When the site cut was done for the Roogulli house, the earthmovers made two piles of the excavated dirt – one of the topsoil, and a separate one of the subsoil. The subsoil pile – largely clay and shale – is gradually being used to make mud bricks and provide rock mulch for paths and gardens.
The large pile of topsoil was a favourite place for the llamas and alpacas to hang out when on lookout duty. Otherwise it was not a thing of beauty and was a source of erosion. After some nifty earthmoving, the pile of topsoil has been turned into a terraced garden. The plan is to use the area for growing larger vegetable crops such as garlic, corn and potatoes and maybe fodder crops for the chickens and alpacas.
After a bit of guesstimating about the amount of soil in the pile (we think there was about 150m3), three terraces have been constructed, each about 20m long and 5m wide. Between the terraces there are swales to catch water and allow it to slowly seep into the soil.
The soil has been stockpiled for about eight years – all through the drought – and it is water repellant and almost completely devoid of organic matter. The challenge now is to bring it back to life. There is another area nearby using this soil that was planted several years ago and now is growing very lush grass.
So what is the plan for breathing new life into old soil?
Before the soil was spread, the compacted ground was ripped. This should blur the boundaries between the existing and new soil and help with migration of soil organisms between the layers.
After the earthworks were done, a light layer of pelletised chicken manure was spread over the surface to add some nutrients to get the initial planting established. It will probably take quite a bit of time, mulch and manure to bring the soil into a healthy condition. In the meantime, a quick cover crop is needed to prevent the area being overtaken by weeds while adding organic material.
How to wet soil when it has become water repellent? There are all sorts of soil additives that can be used to wet soil but these are generally costly. We learned during the drought that applying water slowly is the key to rewetting soils. So the sprinkler was put on low and moved frequently to avoid runoff. It was a slow process, but the gradual application of water was slowly penetrating into the soil. Then nature intervened with 25mm of rain in 24 hours. The whole area was wonderfully hydrated and perfect for sowing - lucerne in the swales and a mix of field peas, vetch, ryecorn and lupins as green manure on the terraces. Some spoiled wheat straw over the top should help reduce evaporation and add more organic material as it rots.