Cultivating News
From "Maple Street Co-op News", Jun/Jul 2005
Soils Ain't Soils!
by Mary Meadows
I thought it appropriate to bring readers' focus to the gradual diminution
of fertile soils. The activity that may impact badly on future generations
is the bad habit planners have of allowing housing estates to be constructed
on these soils. An argument I have heard is: "What are you worrying
about? There is a mass of underdeveloped land in Australia." That
may be true; however, I see farms being subdivided like there is no
tomorrow, and monocultural farms operating on denuded soils having to
supplement the crops with chemicals to get the product to grow. I call
these crops "product" because they are becoming less like
food and more like manufactured commodities.
Without stating the obvious, monocultural farming generally means that
there is no recycling of plant nutrients. These soils when tilled invariably
have no worms or other soil life because they have nothing to feed on,
and there is a paucity of birds for the same reason.
Ploughed bare land with no life force (not even weed seeds) has not
only the potential for erosion, but if rained upon with no crop to take
up the moisture will lead to a compaction of the soil, making it more
difficult for future crops to send their roots down into the soil. Raindrops
that fall on a field protected by living plants will infiltrate the
deeper levels by way of air pockets between the soil particles.
Improving soil structure and fertility
The simple fact is that to improve soil structure and fertility, you
have to add a large amount of organic matter to your land every year.
So compost-making and planting green manure crops are the go, but it
goes without saying that fertile soils don't require the same energy
input as infertile soils.
Successful composting takes place when there is intense bacterial and
fungal activity. Heat is generated and humus is formed. If your composting
methods, like mine, are not that successful (i.e., in getting the carbon/
nitrogen mix correct), there is a recycling method that is quite simple
and effective.
Make a layer of green stuff, lawn clippings, vegetable and flower stalks,
leaves, annual weeds, bracken, tea leaves, peelings, household vegetable
waste and egg shells. Do not use twigs, roots of perennial weeds, badly
diseased plants or meat and fish waste from the kitchen. This layer
ideally is about 20 centimetres flat, not heaped in the middle. Next,
sprinkle a handful of dolomite and a thin layer of soil to provide bacteria,
mop up undesirable gases and absorb water. Keep adding to this pile
until your container is full; always keep it
covered from the rain and don't add water to the mix. A large container
with thick walls to keep the heat in and a rigid cover to keep the rain
out should give you a crumbly, friable brown soil within a few months.
Soil bacteria hold the key to soil fertility. When alive, they produce
heat and transform complex organic materials into simple chemicals.
When dead, they release these plant-feeding materials plus colloidal
gums. It is these gums and not decomposing plant remains that are humus,
the material that cements clay, silt and sand particles together to
form soil crumbs. In a fertile soil there is a minimum of 5% organic
matter. In soil under cultivation, this organic content decreases and
the humus level falls. This means that you have to add
humus-makers. All are bulky organic materials that add to the humus
content of the soil. In addition, when these materials release plant
nutrients, they can be called "manures". This means that garden
compost and seaweed are manures, and peat is not. For example, grass
clippings, fresh cow manure and dug-in weeds contain sufficient nutrients
to stimulate bacterial growth.
Using raw humus is a good way of warming the earth and raising its humus
content. This method of fast-acting stimulation means, however, that
the rapid build-up of bacteria robs the soil of nitrogen, so you may
need
to add a nitrogen-rich fertiliser and wait some time before planting.
With matured humus, the warming effect is lost but tender roots are
not damaged and the nitrogen in the soil is not locked up. Mature humus
is applied at the rate of a bucketful per square metre to improve the
structure
of the soil. Nutrients are usually present, but the plant food content
is often low, slow acting and wrongly balanced.
Fertilisers (Certified Organic is best) are materials containing one
or more major plant nutrients in concentrated form; use a handful per
square metre to feed the plants. Calcium has a vital role to play in
the soil; it is one of the essential elements for all plants.
Dolomite limestone also contains magnesium and is my preferred form
of calcium input. Gypsum (calcium sulphate) is usually
recommended to break up clay soils, whereas dolomite and rock powder
(a variety of minerals) are more beneficial in balancing the pH of the
soil. Test your soil for pH level. If an excessive amount of these powders
is used, the humus breaks down too quickly and some plant leaves turn
yellow because of the lock-up of iron and manganese.
Reference: The Bio Friendly Gardening Guide by Dr D. G. Hessayon,
pbi Publications, England, 1990
[From "Maple Street Co-op News", Feb/Mar 2005; published by
The Maple Street Co-operative Society Ltd, 37 Maple Street, Maleny,
Qld 4552, Australia, tel (07) 5494 2088, email maplest.co-op@serv.net.au,
website http://www.maplestreetco-op.com.au]