Outlook on Agriculture

Certain elements, usually present in plants and animals in only trace amounts, are essential for normal growth and functioning. Absence of these trace elements, or their provision in inadequate amounts, can lead to severe economic losses in crops and farm animals. The essentiality of these elements, coupled with the minute amounts required, suggests a catalytic or enzymic role. This rôle is discussed in some detail with particular reference to copper and cobalt in sheep and cattle.

Any discussion of world food requirements inevitably centres around the provision of protein. Traditional sources in plants and animals are recognised as inadequate and the preferred source—meat—is also expensive. Many programmes to alleviate this situation have been initiated. British Petroleum, having pioneered the production of protein from hydrocarbons by fermentation processes involving yeasts, are now commissioning commercial plants in Scotland and France.

Much has been achieved in the past by traditional methods of animal breeding but the immense progress of recent years would not have been possible without new techniques and the adoption of co-operative measures. Artificial insemination and milk recording have effected great improvements in dairy herd performance. Techniques of egg implantation and oestrus control should enable productivity to be boosted in sheep and beef cattle as has been done in the dairy herd.

The first convincing evidence implicating a specific soil organism in the transmission of a plant virus was not obtained until 1958. The vector concerned was a free-living nematode. Since then a number of soil-borne viruses have been shown to be transmitted by nematodes. Host plants, particularly wild plants, play an important part in the ecology of these viruses and their vectors.

Powdery mildew is believed to be the most important disease attacking barley over a large part of the world. Recent experiments with fungicides have indicated that losses due to the disease arc generally greater than had been suspected. The discovery of a systemic fungicide, which can be applied to the crop as a seed-dressing, a granule or as a spray, promises greatly improved control. The adoption of cultural measures and the use of resistant varieties offer an integrated approach.

The rapidity with which paraquat is inactivated by adsorption on soil is responsible for many of its novel uses in crop husbandry. The same property is also valuable in water weed control. Paraquat, besides being readily absorbed into submersed plants, is also adsorbed onto soil particles suspended in the water and onto the mud at the bottom. Toxicity to fish is low under recommended conditions of usage, which are also designed to minimise the problems of water deoxygenation.

That the interaction between nutrition and the state of health of the animal is a matter of great importance to the stockbreeder has long been known. That this interaction is complex has also been appreciated for many years. This article explores the relationship between nutrition and one form of ill-health—that caused by nematode parasitism of the gastro-intestinal tract of the ruminant. Such parasitism is one of the widely acknowledged hazards of intensified animal husbandry.