Adding Potassium and Boron to soil

Discussion in 'Planting, growing, nurturing Plants' started by petal, May 31, 2008.

  1. petal

    petal Junior Member

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    We are starting a new garden on a building site. It is approximately 400 m2. During the building process topsoil was removed and there have been various amounts of mixing of sub-soil layers. We have built 3 raised beds and imported a soil and organic compost mix to get some veggies growing. So far they are going well.

    For the rest of the garden we have the results of a SWEP soil test and recommendations are to add:
    • - Nitrogen: 8-16 g/m2 (depending on plant type)
      - Phosphorus: 2-14 g/m2 (depending on plant type)
      - Potassium: 10 g/m2
      - Magnesium Sulphate (Epsom salts): 3 g/m2 (to increase Magnesium in the soil)
      - Boron: 0.03 g/m2
    It is the end of autumn here (North-East Melbourne, Oz), and I would love to plant fruit trees and lots of berries later in winter. My plans are to fork in the Epsom salts, dynamic lifter and cow manure and grow lots of green manure/cover crops over winter. This should take care of some of the Nitrogen, the low end of Phosphorus requirements (dynamic lifter), Magnesium, and add some organic matter.

    As for the Boron I have read that it can be easily overdone and can lead to boron toxicity without due care. Also it's highly soluble and mobile element so can leach readily. You can use Borax, which is just over 10% Boron. This would mean I would need about 0.3 grams of Borax per m2, or 3 grams per 10 m2. So 3 grams in a 10 liter watering can for each 10 sq m. Seaweed extract would have some Boron, but in too small amount to enough.

    Organic sources of Potassium include kelp extract and wood ash. I would need to apply a lot of kelp extract for 10 g/m2. I don’t think the council would be happy about me burning wood here. Sulphate of potash would be one way to add Potassium. However, this would also add sulphur, and the soil already has an excess of sulphur. I guess the extra sulphur may be OK because SWEP recommended Magnesium Sulphate for the Mg deficiency. There is also Muriate Of Potash, but has high levels of chloride.

    My main questions (of many) are:
    • - What would be the best way to add the required Potassium?
      - Is there a better way to add Boron?
      - Is there a better overall approach than adding manure, Epsom salts, growing cover crops, and adding additional Boron and Potassium by other additives?
    Any advice would be greatly appreciated.

    Cheers,
    Petal

    For those interested the details of the results are:
    COLOUR : BROWNISH GREY
    TEXTURE : COARSE SANDY CLAY LOAM

    RESULTS (Desirable Level)
    pH(1:5 Water) : 7.5 (5.0-6.5)
    pH(1:5 0.01M CaCl2) : 7 (7)
    Electrical Conductivity EC µS/cm : 339 (< 250 - < 470)
    TOTAL SOLUBLE SALT TSS ppm : 1118.7 (< 825 - < 1551)
    AVAILABLE CALCIUM Ca ppm : 1676 (1370)
    AVAILABLE MAGNESIUM Mg ppm : 138 (181)
    AVAILABLE SODIUM Na ppm : 78.2 (< 116)

    AVAILABLE NITROGEN N ppm : 10.8 (45-180)
    AVAILABLE PHOSPHORUS P ppm : 36.4 (45-180)
    AVAILABLE POTASSIUM K ppm : 78 (174)
    AVAILABLE SULPHUR S ppm : 7.5 (3 - 5)

    AVAILABLE COPPER Cu ppm : 4.7 (2-3)
    AVAILABLE ZINC Zn ppm : 62 (3-6)
    AVAILABLE IRON Fe ppm : 35 (> 20)
    AVAILABLE MANGANESE Mn ppm : 13 (> 20)
    AVAILABLE COBALT Co ppm : 0.4 (0.5-0.7)
    AVAILABLE MOLYBDENUM Mo ppm : 0.5 (0.5-0.7)
    AVAILABLE BORON B ppm : 0.4 (0.4-1.0)
    TOTAL ORGANIC MATTER OM % : 1.8 (3 - 4)
    TOTAL ORGANIC CARBON OC % : 0.9 (1.5 - 2)

    RESULTS (DESIRABLE LEVEL)
    EXCHANGEABLE CALCIUM Ca me/100g of soil : 5.51 (4.30)
    EXCHANGEABLE MAGNESIUM Mg me/100g of soil : 0.76 (0.99)
    EXCHANGEABLE SODIUM Na me/100g of soil : 0.22 (< 0.33)
    EXCHANGEABLE POTASSIUM K me/100g of soil : 0.13 (0.33)
    EXCHANGEABLE HYDROGEN H me/100g of soil : 0.8
    ADJ. EXCHANG. HYDROGEN H me/100g of soil : 0 (< 0.99)

    CATION EXCHANGE CAPACITY CEC : 7.42
    ADJUSTED CEC Adj.CEC : 6.62
    EXCH. SODIUM PERCENTAGE ESP : 2.96 (< 5)
    CALCIUM / MAGNESIUM RATIO Ca/Mg : 7.29 (2 - 4)
    BASE SATURATION PERCENTAGE BSP : 93

    PERCENTAGE OF ADJUSTED CEC
    EXCHANGEABLE CALCIUM Ca : 83.2
    EXCHANGEABLE MAGNESIUM Mg : 11.5
    EXCHANGEABLE SODIUM Na : 3.3
    EXCHANGEABLE POTASSIUM K : 2
    EXCHANGEABLE HYDROGEN H : 0
     
  2. bazman

    bazman Junior Member

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    Re: Adding Potassium and Boron to soil

    Hi Petal

    Do you have a compost bin? I reason I ask is compost or even better humus should offer most of what you are missing if you add a good range of organic matter to you compost bin's, also adding anything missing to compost then spreading that out is a pretty safe way of adding major and minor elements.

    Having a little wood fired BBQ/pizza oven is a good excuse to make ash and charcoal. :D

    Using weeds and adding them to compost or using them to make teas will also add anything you might be missing as they often mine minerals that veggie's can't, that's why Permies love all the different weeds, it's a resource not a pest.

    Cracker dust can also be a great way to add slow release minerals to your soil. I had some excess from building works here and added 10 full wheel borrow loads to the food forest. I doubt I will see any impact from that for a few years.

    I often add seaweed to my compost teas just before pouring them out.

    Raised garden beds are good for wet areas as the water has somewhere to drain, in the dry areas raised beds can increase the need to water them, just something to think about.

    Baz
     
  3. petal

    petal Junior Member

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    Re: Adding Potassium and Boron to soil

    Hi Baz,
    Thanks for your thoughts. These are all things we are doing/or have plans for. Except may be the cracker dust. We do have a compost bin and this will grow to compost bays, when we have more organic matter. We are definitely getting chooks too, and a wood fired oven is on the longer term plans/dreams. We love weeds too, we are very happy when any spring up in our dirt patch, and they stay in the ground until we have something better to grow. They are doing lots of good things to the soil environment, where as the bare soil is detrimental. I plan to apply some compost tea once I get the cover crops planted, as I don’t want to give weed seeds to much of a head start.

    Our current focus is correcting major and minor element imbalances demonstrated by the soil test. We would like to get the balance closer to the desirable levels before we invest in fruit trees. We want to feed the soil before we put too much demands on it.

    My main concern is the Potassium level. The soil test recommends adding 10 g/m2 of Potassium. This appears to be a relatively large amount compared to the composition of many natural fertilizers. Manures, compost and seaweed extract all contain some potassium. But to add 10 grams we would need many, many times the recommended application rate of kelp extract, (which at 6% Potassium, has a fairly high content). I don’t think wood ash is a good idea as it has a lot of Calcium and a liming effect. Our soil already has an excess of Calcium and a pH on the alkaline side. At the moment I am leaning towards using Sulphate of potash. Is this a big no-no?
    It may be that the Potassium deficiency is not to detrimental in the short term, and we should concentrate on using many applications of, say kelp extract, over time, (sounds expensive).

    So back to my main questions:
    • - What would be the best way to add the required Potassium?
      - Is there a better way to add Boron?
      - (modified) Is there a better overall approach than adding manure, Epsom salts, growing cover crops, and adding additional Boron and Potassium by other additives (in the short term) and compost and natural fertilizers (long term)?

    Cheers,
    Petal
     
  4. backyardfarmer

    backyardfarmer Junior Member

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    Re: Adding Potassium and Boron to soil

    You can always add chemicals - but is it the best way to go? Probably not. It might take you longer to build nutrient levels using organics, but the end result will be far better.

    A good source of potassium is comfrey. You grow it as a green maure crop and then dig it in. It would also help with your nitrigen needs. Alfalfa is also high (relatively) in potassium.

    Alternatively, cow and sheep manure have relatively high levels of potassium (along with nitrogen).

    Adding organic materials will help correct the nutrient balance in the medium term, but it will also add the humus that will keep it all in balance in the future.

    So ... do you have to fix it all in a hurry - or can you do it a bit more slowy for a better long term outcome? I'm not sure how low your figures are, compared to what is required for plant growth. prseumably your soil would support growth as it is. You could start to add the organics now - plant some beds out and continue to add potassium as they grow - by way of liquid composts.

    That's one option for you, anyway.
     
  5. Cosmic

    Cosmic Junior Member

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    Re: Adding Potassium and Boron to soil

    Who does soil tests? Any online sources?
     
  6. petal

    petal Junior Member

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    Re: Adding Potassium and Boron to soil

    Two independent companies that have been recommended on this forum are:

    APAL (Australian Perry Agriculture Laboratory)
    https://www.apal.com.au/

    SWEP
    https://www.swep.com.au/


    They are Australia, but do tests for other countries.

    I choose SWEP simply because of cost. Searching past forum posts show some people prefer one over the other. I would probably have chosen APAL if the cost was similar.
     
  7. IntensiveGardener

    IntensiveGardener Junior Member

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    Re: Adding Potassium and Boron to soil

    Hi Petal,
    Crushed granite is a very good long term source of potassium. Add it to your composts as a thin dusting on each layer and it will become available faster.
    The way i look at a mineral deficientcy is that there is a shortage of the actual substance and a shortage of the process which makes it available. The compost should provide both of these to the soil.
    Wood ash is a good source of potasium but it has i liming effect on the soil. I use it because my soil Ph. was 5.3. In your case it may even be detrimental because it could raise the soil Ph. above 7.5 making it too alkaline to grow some plants.

    If i were you i wouldn't fuss too much about minerals. I'v found it to be a misleading way to look at gardening. Just be sure that your organic matter and inputs come from a diverse range of places.
    Compost make from weeds, deciduous leaves, cow and chicken manure should contain all the NPK, and micro nutrients your plants need.

    As time goes on your garden should accumulate more and more of the lacking nutrients provided you continue to import materials and that you compost all the waste from your crops.
    cheers,
    IG
     
  8. SueinWA

    SueinWA Junior Member

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    Re: Adding Potassium and Boron to soil

    Petal,

    The fastest way to add some potassium is probably using liquid fish emulsion. The next fastest way is adding animal manures, and chicken manure tends to have the highest level of potassium.

    If there is a better way of adding boron, I don’t know what it is. Boron is required in such small amounts, just a whiff, that mixing it with water seems the only way to get reasonably even coverage. Even if you mixed it with something like alfalfa meal, you would still probably get very uneven coverage.

    “Is there a better overall approach than adding manure, Epsom salts, growing cover crops, and adding additional Boron and Potassium by other additives (in the short term) and compost and natural fertilizers (long term)?”

    No, there are no quick fixes. You are working with Mother Nature, she moves at her own pace, and she will not be hurried. The farm chemical salesmen got their foot in the door with farmers who were looking for a quicker way to increase crop yield. You know what happened then.

    I would also like to take this opportunity to gently point out a fact to those who have posted here saying that all you need to do is add a lot of compost and green manures, and your soil will be all right.

    That simply isn’t true. Australia and the U.S. both have the problem of wide areas of country that is lacking in certain minerals. Either the minerals were removed by chemical cropping and not replaced, or they were never there at all (or were there in insufficient amounts).

    Just because plants CAN contain certain nutrients doesn’t mean that they DO contain those nutrients. If your soil is lacking in selenium, and you grow a cover crop, that cover crop will be lacking in selenium. When you turn it into the soil, it is still lacking in selenium. When you grow crops in that area, they will also be lacking in selenium. When you eat those crops, you will have a selenium deficiency.

    If you plant a cover crop in selenium-deficient soil, turn it under, and then sow it to a nice combination of pasture grass, that grass will also be lacking in selenium. When your livestock grazes that grass, they will have a selenium deficiency, too.

    There are only two substances that plants can absorb from the air: Oxygen and Hydrogen. That’s it. No selenium, no boron, no sulfur, no manganese, no magnesium, no calcium, no zinc, no other trace minerals. If certain nutrients are missing from the soil in your area, you will have to bring them in from outside. Period. And that doesn’t mean from your neighbor, whose soil is as equally deficient as yours.

    Sue
     
  9. bazman

    bazman Junior Member

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    Re: Adding Potassium and Boron to soil

    I agree with SueinWA, but.... :D In your suburban block you will be adding all sorts of out side sourced material to your compost system, as it sounds like you are just starting to produce your own food you will be adding lots of organic waste from off site sources(food scraps etc), I would recommend finding good sources to help supply your compost as well, I'm making 10k lt of compost a year now and at least a 1/3 comes from off site sources, this in it self will give you a good cross of minerals and help the general quality of compost you produce.

    Another idea is each year source different types of mulch, lucerne hay, sugar cane mulch your work mates grass clippings, I'm sure you get the idea, Mixing sources up will help give your soil a good cross mix of minerals, when things start to balance out in your garden you can produce most of your own mulch, clumping grasses are fantastic sources of fresh free mulch. (and they look great)

    I would say add all you minerals to your compost system, water them into your compost or add it to a good layered compost as you make it, it's a safe way and they will be locked up with humus and mostly readily useable by plants. Read up on "Cation exchange capacity" adding mineral's alone will not balance your soil, Quality home made Humus will make all those added minerals usable to your plants.

    Adding Humus to the soil can be done by mulching, adding worm castings, digging in green manure's, composting, when you have lot's of fat happy worms in your soil you can feel pretty safe you are travelling down the right path. :D
     
  10. Cosmic

    Cosmic Junior Member

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    Re: Adding Potassium and Boron to soil

    On an episode of Gardening Australia, the guy who lives in Wynnum was demonstrating adding boron to your garden. He mixed something like 1tbls of borax with 9 L water and spread it over about 4m area. I am not 100% sure of the spreading area but something like that.
    It should be in the gardening Australia archive.
     
  11. IntensiveGardener

    IntensiveGardener Junior Member

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    Re: Adding Potassium and Boron to soil

    I agree Bazman. If your bringing in plenty of stuff there should be no problems. I wasn't recomending a completely closed system in my previous post. My kitchen scraps for instance are a mixture of biomass from all over the world. coffee grounds (south America), rice (asia), bread (W Australia), banana peel (tropical australia)

    Also remember that the soil test only tests the topsoil.
    Many of my fodder plants are very deep rooted perenials (poplar, tagasasty, comfrey, lucern etc) which draw nutrients from very deep down.
    What about nitrogen and carbon?
     
  12. SueinWA

    SueinWA Junior Member

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    Re: Adding Potassium and Boron to soil

    'What about Nitrogen and Carbon?'

    Yes, there is Nitrogen in the atmosphere, but it can only be converted to useful forms by living organisms, such as nitrogen fixation of legumes by bacteria.

    Carbon requires photosynthesis, as far as I know, although the photosyntheis is affected by the concentration of carbon dioxide.

    I didn't realize how much was lacking in Australia's soil until I read Pat Coleby's Natural Farming and Land Care. I would suggest you read it, it's very interesting. And it MUST be easier to find there than it is here!

    Sue
     
  13. IntensiveGardener

    IntensiveGardener Junior Member

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    Re: Adding Potassium and Boron to soil

    Hi sue,
    I got coleby's book for Christmas and have read it many times since. Very good book indeed :)
    I found its shortfall was that it concentrated too much on the process of re-mineralization. Not a great deal about biology or processes which occur in the soil. Doesn't matter what minerals i add to a hard baked, compacted clay soil with no organic matter it won't fix it.
    Australian soil is indeed very poor minerally. Most of the continent is lacking in molyptinum and/or boron.
    My soil is better than most being red, volcanic and not lacking anything major exept calcium and phos (which are preasent but scarce). I'v had soil tests done yearly since i started gardening and the boron & moly, phos and calcium have all increased to adequate levels. I put down dolomite and some rock phos, also wood ash and added all my kitchen scraps etc but have never added any trace minerals.
    If your putting a lot of stuff from all over the planet into a small area it should ballance itself out.
    cheers,
    ig
     
  14. Raymondo

    Raymondo Junior Member

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    Re: Adding Potassium and Boron to soil

    One way of adding minerals that won't leach too quickly is by creating a humate. So, for your boron, add the boron salt to some fulvic and/or humic acid. The former stimulates bacterial growth and the latter stimulates fungal growth. You can buy these quite cheaply in dry granule form but they're not what would be called 'sustainable' products as they are made from Chinese brown coal. You can make your own by dumping some good compost into a bucket, adding some water, swish it around vigorously, like you were making the biodynamic preparation 500, filter out the particulate matter, add borax and with any luck, you'll have a boron humate, or a humate of whatever mineral you choose. The advantage of mineral humates is that they a) don't leach too quickly, especially in clay soils, and b) they're in a more plant friendly form.
     
  15. kathleenmc

    kathleenmc Junior Member

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    Re: Adding Potassium and Boron to soil

    Hiya,

    Seaweed is full of boron...just add some kelp to a bucket of water and let it sit for a while to make astinky tea. (10 to 1) and it will be the best thing for adding to the soil for you. (Plus a gammit of other vitamins and minerals). I agree with some of the other posters on here about not being to caught up in re mineralisation. What ever is growing on your place now is helping to bring it back to the right ph...Fukuoka's book 'one straw revolution' shows us that weeds and grasses, trees and shrebs etc are there trying to bring a balance back to the land. Pulling them up and either composting, making a tea or just letting them rot down (without seed heads of course) should help. I use rock dust on my small space. I have acidic sandy soils. Lots of composted chicken manure from my girls, seaweed tea and worm juice does the trick for me.

    Goodluck with the job....

    Kathleen :D
     
  16. SueinWA

    SueinWA Junior Member

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    Re: Adding Potassium and Boron to soil

    'I found its shortfall was that it concentrated too much on the process of re-mineralization. Not a great deal about biology or processes which occur in the soil. Doesn't matter what minerals i add to a hard baked, compacted clay soil with no organic matter it won't fix it.'

    IG, the point of her book was the laying of a sound mineral foundation for your soil. Without starting with the mineral content, you aren't likely to get very far with other improvements.

    I suspect that many people resist remineralization of their soil because there are no instant visual benefits. You mix in your lime, magnesium, sulfur, boron, molybdenum, copper, manganese and zinc (etc), and your soil just sits there. It's still just soil. But it's like a baby raised on a wholesome, organic, nutrient-dense diet: you've given her the building blocks for a healthy body.

    For instance, calcium 'opens' the soil, improves soil texture, makes phosphorus and micronutrients more available, works with the soil microbial processes, helps green manures and other organic matter decay faster to release their nutrients to the crop, helps plants form better root systems and above-ground parts, and is what puts all the other nutrients into the plants.

    If your soil is short on calcium, without it all the above processes will take more time, or won't happen at all, depending on the amount of deficiency.

    If you try to start with adding compost or green manure crops, with the plan of adding calcium two or three years down the road, you're working against yourself. It's like building a house starting with the roof, then the walls, and then the foundation. It may be possible, but there are easier ways to do it, like starting with the FOUNDATION. Soil is the same. Why do it the hard way?

    Raymondo, thank you for that very brief and enlightening info on humates. I had read about references to them, but didn't understand what they were. They are said to be a very valuable addition to any soil program.

    Sue
     
  17. Michaelangelica

    Michaelangelica Junior Member

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    Re: Adding Potassium and Boron to soil

    Here is an interesting article on Phosphorus
    https://permaculture.org.au/2009/07/23/p ... -on-farms/

    Does the red scoria gravel/rocks sold in Australian nurseries, for pathways and mulch, contain Phosphorus?
    https://bulletin.geoscienceworld.org/cgi ... 20/3-4/476
     
  18. pippimac

    pippimac Junior Member

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    Re: Adding Potassium and Boron to soil

    Lots of great advice here! Just as an aside, comfrey is wonderful stuff, and everyone should have some in a PERMANENT bed- make sure you want it there forever: if you change your mind/garden, you will have to work around the comfrey as you'll never get rid of it.
     
  19. gbell

    gbell Junior Member

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    Re: Adding Potassium and Boron to soil

    Uh... and Nitrogen.

    The main reason lots of people recommend green manure crops, compost, innoculations, etc. to balance soil out is that a lot of times the nutrients ARE there, just not in plant available forms. As all the soil life comes back on line, it works to make those nutrients available... fungi dissolve rock, humic and other acids do the same.

    And in the case of weeds and other deep-rooted plants, sometimes nutrients are brought up from far deeper than you would've taken your soil samples from. So a deficiency could just be a 'surface deficiency' and corrected with proper biological farming/permaculture techniques.
     
  20. moonlight

    moonlight New Member

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    So old thread, thanks for the great advices guys :y:
     

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