A bush garden produces copious quantities of weeds. At Wirrapunga we use these weeds to produce excellent compost which we then use to produce virtually all our vegetable needs. So, in a way, we eat all our weeds. Someone suggested to me one day that I should get a couple of goats. I explained we already had some.
Jokes aside though, weeds are too valuable to throw away. There are many excellent books on composting. One of the best is called "Composting" by Tim Marshall. I suppose we basically use his methodology.
We have a weldmesh bin in which we place all our discarded vegetable matter throughout the year. Over the year we would collect about three or four cubic metres of material. October-November is my bush garden weeding time. I start at the top of the block and work my way to the bottom pulling out every non indigenous plant. So by the end of November I have a pile of three or four cubic metres of weeds.
I then combine the material from the bin with the pile of weeds to produce a pile of about seven cubic metres. You are supposed to end up with a carbon : nitrogen ratio of about 25 : 1 but I just tend to use what I've got. As I build it I water it so it is fairly wet. It is supposed to be about 50% water. If you can wring water out of it then it is a bit wet. If you cannot then it might be a bit dry. However I can never seem to get it wet enough. I think I let it dry out too much before I use it. It is also important to keep as much air in it as you can. So I fluff it up as much as I can. I end up with a pile which settles to about three metres across and about 1.5 metres high.
The next bit is very exciting. I have a soil thermometer about 150 mm long. I stick it in the side and watch the temperature. At the start the temperature is about 20 degrees centigrade. Once the heap starts to heat up the inside temperature will be about 20 degrees higher than the outside. We want to get the inside temperature up to about 70 degrees for a few days. Therefore we need our thermometer to say about 50. Mine very quickly gets up to about 60 degrees but it is a bit eratic.
This basically cooks the weeds and thereby render their seeds sterile and destroys pathogens. It seems to work because I get very few weeds in the vegie garden.
After about a week to ten days I turn the heap inside out. The secret here is to scrape about half the volume from the outside from the heap and put it in another heap. Then place the remaining material over the new heap so as to cover it as best as you can. Again water it if necessary and fluff it up as much as you can. Mine always needs water. To measure half is a bit deceiving because fluffed up it is about double the volume as settled. Anyway the volume is increased the cube of the diameter. This means you need to scrape off one fifth. In my case that means 30 cm.
After about another week to ten days the first stage has been completed. The material has all been cooked properly and I proceed to the next stage. I turn the pile a few more times, about a month apart, but the most important bit has been completed. I have to turn it every month or my adjoining trees get into it and eat it all.
Once it is not heating up any more then the composting is complete. I then have to protect it from the nearby trees by putting it on something impervious. I also cover it so it doesn't get to dry or leach out the good stuff. I let it cure for a month or two and then use it as needed.
This process allows me to add about 100 mm of good compost to my vegie garden each year and therefore need to add nothing else but water.