# Boiling RO water



## Carper (Jan 24, 2016)

Hi all,

I am experimenting at ensuring my ro water is a slightly higher temp than I normally feed at. I usually allow the water collected to acclimatise to the greenhouse for a few days to around 16C. However, I wish to higher this to around 20C max. Apart from using a heat mat underneath or heater in the water container, I was considering boiling some RO water then adding this back to the existing tank to higher the temp to the required level. 

The simple question. Is the safe and does boiling the RO affect it's properties which might damage my plants? 

Thanks

Gary
UK


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## gonewild (Jan 24, 2016)

Carper said:


> The simple question. Is the safe and does boiling the RO affect it's properties which might damage my plants?
> 
> Thanks
> 
> ...



No it wont.


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## Ray (Jan 24, 2016)

Gary. That seems to be a lot of effort. Go buy a decent aquarium heater and put it in the tank.


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## MattWoelfsen (Jan 24, 2016)

Ray said:


> Gary. That seems to be a lot of effort. Go buy a decent aquarium heater and put it in the tank.




Another pragmatic idea!


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## PaphMadMan (Jan 24, 2016)

As indicated, boiling RO water does no harm. You'd want to add 1 liter of boiling water to 20 liters of 16C water to get to 20C. There is some safety hazard carrying boiling hot water, of course. But I can get an aquarium heater suitable for up to 64 liter volume for $10. Seems a much easier solution to me.


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## Rick (Jan 24, 2016)

I read from a Vietnamese Buddhist monk that if you bring the water to a boil 7 times it will change the energetic state of the water significantly and make it more healthful.

But I'd just add a tank heater.:wink:


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## Happypaphy7 (Jan 24, 2016)

That sounds like some serious superstition, or did that monk come from MIT?
Jokes aside, I've watched a documentary where it reported water at around 6 degree Celsius is observed into the body fastest.
I don't see how temperature of drinking water can affect health in anyway when within reasonable range of course? I mean who drinks boiling water or brain freezing water?? Ok, off topic, sorry, but that monk thing got me.


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## gonewild (Jan 24, 2016)

Happypaphy7 said:


> That sounds like some serious superstition, or did that monk come from MIT?
> Jokes aside, I've watched a documentary where it reported water at around 6 degree Celsius is observed into the body fastest.
> I don't see how temperature of drinking water can affect health in anyway when within reasonable range of course? I mean who drinks boiling water or brain freezing water?? Ok, off topic, sorry, but that monk thing got me.




Observed into or absorbed into the body?

One way would be from Monk research and the other from MIT.
oke:


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## Rick (Jan 24, 2016)

Hard to say how much is from meditation, mind-matter interface, or physics.

He was making tea. Since I've never tried it (he also noted that Americans have no patience for putting that level of effort into the simple pleasure of making tea) I can't say whether it makes a difference or not.

Gets you thinking though didn't it.:wink:


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## Stone (Jan 24, 2016)

There was a Shaolin monk on TV last night who could throw a sewing needle through a pane of glass and burst a water filled baloon on the other side.


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## gonewild (Jan 24, 2016)

Stone said:


> There was a Shaolin monk on TV last night who could throw a sewing needle through a pane of glass and burst a water filled baloon on the other side.



How many times was the water boiled first?
Maybe that is the secret!


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## Rick (Jan 24, 2016)

Stone said:


> There was a Shaolin monk on TV last night who could throw a sewing needle through a pane of glass and burst a water filled baloon on the other side.




That sounds pretty cool. Did the glass break as the needle went though?


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## Carper (Jan 25, 2016)

Thanks for the replies.

As I only mix up 40 litres of feed at a time, which is all I need to feed my collection, I'm only boiling one kettle to bring up the temperature which sounds more economical than a permanent heater. The kettle cost me £5! so as I only feed once per week for the main seems a cheaper alternative. 

Are there any side effects to feeding the plants at these temps, and what are the advantages, ie better nutrient uptake etc?

Gary


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## Ozpaph (Jan 25, 2016)

The 'cost' is in burning risk with boiling the water, not the few cents a day the aquarium heater 'costs' to run.
Raising the water temp by 4C seems to be a waste of time and effort, without any likelihood of measurable benefit, IMHO.


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## Carper (Jan 26, 2016)

Ozpaph said:


> The 'cost' is in burning risk with boiling the water, not the few cents a day the aquarium heater 'costs' to run.
> Raising the water temp by 4C seems to be a waste of time and effort, without any likelihood of measurable benefit, IMHO.



Will the plants take up exactly the same nutrients at either of these temps?


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## gonewild (Jan 26, 2016)

Carper said:


> Will the plants take up exactly the same nutrients at either of these temps?



Nutrient uptake and growth will be more with the warmer water.
Will you be able to see the difference of 4 degrees?.... probably not, but the end result over time will be increased growth.


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## cnycharles (Jan 26, 2016)

I know when we turned off the water preheaters at work the plants reacted noticeably but was winter of course


Elmer Nj


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## Ozpaph (Jan 27, 2016)

Carper said:


> Will the plants take up exactly the same nutrients at either of these temps?



I would think so. Unless someone has information to link solute temperature to absorption (in this narrow temp range). I've seen many great orchid growers and met none who heat their water. (temperate climate). I also think that there are so many other variables that could be adjusted to produce 'improved' growth - optimal light and day length, for example.


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## gonewild (Jan 27, 2016)

There is published research that shows nutrient uptake increases with warmer water. What I read was done using hydroponics as the method of measurement. 

Many Phalaenopsis producers regulate the water to warmer temperatures to maximize nutrient uptake and growth in general.


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## Ray (Jan 27, 2016)

What I wonder is if it is truly as nutrient-rate-of-absorption factor, or whether the warmer water increases the plant's metabolic rate, so the total throughput is increased.


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## gonewild (Jan 27, 2016)

Ray said:


> What I wonder is if it is truly as nutrient-rate-of-absorption factor, or whether the warmer water increases the plant's metabolic rate, so the total throughput is increased.



One of the hydroponic papers I read actually measured the nutrients in the plants at different temperatures. So their result demonstrated that more nutrients were absorbed with increased temperatures. The plants had more mass as well so growth was also increased.

As I recall they found that at cooler water temperatures root mass was greater..... The plants may have needed more roots at cooler temps to get the maximum amount of nutrients they could manage.(my thought)


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## naoki (Jan 27, 2016)

Plants usually show the optimum root zone temp (e.g. 18C is better than 14C or 22C) and not monotonic response. So in some cases, you observe the opposite trend from what Lance mentioned. But these experiments generally maintain the root zone temp constant (or day/night). In these experiments, 4C difference can cause significant difference. If you use warmer water for occasional irrigation, the root zone will quickly goes to ambient temp, so the effect will be much much smaller.

In cooler root temp, roots can reduce wasted energy due to respiration, so they can have larger roots.


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## gonewild (Jan 27, 2016)

naoki said:


> . If you use warmer water for occasional irrigation, the root zone will quickly goes to ambient temp, so the effect will be much much smaller.



For orchids it may not be about the root zone temperature as much as the actual irrigation water temperature.
It is assumed that orchid roots absorb water and the nutrients very rapidly as soon as they are wetted. So in the case of orchids the water temperature may actually have a significant effect. (or not)


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## naoki (Jan 27, 2016)

Are you sure that you are not mixing up the absorption to the dead velamen cells vs the absorption into the cells? Absorption to velamen is unlikely to be temp. dependent. Velamen holds the water (therefore nutrients kept at the range of low concentration where cells can absorb) for a while so that the active nutrient transport can move the nutrient into the cells. The later would take a little longer.


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## gonewild (Jan 27, 2016)

naoki said:


> Are you sure that you are not mixing up the absorption to the dead velamen cells vs the absorption into the cells? Absorption to velamen is unlikely to be temp. dependent. Velamen holds the water (therefore nutrients kept at the range of low concentration where cells can absorb) for a while so that the active nutrient transport can move the nutrient into the cells. The later would take a little longer.



No I'm not mixing them up.
I'm just making an assumption that nutrient absorption probably begins immediately when the dry root absorbs the warm water. 
If the water is warmer than the root then the absorption would be more and if the water is cooler then it would be less. And that assumes that warm water warmed the root and cold water cooled the root or root zone.

As far as I can find all research indicates that nutrients are absorbed faster and in greater amounts with warmer temperatures. That may not mean that the gain is worth the effort. However in my experience using warmed irrigation water does yield improved growth response.


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## Ozpaph (Jan 27, 2016)

can you share the paper?


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## gonewild (Jan 27, 2016)

Ozpaph said:


> can you share the paper?



Sorry I did not save it. There actually were several so not hard to find the info with a google search.


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## Ray (Jan 28, 2016)

gonewild said:


> One of the hydroponic papers I read actually measured the nutrients in the plants at different temperatures. So their result demonstrated that more nutrients were absorbed with increased temperatures.




To me, that still doesn't answer my question. If the plant's metabolism had it pumping more through, of course the nutrients would accumulate, while the solvent (water) was transpired.

What I am questioning is whether "X%" of the nutrients are extracted at one temperature, and "X+%" is a absorbed at higher temps.


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## gonewild (Jan 28, 2016)

Ray said:


> To me, that still doesn't answer my question. If the plant's metabolism had it pumping more through, of course the nutrients would accumulate, while the solvent (water) was transpired.
> 
> What I am questioning is whether "X%" of the nutrients are extracted at one temperature, and "X+%" is a absorbed at higher temps.



Maybe I dont understand your question?
The results showed that at a control water temperature X%/mass of nutrient was in the plant tissue. With an increase of 2c the tissue contained X+% of the nutrients. Step the temperature up 2c more and the tissue contained X++%.

As temperature increased the % of nutrients/mass increased and the mass increased proportionately also. 

The results did show that as water temperature increased so did the amount of nutrients absorbed.

I dont know if the nutrients absorbed + energy to heat the water gave enough extra growth to justify the effort. But it does seem that water temperature affects the amount of nutrients the plant absorbs.

I've not seen any research that shows that water temperature does not increase the nutrient absorption. Let us know if you find something.


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## Carper (Jan 28, 2016)

Ongoing, is it beneficial to feed the smaller seedlings with cooler water to promote the root system until it is well established then as it becomes larger feed warmer. I have been feeding round the 18C mark in my experiments for the last few weeks and all look seems fine for now.

Gary


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## gonewild (Jan 28, 2016)

Carper said:


> Ongoing, is it beneficial to feed the smaller seedlings with cooler water to promote the root system until it is well established then as it becomes larger feed warmer. I have been feeding round the 18C mark in my experiments for the last few weeks and all look seems fine for now.
> 
> Gary





I doubt anyone has an answer for that one.
You'll have to experiment.


Personally I would go with warmer water to encourage leaf growth and let the roots follow at will.


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## Ray (Jan 28, 2016)

Lance, 

What I'm trying to get at is better described by these scenarios:

100 ml of Fertilizer solution contains "X" mg of fertilizer per milliliter.

Case 1 @ lower temperature, in a fixed period of time, the plant absorbs 10 ml of solution, so 10X mg of nutrient, leaving behind 90 ml, still at the same concentration.

So in Case 2 @ a higher temperature, does the plant absorb 20 ml in that same time period, hence has 20X mg of nutrient, leaving behind 80 ml at that same concentration, or will it have taken the nutrients from the solution faster, leaving the unabsorbed solution at something under "X"/ml?


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## gonewild (Jan 28, 2016)

Ray, I dont think the reports I read addressed the volume of water absorbed. They measured the dry mass of the tissue and the nutrient % content of the mass resulting from different water temperatures.


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## naoki (Jan 28, 2016)

Gary, I would rather think the temperature influencing the R:S ratio is more of the acclimation to the environment (their effort to maximize their growth). There is an optimum temperature (say from the view point of total biomass accumulation). So it is probably better to keep it at the optimum. Different species have different optima, and also different amount of tolerance. So it is difficult to generalize, but around 16-18C, higher is probably better. The temperature optima for roots are generally lower than the optima for the leaves in many plants.

Ray, absorption of water is passive, and I believe that most of the nutrient uptake is active (via transporter). So absorbing more water (into living cells) doesn't necessarily mean more nutrient uptake. If more water is taken up, then the solute concentration in the root epidermis cells become lower, and this might make it easier to take the nutrients (which has to move against the concentration gradient because the concentration of solutes in the cells are higher than outside of the roots). This later part is my speculation, but this could cause the correlation. Also does the root temperature increase the water uptake? Higher leaf temperature causes higher transpiration, so it would increase the water uptake (in C3 plants).


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## Ray (Jan 28, 2016)

Naoki, I'm not so sure about the passive uptake of water.

In my experience (OK - my conclusions based upon my observations), water to a plant is like air to a car engine. When you "step on the gas", you're not controlling the fuel input, you're increasing the air intake, which is what allows more fuel to burn. More fuel without the extra air is "flooding", which is counter-productive. Similarly, the more water a plant has access to, the more it can use the nutrients and "step on" the growth.


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## naoki (Jan 28, 2016)

It is indeed a good analogy, Ray. But the uptake of water by itself is still passive. Water can go through cell walls, and cell membranes acts as semipermeable membranes, which means water can goes through, but some other molecules and ions can't. Movement of water in plants follows something called water potential. The uptake control (throttle) mainly comes from the stomata control. 

I think that your conclusion makes sense and here is a little bit of biology behind it. Photosynthesis causes accumulation of O2 in the leaves (O2 released from breaking down: 2 H2O -> 4 H+ + O2). One of the important enzymes for photosynthesis (rubisco) can bind to O2 or CO2. If it binds to CO2, C will get assimilated (i.e., photosynthesis). If it binds to O2, it will lose quite a bit of C (and energy). This is called photo-respiration (don't confuse this with mitochondria respiration), and this can dramatically decrease the growth. To avoid this, the leaf want to have high CO2 & low O2 environment in the leaf. Plants open stomata to do the gas exchange to make sure O2 doesn't accumulate. If the plant is limited by water, roots will tell leaves to close the stomata (they use hormone called ABA) to avoid dehydration. Then photo-respiration becomes a big problem. If there is lots of water, plants can keep the stomata open, so they can grow better without photo-respiration issue. When the stomata is open, they create strong water uptake from roots (described by cohesion-tension theory).

This issue is more relevant to C3 plants than to CAM, but many CAM orchids (e.g. Phalaenopsis) are facultative CAM (meaning they behaves like C3 when there is plenty of water).

So your analogy of "flooding" condition basically corresponds to the photo-respiration. A lot of fuel (light) and too much O2 causes this. I also think that, as you have shown with your semi-hydro, high availability of water without interfering the root respiration (they need O2) is something what most plants like.


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## Linus_Cello (Jan 28, 2016)

My chemistry 101 recollection is that a 10 degree Centigrade increase in temperature will halve the reaction time; how this translates to plant absorption I'm not sure.


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## gonewild (Jan 28, 2016)

From a nursery production company here is their recommendation for water temperature. This is for Phalaenopsis plants from guidelines by Floracultura.

_Temperature of irrigation water
The desired irrigation water temperature for the various sections is:
1. Vegetative section: minimum temperature 25°C.
2. Spike initiation section: minimum temperature 20°C.
The desired temperatures can be achieved using a counterflow system._


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## Rick (Jan 28, 2016)

Without getting too crazy on mechanisms, there's some basic mass balance that has been well documented.

Live plants (at any given time) are about 85% water. 14% Carbon and the last 1% is NPK....... 

Also a C3 plant needs to process about 800 to 1000 moles of water to fix 1 mole of carbon (CAM plants about 1/2).

So growth rate of any tissue is based on the rate it can move water through the plant.

NPK Ca Mg...... is normally incidental and rarely limiting compared to the amount of water and carbon needs to get plowed into the plant.

Also these inorganic salt ions need to be soluble in water to be transported into the plant. 

Orchid roots usually have at least two functions (and probably the bigger split is the difference between terrestrial vs epiphytic species) but they are primarily there as water uptake and storage organs. Also note they are made from cellulose (just like leaves) so roots aren't just inert straws supporting living leaves, but a paired system.

More roots can service bigger leaf area - bigger leaf area requires larger root system to service. Leaves are the pumps / engine (evapotranspiration), but need roots to conduct water to them.

So back to the engine analogy. Bigger / faster engine needs matching intake manifold/24 valve ported heads to get that air/fuel into it.

Sometimes we take things apart to much and get hung up in the nuts and bolts.


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## Ray (Jan 29, 2016)

Oooh, Rick & Naoki. It gives me chills when you talk like that.


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## Rick (Jan 29, 2016)

Ray said:


> Oooh, Rick & Naoki. It gives me chills when you talk like that.



In my youth I raced a 58 Ford 1/2 ton with a 430 Lincoln engine, 850 double pumper Holley carb with a full race grind Howard,s cam.

But think maybe getting off track on the subject of temp.

But before that I've head some interesting research tying droughts in Brazil to deforestation.

Paraphrasing:
Essentially rivers of airborne water are created by the rainforest as it pulls (transpires) the water out of the ground. 
Subsequent cooling and condensation of these airborne "rivers" creates the high rainfall indicative of tropical environments.

All this to say that water is a basic conveyor belt process in plant physiology.


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## Rick (Jan 29, 2016)

Linus_Cello said:


> My chemistry 101 recollection is that a 10 degree Centigrade increase in temperature will halve the reaction time; how this translates to plant absorption I'm not sure.



At least within the physiological limits of the plant this holds true also.

Different enzymes have peak operational ranges, and at certain temps completely break down.

So in living things we see a broad inverted U rather than a linear relationship in chemistry.

There's a broad overlap of these temperature ranges among living things. But different species adapt to optimize activity in different climates.

So can't generalize for all species or even all orchids (maybe not even just paphs given the range of elevations and latitudes the species are found).

I would suspect Paph hirsutisimum to still have pretty decent growth at temps maybe as low as 7-10C while Paph philipinense may not grow below 13C


This regime posted by Lance would certainly be warm enough to support good growth of just about any orchid species.
Temperature of irrigation water
The desired irrigation water temperature for the various sections is:
1. Vegetative section: minimum temperature 25°C.
2. Spike initiation section: minimum temperature 20°C.


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## Ray (Jan 29, 2016)

Doing a little back-of-the-envelope calculations, Rick's numbers above suggest that in order to grow a one-pound plant, over its lifetime it will need to absorb roughly 25 gallons of water, and less than a teaspoon of fertilizer!


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## gonewild (Jan 29, 2016)

Ray said:


> Doing a little back-of-the-envelope calculations, Rick's numbers above suggest that in order to grow a one-pound plant, over its lifetime it will need to absorb roughly 25 gallons of water, and less than a teaspoon of fertilizer!



That does not sound like much fertilizer! But that may be pretty close in reality.
Hydroponic lettuce takes 1 tsp to produce a head that weighs about 4oz. That would be 4 tsp fertilizer to produce a pound of plant. But once you consider the amount of nutrients left in the tank after harvest maybe the plant only "ate" 1/4 tsp of fertilizer.


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## Rick (Jan 29, 2016)

Ray said:


> Doing a little back-of-the-envelope calculations, Rick's numbers above suggest that in order to grow a one-pound plant, over its lifetime it will need to absorb roughly 25 gallons of water, and less than a teaspoon of fertilizer!



A teaspoon at what concentration?

Yup it doesn't take much. Farmers are rarely short NPK, but often short water.


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## C. Rothschild (Jan 29, 2016)

*maybe if there's sphagnum moss with the plant*

Someone told me to use steamed-distilled water for my Sphagnum moss. I have no idea why but he knew what he was talking about.


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## Ray (Jan 30, 2016)

The less than a teaspoon fertilizer was a grab-ass number that assumed 100% nutrients and a bulk density of 1g/cc. It was meant to show the disparity in volumes required, not to be precise.

A better number applies to poinsettias - it is a well-established standard that it takes 1/2 g of nitrogen to take a plant from a rooted cutting to flowering for the Holidays. Once they have their preferred formula, they use pot volume, medium liquid retention, watering frequency and and growing time to determine the concentration to apply.


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## Rick (Jan 30, 2016)

Ray said:


> A better number applies to poinsettias - it is a well-established standard that it takes 1/2 g of nitrogen to take a plant from a rooted cutting to flowering for the Holidays. Once they have their preferred formula, they use pot volume, medium liquid retention, watering frequency and and growing time to determine the concentration to apply.



Yup 500 mg of N for how long a growing time? And it probably factors loss to pot leaching too. Washout is part of the basic equation farmers use for calculating fert needs for basic field crops. In this case most of the water is from rain and not metered (so no-one cares how much water is going through the plant). But without drip irrigation, a big pile of nutrients have to be dumped on a field at seeding, because application after the plants are up is difficult without flattening the field. So by the time you figure out how much the plant actually took up 99% of what was applied washed out in the first month or so of heavy rains.

And during this period the plant is going through orders of magnitude more than its weight in water. And the warmer the plant the more it goes through.


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## Ray (Jan 30, 2016)

Rick said:


> Yup 500 mg of N for how long a growing time?



My understanding is that is a total mass - period - to be applied over whatever duration you have until taking them to market.


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