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