Nerine soil ph

Rodger Whitlock
Sun, 18 Aug 2013 14:18:25 PDT
On 18 Aug 2013, at 11:01, Joseph Kraatz wrote:

> I so frequently hear of John Innes #3 and have no idea what this is.

It is the #3 grade of the John Innes potting composts. Devised during the 1930s 
at the John Innes Institute in England.

It's a mixture of rotted turves, peat moss, and fine sand, plus fertilizers. 
Many of the ingredients, such as "Cornish silver sand" and "hoof and horn 
meal", are no longer available even in the UK.

The three grades of potting compost are distinguished by the #2 and #3 
containing two and three times as much fertilizer as the #1 grade.

There is also a JI seed compost, which has a somewhat different formula.

The particulars of this potting mixture include:

1. The soil that goes into the mix (rotted turves in the original) is steam-

2. The pH is carefully adjusted by the addition of lime at two different stages 
of the process, first when building the pile of turf to be rotted down, and 
again later during the mixing stage.

3. Superphosphate is a key ingredient in the fertilizers.

Undoubtedly I've forgotten other details.

The JI Institute published a book on their findings:

"Seed and Potting Composts", by J. Lawrence and W. J. C. Newell.

A used copy will run you $20-30 according to

I used to use a mix formula based on the JI recipes, but substituting in a 
rational way what's available where I live.

My formula is (was):

To make 180 litres (two large garbage cans full):

 80 litres	pasteurized soil
 40 litres	coarse peatmoss, screened
 30 litres	#2 granite grit (sold as poultry grit)
 30 litres	horticultural perlite
216 grams	bloodmeal or gelatin
216 grams	single superphosphate (fine powder)
108 grams	potassium sulphate
108 grams	ground limestone
 36 grams	fritted trace elements, ground fine

I originally bought pasteurized soil from a small nursery here, but that source 
dried up a long time ago, so I switched to a "top soil" sold cheaply at 
Canadian Tire. This top soil, excavated from an old lake bed and containing 
clay, silt, and peaty materials, proved to be quite acidic, with pH about 4-4.5.

I later simplified the formula:

30 liters pasteurized soil
6 liters horticultural perlite
144 g granular organic fertilizer, analysis 4-6-8
7 g fritted trace elements
lime depending on pH of soil. pH 4, 203g; pH 4.5, 168 g; pH 5 135 g.

I will say, however, that this revised formula never gave entirely satisfactory 
growth of bulbs potted in it, perhaps because the texture wasn't right for 
them.. I give the formula details here only for information, not as something 
carved on stone tablets and brought down from a mountain top.

Note that when I write "lime" I mean calcium carbonate in some form: chalk, 
agricultural lime, or ground limestone. NOT dolomite, which is much less 
soluble and not as effective at raising the pH of acidic soil.
Rodger Whitlock
Victoria, British Columbia, Canada
Z. 7-8, cool Mediterranean climate

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