Outlook on Agriculture

The potential of ammonia as a lower cost source of nitrogen was first realized in California in the early 1930s when ammonia gas was added to irrigation waters. Direct injection followed in 1939. Increased availability of ammonia gas after the Second World War provided the impetus to subsequent commercial development. The agronomic and economic implications of pressure and non-pressure systems and the practical significance of nitrogen source are discussed in detail.

The significance of molybdenum in the metabolism of higher animals and its association with copper were demonstrated in 1938. Since then much has been learnt about the interaction between copper and molybdenum in both ruminants and non-ruminants. This knowledge has contributed greatly to our ability to prevent or to treat ‘teart’ and ‘peat scours’ in ruminants. The copper-molybdenum interaction may also be involved in chronic copper poisoning and copper deficiency.

Only in recent years has the significance of selenium in animal nutrition been acknowledged. Deficiency of the element in the nutrition of ruminants is now known to be associated with certain muscular dystrophy conditions. In Australia these conditions occur more frequently in high rainfall areas and on soils originating in non-sedimentary rocks. They would appear to have been aggravated by certain pasture improvement techniques and by intensive husbandry. Nowadays they are yielding to control by various methods.

Whatever solutions are eventually found for our present production and distribution problems with protein, meat will be the preferred form for the foreseeable future. Beef production in the tropics, where human nutrition has often been characterised by protein deficiency, has long been bedevilled by a variety of difficulties. Recent work in Cuba shows how sugar cane, in conjunction with inorganic nitrogen, can contribute significantly to the solution of some of these problems.

In the progressive intensification of sheep production increased prolificacy is already attainable by refinement of current techniques; larger litters could be achieved by breeding specifically for this character. Simple graphical models for hill and lowland conditions show how costs of artificial feeding of lambs influence the cost per lamb at different levels of prolificacy. Recent research findings provide the links for the integrated chain of techniques that leads to optimal commercial systems.

It has been known for some time—from observations in zoological gardens and from experimental studies—that the behaviour of animals is affected by the size of group and by the population density. The significance of social hierarchy in these manifestations has also been repeatedly demonstrated in wild, in captive and in domesticated animals. This field of investigation is becoming increasingly important in animal husbandry as production systems become progressively intensified.