N P K Soil Testing Kits

Can anyone recommend a reasonably priced Soil testing kit for N P K analysis not the PH.

I only need to do about 4 tests but I am loathed to send off samples and pay about �£25 a pop to a Lab.

Any suggestions would be appreciated.
Thanks.

 

You should be able to get a full kit from your local garden centre, vegman, It will probably cost you no more than a tenner.

 

Cheers,just found one on Ebay.

It's just for my Exhibition Onion Beds in the Polytunnel as they are never left open to the elements so they don't get a good dose of rain to wash out any of the fertilizer I'm curious to see what the nutrient levels are.
Cheers...

 

Your welcome, let me know the results.

 

Well did the test and got some surprising results.

PH 6.5 Perfect
Nitrogen : slight excess
Potash : Depleted to deficient
Potassium : Depleted to deficient.

I can't understand a deficiency of anything since I have been adding 8-10 oz of fertilizer per square yard for the last 8 years and as it never gets rained on then It never gets flushed out.

I can only assume that as Onions are potash hungry and I suppose growing up to 50 lbs from just 4 square yards will deplete it somewhat.

Anyway I'm going to use Vitax Q4 I think as this is 5:10:7 so less nitrogen content.

What do you reckon ?

 

"I can't understand a deficiency of anything since I have been adding 8-10 oz of fertilizer per square yard for the last 8 years and as it never gets rained on then It never gets flushed out."

A combination of the onions using it and leaching out when you water.

 

You've been growing onions in the same soil for 8 yrs vegman?
What else are you adding other than the fertilizer.

 

I'd chuck some muck on it - not very scientific but it's supposed to be the cure for all ills...

 

Vegman, what fertilizer are you using?

 

I add well rotted horse muck,seaweed meal and compost yearly.

I've been using blood fish and bone and / or Vitax Q4 and a touch of Growmore.

What I can't understand is that there was a significant deficiency of P + K inside a polytunnel.I was expecting an excess.

I suppose it's better to have low nutrient levels that you can fix than far too high ones which can damage the roots.

Don't get me wrong It is fantastic soil,I regularly grow 5Lb+ Onions on it at only 12 inch spacings so I can't wait to see how big they'll be this year when I boost its nutrient levels up.

 

Onions are gross feeders as you know, so it`s no real surprise the ground is deficient. Have you ever tried Nitrate of Soda on your onions? you will be impressed.

 

But as I have an excess of Nitrogen according to the test will this not just increase the inbalance further ?
I seem to be ok on the Nitrogen front.
I'm also wary of giving onions too much nitrogen as you know it tends to give them thick necks which are no good for showing.
I think I'll stick to Vitax Q4 as this is 5:7:10 so It should boost the deficencies without raising the Nitrogen much more.

Cheers,Dan