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brass_tacks

Watering and Moisture Meter Questions

brass_tacks
16 years ago

I must get a moisture meter. Please help me out with the name of a nice, reasonably priced meter.

?Questions? How much water is enough, and does it matter how fast the water flows within the canopy? I am thinking that the only way to keep the water away from the trunk is to water very slowly, and more near the drip line. Does that sound right? Also, just how damp should the soil be outside the canopy area?

The area outside the canopies is very dry -- nothing growing (I keep the weeds pulled). We have been in drought conditions for about a year. There has been rain, but so little that the shallow ponds are going dry.

I'm watering about 1 gal. every 3 minutes, for 30 minutes. The days between the waterings have been inconsistant -- as I'm just guessing what the tree needs. The canopies are about 2 1/2 or so feet away from the trunks. The old leaves (other than the leaf miner leaves) have not been cupped and are not yellowing. Worrying that I might be watering too much, I cut back on the time between the waterings and didn't water for over two weeks. When I finally watered the trees, the trees with the leaves started shedding lots of leaves. (the trees that I had practically defoliated by removing leaf miner damaged leaves had lost just about every leaf that was left when we had a heavy frost. The trees that had the good-sized canopies weren't damaged very much from the heavy frost--other than some growth on top.) I reasoned that the leaves were dropping because the soil must have been too dry for too long before I watered. After over two weeks, the leaves are still dropping with every little breeze. So maybe the roots have been kept too wet. I am all mixed up. The trees that had only a few leaves left are now filling out with all brand new leaves. Even the trees that have the plump canopies and loosing lots of leaves every day are also getting many brand new leaves.

You can see why I must get a moisture meter.

Thanks so much.

Pat

Comments (18)

  • bencelest
    16 years ago
    last modified: 9 years ago

    My experience with the moisture meter that I bought for $11 at Orchard was not good.
    It was very inaccurate.
    I ended up throwing it away.
    So i just water my citrus with my gut feeling.
    When I see that the top soil is dry I water and soak them good.

  • jbclem
    16 years ago
    last modified: 9 years ago

    I had the same problem last summer during the hot weather we had. I wanted to keep watering my fruit trees, but the top soil wasn't really dry...although the trees looked stressed. I tried several of the cheap moisture meters but ended up not trusting their readings.

    I looked into better quality moisture meters and discovered the Irrometer, used in agriculture and by orchard operations. It's a tensiometer, measuring the amount of energy(suction?) that roots must exert to extract water from the soil. I see them on Amazon.com for $149.00. I bought mine for about $20, a lucky find considering it was unused/new/old stock probably. It's really designed to be left in one place, although I'm planning on moving it around. And ideally you have two of them, different lengths (25% of root depth, and 75% of root depth). I have a 12" one and we'll see how that works. It can't be worse than the cheapo moisture meters, and I'll have a much higher degree of confidence in its readings.

    Also, there seems to be a Soil moisture/pH meter made by Control Wizard, auctions on eBay starting at $49.95, Buy it Now at $100. A Hong Kong identical looking version, also on eBay, for $31 (incl. shipping). I've sent them an email to see if I can get any specific information out of them, but it looks like a good compromise if it shows any kind of accuracy and consistency in its readings.

    The other method I've tried is to use the 3 cheapo moisture meters I have and compare readings, thinking that if they all show similar readings than that may mean something.

    As the weather warms up I'm feeling the urge to water plants and trees...all the time! Here's hoping one of these meters will keep that urge in bounds.

    jc

  • brass_tacks
    Original Author
    16 years ago
    last modified: 9 years ago

    Thanks for answering. More answeres welcomed.

    Here is an idea that I came across while searching for some answer. Sink a rod/probe into the soil; when the rod won't easily sink any further, the soil is dry.
    Pat

  • tapla (mid-Michigan, USDA z5b-6a)
    16 years ago
    last modified: 9 years ago

    Sink a rod/probe into the soil; when the rod won't easily sink any further, the soil is ............ too compacted for the rod to sink any farther. ;o)

    If the idea you set forth held water, you'd be unable to use it to test because the driest soil is to be found at the top of the container and you wouldn't be able to penetrate it.

    Al

  • gardner_dragon
    16 years ago
    last modified: 9 years ago

    I used to follow the finger method but found that it was faulty in most cases north, east, and west of the inground growing areas. I would water when the top couple inches of the pots were dry. This I believed caused my problem of root rot. The perched water table of my pots seemd to be very high and right in the middle of my trees root zone. While the top and the outsides of the pot were dry, the middle and lower 2/3's was sopping wet and mushy. Now I always use the moisture meter and water when its on the dry side. I place the probe at a depth of 2/3's the depth of the pot and check the moisture there. I water with a hydrogen peroxide solution to insure the roots get extra oxygen during prolonged periods of wetness. I don't try to actually water at this time but rather just get the hydrogen peroxide in to the wet portion of the pot. The top and sides will still show somewhat dry as there is not time enough for this area to absorb the water.
    Andi

  • laidbackdood
    16 years ago
    last modified: 9 years ago

    Sorry but you didnt state if your plant was in a container
    or not? If so,what size and composition?I have tried all sorts
    of mediums eg coconut husk chips,potting mix with water crystals,inorganic and organic mixtures,peat etc. I have killed many citrus trees.My biggest problem has been wet feet.
    The roots hate it and drop their leaves and twig die back.
    I have removed all existing soil from the tree and transplanted into chc/peat and chc/coir and they all snuffed
    it.After two years messing about i have found what has worked me.
    firstly,i have found it a bad idea to remove all the existing soil and replacing it.The roots dont like it and then they dont take up water after that.
    Secondly,increase the pot size by 2 inches only and keep
    the dwarf citrus slightly rootbound.When moving up a pot size,remove the outer two inches of soil and tease the roots
    out a bit,so they will grow into the new soil.Mix the soil
    you remove with the new potting soil( dont ask me why but
    they seem to like that).
    I use standard potting mix which has pummice in
    it and add a small amount of perlite and slow release fert
    and i use terracotta pots.Its not that hot in new zealand
    but we get a lot of rain.These pots can breath and let air
    get to the roots.soak the pots for 24 hrs before in a bucket
    of water,so the pot doesnt act as a wick.
    I dont use potting mix with wetting agents or
    water crystals but if its very hot where you are,it might
    be good.
    I have 4 small trees in 25cm terracotta pots and
    they are all loving it.They are not in full sun either.They
    dont seem to like that.(maybe its because the ozone is thin
    here,i dont know)They get 4 to 5 hours of morning and afternoon sun. I have a satsuma mandarin in the ground,it
    only gets 2 hours of sun early in the morning! the rest of
    the day is shade.Growing very nicely thank you!
    You might need to water more often with the terracotta but its worth it.I agree with tapla about the
    watering bit.A wooden skewer stuck into the pot,lift it out.
    If its damp,dont water.I must admit i use a meter,i bought
    from the uk that can test moisture,ph and light.Plant progress in relation to the meter readings has been good and i use it for=citrus,tomatoes,chillis,blueberries,pomegranite,passionfruit,
    All with good success.If you water very deeply once in a while,then just leave them alone,the roots will search for
    water at the bottom if they need it.Make them work for their
    water.You can always fill a tray of water and stand them in
    it for 30 minutes and let them wick the water from the bottom,suck it up.DONT leave them in this water longer than
    that.They dont like standing in water.If the top half is dry
    and the bottom half is moist,what are the roots supposed to
    do? That is what works for me but you are in a different part of the world.Personally,i would soak them in a tray for
    30 minutes whenever its very hot.The water will evaporate
    and provide humidity too.Cheers and good luck.

  • gardner_dragon
    16 years ago
    last modified: 9 years ago

    My trees are in containers. The original poster has theirs in the ground, or so the post reads. I have never pulled weeds from the canopy area of a containerized plant.

    I don't think a moisture meter would work for an in ground plant as the ground water would be different. The root systems of ground planed trees would also be quite different as they would be allowed to spread much further. In this case I would use the wooden dowel method.

    My container plants are planted in a mix of soil conditioner ( small bark pieces, perlite, sand, potting soil, and peat). This comes pre-mixed from the nursery so I have no idea what the ratios are. It takes a while to get wet and holds the water a bit longer but its very light and airy. IF we get a lot of rain to where the pots are very wet, I will use the hydrogen peroxide to provide extra oxygen to the root zone.
    Andi

  • laidbackdood
    16 years ago
    last modified: 9 years ago

    Hey garden dragon,do you find your containers stay wet for a
    long time? are they plastic or wood etc?We get a lot of rain here,especially in winter and i have found plastic stays wet
    too long.I use the hydrogen peroxide sometimes but my mix is
    drying so nicely,i dont need to use it much.The terracotta
    breathes anyway.I also drill plenty of holes in the pots.I
    use masonary drills.Start small and work your way up or the
    pots can crack.I put a mesh on the bottom of pot.Then just
    use my mix,nothing to improve drainage.Its fine like that.I also keep the pots off the ground on plastic bottle tops,so
    air can circulate under the pot,especially in winter.Ive had
    problems with plastics for other plants.just an idea.good luck

  • brass_tacks
    Original Author
    16 years ago
    last modified: 9 years ago

    My citrus trees are all in the ground, but all these posts have been so interesting.

    Now I'm wondering if I should have a shallow trench around the outside of the canopies rather than a birm of dirt.

    The more I think about it, I must find another way to water. I think that just too much water is being put down in the half hour watering (10 gal.). I change the position of the hose every ten minutes and place the hose on top of the birm so that the water flows under the canopie; water flows to the trunk (probably because the water is going down too fast). The trees sunk a little more than was expected after planting, so I have to keep an eye on the level of dirt that will easily slope toward the trunk when the dirt in the birm moves little by little.

  • jbclem
    16 years ago
    last modified: 9 years ago

    garden dragon...could you tell me more about using hydrogen peroxide, how much do you mix in one gallon of water?

    jc

  • gardner_dragon
    16 years ago
    last modified: 9 years ago

    I don't dilute the peroxide unless I am using it on seedlings. I also only use 3% formula from the dollar store. Its pretty dilute already. If using on seedlings I dilute it 1/4 H2O2 to 3/4 water.
    Andi

  • brass_tacks
    Original Author
    16 years ago
    last modified: 9 years ago

    Tapla,
    About the idea of putting a probe into the soil to see how far down the soil is damp/wet...

    Yes, I see what you mean -- to a certain extent. But if I have just finished watering(talking about a tree that is planted in the ground) and am wondering how far down the water has gone -- then don't you think the probe would work? I just haven't found anything around the house that is strong, narrow or long enough to use.

    It sure helps knowing how folks handle their watering -- their logic and all.

  • rhizo_1 (North AL) zone 7
    16 years ago
    last modified: 9 years ago

    brass tacks, you can find wooden dowels at any hardware store; they are typically 3 feet long and come in many different sizes (diameters). Moisture meters are famously inaccurate.

    Most tree roots live in the top 24 inches of soil, though most of the water absorption occurs in the top 6 inches. When I test for watering efficacy or rainfall penetration into my hard clay soils, I only concern myself with the the top 6 inches. (This is for trees planted in the soil.)

  • brass_tacks
    Original Author
    16 years ago
    last modified: 9 years ago

    rhizo,
    So, if the first 6 inches or so should be moist after watering, do I wait for the area to get fairly dry before I water again? What about the area outside the canopy -- do I try to maintain the same kind of moisture that is under the canopy?

    The ground here has gray and green clay -- I removed the clay from the planting hole at least 3 times the width and depth of the root ball some three years ago. Outside the canopy areas there would be clay closer to the surface -- maybe a foot or deeper from the surface.

    Thanks so much for your insights.

  • rhizo_1 (North AL) zone 7
    16 years ago
    last modified: 9 years ago

    Gray and green clay!! Oh no! How did you miss out on that nice red stuff? ;-) Tell me, if you were to dig a hole (not a real big one) in that stuff and fill it with water, how long would it take for the water to drain away? Those colors tell me that it might take a very long time. (Is my guess right?)

    You need to be extra careful about overwatering in your situation. You've got a nice planting basin in the midst of all of that clay. Moisture will be very slow to leach down and out into that native clay soil. I can visualize a nice bathtub full of amended soil and plant roots.....always full of water. Eeeek

    With citrus being susceptible to root rots of various sorts, I'd be conservative with the water.

  • brass_tacks
    Original Author
    16 years ago
    last modified: 9 years ago

    Rizo,
    Yes! You are describing exactly what I've been worried about. Lately I've been having to prune dead wood, and just hoping the twigs are dead because of the heavy frost we had not so long ago (unexpected and trees not protected).

    Several days ago I dug a hole to see how far down the clay started. First thing in the morning I'll fill it with water and time how long it takes to empty.

    Please keep me tuned.

  • norwood1081
    15 years ago
    last modified: 9 years ago

    I may be a year late but I'd like to thank Tapla (Al) for his post. Two-thirds of a 6' Blue Cypress tree I purchased a month ago is going pale. My wife noticed it this morning. It's gone 10 days since adding mulch and deep soaking it and the cheapo moisture meter still reads WET! It was measuring the electrical conductivity of the soil. I've soaked it for the past 4 hours but I think it's too late. Since I live 35 miles SW of Tucson, Az. I found a 1/2" X 3' Saguaro Rib, sanded it and sharpened the tip and it cost me $0.00! No Home Depots out here. This is in the Citus Forum because last year I lost 2 Orange trees to what I thought was 'over watering'! This year the Navel Orange tree is doing good because I'm watering it on instinct.
    Ric...