The Sebastopol Demonstration Energy Garden is located within the Sebastopol Sandy Loam series, which is described as a moderately fertile, well drained soil. Permeability is moderately slow in the subsoil, runoff is medium, and the hazard of erosion is moderate.

Soil texture is determined by the relative proportions of sand,
silt and clay and organic components that soil has. Sand is the largest particle, silt particles are smaller than
fine sand but can still be seen by the human eye, and clay particles are
microscopic.

Sandy soil—tends to be very
light and dries out swiftly. Water drains very quickly and makes the
soil easy to dig. It is the first to warm up in the sun.

Silt soil—retains moisture and feels slippery when wet. Retains nutrients better than sand but does not dry out as quickly.

Clay soil—a
very heavy soil, it holds moisture for long periods of time when wet
and dries hard as a brick. Clay soil retains nutrients and is very
fertile but is heavy, sticky and very hard to dig. It is the last to
warm up in the sun.

Loam soil—the ideal
soil texture, it is composed of sand, silt and clay. The ideal loam
soil contains 40% silt, 20% clay and 40% sand and organic matter. Loam
is a separate category because none of its compontents account for more
than 50%.
Loam soils are ideal for most plants, although many plants grow well in non-loan soils.

8/3/07 8/11/07

So as to test soil texture, we performed a comparitive test of samples from different parts of the garden.

A) Soil sample from path; untreated

B) Soil sample from bed; ammended with mango mulch

C) Sample of purchased compost; mango mulch ammendment

D) Sample of the compost developed on site.

We filled recylcled mason jars a quarter full with a portion of each sample, added water and a couple drops of biodegradable dish washing soap, and allowed them to settle for a week. Based on the thickness of each settled layer, we determined the proportions of sand, silt, and clay in our soil.

Using a basic LaMotte soil test kit and a soil auger, we tested each sample's pH, and the quantities of available nitrogen, phosphorous, and potassium.

The pH of our soils ranged from 6-8 and it appeared that the more organic materials that the soil contained, the more alkaline it was. The phosphorous content of our samples ranged from medium to high (75lb/acre-100+lb/acre).

The nitrogen content of our compost is tremendously high compared with the other three samples which could be expected because our chickens are allowed access to the piles. Aside from sample D, merely trace amount of nitrogen were present. The potassium content of our samples correlated with the proportion of organic marterial in the soil. The purchased mango mulch expressed the highest content, followed by the compost we have developed.

Nitrogen- stimulates leaf and stem growth. Nitrogen deficiency
causes reduced growth and pale yellowish green leaves. The
older leaves turn yellowish first since the nitrogen is readily moved
from the old leaves to the new growth. If the soil is cold and wet,
nitrogen in the soil is not as available to the plants. Excess nitrogen
may cause potassium deficiency.

Phosphorus-is important in the germination and growth of seeds, the
production of flowers and fruit, and the growth of roots.
Phosphorus deficiency causes reduced growth and small leaves that drop
early, starting with the oldest leaves. Leaf color is a dull,
bluish green that becomes purplish or bronzy. Leaf edges often turn
scorched brown. Excess phosphorus may cause potassium
deficiency.

Potassium- promotes general vigor, disease resistance and sturdy growth. Potassium deficiency causes stunted growth with
leaves close together. Starting with the older leaves, the leaf tips and edges turn scorched brown and leaf edges roll. Excess
potassium may cause calcium and magnesium deficiencies.

Using a disecting microscope at a magnification of 30x we analyzed the
contents of each sample, here looking for the amount of sand, clay,
silt, and organic materials. At this magnification the mycelium of
fungi was visible.

A. B. C. D.

A. Mostly sand w/ small amounts of silt

B. Finer sand particles and more silt than A.

C. Mostly organic materials. Mycorrhizae present among other mycelial growth.

D. More silt than A and B. Mycellial growth present as well as organic remnants.

Using a microscope at a magnification of 600x we analyzed the biology of each soil sample.