WHEAT YIELDS IN N.Z.

Press, Volume XC, Issue 27303, 20 March 1954, Page 5

WHEAT YIELDS IN N.Z.

Influence Of Good Pasture

NOW AMONG HIGHEST IN WORLD The New Zealand average wheat yield is among the highest in the world, but it could be raised still higher if. irrigation became general, according to Professor J. W. Calder of Lincoln College, in an article in the Wheat Review, the journal of the Wheat Research Committee which has just been issued. The rapid increase in the average since 1944 is the result of a greater use of high-producing pastures, and also of the reduced acreages, which have tended to keep wheat on the better land. The article discusses the graph reproduced on this page.

In the Wheat Review for 1946 average wheat yields for New Zealand (five-year moving averages) were presented in graph form, says Professor Calder. Certain periods were clearly depicted showing falling and rising trends and these were related to certain changes in farming practices., The rise in average yields in the period 1935-45 was credited to the increasing use of high-producing pastures, heavily limed, regularly top-dressed with superphosphate, and containing vigorous clovers. The development of high-producing pastures is regarded as the most important advance in Canterbury farming since the introduction of refrigeration in 1882, which caused the change from one-crop, exhaustive wheat-growing to mixed farming. In the 1946 article this cause of the rising trend was discussed and it was stated “There is still room for considerable development along these lines and we may expect yields of wheat to continue to rise.” When we look at the graph of yields of wheat since 1944 we find that they have continued to rise rapidly to a surprisingly nigh level. By 1952 the five-year average had risen to over 40 bushels an acre. This brings New Zealand level with the group of countries in the north-west of Europe with the highest average yields of wheat in the world, and this is an outstanding achievement. These high yields are, basically, a reflection of the high level of fertility of our wheat-growing soils which has been improved by a high standard of husbandry based on the high-producing pasture. We must realise however that there are several other changes which are helping to raise the average yield. It is well known that the area of wheat has declined from a five-year average of about 230,000 acres up to 1945 to about 100,000 acres since then. It is believed that the greatest decline in area has occurred on the lighter and more marginal cropping soils. This means that a greater proportion of the wheat crop is grown on the heavier land in the country, with a consequent influence on yields.' Another factor to be considered is the effect of new varieties of wheat

on yield. Tne yielding capacity of oar wheat varieties has been cared for by the plant breeder. Cross 7, which is the standard variety, has had the capacity to stand up to the increased fertility of the soil throughout the period of rising yields, and has contributed, along with other* high-yielding varieties, its share to the rising trend. We see then that there are three main contributing causes of the rise in this latter period, namely the improved fertility of the soil, the increased proportion of the crop grown on heavy land, and improved varieties. These three causes are still operating, and the question naturally arises—when will the rising trend stop?. The upper limit cannot be much -higher under our climatic conditions because our average rainfall of 25-26 inches must set -the limit near its present level; but should irrigation become widely practised then we can expect the limit to rise to still higher levels. It may not be so much through direct irrigation of wheat, winch no doubt will occur to a greater or less degree,

but indirectly through the improved moisture-holding capacity and fertility of pasture land developed under irrigation. There will also be counteracting forces tending to lower the average yields. The most obvious one is an extension of wheat-growing to light land as a result of a change in the relative profits from wheat and other forms of land utilisation. Let us look at the long-term trend in wheat yields on the graph. This was drawn by joining the mid points of each of the major trend#, which have been named in chronological order: (1) One-crop, exhaustive wheatgrowing. (2) The rise of mixed farming. (3) The rise of dairying. (4) Good husbandry—the use of fertiliser.

disease control pure seed, tractors. (5) The depression. (6) Improved husbandry—improved pastures, reduced proportion on light land, the long-term trend of yield was set at an average of 32 bushels an acre.. Since 1944 the rise in yield has been so rapid that the long-term trend of yield has risen in 1952 to over 35 bushels an acre. The average yield of wheat in the eighties of last century was about 25 bushels an acre, so that the improvement in average yields is as «much as 10 bushels an acre of 40% over the last 70 years. These facts are very encouraging and indicate that we can continue to produce wheat and other farm products without ruining our land. We can farm on a permanent basis provided we adhere to the principles of good husbandry, including the use of the high-producing pasture which plays an essential part in our present systems of farming.

Tn yesterday’s report of the first day of the Christchurch Flock Ram Fair, the list Of individual sales of Southdown rams sold by Pyne, Gould, Guinness Ltd., was transposed and was printed under the Suffolk sales instead of in its right place.

The Brussels correspondent of the International Wool Secretariat, London, has reported an outbreak of myxomatosis among ‘rabbits in Belgium. The disease is thought to have spread from France and Belgian authorities believe that unless its progress is checked it could prove disasteom to commercial rabbit breeders.