PDC…..Week 11

This week Cam was interstate, so his friend Dan Palmer took our class. Dan is the founder of Permablitz, runs Very Edible Gardens and has worked overseas with noted permaculture teacher Rosemary Morrow.

We started with a look at designing gardens in a couple of different climate types to the temperate climate we’re familiar with—the humid tropics and drylands (the way Melbourne’s rainfall is going, we may get to use dryland strategies yet!).

Soils in tropical regions are generally old and heavily leached. The nutrients are held predominately in the plants and animals, not in the soil as in temperate regions. A combination of warmth and soil fungi ensures that organic matter on the forest floor is broken down quickly and taken up by plants, before it can be washed away by heavy rains. Therefore soils should be covered at all times (mulch, mulch, mulch!) and tree systems are better than annual cropping systems.

The tree canopy in a tropical system may consist of avocado, mango or jack fruit. The understorey may have babaco, paw paw and dragon fruit. Coffee might occupy the shrub layer. Herbs such as comfrey and sweet potato are in the herb layer and clumping plants like ginger and arrowroot are scattered throughout. Vines climb everywhere. It’s a very productive system foodwise.

House design in the tropics concentrates on heat reduction—keeping things cool. The house is best oriented to the prevailing air movement. Breezeways to bring in cool air and white walls to reflect heat. Cooking areas are best kept separate from the house.

Growing food in dryland systems is a real challenge. Winds (rather than rain) are the predominant shapers of landscape. In the soil, termites and ants are more effective than worms as aerators and decomposers. Rainfall is episodic and every drop needs to be captured effectively.

There’s a very good short video of permaculture design in a desert situation. It’s called Greening the Desert and it features permaculture guru, Geoff Lawton. See it here. There’s now a longer follow-up version and it’s here.

Our final design project occupied most of the afternoon session. Only a week more to go on this and most of the final day of the course will be taken up with presenting our designs.