Crop Steering in coco. How to determine optimal EC?

[cannalyst]

The conductivity measurement isn't very useful beyond verification of a known solution.

In order to deliver precision nutrient you'd need to calculate for the elemental requirement of the plant and dose accordingly.

Nutrient lines abstract away this knowledge for profit and have everyone blindly dosing their crops to mixed effect.

 

[Ca++]

Dosing individual elements is awkward, even if you can measure what's been taken.
If we had the perfect feed to start with, the speed the plant takes each element, isn't equal. The K might be taken in hours, and putting it back at the rate it was vanishing, would be toxic. We see N studies of 160ppm in dwc, but that solution might last a week, with a top up solution being used, that doesn't have everything in it. If we keep N constant, it's more like 30ppm needed.

Now as we look at our commercial feeds, we should be able to see that one suited for 6 fertigations per day, may not be so suited for a DWC meant to run a few days. Some feeds will talk of using less EC with higher frequency fertigation. It's hard to be more specific with their formulations, as all our plants differ somewhat in their daily needs.

It's not all doom & gloom though. We have people here, doing well, with tanks set for long term us. There is an idea that the feed is either in the tank, or in the plant, it can't escape. So all you really need do is top up. Which they do with the same feed. It works. Though in fact, the top up feed should actually be a bit more specific. If we could formulate that. It has a name, but it's not engaging my brain right now

 

[LostTribe]

Jacks 321 full strength. Make sure you get 15% runoff every watering. Nothing more nothing less. You arent going to re invent the wheel. And LED sucks in my very honest opinion due to lack of heat for your root zone and your leaf zone FYI. No point in LED as this fad came around for the cost saving of running these lights. Well they dont take into account you will have to run heating directly into the garden to compensate which defeats the purpose and nullifies any cost savings whatsoever.

 

[LostTribe]

yeild of green plant matter is not the goal. Fat trichome heads is the goal. HID reigns king.

 

[Ca++]

If you are going to practice crop steering with a couple of drybacks late stretch, then an organic soil grower need not worry, but a more hydro like (available food in water) might mean a lower ec for those times. To combat the expected rise.

This is all in flux really, but hard dry backs in veg likely trigger a veg response, that involves growing a bigger root system to assist if it happens again. Growing a bigger root system is nice, though you might not want to spend time doing so.
Later in bloom, we pretty much can't grow a new root. Not watering, will be more like a trigger to stop getting bigger, and hurry up.
Reports are still coming in, but there is a strong lean towards losses when people try and steer with dry-backs during bloom. They are a vegetative trigger. To be used when vegetative root growth is wanted.

Next year, I might be eating my words. This is where we are today though. Withholding during bloom, is just looking a bit crazy, as we work faster and faster plants. The long flowering guys might tease out more roots though, if for some reason they didn't have a good veg period.

 

[XYZVector]

So the EC they are giving isn't the inflow EC it is the Pore EC of the media. This is not the same as the EC of the nutrient solution your feeding the plants. Pore EC consists of the temperature of the media, it's water volume content, the dielectric constant of the media, and the inflow EC of the nutrient solution. In order to properly crop steer you need a special media sensor. These sensors cost 300 bucks and the aquisition system is about $500-$2000. Then you need a system that can take the data and generate the correct fertigation cycles based off the data the media sensor(s) collect. You can approximate it but unless you know the PoreEC of the media it is hard to get right without burning your plants with salts. I built and programmed my own crop steering system, and there are sources of media sensors that are 10x cheaper than the ones they are selling. However you have to know how to program, and talk to these sensors.

 

[RuBp]

Everyone gets stuck on crazy high EC as the only way , when its not the only way to accomplish the same goal, and probably not the best option in coco at least. You control the environment, you control the amount and type of growth. I got a feeling a fertilzer maker/seller brought crop steering to the weed world, its normally just called hardened off growth or rank growth in the nursery/greenhouse industry.

 

[LJ farming]

Jacks 321 full strength. Make sure you get 15% runoff every watering. Nothing more nothing less. You arent going to re invent the wheel. And LED sucks in my very honest opinion due to lack of heat for your root zone and your leaf zone FYI. No point in LED as this fad came around for the cost saving of running these lights. Well they dont take into account you will have to run heating directly into the garden to compensate which defeats the purpose and nullifies any cost savings whatsoever.

Damn Right Lost Tribe! You helped me understand this a lot better a few years ago!

The plant will not take .1 EC more than it requires so everything else goes down the drain!

 

[LJ farming]

If you are going to practice crop steering with a couple of drybacks late stretch, then an organic soil grower need not worry, but a more hydro like (available food in water) might mean a lower ec for those times. To combat the expected rise.

This is all in flux really, but hard dry backs in veg likely trigger a veg response, that involves growing a bigger root system to assist if it happens again. Growing a bigger root system is nice, though you might not want to spend time doing so.
Later in bloom, we pretty much can't grow a new root. Not watering, will be more like a trigger to stop getting bigger, and hurry up.
Reports are still coming in, but there is a strong lean towards losses when people try and steer with dry-backs during bloom. They are a vegetative trigger. To be used when vegetative root growth is wanted.

Next year, I might be eating my words. This is where we are today though. Withholding during bloom, is just looking a bit crazy, as we work faster and faster plants. The long flowering guys might tease out more roots though, if for some reason they didn't have a good veg period.

IMO not one root is grown after Stretch! So veg is 100% over after transition and feed the flowers! N gets reduced the final 5-6 weeks as well!

 

[LJ farming]

Everyone gets stuck on crazy high EC as the only way , when its not the only way to accomplish the same goal, and probably not the best option in coco at least. You control the environment, you control the amount and type of growth. I got a feeling a fertilzer maker/seller brought crop steering to the weed world, its normally just called hardened off growth or rank growth in the nursery/greenhouse industry.

Absolutely bud!

IMO nutrients are the least important part! NPK and CalMag are baby shit easy!

Dial in Environment 1st, then light intensity, then environment again, maybe think about CO2 then perhaps you might need more than 1.5-2 EC! I seriously doubt it! Nutrients are the easiest and cheapest thing to manipulate and most get hung up on them.

The plant will only uptake a certain amount of nutrients!

Worry about EVERYTHING ELSE first then maybe mess with nutrients!

1.5-2EC is ample in my experience! Closer to 1.5

 

[LJ farming]

Absolutely bud!

IMO nutrients are the least important part! NPK and CalMag are baby shit easy!

Dial in Environment 1st, then light intensity, then environment again, maybe think about CO2 then perhaps you might need more than 1.5-2 EC! I seriously doubt it! Nutrients are the easiest and cheapest thing to manipulate and most get hung up on them.

The plant will only uptake a certain amount of nutrients!

Worry about EVERYTHING ELSE first then maybe mess with nutrients!

1.5-2EC is ample in my experience! Closer to 1.5

If your light intensity is less than 40-50 watts per sqft More/different/better nutrients will never do anything besides take money outta your wallet!

 

[Ca++]

~day 18, it's likely the runoff EC will jump. Some watch for the pH drop that comes hand in hand. This is a good indicator you need to switch to bloom foods, and so is the cornerstone of a steering event. Switching feed earlier might lead to weaker plants, and any later to a weaker bud response.

Looking at the plants, this is the transition from stretch to bud. At this time, water use increases. Buds and there hairs that want keeping moist, don't have the stomatal regulation of leaves. Instead, they loose a lot of moisture, that didn't actually need to bring so much feed with it. The root system becomes worse at the passive intake of calcium now. All leading to higher water use, so we see the feed left in the pots increase.

Some will increase runoff to control this EC increase. Others will reduce EC to try and maintain the rootzone EC in range.

It is something to watch for, and respond to. It is the crop steering us, it would seem. The recirc guys would be changing their tank perhaps. Which might of jumped over 25%.

We are still some way off knowing enough about what's really happening, so just take this post as ideas, and possible explanations.