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THE SOIL tests I undertook on the advice of agricultural experts. The sheep adviser had suggested a test for calcium deficiency. The sheep man's idea was to supply the flock with a small amount of bone meal mixed with salt, in the ratio of 10 parts meal to one part salt. It was disastrous advice. The sheep who tried it did not improve. In fact, within half an hour the bone-meal lick had paralysed 23 ewes, all of whom rapidly died. Some managed to stagger only a few yards from the trough before dying. The vet diagnosed pulpy-kidney.

It seemed for the moment that calcium deficiency was not the problem. Nor was it obvious to me that phosphorus, which is necessary for growth, was over-supplied in the soil as I knew it to be in the ground fertilised for tobacco. The fact is that I had become accustomed each year to the cheerful sight of lush green pasture pushing up on the flats with the help of super and I didn't want to risk famine by withdrawing this feed to my sheep. So I decided to play it safe. Come autumn 1939, I spread another bag of super to the acre. This brought real trouble. The unsold sheep became even thinner, and examination of veins of the eyes showed lack of red blood cells. Normally they would be shorn in August and sold, but this year the shearers were late and so examination of the whole flock came did not come until the shearers arrived in November, by which time the sheep had been exposed to the full heat of the summer sun. Many sheep were found to have developed arthritis in the leg joints, and cancer lesions, mostly on the ears. One could say that the whole flock was suffering from anaemia.

Watching the sheep die like this reminded me of the rabbits suddenly paralysed by the baits I laid as a boy at the creek flat. Reflecting on this, it occurred to me that calcium is not the only active ingredient in bone meal: about half is phosphates. So phosphorus could be at work in sheep in the same way. When some old ewes had to be killed, only a small amount of thin, watery blood came from them. Even the lambs were small and thin, like a child with leukemia; the early anaemic signs had given way to this more serious condition. An abundance of superphosphate had led to arthritis, skin cancer, and anaemia. Here was cause and effect!

It dawned on me that the poverty of the soil could be turned to my advantage if I switched to an experimental approach. I would give the sheep mineral supplements. As the flock loved salt, a source of sodium lacking in the soil, I ordered two 200-pound bags of different varieties - one of sea salt from Geelong, another of common salt from Lake Charm in the Mallee. They preferred the sea salt with its trace elements.

The sheep would expect to find the salt in their trough. There were several of these small troughs scattered over the paddock. Next, to test their reaction to calcium, I placed a small pile of finely powdered limestone in the trough at the end opposite to the salt. This was also to their liking; they instinctively and regularly took a small dose, enough to satisfy their needs. When I was sure how much they needed, I mixed the two as one lick. I then introduced another mineral and began a new test. In this way it was possible to gauge both the amount and the type of chemical to supplement their feed from pasture.