fertiliser dilution for vanlet irrigation system
 

We have a vanlet system watering our greenhouse tomatoes very
efficiently. Does anybody else out there have a vanlet too? We have
lost the instructions for the dilution ratio for water soluble
fertilisers such as MiracleGro - can anybody help, please?
--
Susie Thompson, Isle of Arran
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In message , michael adams
writes

It should be possible to work backwards from the standard
dilutions for watering with a watering can, to what your system
requires.

AIUI the vanlet has a 2 litre feed resoirvoir which is topped
up, and which feeds into othe main tank which can be set to
deliver between 10 and 150 litres of water in 24 hours.

So the first question to ask is how often the feed reservoir
is filled, and how much water the system delivers in 24 hours,

The standard dilutions for all formulations of Phostrogen - the
water soluble feeds - and Gromore formulations are similar - is
as follows.

1 in 50 or 2% - 2 grams per litre which ISTR is quad strength
1 in 100 or 1% - 1 gram per litre double strength
1 in 200 or 0.5% - 0.5 gram per litre normal strength
1 in 400 or 0.25% - .025 grams per ltre half strength.


These figures - but not the "strengths" used to be on the leaflets,
and are taken from a technical page on the Phostrogen website which
has since been taken down. The site being generally dumbed down.

The Gromore carton may include a plastic dipenser cap which if you weigh
the recommended no of capfuls should correspond with the above.

So this is what a person with a watering can would be using.

With tomataoes one recommendation is normal strength up to the setting
of the first the truss, double strength at the secod truss and then
daily feeding after that.

Now if you're use 100 litres of water over 24 hours, and you fill
the 2 litre tank daily, then to achieve half strength feeding -
equivalent to normal strength every other day - you'd need to
use 25 grams of feed in the feeder tank.

To recap:

According to the phostrogen figures -

Half strength is 0.25 grams per litre and so to produce 100 litres
of half strength feed - on the assumption the feeder tank empties
daily - you'd need 25 grams of feed.

If however the feeder tank only empties over 4 days, you'd need
100 grams of feed.

You'll then need to adjust the strengh of the feed as the tomatos
progress.

There should be recommendatons about adjusting feed strength on
the Gromore carton in any case, which should remain valid whatever watering
system you adopt.

But basically its simply a case of working backwards from the calculation
you'd use when using a watering can to what your system is doing. How much
water and dilute feed its using over an equaivalent period.

Just taking care to double check the calculations.

Including my own above, it goes without saying.

Watering made simple in other words.



michael adams

...
Thanks - We'll give it a go.

--
Susie Thompson, Isle of Arran
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