blessing to a large extent. But, annual crops would be much better if they were broken up by swaths of woodland crops (i.e. fruit trees, nut trees, and berries) so that there wouldnÂ’t be endless fields of a single crop. Crop rotation and companion planting should be much more common with field crops. This article illustrates these points beautifully, and brings up many other valid points. I have planned to create woodland garden to surround my home for a long time now. A woodland garden in Arizona would be different from an English woodland garden (irrigated for one), but this article nonetheless confirmed my ideas and gave me more material to work with. I think this system would be most valuable around homes and towns, where people were nearby to micro-harvest. Most of the desired annuals could be grown in gardens and small fields with minimal impact on the environment. I imagine that these woodlands would have a very pleasant and park-like atmosphere, granting relief from the city and/or endless fields of single crops. This would bring nature closer to the people and the people closer to nature. I see this as one step closer to recovering the Garden of Eden.
Why Perennials
rafix
Mon Nov 17 13:47:12 2003
1. any plant is eatable (the dosage is extremly relevant!)
so for instance a amanita muscaria or other so called toxic plants can harm or kill you only if you eat them un prepared (uncooked-unwatered,like bitternes can be wash out with several houers treatments )or just a overdose
2.apropos perennial cultivation
thats very convinient endeed,but the anual crops should be cultivated complimantory.
lets reencounter us urgently with the laws of nature.
see my page below:
we are all one!
Out in the US northwest they are now breeding (not engineering)
perrenial wheat. They started by taking domesticated wheat and
cross breeding with wild perrenial grasses. They now have plants
which have continuosly produced for 5 seasons. These strains are
bred for the dry climate of eastern Washington State,
so I'm curious what the result would be in wetter climes.
Why Perennials
jjjjjjjjjjjjjjjjjjjjjjjjjjjj
Wed Nov 9 2005
It doesn't say a thing about the disadvantages of artificial fertilisers this site is truly dreadful and disgraceful this site is a complete waste of time and it's also a scam
Why Perennials
Krystle C.
Thu Dec 15 2005
Fantastic article. It reminds me of one day at work (on a farm), when a Jamaican co-worker was going around collecting wild "callaloo" which was growing like a weed all over the place, and makes for a common Jamaican dish; meanwhile, there was a half acre planted with corn that required a ridiculous amount of maintenance. What a difference.
Indeed, perennials add a lot to the food system. I feel annuals do add value to the system, too;
as long as they aren't planted in big monocultures. I've started eating Linden leaves this year,
which tastes mild like lettuce. Pfaf.org goes into good detail of many of varieties of plants
that have use for a simpler and more fulfilling life. As the article states, perennial system takes
less energy and is environmentally safe. And, if trees such as apples are integrated into the woodland
system they tend to not suffer from as many pests as when planted in monoculture
orchards. The natural system has a way of correcting itself when a population explosion of pests is counteracted
with a a balance of predators. I've also added bamboo to the perennial equation
With the many uses of bamboo, it should be grown where climates allow it to survive and prosper.
Very helpful, thank you. Keep up the good hard work.
0 0
*
V
Why Perennials
Sat Apr 8 2006
jjjjjjjjj you are a pathetic hypocrite who has no life to insult this
site. If it's so bad then try making a better one. A large amount of
effort has gone into this site and your pathetic babbling does not help.
SCAM??? Are you that stupid and uneducated. Please go back to school.
This site is good, jjjjjj is and idiot :-)
Why Perennials
ecoradical
Tue Jul 18 2006
Ok, so we need to all go out and live in and manipulate natural ecosystems to acommodate our "environmentally friendly" woodland garden. First of all that would require a person to be financially able to purchase the land. Not applicable to most! Second, to make it convenient you would have to live nearby, thus build a house nearby (good ole urban expansion). Houses are not very environmentally friendly. Third, if you dont build a house there you have to drive to it. Driving uses fossil fuels. If everyone was driving to thier own little "gardens of Eden" more fuel would be used than a piece of farm equipment. In fairness, i guess you could ride a bike. Who has the time to ride a bike to thier little slice of heaven outside of town? So, in order to feed people that cant afford to own land, drive a lot, or dont have the free time to bike to thier garden and grow food because they work for a living; we grow large monocultures that are easily harvested and economically feasible. The underlying problem with creating a perfect system is that it has to economically feasible. This article does not look at annual and perrenial systems fairly as pointed out above. People that can call others a hypocrite be reading two sentences must be well educated (sarcasm). Sorry if this was not well written, please dont call me stupid and uneducated because i didnt want to waste time with this site. I just stumbled across this sites stupidty and had to write something to add to the stupidty.
Why Perennials
Cathy
Wed Oct 4 2006
I agree, this site has many facts and information that I enjoy. and MR. jjj was overly irrate I find,
when there is clearly so much info that is available and well presented.
I've bookmarked this site, will keep enjoying it. This after all is not the Bible and if there is info
that is not mentioned, then perhaps using this page to ask for it would have been more useful than being RUDE!!
Why Perennials
Curt
Sat Jul 14 2007
Thanks for sharing this information it is very helpful. I can see a whole industry being developed to promote edible perennials.
Why Perennials
Hal Fox
Mon Jan 7 2008
Dear Friend,
In my garden in the bench area east of Salt Lake City, Utah, I began by digging out
large and small rocks that were in the almost barren ground. Then I began composting all of he scraps from my kitchen and digging those scraps into my garden spot where the rocks had been moved.
In this fashion, over the years I now have a couple of feet of soil that I have developed. In this
soil I now produced most of the food that we eat. In addition, I have planted three peach trees.
From these trees we bottle over one hundred quarts of peaches for our winter use.
The message is that some farmers lose the soil. Some farmer reserve or build up the soil and provide the food that we enjoy.
Best regards, Hal Fox, a former farmer when a youth.
Why Perennials
jan hemingway
Sun Apr 27 2008
Ust as a comment from a gardener--red root is a healthy perennial that comes up every year in the garden it is ahead of most of my efforts and makes a great addition to salads and cooked greens. i also use the wild mustard that comes in and lambs quarters and dandelionns. I have been known to "graze" in the fields of dandelion blossoms. they are nutritious and delicious --pick and eat.
Why Perennials
Jane Morrow
Thu May 15 2008
This site has made me pause and think. That must be a good thing. I would like to know if anyone has devised a guild that includes Vicia faba in an anual system. I'm interested in this as we have very low summer rainfall and deep sand, hot summers and wet winters. While my trees are becoming estblished I am filling in with broad beans and think I could create a polyculture instead of having 'weeds' inbetween.
Why Perennials
rosemarin
Fri May 23 2008
I liked this site.have been eating nettles for years and now will try lime leaves which are mentioned in my book of edible herbs. yes by all means plant fruit trees and chestnut and walnut if you have the room. Agriculture is OK only if its organic and so in balance with nature as far as possible
The conventional industrial scale agriculture with all the chemicals eliminates most wildlife and is not sustainable.
Why Perennials
Kilian
Thu Oct 9 2008
I found a nit to pick, you said:
"It can be argued that yields of wheat have increased dramatically in the last 100 years, from around 1 ton per acre at the beginning of the century to 3 tons or more now.
But is this sustainable? No it is not! In fact when you take into account all the energy that is expended in making the farm machinery, in fuelling it, in making the
fertilisers etc. and all the other things that need to be done in order to produce the food, far more energy is actually used up in growing the food than the food itself
yields in energy! This ridiculous state of affairs is only possible due to the current abundance of fossil fuels, but how long are they going to last? "
I just discovered a great book in my nearest university library called
"Food, Energy, and Society", David and Marcia H. Pimentel, CRC Press, 3rd edition
which has some nice tables listing energy inputs/outputs for plants and other things.
Interestingly there are many plants (not all) which produce an energy surplus when grown with modern methods:
US soy bean: 3.19kcal output for 1kcal input per hectare
US wheat: 2.13kcal output for 1kcal input per hectare
US corn: 3.84kcal output for 1kcal input per hectare
Now this doesn't seem to take the solar energy input into account, but I guess
you didn't take that into account either. Any energy conversion is lossy
and you wouldn't change that even if you were just foraging in the woods.
BTW, From what I have read, plants are horrible in terms of energy conversion - from
0.1 to 2 percent efficiency.
The energy argument you made isn't necessary to convince me though that fossil fuels cause a
problem. They are not renewable, we use them heavily and we will have to change more than we
would like some day, once they are gone or climate change needs to be averted. That is bad
enough already no more convincing is required.
Another aspect is that replacing fossil fuels is hard because the alternatives partially require
less energy efficient conversion methods or require yet unknown future technologies.
The book above mentions the production of nitrate fertilizer from electrical
energy which needs 3x more energy compared to the fossil fuel method. So reducing the
amount of fertilizer needed will definitely help.
After all, I'm convinced that we will change in the future towards a more energy efficient way of living. Especially the abundance of meat in our diet I see going away.
Supposedly only 10% of the energy invested into the previous link of the food chain is passed onto the next. In preparation of this I'm browsing
your great data base. I suspect I won't find the miraculous steak tree in it, but I do really hope.
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