permaculture

[Stephan Maré <gsmare@gmail.com>]

Hello all

I've recently come across permaculture and am convinced of its virtues.

We have a farm near Nelspruit ("Nel's stream" in Afrikaans) in the
Mpumalanga ("Place where the sun rises" in Zulu) province of South Africa.
Below is some climate data for Nelspruit.  (The farm is at a higher altitude
than Nelspruit - about 930 metres above sea level, and also a bit cooler.)
The farm is 90 ha (220 acres) in total, of which about 40 ha (100 acres) is
planted with macadamia nut trees.  Half of the trees are under micro
irrigation.  The trees are relatively young, with the oldest ones about 4
years old now (and bearing their first nuts) and the youngest ones recently
planted.

The farm's soil is very deep with a clayey consistency and relatively
acidic.  The topsoil is about 30cm (12 inches) deep and less clayey.  Prior
to the nut trees being planted on the farm, grasses and acacia trees were
the main flora.  The area is a summer rainfall area, and the slope of the
farm faces north (sunny side in the southern hemisphere).  The area is not
very windy, but a gentle breeze stirs the air most of the time (usually from
the east).

We are concerned about the nutritional value of produce and sustainability
and the environmental impact of farming practices.  As such we would like to
run the farm organically, using clever design instead of a brute force
approach to solve problems.  South Africa is often quite isolated from the
developed world and as such it is often difficult to get locally applicable
info on global movements such as permaculture.

I have a number of questions and concerns, but lets start with the following
one.  Many of the trees have recently contracted phytophthora which is
causing the appearance of deep vertical fissures running through the bark.
Does anyone have some advice to offer in the treatment of this malady?

Secondly: The macadamia trees are planted with a spacing of 8m by 4m (26 by
13 feet).  The tree rows face north so that light penetrates between the
rows.  What would be a suitable plant to plant between the macadamias rows
to fix nitrogen and to provide mulching etc.  I've been thinking that
comfrey would perhaps be suitable?  We would like to encourage earthworm
activity in the orchard.  Would the comfrey be suitable for this?  Perhaps
some sort of legume like lucerne would be better?  In a couple of years,
light will be quite dim underneath the trees.  Is there a suitable plant to
grow under the trees to prevent erosion, provide mulching etc.?  Obviously
15 000 macadamia trees is pretty much a monoculture, but the trees are
planted and we'll have to think of ways to increase diversity in the
orchard.  Any suggestions?



Regards
Stephan Mare


Climate data  Nelspruit  *Position:* 25° 26' S     30° 59' E  *Height: *671m
*Period: *1961-1990  This climatological information is the normal values
and, according to World Meteorological Organization (WMO) prescripts, based
on monthly averages for the 30-year period 1961 – 1990   Month Temperature
(° C) Precipitation  Highest Recorded Average Daily Maximum Average Daily
Minimum Lowest Recorded Average Monthly (mm) Average Number of days with >=
1mm Highest 24 Hour Rainfall (mm)  January  40   29   19   11   127   14  113
February  39   29   19   11   108   12   130   March  38   28   18   10   90
  12   83   April  36   27   14   5   51   7   72   May  35   25   10
 2  15  4  37
June  32   23   6   -2   9   2   46   July  32   23   6   -1   10   2   44
August  35   25   9   -1   10   3   32   September  38   27   12   2
26  5  74
October  40   27   14   5   75   11   77   November  38   27   17   10   115
  15   73   December  38   28   18   10   131   14   65   *Year*  * 40 *   *27
*   * 13 *   * -2 *   * 767 *   * 100 *   * 130 *