Re: FW: This is not a weed question

The two most over-diagnosed problems of modern landscaping:
1.  Earwigs  {hide out in dark places, poor things get blamed for
everything nocturnal}
2.  Heavy metals.  Sludge products contain some invariably.  Research
seldom, if ever, finds uptake of these ions even in root crops.  If your
friend's soil were so contaminated it probably wouldn't affect the
cauliflower, and if they did you'd observe some pretty spectacular foliar
symptoms.

I vote for a simple nitrogen deficiency.  2.2 ppm nitrate is very low.  An
annual crop like cauliflower would likely need many times that much to
thrive.  Lavender would be much more tolerant of such a deficiency since
they are native to sandy, relatively impoverished soils.  That (extremely
thorough) soil test showed no other obvious deficiencies or toxicities,
though I confess I don't know what the unit 'nm' is for iron.  The sodium
absorption rate is less than one; no sweat there.  Phosphorus is well above
optimal.  Salts at .09 is fine.  A pH of 6.2 might produce a little
chlorosis in rhoddies but I wonder if the yellowing is in the new growth?
the old growth? (I'd bet old growth--the inside of the plant and the lower
parts.  That would cinch it for N deficiency).

I propose a test.  Take the most responsive crop available on site, an
annual preferably or a soft perennial.  Mix 2 teaspoons of ammonium sulfate
in a gallon of water.  Stir.  Pour mixture over root system of target
plant.  If you observe a growth stimulus within 72 hrs. you've diagnosed a
nitrogen deficiency.

Jerry Heverly, Oakland, CA







At 8:03 AM 6/29/99, Randall, Rod wrote:
>Hi Folks, a friend of mine in Queensland has sent me a doozy of a question
>and while I've suggested maybe a trace element imbalance (either toxicity
>or lack of) or maybe a fungal problem.... I'm not really sure.
>
>
>> I received the following enquiry from relatives who live in the Kurrajong
>> district, NSW.
>>
>> "The problem we are having with the soil is as follows:
>>
>> The soil was supplied in bulk as a 'garden mix' some nine months ago, and
>> was used to fill a  landscaped garden bed.  According to the suppliers, it
>> contained, amongst other things, rice husks and processed sewerage sludge.
>> It also contains a reasonable measure of sand.  We planted a number shrubs
>> in the soil including camellias, azaleas, rhododendrons and lavender,
>> along
>> with some herbs and sundry native species.  The plants were well-mulched
>> (shredded tree prunings) and well watered.  We had good rainfall over
>> spring
>> and summer, and the soil is well drained.  After many months, we find that
>> only a few of the plants seem to be doing at all well (lavender), and that
>> most of the other plants look sickly. No new growth is evident from the
>> last
>> good season (while the rest of the garden in native soil has thrived). The
>> camellias and azaleas are yellowing, and some natives are not healthy.
>> Recently our son conducted a school science experiment by planting
>> cauliflower seedlings in a number of soil samples including the garden
>> mix.
>> Those seedlings in normal or supplemented (enriched) normal soil are
>> growing
>> very well after several weeks, attaining some 12-15cm in height. Those in
>> the garden mix have grown little, if at all. They are 4-5cm in height, are
>> discoloured and distorted. The addition of fertiliser to one of the
>> samples
>> has made no difference.  We are very concerned that the garden mix is
>> either
>> toxic, or deficient in vital nutrients. The suppliers have suggested that
>> the soil may have a pH problem and that we should use iron sulphate to
>> correct it; but we think the near death of the cauliflowers suggests there
>> is some other problem."
>>
>> Since the paragraph above was written, the lavender has also started to
>> "droop".
>>
>> Soil testing revealed the following results:
>>
>> pH in water = 6.2;  pH in CaCl2 = 5.0;  Ec = .09
>> Na = .13meq%, 3% of ECEC;  K = .44meq%, 10.10% of ECEC
>> Ca = 2.38 meq%, 54.7% of ECEC; Mg = 1.4meq%, 32.2% of ECEC
>> Ca/Mg = 1.7
>>
>> Phosphate - P = 92.2 mg/kg; Ammonium - N = 2.2 mg/kg; Nitrate - N =<2.5
>> mg/kg; Sulphate - S = <5 mg/kg
>> Iron = 90.5 nm/kg; Zinc = 5 mg/kg; Copper = 1.5 mg/kg, Manganese 7.7
>> mg/kg.
>>
>> While some imbalances were evident, the soil lab was not convinced that
>> the
>> problems were solely nutritional, and suggested that heavy metals or
>> pesticide residues might be the problem.  The latter comment made me
>> wonder
>> whether any enviroweeders had experienced similar problems?
>>
>> Barbara Waterhouse
>>
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> Barbara Waterhouse
>> NAQS Botanist
>> AQIS
>> C/- Centre for Tropical Agriculture
>> PO Box 1054 (28 Peters Street)
>> MAREEBA QLD 4880
>> AUSTRALIA
>>
>> Tel.  (07) 40928546; (Int.) +61 7 40 928546
>> Fax   (07) 40923593; (Int) +61 7 40923593
>>
>> E-mail        barbara.waterhouse@aqis.gov.au
>>
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>
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