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Using lime to correct pH  RSS feed

 
Paulo Bessa
pollinator
Posts: 356
Location: Portugal (zone 9) and Iceland (zone 5)
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Hi all,

I have never used lime before. But my garden soil is acidic (pH 5.5), and now after 2 years of adding plenty organic matter, I decided to add some lime to help correcting the pH. Its not my preferred choice, but I am going to do this as a one time measure. Because I basically live in a "almost" peat bog.

Main question is that I am not fully sure about what type of lime I bought at a local nursery because the label is written in a foreign language But I decided to mix it with water, and the pellets dissolved somewhat to a suspension and the water did not heat a single bit. I do not have a pH reader at the moment, but obviously it is not very alkaline, it does not burn my skin as hydrated lime would do. The bag says 40% calcium, 5% magnesium. I guess it is dolomite or limestone pellets.

What form of lime is this? Can I add it directly to the soil outside, even with some plants (perennials) already on it? Will it burn the plants if it touches their leaves and stems?
Can I use the lime water and use it to water some indoor containers at a very diluted rate?

I intend to cultivate into the ground so as to help it dissolve it more easily. I also guess there is a deficiency in magnesium in my soil (not sure) because some plants, especially legumes, exhibit yellow discoloration of their leaves while keeping their veins green. So the lime will probably be a great help.



 
Leila Rich
steward
Posts: 3999
Location: Wellington, New Zealand. Temperate, coastal, sandy, windy,
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Paulo, my ph is about 6.9, and while I've done some work on low ph land, I'm not very familiar.
Hopefully someone will give you more specific advice than I can!
Have you had a lab test to get your ph result? I ask because home kits can be really innacurate, and with ph's logarithmic scale, 5.5 and 5.6 look pretty different...
It's not everyone's thing, but as a one-off it can be very useful. For instance I discovered that my phosphorus levels are off the charts, so I avoid high-phosphorus amendments like animal manure.
Paulo Bessa wrote:I am going to do this as a one time measure

Soil will start heading back to its natural ph once the soil bacteria have processed the lime, so it's an ongoing process.
NZ farmers in low-ph areas generally lime every 2-3 years, with the soil bacteria generally taking at least 6 months to make the lime available.
Paulo Bessa wrote:The bag says 40% calcium, 5% magnesium. I guess it is dolomite

I think so too, although I've only seen dolomite in powder form.
Paulo Bessa wrote:Can I add it directly to the soil[...]Will it burn the plants if it touches their leaves and stems?
Can I use the lime water {to water} indoor containers at a very diluted rate?

As far as I know, lime's safe to sprinkle dry over plants. Dissolved lime I know nothing about.
Paulo Bessa wrote:I also guess there is a deficiency in magnesium in my soil (not sure) because some plants, especially legumes, exhibit yellow discoloration of their leaves while keeping their veins green

Sometimes it's not an actual defiency, but the ph which makes various minerals unavailable.
Liebig's got plenty to answer for, but his 'law of the minimum' is useful nutrient barrel
I also like these charts; it gives a good idea of the relationship between ph and nutrient uptake mineral uptake chart
 
Mateo Chester
Posts: 148
Location: Zone 4b
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Paulo,

That is definitely NOT dolomitic limestone, as this material almost always has a ratio of 2:1, calcium:magnesium - CaMg (C03)2. What you have sounds more like calcitic limestone. As Leila said, both these materials take quite a long time to break down. That being said, I find nutrient availability to be more reflective of microbial activity than anything else. Have you tried applying compost/earth worm casting teas to help re-establish microbiological populations? This will help accelerate the cycling of any magnesium already present in the soil, perhaps unavailable to the plants.

If you have in fact diagnosed a magnesium deficiency, what you have, if it is calcitic limestone, will not do much. Neither of these materials will be effective as a drench, given the expressed need for microbial cycling. If you are looking for quick fixes in the magnesium deficiency arena, a material called langbeinite (sul-po-mag) is very effective. The quicker release materials might be a good hold-over until the more long term liming agents are able to break down.

Either way, like you probably already know, building organic matter and providing numerous cation exchange sites will greatly increase your soils ability to hold onto magnesium. Also, as it is a cation, it is susceptible to leaching, so keeping that in mind when watering your plants will also help. In speaking of CEC, incorporating clays and various rock dusts/minerals into your soil will also increase your CEC, ultimately providing more cation exchange sites. And also, if you can mix the liming agents INTO the soil, they will become available to the plants much more quickly. Hope this helps. Ciao.

Matt
 
Mateo Chester
Posts: 148
Location: Zone 4b
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Could anyone elaborate on the correlation of soil pH and the microbiological avtivity of soil vs. liming agents? I am under the impression that for the most part, it is the SFW that dictates the pH of soil through a dance with the root exudates. My understanding is that the soil biota have a greater impact on pH than that of liming agents.. If this is the case, compost, earthworm castings and their respective "teas" would be the way to go. IMO
 
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