FRICKITYFRICKTYFRESH
Well-Known Member
I've been told by multiple people that watering to runoff in living soil is doing more harm than good. Just looking for opinions from the people that have been doing this a lot longer than me. thanks.
watering to runoff in living soil?
- Thread starter FRICKITYFRICKTYFRESH
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PadawanWarrior
Well-Known Member
Try not to do that, unless you're trying to flush stuff out.
IIReignManII
Well-Known Member
I try to have no runoff
Did any of them explain why?
The reason you don't want to water until runoff is when you are growing organically, all the magic happens in the soil. So if you start heavily watering you can wash away the beneficial bacteria/nutrients. You want to water until saturation and stop once you start seeing it trickle out from the bottom.
On the other hand, if you are using bottled nutrients / synthetics, you run the risk of letting the salts build up in the soil if you don't water until runoff. This is what causes nutrient burn and all sorts of other problems.
Someone can correct me if I'm wrong but I'm pretty sure this is the reason.
On the other hand, if you are using bottled nutrients / synthetics, you run the risk of letting the salts build up in the soil if you don't water until runoff. This is what causes nutrient burn and all sorts of other problems.
Someone can correct me if I'm wrong but I'm pretty sure this is the reason.
FRICKITYFRICKTYFRESH
Well-Known Member
Can you support your assertion with a credible source of horticultural or agricultural science?
No I can't link to a specific article or scientific journal but it seems to be the commonly accepted practice when it comes to watering organic vs synthetic. I'm sure someone more knowledgeable can step in and give you the exact science behind it. But I imagine for what the OP is asking for, it should suffice.
waterproof808
Well-Known Member
watering to run off in living soil is just wasting water. You just want the top few inches of your soil to remain moist as the majority of microbial activity takes place there...this is why using mulch is important for living soil.
weedstoner420
Well-Known Member
Just like different nutrients are mobile or immobile within plants, they also have different degrees of mobility within the soil. Nutrients that are immobile in soil have a strong bond to soil particles at a molecular level, whereas nutrients that are mobile in soil are not strongly attracted to the soil particles and can easily be dissolved and washed away by water. So if you water to too much runoff, you'll end up washing out the soil-mobile nutrients, and end up with soil that is either deficient or way out of balance.
The chart in this link breaks down which nutrients are mobile and immobile in plants vs in soil:
Hey, I appreciate the effort! I am quite familiar with the form and function of soil chemistry, the concept of leaching, and the differences one should consider when applying agricultural science to potted container growing.
I'm looking for peer reviewed science that demonstrates an appreciable loss of soluble nutrient ions and microbes (
) from potted container mixes when water is allowed to flow from the bottom of the pot. If anything, occasional flow through is beneficial, as it helps to remove some concentrated soluble nutrient ions from the bottom of the pot where they build up over time by repeated applications of water under the "keep it moist" living soil watering paradigm. This is especially important to those using irrigation water with questionable TDS concentrations. CO2/O2 gas exchange in the lower reaches of pot is also benefited by the occasional flow through. Effectively "flushing" the soil solution of soluble nutrient ions from a potted container requires a comparatively enormous amount of water.Also, when one understands the concept of leaching in agricultural soils, one will begin to recognize how irrelevant cation exchange capacity is to potted container gardening.
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weedstoner420
Well-Known Member
Whoops, didn't realize you already knew all that, lol. I think I misunderstood your question. I wasn't trying to say watering to runoff is bad or unnecessary in organic soil, just that nutrient leaching is a real thing (I dunno about bacteria and other microbes though), which might lead some growers to think that you shouldn't water to runoff.I appreciate the attempt. I am quite familiar with the form and function of soil chemistry, the concept of leaching, and the differences one should consider when applying agricultural science to potted container growing.
I'm looking for peer reviewed science that demonstrates an appreciable loss of soluble nutrient ions and microbes (
Also, when one understands the concept of leaching in agricultural soils, one will begin to recognize how irrelevant cation exchange capacity is to potted container gardening.
As you said, in some cases it can be good or even necessary to maintain soil health. I'm still learning about this topic myself, but I look at it as trying to achieve a balance. Too far in either direction and you can end up in trouble.
True, most of the research I see out there is related to agricultural soils, not containers. I'd be curious to know how much runoff is okay or even beneficial in containers, and how much is "too much" and what the negative effects would be, but I can see why researchers might just not care enough to find out. Home container gardeners probably tend to over-fertilize more than large-scale farmers in the first place, and in containers it's easy enough to top-dress or add synthetic fertilizers as needed should any deficiencies arise.
dbz
Well-Known Member
There is a lot of information on Leaching. This process happens is observed scientifically in many papers in regular soil. For some studies they conducted experiments with and without additional fertilizers. Leaching happens. If it happens in soil in open areas, it will also happen in potted plants, due to a much smaller root system logic would dictate this process would be much more profound.
https://www.britannica.com/science/leaching-geochemistry-of-soil
This one looks at nitrogen leaching with fertilizers and without
journals.plos.org
A host of the following ones look at phosphorous and other micronutrients specific to no till as well
www.preprints.org
If you are looking for peer reviewed research specific to potted plants or cannabis good luck. However regardless of with potted plants or not the principles remain true. So if you have a potted plant especially with a living or really hot soil like SOHUM or Kindsoil, that would probably be why the manufacturers highly recommend not watering to run-off.
When you are using synthetic nutes the salt content becomes much higher and run-off is much more important. I think what happens with Cannabis growing is these two areas get conflated when they are quite different.
Sure I haven't grown tons of cannabis, but I do grow a lot of garden plants and other plants and have for a long time, and taking all of these things into consideration has certainly merited benefit for me at least in my opinion. Most people that I have seen in the Organics and no till threads have said mostly the same things that I have seen here.
https://www.britannica.com/science/leaching-geochemistry-of-soil
This one looks at nitrogen leaching with fertilizers and without
Nitrate Accumulation and Leaching in Surface and Ground Water Based on Simulated Rainfall Experiments
To evaluate the process of nitrate accumulation and leaching in surface and ground water, we conducted simulated rainfall experiments. The experiments were performed in areas of 5.3 m2 with bare slopes of 3° that were treated with two nitrogen fertilizer inputs, high (22.5 g/m2 NH4NO3) and...
A Single Incident of Soil P Leaching in a Mature Forest Corresponds to 10 Years of Average Leaching
Incidental P losses from non-point sources may contribute to eutrophication and to decreased soil fertility. These incidents have been related to heavy rainfall on freshly fertilized agricultural soils and little is known about such incidents on more natural soils or in forests. The aim of this...
If you are looking for peer reviewed research specific to potted plants or cannabis good luck. However regardless of with potted plants or not the principles remain true. So if you have a potted plant especially with a living or really hot soil like SOHUM or Kindsoil, that would probably be why the manufacturers highly recommend not watering to run-off.
When you are using synthetic nutes the salt content becomes much higher and run-off is much more important. I think what happens with Cannabis growing is these two areas get conflated when they are quite different.
Sure I haven't grown tons of cannabis, but I do grow a lot of garden plants and other plants and have for a long time, and taking all of these things into consideration has certainly merited benefit for me at least in my opinion. Most people that I have seen in the Organics and no till threads have said mostly the same things that I have seen here.
That's because most potted container gardening takes place in a soil-less medium, especially peat moss. Peat moss has an incredibly high CEC, especially when you adjust its pH to 8! Our plants wouldn't enjoy that though. Obviously the CEC of these growing mediums even at usable pH has some effect on nutrient retention and pH buffering, but not nearly enough that it can be relied upon to sustain plants for an entire grow cycle. This is especially true for available magnesium and calcium. And thus the "feed with every watering using drip irrigation" regimen was born.
No-till however isn't necessarily the same as conventional potted container growing. Here we must rely more on CEC and we include amendments and additives with the goal of increasing CEC sites. The buildup of stable organic matter will help, but it's gradual and takes a long time. Store bought peat moss isn't exactly like regular stable organic matter because the kind we use hasn't undergone significant humification yet due to the conditions that created it.
Other no-till methods don't worry about CEC much at all, and call for the periodic topdressing of "organic" material that already contains a lot of readily available nutrients that continually leach into the rhizosphere with each top watering. Since I'm getting lazy in my old age, I prefer caring about CEC and not having to worry so much about plant nutrition, rather than the other way around.
Edit: Forgot about the original purpose of the thread! Lol
Yes, I do water to run-off in my style of to-till - but only a couple times during the grow cycle, and a good one in preparation for the next. I'm guessing I have a CEC level that does retain enough nutrients, so a periodic light flush can only be helpful for the specific reasons you mentioned. I plan on passing this soil onto my grand kids, so I'm obligated to prevent it from turning into a toxic anaerobic mess of salts and fluoride by that time.
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