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Breeding for dew collection, or my experiments with dryland farming

 
R Ranson
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I'm wondering if different shape leaves collect more dew and thus, make a plant more drought tolerant? If it's true, I bet someone's already done work on it... I'm just not good enough with google to find out where.

On a normal year, our summer drought begins about now. In the city, they may get a rain in June, and another few showers at the end of August, but these usually miss out my farm. May 1st through Oct 15th is my draught on a normal year. One of the advantages is that we get a heavy, morning dew for much of the summer.

One of my goals is to grow and breed plants that can withstand our dry summers WITHOUT irrigation. I drive past the commercial organic farms and think, what are they watering again!?! The city came close to imposing strict water rationing last year. Our local food system would collapse if they couldn't water. Most of these are small farms which can't survive a year without harvest. No water means no harvest for them. We need better resilience.

I've been playing around with different air well ideas lately. I have a few field stone piles started, and am doing some experimenting with what I'm calling a peasant air well. I'm doing this in the part of the farm that is dryest, and everyone knows how dry it is because the neighbours have all done their duty and told me that nothing grows on that side of the ridge. It's also in public view, so if it's successful, then it might inspire others to try dry land farming, or possibly buy my seeds.

Every morning I walk my dryland experiment field. I walk it at least three times a day, observing what it can tell me. Once before the sun hits it, sometime during the day (often several times) and again in the evening. It's terraced, but poor soil. I have a whole range of plants from lentils, to chard, to grains, to mangelwurzels...&c. I also have some amaranth and sunflowers planted because they grew without water last year, but in a wetter place. Let's see how they do with excessive drainage.

One thing I noticed is that some plants hold water better than others. Where the soil is empty, there is no moisture after sunrise. Chickpeas are exceptionally good at holding water. Some kale shapes keep the water on them throughout the day, and the soil at their base is slightly moister than elsewhere. Poppies are the master at gathering dew. Lentils don't seem to have much dew on them, but they are growing like they are irrigated. The soil under them is moist. The soup peas are not doing so good in rows, but where I crammed them in, they are thriving, but smaller leaves. Most of the places I've mulched have dry soil under the mulch and the dew cannot penetrate. Where I've planted crimson clover instead of mulch, the soil is moist in the morning, dry during the day, and moist again after sunset. Where I've mulched and have intensively planted so that the plants are a higher density than they 'should' be, these are doing the best.


What I want to do is to take my observations, and use them in my Giant Kale breeding programme.

So what are your thoughts? Can plants be their own air well? Is there already work done on this topic?


Here are some photos I took mid afternoon yesterday. (okay, so computer hates me. poo poo to it. I'll attach the pictures to this post soon as I can bully my PC into behaving. woot, it worked.)
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Dry land field - early May 2016
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This weed is exceptionally good at capturing dew, the soil stays moist under it all day.
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Kale catching dew, the red colour seems to make it less susceptible to sun burn from dew drops
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Another that is doing well. White russian perhaps?
 
Tyler Ludens
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The giant redwoods are the most famous dew/fog collecting plants on Earth, I think.

Here's a page with some references about plants as dew/fog collectors: http://www.harvestingrainwater.com/2014/08/01/fog-harvesting-with-living-systems/
 
R Ranson
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Tyler Ludens wrote:The giant redwoods are the most famous dew/fog collecting plants on Earth, I think.

Here's a page with some references about plants as dew/fog collectors: http://www.harvestingrainwater.com/2014/08/01/fog-harvesting-with-living-systems/


I really enjoyed that link, thank you.

The author included some additional fog harvesting resorses, so I have a nice pile of things to read this morning.

Is there a difference between fog harvesting and dew harvesting? We don't get much fog on that ridge, but we do receive plenty of dew.
 
Tyler Ludens
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I think dew has more to do with the difference in temperature between the air and the surface, which causes condensation. Large leaves hold more dew, but I'm not sure if they create more dew. Fog capture is a function of leaf shape - many tiny leaves trap more fog.

 
Tyler Ludens
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I think you might want to try to breed the kale into more of a vase shape to funnel more dew to the roots. Maybe?
 
R Ranson
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Tyler Ludens wrote:I think you might want to try to breed the kale into more of a vase shape to funnel more dew to the roots. Maybe?


This is my thought too. But then I noticed that feathery and small leaves also capture a lot of dew. Chickpeas, for example, are really good at it. Hairy leaves like sage seem to be dew magnets.

I think, in the end, funnel leaves, like poppies, make the most sense to me. I envision big flat leaves, that capture the dew and stems that channel it down towards the main stalk.

Then again, I might be wrong. This is why I'm spending so much time observing condensation.



 
R Ranson
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Here's a picture of my soup peas. In the foreground, you can see they are in rows, and towards the back of the photo, they are in a great big clump. There's only a couple of weeks difference in the planting dates, not enough to make this much difference in growth. They are the same (mix of) variety.

The rows of peas are pitiful. I don't know if any will survive to reproduce.

The clump of peas have a small layer of maple leaf mulch on top of them. Most of the places I put this mulch, the soil is dry underneath. However here, densely packed full of plants, it is moist under the mulch. The same thing happened where I put mulch on my chickpeas. Where there are few chickpeas, the soil is dry under it, where there is dense clumps of chickpeas the soil remains moist under the mulch. This is counter to what I expected, as I thought more plants would use up the soil moisture quickly. I wonder if it will have much effect on yield. Too densely packed might mean less yield than sparsely placed plants.
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Peas in rows and peas in clump
 
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R Ranson wrote:I wonder if it will have much effect on yield. Too densely packed might mean less yield than sparsely placed plants.
Do you have enough patches to experiment with a bit of chop and drop as a comparison against leaving the dense stand all growing season long?

I'm thinking right around flowering time making a few quick cuts to open up edge for more sun to the plants left for production might increase the yield as opposed to leaving the dense growth intact.
 
Tyler Ludens
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Your experience with the clumped plants versus the row plants is similar to mine. I notice that groups or beds of plants do much better than individual or widely spaced plants, with the same amount of irrigation.
 
R Ranson
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Cut and drop just before flowering. That would be this week. Sounds good as the peas on the outside of the clump are much bigger than the ones in the middle.
 
R Ranson
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A little bit more about this patch of land, because the plant breeding project and the land are interrelated.

The goals are twofold
  • breed plants that can thrive with little or no human assistance, in marginal soil, while improving the soil.
  • improve the soil


  • On this patch of land, I've been applying many of the permaculture techniques I've learned from this site. I want to see what the theory looks like in practice and to see what works for my location.

    The only thing is, when I look at the area with the theory in my head, I miss out on important observations. If I'm focused, for example, on what I learned from the air well thread, I might miss some other method of gathering water like the plants.

    So instead, I've been trying to take a lesson from Fukuoka's book. I go to the field, and I try Know Nothing Farming. I simply observe and ignore the why it is. The theory about why what works and how, stays in the house. I try to enter the field with no preconceptions of what I will find.

    Got to run, but later when I have more time, I hope to share a list of observations... then we can see if any of them can be applied to dew harvesting plants.
     
    R Ranson
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    So here we go. Today's know nothing observations. I did my best to leave all my answers at home, and take my eyeballs and questions.

  • Overnight, moisture comes from the air and also from the ground
  • Harry leaves trap the moisture on the leaves
  • smooth leaves encourage the moisture to travel down the stem
  • small leaves confuse me what they are doing by they appear most wet of all
  • where the soil is light and fluffy, more moisture gathers in my footprints and stays moist longer throughout the day... however, where the soil is compact, it appears to have less moisture.
  • the soil under many weeds is moist longer in the day than the soil in areas with no weeds.
  • Hollows seem to gather more dew than flat soil
  • So I dug some holes (also to slow down erosion in the winter) and these holes have a lot more moisture in them than the surrounding area. However, the plants I put on the mounds made from the hole soil, are growing almost double the speed than the same plants in normal conditions.
  • Kale planted with clover, lettuce, or minors lettuce accidentally included, are growing faster than their cousins who didn't get the companions. (see attached)
  • Tall plants (favas) shade smaller plants (lentils) and younger plants, thus making the morning dew remain on the smaller plants longer.


  • Questions I'm asking myself:
  • Do big leaves catch more moisture?
  • How much moisture do plants absorb through their 'skin'?
  • Some plants perspire - lose moisture through their leaves. What time of day do they do this the most and would it actually be a way to capture more moisture? So, if it was in the evening, evaporation cools down leaves faster, then overnight they gather more moisture than they lost? Nah, that wouldn't work. Would it?
  • Is the miners lettuce, clover, lettuce, whatever, helping harvest dew? Wouldn't two plants together compete for moisture? That's what modern gardening taught me.
  • perhaps smaller leaves have more surface area than big leaves, so they capture more moisture? Is that how it works?


  • What I learned is that it's really difficult to observe without applying the theories of what I already know are 'true'.

    Now to take my observations and combine it with my 'knowledge'. I can already see some conflicts there (plants are supposed to compete for water, not help each other - then again other books say they help eachother...).

    IMG_0800.JPG
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    kale with companions
     
    Tyler Ludens
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    Have you watched that Gabe Brown Keys to Healthy Soil video? He talks about how plants are supposed to compete for moisture but appear not to do so in reality.

    I can't remember where in this video he describes doing an experiment:
     
    Steve Farmer
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    Interesting thread. I'm far in favour of using plants themselves to catch moisture rather than fog nets or metal condensation panels.

    Temperature of the condensing surface is key. For every specific scenario of temp and humidity there is a dew point - the temp at which water will condense out of the air onto ANY surface. The temperature of the leaf is much more important than the shape of the leaf. There is lots of bare soil in your photos. If you can establish 100% ground cover with drought hardy plants then the field in question will be cooler than its surroundings. If dew is already common then your cooler-than-its-surroundings zone will get lots of dew.

    I don't know what your temp range is, can you find drought tolerant shade cover plants that are also cold hardy in your zone? Maybe there are cold hardy prickly pear or aloe vera that could survive. These plants will easily survive a 6 mth dry period each year.
     
    R Ranson
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    I too am worried about all the empty soil. To be honest, I was counting on the April rains to make everything grow faster and have the soil smothered with crops by now. "They" promised that we would have a wet spring, but actually the heats arrived 6 weeks early, the rains have been sparse the last month or so, and the killing frost on the farm, if memory serves, was early Jan (instead of Mid April).

    To make the terraces we had to move the soil about, so we tilled it last fall. The goal is not to till it again, just disturb the soil a bit to reduce the weed load when we put seeds in, and only the spots we put seeds in, so that the crops can compete with the weeds.

    If it had been a 'normal' year, or if it had been the weather that 'they' forecasted, then I think we would have had plenty more plants growing. But alas, we are having unusual weather. It's also pretty poor soil.


    So I'm listing to the video Tyler linked to above while I write this. We got to this part:

    Cover crops - "a diverse mix that enhances the life and the function of the soil"

    I love it.

    On the farm, where plants are growing, more plants grow. Where no plants are growing, no plants grow. Trying to get a diversity established before the drought (if we get a drought this year, who knows) hits, I think, is essential to making a go of this plot of land. If this little section can produce a summer crop, on land that no-one in the neighbourhood or town thinks is arable, then I will be ecstatic. I think it's going to take a few years improving the soil to get there, but then again, this year is already showing great promise with the garlic and favas. I have had massive kale and chard harvests already.
     
    alex Keenan
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    see if you can find Alternative Irrigation: The Promise of Runoff Agriculture it is on google books is nothing else.
     
    Shawn Harper
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    Tyler Ludens wrote:Have you watched that Gabe Brown Keys to Healthy Soil video? He talks about how plants are supposed to compete for moisture but appear not to do so in reality.

    I can't remember where in this video he describes doing an experiment:


    You post some amazing stuff and i don't think you hear thanks enough, so thanks!
     
    R Ranson
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    Today's biggest observation was that even though we didn't get a dew (humidity was low, dew point minus 1 C at the nearest weather station), the soil was still wet in places early in the morning. Hollows in the soil, and where there is mulch stayed damper longer. Even my 'weed mulch' was working.

    Weed mulch - I'm letting the weeds grow, and every day or so, go around pulling up ones that are about to flower (but haven't yet). These get put upside down in between the rows of plants. These weeds die and dry after a few hours to two days, then they act like mulch for the plants. The living weeds are also acting like mulch and dew collectors, so I let them stay until they flower, unless they are bothering the plants.

    One thing about this plot of land is that we don't have any 'fertility' to add to the soil right now. All the manure and compost are busy elsewhere. But that's great! Because I can use it as an experiment to see how much soil we can build using what's available on site. The maple leaf mulch came from the tree in the corner of the field. As I harvest, the excess veggie matter will become mulch. Any invasive plants like periwinkle, or weeds that have gone to seed, I'm experimenting with heat composting to see if I can make soil while reducing the weed load.

    Weed is basically anything I don't like to eat and/or look at. Very egocentric view of a weed vs not-a-weed. Not-a-weed also includes plants I might eat in an emergency situation like dandelions.


    Why I'm growing in rows instead of a massive carpet of polyculture - it's visible to the public and I want to make a display that is sort of a hybrid between what they "know" to be gardening and permaculture techniques. Maybe they can get ideas that will bring them one step closer to permaculture. Also, I like narrow strips of veggies, two rows of lentils, three rows of favas, one row of chard, &c. That way, as one crop is about to finish, I can really easily plant the next crop in between them. Times, like early spring, when there is a lot of rain and things grow fast, I plant several rows close together. This time of year, I plant one row where earlier in the year there would have been two.


    As for this year's rainfall. Thanks to February, our city's reservoirs are doing fairly well. The total water is below normal, but better than last year. However, April gave us less rain than normal, and less rain than last year (a drought year). I don't think we are in for water rationing this year, but if we don't get our regular rainfall this winter, we are probably looking at water restrictions next year... for everyone else. I'm not on city water, and I irrigate only the kitchen garden near the house.

     
    R Ranson
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    I suspect part of breeding for drought survival also includes selecting (or letting nature do the selecting for me) plants that lose less moisture through their leaves.

    Yesterday, quite a hot day for us, 29 degrees C, safflowers, even the ones I transplanted that morning and forgot to water, were fine. Kale in the no-water zone, some were doing fine (especially the heavily lobed thick stemmed Russian varieties) but some of the thin broad-leafed ones were sulking. Other broad-leafed kale were happy as can be. I deliberately didn't label so I wouldn't be prejudice as to which variety gets what treatment, so I don't know if these were the same variety or different ones. But interesting. I didn't think to ask if certain shape leaves have different heat tolerance.
     
    alex Keenan
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    If dew point temperature and humidity are key that should you not look at ways to increase the cooling rate. Right now you are depending on surface area to catch the dew that forms. This is an important factor but what can you do to allow areas to cool down to the dew point faster? One key to growing zone marginal plants is to put them in areas that can radiate heat. There is alot of info on collecting and storing heat. By looking at this info you can find conditions that do not lead to heat storage. For example in my area mulched soil tends to remain cooler than bare soil in the summer. Shaded soil also tend to absorb less energy during the day.
    I also know of examples of where solar heated water is ran through pipes to heat soil for seed beds.

    By looking at many of these example it may be possible to work them in reverse. For example water pipes under the soil. You could run cooled water under soil area once sun is down to increase cooling rate. Water will warm but cool the soil. As temperature drops to point where water is same temp as soil you can switch to radiator air cooling the water in the pipes. When water temp equals air temp the unit is shut down and the cold water stored under ground.

    You can do the same thing with are and rock or ceramic heat storage. Only you are flowing air through the heat storage material.

    In Alaska they use a refrigerated pilings. A material that turns liquid at low temp and vaporizes is used to cool when temp rises.

    It is also possible to use heat to provide the cold to condense the water vapor.
    Solar heat distills pure ammonia vapor from the water-ammonia mixture. This is old tech that has now been adopted to used solar energy as the heat source to drive the ammonia out of the water-ammonia mixture. With several of these running you could create cold sources to condense water vapor or cool ground.

    This was posted on another thread
    Rocks, rocks and more rocks .... Rocks seem to be a major component in everything Sepp does. Rocks have a powerful thermal intertia ... If you stack a pile of rocks, air can move through the pile. And the rocks in the middle will be quite cool. If humid air moves through the pile, water will condense on the cooler rocks, thus creating a poor man's drip irrigation system.
     
    R Ranson
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    The more I observe this field, work on the project and read this thread, the more I come to realize that leaf shape alone, is too tiny a thing to focus on. Of course, it's all interrelated, but I thought maybe this one aspect would be a key.

    I think selecting plant genetics and having a great diversity of genes to choose from, like a landrace, will be a really big part of this. I would still like to know if different leaf shapes collect different amounts of dew, but I think, when I get to the selection part of my giant kale project, I will probably be selecting for leaf shape that I like to use in the kitchen.


    Alex, thanks for the great ideas. Pipes under the soil are a really interesting idea. I have some thoughts where I could use a set up like that. This field, however, I'm trying to do without importing anything (except seeds) from outside. An experiment for myself to see if I can build soil fertility without spending money or stealing it from elsewhere. These ideas you mention, I think they are great. Now to find ways to get the same result, only making nature do the work for me.
     
    Steve Farmer
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    R Ranson wrote:I would still like to know if different leaf shapes collect different amounts of dew


    thickness of leaf may be important. Let's say leaf A has a similar surface area to your hand, but is wafer thin - it will have almost no mass.
    Let's say leaf B has the same outline but is as thick as your hand (eg a cactus pad), it will have much more mass.

    Now, consider what happens when both leaves are just below the dew point...

    Once a small amount of water has condensed onto leaf A, the latent heat of condensation released by the water will heat the leaf to above the dew point, and no more water will condense.
    For leaf B, it will take much more condensation for the latent heat to bring the temp up to the dew point.

    The difference in the amount of water the two leaves can condense will be approx. the same as their difference in mass.

    https://en.wikipedia.org/wiki/Latent_heat

    PS why does it have to be a leaf? Water could condense on an apple or a pumpkin. Following the logic above, the heavy fruits will condense more water than the lighter leaves.
     
    R Ranson
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    That's true. I suspect there are a lot of other factors at work too.

    Large mass, also takes longer to cool, so thick leaves may actually be warmer at night. I don't know. Just something to think about.

    Leaves perspire and they breathe. The way they do this will effect how they cool. They also absorb moisture through the leaves.

    PS why does it have to be a leaf? Water could condense on an apple or a pumpkin. Following the logic above, the heavy fruits will condense more water than the lighter leaves


    It doesn't. Just my breeding project is for kale, which has neither apple nor pumpkin. But if I can get my kale to grow tall enough fast enough, then I could foresee using pumpkin as a ground cover.
     
    Hans Quistorff
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    What are your observations where late afternoon shade gives a longer cooling time?
    My house is oriented with the length North to South with large overhang porch roof. The grass on the east side collects lot of dew but the South end only collects dew where it is shaded by the apple tree.
    The West porch collects the evening sun except where it is shaded by the plum trees. The Northwest hillside gets no shade until it gets to the apple tree and from the tree to the house gets no dew and the only thing that survives on it without sprinklers is a tiny yellow clover.
    My berry rows also run from North to South and the grass between collects the most dew. The grass gets mowed to 4 inches and between the rows grows back all summer but the west side does not.
     
    alex Keenan
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    To do what you are doing with just plants you will need to find ways of cooling without resorting to high plant moisture loss.
    Most of the leaf stuff is surface area, which will collect your dew.
    One thing you may wish to consider is creating sways that follow the sun line.
    Thing of using a potato hiller to create a high spot next to a low spot.
    Now if the running potato hill has sun on one side and shade on the other it can give you something to work with plant wise.
    On the sun side you want something that can shade. On the shade side you want something with surface area to collect dew.
    The shade side should cool down faster than the sun side if you do not use plants that will insulate. Think more grass type plants.
    On the sun side you would want shade but also air flow. So you get more dabbled shading that will allow air to flow to shaded side.
    Sunny side will likely need to be more dry soil tolerant.

    You can get thermometers that record temp and can be downloaded to PC.
    These would likely be very useful to record ambient temp, soil temp, dew collecting plant temp, shading plant temp.
     
    alex Keenan
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    This might help you get started.
    Foliar water uptake: a common water acquisition strategy for plants of the redwood forest
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727584/

    This is a evaluation of plants growing in the redwood forest of California for foliar water uptake.
     
    Hans Quistorff
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    alex Keenan wrote:This might help you get started.
    Foliar water uptake: a common water acquisition strategy for plants of the redwood forest
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2727584/

    This is a evaluation of plants growing in the redwood forest of California for foliar water uptake.

    How many read the study?
    It is easy to get put off by all the statistical language but just skip through it. Such language is only there to demonstrate academically that confounding errors did not skew the results.
    I really would like to do a therapy study but the time and stress to compose the statistical analysis would be too much for me but if I did a careful enough collection of random controlled data some post graduate student could co=author the study for the statistical annalists to advance their academic career.
    Anyway it is comforting when ones observations are scientifically validated.
    Hey how much is the condensation on the inside of my high tunnels that drips on the raspberries contributing to their summer hydration?
     
    John Weiland
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    @Hans Q.: "I really would like to do a therapy study but the time and stress to compose the statistical analysis would be too much for me but if I did a careful enough collection of random controlled data some post graduate student could co=author the study for the statistical annalists to advance their academic career. "

    Hans, send me a PM with a cursory description of what you have in mind....I may have someone with whom you could partner by EMail for this type of statistical analysis.

    The issue of foliar water uptake is interesting. Since the waxy surfaces of plant leaves bias our thinking of water penetration through that surface and in-furrow irrigation is so common and more water-conserving than pivot or other types of aerial irrigation, we get it lodged into the brain that foliar water is inconsequential. But, anecdotally considered, it's fascinating how often the lightest of rains that don't appear to reach the roots can bring about a plant response that is more observable than one would think. Limited research has been supporting this importance, but still much work needed to go in comparing environments and plant species.
     
    shauna carr
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    Since you mentioned starting to look at more than just the dew collection, I wanted to share what some of my own experiences have been in the hopes that it might give you some idea of some of the details you can be monitoring, especially because some of the things we hear as 'absolutes,' like intense mulching, have turned out to be not as absolute as I thought. Iguess maybe that's why I so like Know Nothing Farming, because we can always find out new things that turn out to be opposite for what we thought was true, yeah? I'm just a bit impatient so I try to combine it with 'intensely researched farming with respect to my growing conditions,' heh. ^_^

    Dew collection - This is really a great idea, but depends completely on the area having a high enough humidity. If you don't have a very high humidity naturally, or if a drought lowers the humidity, then this becomes not as viable a method of collecting water. The fog collecting redwoods are actually already having problems right now because the drought has done just this in CA and the fog level is lowering in the redwood's area (http://www.wired.com/2010/02/fog-decrease-threatens-coastal-redwoods/). So something to think about would be not what the humidity is now, but what it may be during a drought in your area, you know? Where I am now, during some seasons, the humidity is so low out of the rainy season, dew collection is quite negligible. And the temperature is so high, what little dew there is evaporates before it would hit the ground. But again - this is where I am, not where you are, yes? I would definitely say on the hottest, driest days, looking at the dew levels would be very helpful to try and estimate what might be going on in that area during a drought.

    Mulch - This is something that is actually much more site specific than I realized and I would definitely make study of what mulching works well in your area one of the factors you look at. I found an interesting study a long while back on how quickly water evaporates from the MULCH (as opposed to studies on evaporation from bare ground vs. mulch). And it evaporates pretty quickly, actually, especially from mulch made from organic materials. If rocks or sand were used as mulch, there was very little evaporation. But with organic mulch, it can break down and add to the soil, whereas the sand and rocks prevent that, so there are other considerations, too, yeah?

    This has turned out to be very good information for my area. And curiously was born up by a few pieces of traditional farming practices in the desert, too. Where I am the average high in the summer is 37 C - with the last couple of years having at least a week of daily temps around 43C. Rainfall is around 12 inches a year on NORMAL years, but has been closer to 9-11 inches the last few. Evaporation rate is higher than the rate of rainfall. And one thing that a number of people here have noticed is that if you are are relying on organic mulch to help keep the moisture in the ground, you have to have a large enough SOURCE of moisture. Otherwise, the rainfall drops onto the mulch and evaporates from it before it even reaches the soil. So folks here mulch their watered crops deeply, but do NOT mulch their native, watered-by-rainfall plants very deeply at all. Some, yes, but not deeply.

    I also happened across an interview with a Zuni woman from New Mexico, USA who grew up following one of the traditional forms of gardening that have earned the name 'waffle garden' due to their shape (numerous square basins surrounded by low walls). I found it very interesting that when they would make it, they would add sand on top of the basins and the walls, to keep them moist. I was also privileged to be able to see an experiment by a botanist and archaeologist with the forest service in New Mexico, USA to try and recreate one of the gardening methods that had been speculated to exist with the Anasazi (ancient, extinct tribe in that area). They built a garden down in a valley (but still high desert) and after the crops came up, they covered the entire garden with large, rounded river stones, just leaving room for the seedlings to poke through. I cannot recall any longer whether it was never watered after that point, or almost never, but the experiment was a success and the garden did quite well.

    Seemed to be another point in the favor of sand or rock mulch, yes? Except when I tried these in my area, they tanked as methods. The small pile of rocks with the cooler inside temperature? Tanked as well. After doing some investigating, I found out that the area in New Mexico where this was done had temperatures that were at least 10 degrees C cooler than my area on average, and I remembered that the rock mulched garden had been in filtered shade for a good part of the day, down in the canyon. I finally tracked down yet another study on rock mulch from an area merely 5 C cooler than my own and it turns out that rock mulch alone will raise the surrounding temperature at least 5 C at that level of heat.

    So basically...the sand and rocks and rock mulch heat up so much here they were frying the surrounding plants here with the raised temperature. But deep mulching would capture the water before it hit the soil, and not-so-deep mulching doesn't keep the soil nearly as moist. It was very frustrating, and confusing. All the gardeners I knew here were simply using up water like mad and using deep mulch, but I wanted to do somewhat like yourself: try a method that I can do with just dryland farming, or close to it (we have a little too little water to do truly drylands farming except with native plants, as i understand it).

    What I am experimenting with now, based on just looking around my area to see what's happening naturally, is to let the weeds grow TALL around my plants. They provide shade, which lowers the temperature and that's been a huge boon for the plants in my type of environment. The things is, though, when I have the shade, I can put a large stone or two by the garden plants, and the area underneath these stones will stay very damp far longer than the surrounding area, but the shade keeps it from heating up as much. I let light mulch cover the remaining area. If I try adding even a few rocks near a plant where there is no shade, then most of the crop plants literally fry - you can water them three times a day and the heat is still too intense for them. :-/

    I have also done things like bury a few fist sized stones near or surrounding the crops, and again, moisture has remained higher under them - but not poking above the soil, they don't add to the surface temperature. I'm experimenting a bit with how many rocks I can add without interfering too much with the roots.

    I have been doing as you have with the weeds, too, and I have discovered some fun things about letting them grow larger. One, they have acted as trap plants for some things. A certain type of nightshade, for example, wild seeded near my tomatoes, and as it had pretty flowers, I left it there. The tomato hornworms all turned up on the native species with only one single one left on my tomatoes. The shade has been a big bonus, especially in areas with more open dirt. For annuals, if I chopped them down rather than pull them out, the roots rot in the soil and add nutrients that way, and the dead weed is used for mulch on top, as you've been doing. I have also noticed that if I figure out WHICH weeds the birds take seeds from, especially during periods before the crop seeds come, and plant them on the edges of the crops, they will attract more birds which were instrumental in keeping it pest free, too. I've also had some interesting experiences with sacrificial native plants that weren't for insects, but rather animals. I had a garden next to a huge patch of native weeds. I have seen little rabbits sit in the patch of native plants, eating them, right next to crops they could have eaten instead.

    I am trying to research which plants the native animals are more partial to and see how helpful it might be to grow them surrounding the crops, the next few years (gonna take some major research, I think!)

    The closely grown plants doing better - that has been my experience as well. People here talk about it creating a microclimate within the bushiness of the plants that is cooler and a little more moist, as well.

    The small pits - not only does it collect water, but during dry spells, it can simply be cooler as well. Cool air will pool in pockets like that at night and stay cooler a little longer after the sun rises - I'm currently trying to sink a small corner of my yard to grow plants that are used to slightly cooler weather. Some folks in my area seem to have used it with success.



    Anyway, that's how things work in my area, and what I've noticed during some of my experiments. Obviously not quite the same environment as your own, but again, thought it might be useful to see how some of it works where I am, so you can have some ideas for what might or might not be going on where you are, yeah?


    Oh, one other thing - you mentioned one of your legume types not doing well, yeah? And this is an area that you've mentioned everyone seems to agree does poorly, is poor soil, and so on, yes? I've run into something similar with my own legumes in some of our soils, and I have figured out that at least in some cases, part of the problem is that the soil has been so poor, no legumes have grown there - native or not - and so the soil has very few of the microbes that they need to collect that extra nitrogen they need. I found that growing successive plantings of the legumes has slowly seemed to increase the level of the proper symbiotic microbes in areas where this has been the problem (I compare this to areas where the legumes simply weren't growing well, due to heat, for example, where successive plantings never do anything but kill more plants ).

    Good luck! I look forward to seeing how this experiment goes!

     
    Tyler Ludens
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    Lots of dryland resources: http://www.harvestingrainwater.com/
     
    nikos pappas
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    Hi there, this is my first comment i would like to add to the discussion. As it was mentioned beforehand :
    [b]I think dew has more to do with the difference in temperature between the air and the surface, which causes condensation. Large leaves hold more dew, but I'm not sure if they create more dew. Fog capture is a function of leaf shape - many tiny leaves trap more fog.
    So first you need dew to exist/happen and second you need good dew "traps" (small and bizarre shapped leaves have bigger surface, tiny hair on the leaf also). I live in a coastal town in Greece and the med climate is really dry and hot. What i have done is surround the garden with windbreaks (evergreen bushes) to create a favourable microclimate, then i planted all my leafy vegetables/pulses very dense like a carpet. I still have to water them (remember there is only 600-700mm of rainfall/year) but i use a very small amount of water. This is a generalisation, how the plants are going to grow depends on many factors like the plant variety (chickpeas are really drought tollerant, lettuce is not), the condition of the soil, the climate as well as the microclimate.
    you can see at the picture attached that the raised bed is surrounded with bushes, ignore the bed per se, the rest of the area is green because of the dew.
    bed.JPG
    [Thumbnail for bed.JPG]
    raised bed
     
    nikos pappas
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    this might be usefull also
    Filename: cover crop chart - Holly Johnson.pdf
    Description: cover crop chart
    File size: 6621 Kbytes
    [Download cover crop chart - Holly Johnson.pdf] Download Attachment
     
    Tracy Wandling
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    Location: Cortes Island, British Columbia. Zone: 8ish Lat: 50; Rainfall: 50" ish; sand and rocks; well water
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    bee books chicken forest garden fungi hugelkultur trees
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    Hi,

    I'm wondering how your experiments are going? I, like so many others, am very interested in growing with the least amount of irrigation possible. Although I live off the 'left coast' of Canada, where things are just so lush and 'growy', water is going to be a main concern going forward in the garden area. Lots of experimenting to do, but so many good ideas here to help along the way! We're going permaculture all the way - we spread that $#*@ everywhere!

    Being new to the property (I introduced us here http://www.permies.com/t/56720/projects/garden-fence-finally-finished-rainbows ) we have spent the last almost 2 years observing. And while we have a lot of treed land, our soil sand does not have many redeeming qualities. I am hoping that the buried wood beds will help considerably. And have new hope concerning new ponds after watching Michael Newby's pigs do their thing! Very exciting.

    Anyway, just wanted to say hi, and introduce myself, and see what's happenin' in your dryland garden area.
     
    Tracy Wandling
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    Hi R;

    I have been doing lots of research about dryland farming lately (this thread has a lot of great info!), and am curious how your experiment went in your dry area. Did you get more summer rains this year like we did? I know you're probably busy this time of year, but I'd be very interested in hearing about your experiences with your first year dryland garden area.

    Cheers
    Tracy
     
    Jotham Bessey
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    Location: Newfoundland, Canada
    solar woodworking
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    Tyler Ludens wrote:I think you might want to try to breed the kale into more of a vase shape to funnel more dew to the roots.  Maybe?


    I think this thread is about the characteristics of crop plants themselves so I'll speak on that.
    I don't know about what work is being done to develop drought tolerant plants but I do know something about what mother nature has done.
    In dry areas that get fog, usually from sea breezes, hairy leaves capture and absorb moisture.

    However, to capture dew, a different approach is needed.
    Dune Grass: These have broader leaves than normal grass and form a v shape channel that funnels dew back to the base of the plant
    Trees: trees in wet regions have branches that hang down and thus sheds water away from the tree. During rain you can get by the trunk to stay dry. trees in dryer areas have branches and leaves pointing up. This funnels water back to the trunk and root system.
    Cactus: the thorns on a cactus provides shade for the skin of the plant.

    Kale is a plant that I think can have characteristics that serve all three.
    1.) The leaves can form a broad channel like the dune grass does.
    2.) Having the leaf spine straight and pointing angled upward, (say, 45 degrees?) would channel water to the roots.
    3.) curly leaf edges would provide shade to the main surface of the leaves.
     
     
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