Tidal forces and soil moisture

A quote in this article on asparagus growing set off my internal BS alarm:

...during a full moon, you have water that’s coming up in the soil, which gives the plants more oomph.

Is there any truth to this, and if so, how?

The tides in the ocean lift water up on the side of the Earth facing the moon (as well as the side away from the moon) only because the surrounding water is squeezing in on all sides. Without the surrounding water, the decreased gravity alone would not be enough to lift water or anything else upwards. So unless your asparagus bed is completely waterlogged and covers a significant portion of the Earth's surface, tidal forces are not at work here.

Is there some other force at play, or has this guy had too much moonshine? Thanks in advance for weighing in.

Moonshine definitely - you are right that tidal forces only come into play over massive bodies of water. It is to do with the comparative differences between gravitational forces separated by a sizable fraction of the earths circumference. The water has to be connected in a single body.

A good way to call bullshit on a claim like this is to look at a local lake, pond or puddle - they don't overflow at the full moon because the groundwater is rising beneath them.

Well it works on oceans, hence the tides, so it's not complete BS. There is also some evidence that the moon can also effect magma within the Earth and trigger earthquakes. link here

I believe that this idea is much used in biodynamic gardening, which many people use with great success. So, who knows?

Magma and oceans are massive connected bodies of fluids which are free to flow. They flow under tides because of the difference of gravitational force exerted from place to place.

Imagine a long tube full of water, like those used for levelling swales.

If you suck on one end of the tube the water will flow a small amount towards that end because of the difference in pressure between the two ends. This is analogous to tides operating over vast distance - one end facing the moon, one end facing perpendicular to the moon, out of the side of the earth. A very long hose indeed.

Now instead of sucking on one end of the hose, suck on both ends... the water won't move because there is no difference in pressure. Water can't expand so it just sits there in the tube unaltered. This is analogous to gravity acting over small bodies of water (lakes, ponds, puddles, or pores filled with water in the soil) where all parts of the body are oriented the same way (ie towards the full moon) and so experience equal gravitational pull. Water simply won't flow.

Now if you are not saying these are tidal effects, instead merely due to "everything being lighter due to less gravity"... you need to think about your experiences. Do you feel lighter at the full moon? Do the weighing scales in the bathroom knock a few pounds off? No, and that is because the relative effect of the earth is so much much greater than the relative effect of the moon. I couldn't find the figure quickly, but the variations due to gravity due to the moon are tiny fractions of a percent of the total gravitational force experienced.

This is one of the reasons I, and others, are sceptical of the claims of biodynamics... they use the language of physics (and the physics of tidal forces is very well understood... hell, I get my 17 years olds in maths lessons to do calculations predicting tidal heights in maths lessons) to dress up magical thinking. There may be something else going on with the moon - lots of organisms show some adaptation to lunar cycles as a means of synchronising fertility - but it is not a tidal effect.

We have a very high water table in Michigan. You have me wondering 2 things:

Could there be tidal effects on an underground aquifer?

Could the flow of an artesian well be affected by that force?

Obviously there are multiple forces at work here.

From NOAA on the Great Lakes and tides:
"True tides—changes in water level caused by the gravitational forces of the sun and moon—do occur in a semi-diurnal (twice daily) pattern on the Great Lakes. Studies indicate that the Great Lakes spring tide, the largest tides caused by the combined forces of the sun and moon, is less than five centimeters (two inches) in height. These minor variations are masked by the greater fluctuations in lake levels produced by wind and barometric pressure changes.

Consequently, the Great Lakes are considered to be non-tidal."

Just because it isn't the strongest force doesn't mean you can rule it out, in my opinion.

Steve Hoskins wrote:

Just because it isn't the strongest force doesn't mean you can rule it out, in my opinion.

Perhaps not, but the significance of tidal forces on small scales is so tiny as to be swamped by all the other effects. (daily weather, climate over the past few weeks/months, local variations in microclimate...)

You mention the great lakes... on the scale of an enormous body of water the tidal effects are so small (5cm variation) as to be safely ignored. Tidal effects get less significant as objects get smaller - there is a clear observable pattern in nature of tides getting less significant as bodies of water get smaller, so why should it suddenly become significant again when we are looking at the microscale?

Claiming tidal forces are making plants grow better is akin to dressing up magic in science terminology - it isn't backed up by evidence, it is unsupported by even casual observation of the real world.

My big beef with these kind of claims is that it distracts from potentially interesting observations that might make a real difference to our understanding of the world. By sticking the false label of "tidal forces" on anything to do with the moon you preclude the possibility that there might be something far more interesting and subtle going on. Perhaps plants have a "body clock" that is synchronised by the light of the moon? Synchronisation of breeding cycles is important for so many species (ensuring that all trees flower simultaneously increases the chances of successful pollination and reduces the likelihood of animals consuming all seeds) that it may well include lunar cycles.

I make no claims, just asking questions.

Are you saying this is discussion is distracting us from the real effects of the moon, or are you saying that all discussions of the moon are distracting us from permaculture?

A bit of both.

How the moon affects plants... (2 part article)

Delving into the Scientific Literature

A good place to start turned out to be a brief review on the subject written in 1946 by Dr. C.F.C. Beeson (see ref. 1 below).

Dr. Beeson introduced the subject this way:
“The literature on the moon and plants can be assigned to two groups: one comprising reiterations of peasant beliefs, myths and rules, both ancient and modern, and similar unsubstantiated statements; the other comprising experiments supported by numerical data capable of statistical analysis. This second group consists of (a) experiments mainly of the anthroposophical school, which demonstrate the existence of lunar effects on the growth of plants; and (b) experiments of professional horticulturists and foresters, which prove that there are no such effects, or that, if they do exist, they have no value in agricultural practice.“

"the anthroposophical school" refers to Biodynamics. Hardly an unbiased source of scientific data, as their whole school of thought is based on lunar planting etc...

In permaculture we base our actions on observation, an attempt at deeper understanding of complex interactions and try to break away from "traditional agriculture" which is rooted in the mythologies associated with plowing, fertilising and cash crops. Leaping onto a different, unsubstantiated, mythology (eg biodynamics) doesn't seem to be a step forward. Properly breaking down the processes behind the beliefs of biodynamics might yield something worth bringing into the larger permaculture fold. However, given that most of the evidence has turned out to be at best neutral there are probably more accessible fields to spend time and effort researching - low hanging fruit so to speak.

Word.

Here's a brand new article on the subject, an interview with "Professor Silvano Fuso, one of the major Italian scientific experts and a member of CICAP (Comitato Italiano per il Controllo delle Affermazioni sulle Pseudoscienze – Italian Comitee for the Investigation of Claims on Pseudoscience)" : http://www.growtheplanet.com/en/blog/learn/article/639/moon-the-influence-of-our-natural-satellite-on-plants

Here how to know it is bunk. The tide comes in and out twice a day. If the moon had an impact on ground water it would be higher when the moon was overhead (or underfoot) and lower when rising or setting. Full moon would have nothing to do with it.

Another way is the word 'oomph'. If they don't know what to call the effect, it likely isn't real.

Many things seem impossible, and are scoffed at by those needing more 'proof'. Then one day, more comes to light, and something previously the source of ridicule becomes 'common knowledge'. Consider the mechanics of the atom, for example.

There are more ways of knowing than just science. Consider the insights from science fiction, or shamanism. Again, frequently scoffed at and ridiculed, yet ultimately found to be 'true', many times decades later.

Do what works for you, follow your beliefs. It's okay if other people have notions that you dont comprehend or deem correct. Science is but one way of knowing, a fact that is often hard to swallow for its advocates.

There is much more to this world than what science comprehends- that's all.

Topher Belknap wrote:
Here how to know it is bunk. The tide comes in and out twice a day. If the moon had an impact on ground water it would be higher when the moon was overhead (or underfoot) and lower when rising or setting. Full moon would have nothing to do with it.

Except that tides are more extreme during full moon and new moon, when the gravitational effects of both the sun and the moon are in alignment. The only question is 'does this also affect ground water?'

Burra Maluca wrote:

Topher Belknap wrote:
Here how to know it is bunk. The tide comes in and out twice a day. If the moon had an impact on ground water it would be higher when the moon was overhead (or underfoot) and lower when rising or setting. Full moon would have nothing to do with it.

Except that tides are more extreme during full moon and new moon, when the gravitational effects of both the sun and the moon are in alignment. The only question is 'does this also affect ground water?'

In other words, they are much LOWER as well, and that varies on a 12 hour cycle. So the 'only' question is did you plant in the right 20 minutes when the tides is actually higher than its normal high, or did you perhaps plant in the 20 minutes when the tide is actually lower than its normal low. I have more things to plant than I can accomplish in 20 minutes every 29 days. Honestly people, go stand in a tidal basin, and see if you can even tell what phase the moon is in.

Adam Klaus wrote:Many things seem impossible, and are scoffed at by those needing more 'proof'. Then one day, more comes to light, and something previously the source of ridicule becomes 'common knowledge'. Consider the mechanics of the atom, for example.

And the scoffers were right to question, and ask for evidence. There were far more WRONG mechanics of the atom suggested, than RIGHT ones. If one only considers that evidence was demanded for the right one, and not the wrong ones, then one is engaging in confirmation bias. Anyone prepared to announce *now* which theory for dark matter should not be scoffed and which should?

There are more ways of knowing than just science. Consider the insights from science fiction, or shamanism. Again, frequently scoffed at and ridiculed, yet ultimately found to be 'true', many times decades later.

There is a reason they call it 'fiction'. Are you going to claim that ALL science fiction will eventually be found to be true? If not, how do you determine which is true? Yes, that right, 'ultimately found to be true' comes from science, as you, yourself acknowledge.

Science is but one way of knowing.

True, but it is the only one that seems to work reliably.

There is much more to this world than what science comprehends- that's all.

TRUE! Which is why we have scientists. That is what they love.

I don't get the reason why people are so anti "scientist" or "science"

All "science" is, is a systematic way of asking questions and looking for evidence to confirm answers. Further actions are then based on evidence rather than guesses/superstitions/something-the-chap-down-the-pub-said.

If an effect exists that we should be able to come up with some way of isolating it - that is comparing the circumstances with and without that effect present. A result that doesn't confirm a theory isn't a failure of science, a scientific method is showing you that the effect doesn't exist or is so insignificant as to be irrelevant.

In the context of this discussion (biodynamics/planting by phases of the moon) the only people who have published evidence supporting biodynamics are trying to "sell" the approach. Their results have not been able to be replicated elsewhere. At worst we have fraud in the original experimenters, at best we have selection bias and wishful thinking. Biodynamics is not a theory yet to be tested (hence still capable of being proven true) - the experiments have been done and came back a resounding negative from repeated testing. The reason it has such appeal has much more to do with people's psychology than any effect of the moon on plants themselves, so supporters of it deflect by trying to weaken the idea of science itself (which is basically ask a question, look for evidence) saying science cannot explain everything.

They instead claim that their evidence cannot be measured by science - that is simply the same as saying that their evidence cannot be measured, which is the same as saying the effect they claim is to small to be measurable.

I would argue that anyone with a bit of nouse could devise questions based on the claims of biodynamics, and then go on to design a trial to seek evidence based answers to those trails.

I dunno, people are willing to pay extra for meat that was killed in a particular way (kosher/halal) or food that was prepared in a kitchen where meat and milk were kept strictly separate from each other and from parve foods; if people want to pay extra for crops that were planted at a particular phase of the moon, that's OK by me.

What's not OK by me is claiming a scientific-sounding mechanism for why one thing is better than another, when the mechanism specified is demonstrably not a factor. People who adhere to kosher or halal practices have the good sense to say they're doing so because they're following divine will as they believe it to be, not because of any scientific reason.

I have always been stumped by this topic . OK , the moon has an apogee [farthest from the earth] and perigree [closest] . It has full and new moon cycles both close and far away . How is it that a new moon at the perigree exerts less gravitational force than the full moon at the apogee ?

Because the gravitational field force is affected by both the sun, earth and Moon - not the moon alone. You can calculate isograds for different configurations of the three bodies - essentially lines of equal gravitational field strength, a bit like contour lines. Locally it is also affected by things like mountains and the density of the local rocks. I used to be able to do these calcs at uni, but that is long gone from my brain now.

So , are you saying that because the moon at its apogee is reflecting the suns light back to earth that it is exerting more gravitational force than the waning phase at its perigree ? What gravitational effect does the suns light have on tidal forces ? Does a full moon at the perigree exert more force than the full moon at the apogee ?

Nothing to do with light! With a full moon the sun is on the opposite side of the earth - the gravitational pull of the moon is aligned with that of the sun.

I found this and I am still baffled :

When the Earth, Moon and Sun are aligned for Spring Tides, are they highest at Full or New Moon?
"Spring tides are about the same height whether at New or Full Moon, because the tidal bulge occurs on both sides of the Earth...the side toward the Moon ( or sun) and the side away from the Moon (or Sun). They will not be equally high because the distance between the Earth and Sun, and the Earth and Moon both vary and so will their tide producing effectiveness. The highest Spring tides occur when the Moon is at its closest to the Earth...the so-called Perigee Tide."- Dr. Odenwald's ASK THE ASTRONOMER

Good find Burra - that video gets the idea across nicely.

It would have been good to see (at around 0.58 in the video) the effect of the moon on the far side of the earth from the sun. The bulges line up again so we get a spring tide at full moon as well as new moon.

Here is a link to the site I quoted above :

http://home.hiwaay.net/~krcool/Astro/moon/moontides/

If the moon has an effect on our horticultural plans should we not be more concerned with apogee and perigree than with full or new moon cycles ? That is what has always baffled me . The effects of the moon on tides I have known since grade school .

Michael Cox wrote:

It would have been good to see the effect of the moon on the far side of the earth from the sun. The bulges line up again so we get a spring tide at full moon as well as new moon.

This one covers that idea a bit. Not explained brilliantly, but it might help.

wayne stephen wrote:If the moon has an effect on our horticultural plans should we not be more concerned with apogee and perigree than with full or new moon cycles?

Ask a sailor. If you are concerned about tidal forces, the VASTLY most important factor is the rotation of the Earth (and it relation to the position of the moon). Around me, we have 10 foot tides, 1 foot difference between spring and neap tides, and a few inches difference between apogee and perigee. So the big question is where is the moon in the sky?

Next question, why is when you *plant* so important (in regards to the moon phase)? The plant is going to be in the ground from then on, it could well be more stressed at other times. Why this obsession with what is going on when we *plant* it?

wayne stephen wrote:I have always been stumped by this topic . OK , the moon has an apogee [farthest from the earth] and perigree [closest] . It has full and new moon cycles both close and far away . How is it that a new moon at the perigree exerts less gravitational force than the full moon at the apogee ?

It doesn't.

The Moon, taken in isolation, exerts a gravitation force on the Earth which is *solely* dependent on its distance from the Earth (disregarding any slow small changes in mass of either). [note: the Moon's speed towards or away from Earth is on the order of a car's speed]

The total gravitational force on the Earth is (mostly) from the Moon and the Sun. Thus higher (more in sync) during full moon and new moons.

- O.K., so we want to talk science, Then we make an observation, come up with a hypothesis, and design a way to test it ! So- Tides are a measurable phenomenon
on the Great Lakes. The question is- Within a Groundwater Basin which may have multiple Rivers cutting through itself and modifying the height and depth of the Basin,
is it possible to design a test sensitive enough to determine is the entire basin affected as an entity, or is the Effect localized and so not measurable !

I actually think that The Great Salt Flats and simple "Earth Batteries'' would quickly tell us if there was a Measurable local effect ! However- there is a New
(6-months old ? ) N.A.S.A. Satellite that was put in place to Measure Soil moisture content world wide so perhaps this question is being addressed !

Does anyone else see a major problem with my very hypothetical testing system, or have an alternate proposal ! For the Good of the Crafts ! Big AL

Allen - your proposed test won't go so far as to support any of the claims of biodynamics.

Measuring that the moon does, or does not, have some effect on soil moisture levels (which personally I doubt will be measurable) does not then support the conclusion that planting with a biodynamic method has any bearing on plant development, yield, flavour, nutritional value etc... which variously get claimed as benefits of BD.

I personally cannot see how planting seeds on a particular date in relation to the moon can have a bearing. Different species of plants have different germination times, take different times to absorb moisture from their environment, grow at different rates. How can time of planting - when the seed is still dormant, has no roots, stem, sap flow etc... - be affected by lunar cycles which take place over totally different time and distance scales. I just don't buy it.

If you stick a seed in the ground at high tide there is no internal stopwatch that starts ticking the seconds off - it's development is pretty much determined by it's ability to absorb moisture, it's genetics and temperature. By the time it even has sap "to be pulled up by the moon" (quoting a BD site I read just now) the phase of the moon will be totally different.

The moon is an interesting thing, and I think we're lucky to have it, but (contra Bill O'Reilly) the tides are a well understood phenomenon, purely naturalistic and much misunderstood. I've heard people (wrongly) say that water is attracted preferentially towards the moon. This is because they don't understand what gravity is actually doing. But the reality (as always) is far more interesting. The same tidal effects very probably heat the interior of Jupiter's moon Io, making it highly volcanically active. Europa has a subsurface ocean because of tides. The tides even slow down the rotation of Earth and push our moon further away!

And although the best bets for tbe origin of earthly life lie in deep ocean hydrothermal vents, the constant cycles of wet/dry, cold/warm, light/dark at least partially related to tides (but mainly day/night I suppose) very likely played a major role in accelerating early evolution.

And that, of course, is why we have life and biodiversity and why permaculture fits in beautifully with the best scientific idea that ever occurred to anyone. Messrs Darwin & Wallace, well played, sirs!

Michael Cox : perhaps you should re-read my post, I merely proposed a way of measuring local effect!

At the point that one COULD Prove or Dis-Prove Local effect - well actually it would certainly not be any proof of a positive effect, and indeed as
all sprouted plants need well aerated soil, it would tend to call into question the possibility of positive Biodinamic effects.

My hypothesis and test were clearly stated I Think to look for local effect which should be observed 2 Xs a day !

This disregards Whether the playing field is level or how far away the goal posts are, by saying it will not prove or disprove Biodynamics, you seem
to be trying to change amend the scientific process.

The question of Dynamic accumulation, and Biodynamics I will leave generally to thousands of generations of 'Former Hunter / Gatherers' and their
descendants whom we call farmers, who still cross their collective fingers, plant with the seasons and tell each other "Climate is what you Expect !
Weather is what you Get "

My Former Closing question remains, Can YOU think of a fairer test of whether there is an appreciable effect on local soil moisture than my proposed
test, or alternately as the Earths Gravitational bulges and dips are now well understood , and as we have presently in L.ow E.arth O.rbit a N.A.S.A.
satellite capable of measuring seasonal moisture content of the Earths surface, are You willing to look deeper into the question or do you want your
understanding of "The Facts'' to stand alone without an attempt to shine the light of Scientific Research and Possible understanding on the Question !

For the Good of the Crafts, Think like Fire, Flow like A Gas, Don't be the Marshmallow! As always, your Comments and questions ARE Solicited and
Welcome ! Big AL

allen lumley wrote:Michael Cox : perhaps you should re-read my post, I merely proposed a way of measuring local effect!

I re-read your post, and I don't see a proposal for measuring anything. Perhaps you can try again? Are you proposing a test that can be run by anyone, how do you propose to control for all the variables which also affect soil moisture. Sorry, I am not getting what you are saying.

My Former Closing question remains, Can YOU think of a fairer test of whether there is an appreciable effect on local soil moisture than my proposed
test

I can't think of a fair test at all.

as we have presently in L.ow E.arth O.rbit a N.A.S.A. satellite capable of measuring seasonal moisture content of the Earths surface

Seasonal moisture levels are not going to help on this question, hourly moisture levels might. Are NASA going to do that?

And at the end of the day, if we prove that there are daily cycles of moisture in the soil, correlated with the moon, that to me will be evidence AGAINST the idea of planting during particular moon phases, for the reasons I have already given.

Topher Belknap wrote:how do you propose to control for all the variables which also affect soil moisture?

For me, this is the whole issue in a nutshell. Science works, when we contrive unnatural situations that are separated from the vast context of the living world. Science works when we can isolate variables. Natural systems dont work like that. They are infinitely complex and intertwined. Science works great for scientists, but not for the real world that it purports to understand.

Maybe science is the *best* tool there is. Maybe. It certainly is a tool that demands a reductionist approach to the natural world.

The big question for me is- Do we lose something of the whole when we limit the number of component parts that we consider? I think we do. Just my 2cents.

Carry on....

Adam Klaus wrote:

For me, this is the whole issue in a nutshell. Science works, when we contrive unnatural situations that are separated from the vast context of the living world. Science works when we can isolate variables.

Science works BEST when we can isolate variables, but it can certainly still be applied in complex systems with "messy" data. Medicine is a classic example - you can't isolate any single variable when associated with health, lifestyle, diet, genetics etc... However with sufficient data and carefully designed studies of that data you can begin to tease apart the interactions and comparative weights of the effects. Smoking is the classic example of course, where prior to statistic analysis of lung cancer rates doctors were even advocating smoking as being good for you!

Pretty much every big scientific breakthrough in medicine has come from statistics applied to big sets of messy data. Reductionist experiments when possible are usually easier and cheaper, not needing so much data.

Personally I find the idea that science cannot be used to look at complex systems absurd - it is already being done in field after field after field in the biological sciences. I've recently been reading about studies to do with all the complex interactions between vitamin D levels and health. Reductionist science advocated avoiding sun exposure to reduce skin cancer risks, modern statistical analysis instead shows that moderated sun exposure has massive and varied health benefits that outweighs the incidence of skin cancer deaths. No one is collecting groups of humans and exposing them to sun to measure the effects - it is all being done on studies of large numbers of people in the real world with no isolation of external factors.

The big question for me is- Do we lose something of the whole when we limit the number of component parts that we consider? I think we do. Just my 2cents.

I would agree - isolating factors totally from their context can lead to very misleading results. But at the same time it can lead to some insightful understanding. One of the challenges of human nature (as opposed to the scientific method) is a tendency to extrapolate results beyond the circumstances where they were measured. Identifying a new mechanism through lab work can be really exciting, but for results to be then taken to the real world more experimentation is needed - the lab work steers you to where to look and what to measure in the messy real world.

Michael Cox wrote:I don't get the reason why people are so anti "scientist" or "science"

All "science" is, is a systematic way of asking questions and looking for evidence to confirm answers. Further actions are then based on evidence rather than guesses/superstitions/something-the-chap-down-the-pub-said.

If an effect exists that we should be able to come up with some way of isolating it - that is comparing the circumstances with and without that effect present. A result that doesn't confirm a theory isn't a failure of science, a scientific method is showing you that the effect doesn't exist or is so insignificant as to be irrelevant.

In the context of this discussion (biodynamics/planting by phases of the moon) the only people who have published evidence supporting biodynamics are trying to "sell" the approach. Their results have not been able to be replicated elsewhere. At worst we have fraud in the original experimenters, at best we have selection bias and wishful thinking. Biodynamics is not a theory yet to be tested (hence still capable of being proven true) - the experiments have been done and came back a resounding negative from repeated testing. The reason it has such appeal has much more to do with people's psychology than any effect of the moon on plants themselves, so supporters of it deflect by trying to weaken the idea of science itself (which is basically ask a question, look for evidence) saying science cannot explain everything.

They instead claim that their evidence cannot be measured by science - that is simply the same as saying that their evidence cannot be measured, which is the same as saying the effect they claim is to small to be measurable.

I would argue that anyone with a bit of nouse could devise questions based on the claims of biodynamics, and then go on to design a trial to seek evidence based answers to those trails.

Very well put, thank you for being the voice of reason.

Adam Klaus wrote:Maybe science is the *best* tool there is. Maybe.

If you have another candidate, I am all ears.

If Bio-dynamics claims to have discovered that the moon cycle at the time of planting is important, how was that knowledge garnered?

Thank You Kindly,

Topher