+/-6:1 +/-12:1 +/-25:1 +/-50:1 +/-100:1
Bone Meal Vegetables Summer grass cornstalks (dry) Sawdust
Meat scraps Garden weeds Seaweed Straw (grain) Paper
Fish waste Alfalfa hay Legume hulls Hay (low quality) Tree bark
Rabbit manure Horse manure Fruit waste Bagasse
Chicken manure Sewage sludge Hay (top quality) Grain chaff
Pig manure Silage Corn cobs
Seed meal Cow manure Cotton mill
waste
The lists in this table of carbon/nitrogen ratios are broken out as
general ranges of C/N. It has long been an unintelligent practice of
garden-level books to state "precise" C/N ratios for materials. One
substance will be "23:1" while another will be "25:1." Such
pseudoscience is not only inaccurate but it leads readers into
similar misunderstandings about other such lists, like nitrogen
contents, or composition breakdowns of organic manures, or other
organic soil amendments. Especially misleading are those tables in
the back of many health and nutrition books spelling out the "exact"
nutrient contents of foods. There is an old saying about this:
'There are lies, then there are damned lies, and then, there are
statistics. The worse lies of all can be statistics.'
The composition of plant materials is very dependent on the level
and nature of the soil fertility that produced them. The nutrition
present in two plants of the same species, even in two samples of
the exact same variety of vegetable raised from the same packet of
seed can vary enormously depending on where the plants were grown.
William Albrecht, chairman of the Soil Department at the University
of Missouri during the 1930s, was, to the best of my knowledge, the
first mainstream scientist to thoroughly explore the differences in
the nutritional qualities of plants and to identify specific aspects
of soil fertility as the reason why one plant can be much more
nutritious than another and why animals can be so much healthier on
one farm compared to another. By implication, Albrecht also meant to
show the reason why one nation of people can be much less healthy
than another. Because his holistic outlook ran counter to powerful
vested interests of his era, Albrecht was professionally scorned and
ultimately left the university community, spending the rest of his
life educating the general public, especially farmers and health
care professionals.
Summarized in one paragraph, Albrecht showed that within a single
species or variety, plant protein levels vary 25 percent or more
depending on soil fertility, while a plant's content of vital
nutrients like calcium, magnesium, and phosphorus can simultaneously
move up or down as much as 300 percent, usually corresponding to
similar changes in its protein level. Albrecht also discovered how
to manage soil in order to produce highly nutritious food. Chapter
Eight has a lot more praise for Dr. Albrecht. There I explore this
interesting aspect of gardening in more detail because how we make
and use organic matter has a great deal to do with the resulting
nutritional quality of the food we grow.
Imagine trying to make compost from deficient materials such as a
heap of pure, moist sawdust. What happens? Very little and very,
very slowly. Trees locate most of their nutrient accumulation in
their leaves to make protein for photosynthesis. A small amount goes
into making bark. Wood itself is virtually pure cellulose, derived
from air and water. If, when we farmed trees, we removed only the
wood and left the leaves and bark on the site, we would be removing
next to nothing from the soil. If the sawdust comes from a lumber
mill, as opposed to a cabinet shop, it may also contain some bark
and consequently small amounts of other essential nutrients.
Thoroughly moistened and heaped up, a sawdust pile would not heat
up, only a few primary decomposers would take up residence. A person
could wait five years for compost to form from pure moist sawdust
and still not much would happen. Perhaps that's why the words
"compost" and "compot" as the British mean it, are connected. In
England, a compot is a slightly fermented mixture of many things
like fruits. If we mixed the sawdust with other materials having a
very low C/N, then it would decompose, along with the other items.