 Hi everyone, I'm Kirstie Yates, I work at the Australian National University and I work with producers. So the farming community and working with them to help them develop new innovations and how they manage their landscapes and to help them improve how productive they are, how resilient they are and how profitable and easy they are to work with. So today we're going to be talking about biogeochemical cycling of matter. So what on earth is that? So let's break that down. We've got the bio, which is the biology, so it's the living part. The geo is the earth, so what's coming out of from below our feet. And chemical is about the interactions and the processes that happen between different elements and compounds and other matter. What we're going to talk about is about the processes that lead to the cycling of different matter and energy between all of those different components. So just like a car, we need a bit of a kickstart and a source of energy. So for earth and for our plants and all the living things around us, our energy originally comes from the sun. Plants are pretty clever in that they convert the energy from the sun into sugars and then they use that to those sugars to help them grow themselves and they share that energy with other organisms who either eat the plant or they share it with organisms in the soil which we'll talk about in a little moment. But it's a pretty clever process and so anywhere that you see green, this process of what we call photosynthesis, so this really important conversion of solar energy into energy that we can use into carbohydrates and sugar is happening around you. So how does this process work? Plants will take the solar energy, they'll also take in carbon dioxide and they'll take in water through their roots and they'll convert, they'll use that energy and convert all of those components into carbohydrates or sugar. So rather than how we get most of our food, where we pop down on the supermarket or to the local store, plants create their own food from the resources that they can find around them. As they create their energy, they use that to start growing, to maintain their life processes so they can continue to function, but they also use that energy to trade with other organisms in their environment. So plants are pretty clever and down in their root system, what they'll do is share those sugars out, either as liquid that comes out of the roots that we call exudates, although form friendships, really close friendships with other organisms where those organisms live within their roots. And the plants will share those sugars and carbohydrates and those other organisms will give them nutrients and other resources that they need to survive.