Hi
With the advent of summer some of my
established plants, especially Lavender and Barleria, are showing signs of,
what I believe, is nitrogen deficiency. That is, their leaves are yellowing
and, although the growth doesn't seem to be affected, it is unsightly.
Two questions:
Is there any other possible explanation for
the yellowing?
I am looking for a long-term low-maintenance
solution. I know there are plants that fix nitrogen in the soil and my
intention is to companion plant the ailing plants with these. Have any
members got any suggestions for waterwise plants that could fulfil this role
and would also survive acid sandy soil and hot salty winds?
Charl,
I have just given an explanation to Diane
Whitehead about legumes and nitrogen-fixing bacteria, but I think your
probem is much more a case of aestivation (summer dormancy) which I
also explained in detail to her. If your plants are in an acid sandy soil
with minimum watering it is quite likely there is not in summer enough
water to do more than keep them alive until the autumn rains.
This sort soil is also most unfriendly to
any type of legume, and certainly to one with effective N-fixing nodules.
The ideal for any sort of legume that is expected to fix Nitrogen is a a
soil with a reasonable moisture level throughout the season and
preferably a pH close to, or above neutral.
Unless you can improve your soil with lots of
organic matter and provide more summer water I suspect you may have to
resign yourslf to some plants looking yellowish and unhappy at that time. I
am pretty sure they will revive again when rain
comes.
