[Chappers]

I think i probably ought to test the soil on my lotty but am not sure which kit to get. Do i need one that only tests PH or a bit more expensive one that tests PH, N, P, K. I only grow veg if that makes any difference.

cheers Paul

[JayG]

pH testing will indicate how much free lime there is in your soil, i.e whether it is acid, neutral or alkaline. This will determine what you can easily grow and/or whether you need to lime for other crops.

Very light soils lose their nutrients NPK quickly, clay soils less so, but since no doubt you will be manuring/fertilising anyway I don't really see the need for more extensive testing.

[Salmo]

JayG is spot on. Just buy a pH kit. You want the ones with test tubes, probes with a meter are in my experience not reliable.

It is best not to test spot samples as you may hit a spot where there is manure or where lime was spilt in the past. An average reading for each part of your rotation is what you need.

Take a trowell and dig samples to 6 inches deep at random all over each plot. Place in a bucket and mix thoroughly. Test samples of this mixed soil.

[Chappers]

Thanks guys, is this ok

long linky edited

Cheers Paul

[Babstreefern]

I've got a PH tester that you stick into the ground and the reading shows on a meter (its the one with a curly wire).  Its very good and well worth the money (they are about £14), especially if your soil is either one end of the scale or the other.  My plot is mainly acid, although funnily enough, it reads very acid on the first 20ft and drifting over to neutral towards the top end.  So really, one of these is cheaper than buying the test tube type, as you get different readings in your soil, and at approx £2 per test, you can see its value.  And if you do have acid/akaline soil, just because you neuterlise it for one year, the soil will eventually go back to its natural tendancies.  With me, I've put lime on part of the plot which is very acid, so it will be ok for next year, but also, where its a bit acid, but not too bad, with a reading of about "4", I've put on some Calcified seaweed, which will slightly neutralise your soil - in other words, its not as strong as lime.

[Yorkie]

Just edited your post so the link didn't send people's screens off the planet 

It is generally said that the chemical ones are more reliable, but you will need to test in more than one location around the plot.

[Salmo]

Babstreefern - if you are getting a reading of pH4 I would question the accuracy of your meter. Anything below 5.5 is very acid indeed. Keep in mind that the pH scale is not straight line but logrithmic. I think I am right in saying this means that pH5 is 10 times as acid as pH6 and pH4 is 10 times as acid as pH5.

[Babstreefern]

Believe me, the meter went off the scale at the acid end.  I used the meter all over my plot (others have used it as well).  That's how I found that my plot has various levels, hence very acid and one end and rising up to around 5.5 to 6.  That's why I've put lime down.  I did it a few weeks ago, and I've tested it again, and its now showing 5.  I'll test it again in a couple of more weeks, and if it is staying at 5, I'll put some more on.

[Salmo]

I still stick to my opinion that these probes are less reliable than the test tube kits.

At least your probe has shown you that there is variation between parts of your plot. Whether it is reading the correct pH is another question. I would guess that it may be reading a pH unit too low.

The effects of lime are not instant. If the pH is very low then it will take many months for the lime to neutralise the acidity. You should probably wait at least until the Spring before retesting. The lime should be well worked in to digging depth. Too much lime all at once can cause problems with locked up nutrients.