Welcome to this talk on soil science and organic farming
Dirt, soil, earth, loam, mud or dust - it doesn't matter what you call it -
is of primary importance in the production of food and other crops
Most people think of it just as a substrate (or medium) in which plants grow but it's more than that
it's actually a living entity - or it should be if it's healthy and human health is affected by the health of the soil
Healthy, living soil is literally crawling with life
there are the obvious earthworms, which burrow in the soil and help to aerate and improve it,
beetles and other hard-backed insects and various invertebrates like centipedes
Then there are fungi and bacteria - also living forms
Healthy soil needs food, air and water to help plants grow
and the more nutrients in plants, the more available for humans and livestock
It stands to reason, therefore, that plants grown in poor soil will have few nutrients to pass on to the consumer
whose well-being will be worse off over
the long term
So where do plants get their nourishment?
Most of it comes from the soil
Some nutrients are made up of minerals from the earth while others come from dead plant and animal matter
which is broken down over time by the living insects and other organisms in the soil
Plants depend on these little living creatures to convert minerals and other vital elements
into a utilizable form that can be taken up by the plants
And it's a synergistic relationship - in turn, the plants assist those helpful organisms by releasing sugars and enzymes back into the soil
Before I go any further, let's take a look at the structure of soil
Now if you look at the diagram, you will see that soil is made up of many different layers
Let's start at the bottom - this is the bedrock under all the other layers
The layer above that is called regolith - here the bedrock is slightly broken up
but plant roots don't penetrate this layer
Moving up the chart, to the next layer, we come to the subsoil which contains clay and mineral deposits
On top of that, is the eluviation (or leaching) layer
this is quite light in color and is mostly just sand and silt
As we get near the surface, we find the topsoil
You will hear a lot of talk about topsoil amongst farmers and other agriculturalists
It's the most important layer of all because it's where seeds germinate and roots grow
Now, at the top of the chart, you will see a comparatively thin layer
this is organic matter that is still in the process of decomposition
It mostly consists of leaf litter and humus
just think of the surface of the forest floor - partly-decayed leaves and twigs - that sort of thing
As you can imagine, good soil forms very slowly over time but it can be lost very rapidly through erosion
And, in addition, soil quality can be affected by pollution
due to anything from industrial waste to the artificial fertilizers used by conventional farmers
which have been shown to suppress the diverse life forms in the soil
This is why organic agriculture is the way of the future
Let's take a quick look at the conventional system
which is often based on monoculture - the production of a single large crop
It relies on chemicals for fertilizer and pest control
It is also becoming an increasingly common practice to use genetically-engineered seeds
And more chemicals are used to control insects and fungi which attack crops in storage and during transportation
Also, did you know that there is no requirement for conventional growers to maintain records of their production practices?
Organic growers, on the other hand, choose the most environmentally-friendly options
for dealing with pests and disease problems working towards prevention in the first place
Some of the strategies they employ include alternating the crops grown in each field (as opposed to mono-cropping)
Because different plants add different nutrients to the soil, by rotating crops, the soil is naturally replenished
This can do away with the need for pesticides because the problem insects' life cycles are naturally interrupted
Surrounding crops with green waste can not only conserve moisture in the soil
but it can prevent weeds from springing up and it also feeds the beneficial micro-organisms
When it's ploughed under, it feeds the soil by building more organic matter
Organic farmers often release beneficial insects as predators which precludes the need for artificial pesticides
Animal manure combined with green waste materials, correctly composted (to kill pathogens and weed seeds)
fertilizes the soil in a way that encourages life rather than suppressing it
And by the way use, of manure in organic farming is highly regulated
in fact, all agricultural inputs are evaluated for their long-term effects on the environment
regardless of whether they are synthetic or natural
To sum up, organic farming is the only sustainable way of feeding the people on this planet
and keeping both the planet and the people in good health