Copper and manganese studies on calcareous sandy soils in the Gibeon district, S. W. A

Abstract

Abstract by author:

The region lies on the division of Ecca and Dwyka and the calcareous sandstones and conglomerates. Calcareous conglomerates, with sand dunes covered with grass, bushes and trees on top are found on the farm. One half of the farm consists of calcareous conglomerates with calcareous outcrops, called the "Kalk", and the other half is covered by dunes, with calcareous ouycrops occurring in some valleys between the dunes. The vegetation consists of several aristida species of grass, thornbushes, thorn and flat-topped trees. On the "Kalk" the vegetation is more sparse and not as high as in the dune area. Vleis occur quite frequently on both the "Kalk" and in the dune region. The grazing was known to be deficient in phosphorus and was supplemented by a lick consisting of di-calcium phosphate, salt and molasses. Occasionally other licks containing many elements were given. The analysis of the vegetation samples taken on the farm drew the attention to the deficiency of manganese, magnesium and copper. An experiment, in which copper, manganese and cobalt salts were administered weekly was laid out. Karakul ewes were used as experimental animals, but unfortunately the experiment had to be conducted during a season in which the grazing was adequate for the needs of the animals

In an agricultural country such as S. W. A, the deficiency of micro-elements in the natural grazing and subsequent effect on the health and well-being of the animals is of even greater importance. Because of the lack and the irregularity of the rainfall, agronomy is only practised on a small scale and animal husbandry is of primary importance. Farming on the whole is practised on an extensive basis

This study was undertaken on account of the apparent inadequacy of nutritional value of the grazing on the farm Eirup, District Gibeon, especially during the winter and spring of 1956. The average rainfall of this region is about 250 mm. annually with the highest precipitation from December to March. During the 1955/56 season the rainfall exceeded this average causing a subsequent luxuriant growth of the grass. Frost occurred early in the winter, and the tall grass turned brown and hay-like in appearance. The cattle and especially the sheep were reluctant to take this as feed, resulting in a poor condition. Great losses of stock were recorded during 1956 and the apparent reason was the presence of internal parasites. The poor condition of the sheep necessarily also had something to do with the abnormal high losses experienced