Lenzie and Ailsa Duffy wanted to grow many of the sub-tropicals we all want to produce on their new farm. However, after purchasing the acreage near the ocean at Hervey Bay in Queensland, they received the bad news from their Department of Agriculture. Their soil (called Wallum Country - The term 'Wallum' is commonly used to describe coastal vegetation types growing on sand dunes or flat, undulating country with acid soils and a high water table) is a pasty grey fine powder that blows away in the wind. The soil itself is very high in aluminum with a pH of 3.7.
They soon realized that they couldn’t grow in the conventional way so Lenzie had to work around the problems that his land presented.
First, he brought in a tractor to push up what topsoil he did have to create two-foot high banks. He then made charcoal for the banks by piling up heaps of the shrub and native trees to burn. Once the burning pile began to collapse on itself, he had the tractor cover the embers with soil and he sprayed with water to stop the final combustion—thus creating charcoal. After cooling, the ash and charcoal was spread two inches deep on the banks.
He brought in trailer loads of compost made by the local council recycling centre from shredded trees and landscape prunings. This was piled onto the banks he had created by his own soil and charcoal to become five foot wide and two plus foot deep.
His trees are planted just eight foot apart at the top of the banked mounds. Between the trees he plants papaya. In tropical climates, papaya grows rapidly and produces a first crop just one year after planting. Once the first crop of papaya is harvest, he cuts the plants off at ground level. The dying papaya roots are thus available to rot and feed his nearby young trees.
Natural insects, worms and bacteria now work on the mulch to produce nutrients for the growing trees. Each year he adds a new layer of fresh mulch on top, and, with the leaves that have fallen in the last year, his raised banks are renewed. Lenzie never uses any type of fertilizer; not chemical nor manures. He relies solely on the worms and the other soil critters to breakdown the mulch to produce the needed nutrients.
Note from Sheryl - We took Roger and Shirley, and Roger’s Mum up to visit Lenzie & Ailsa and they very kindly home hosted all of us for the weekend. Roger wrote this article and I spent much time on the phone with Lenzie getting it ready for publication. It first appeared in Tropical Fruit News (http://tropicalfruitnews.org) in Florida before we were allowed to reprint it.