Substantial yield increases with irrigation

Press, Volume CX, Issue 32439, 28 October 1970, Page 21

Substantial yield increases with irrigation

A district agricultural show should not only display the quality of its livestock, the prowess of horses and riders and the intelligence of its working cbgs, but it should also focus attention on the many and varied aspects which contribute to the farming systems of the area.

In the Ashburton County irrigation contributes substantially to the over-all economic activity in the area and the areas which are irrigated continue to expand each year. Irrigators are matching their skills against a climate, the vagaries of which are unpredictable. The past season and the one just being experienced are an excellent illustration of this. It is important, ■however, not to let short term happenings influence decisions where everyone is in favour of irrigation in 1969-70 and no-one in 197071. The increased potentials that irrigation offers to the Canterbury area are far too great to permit this sort of thinking. In Canterbury •'drought” should not be thought of in terms of when and how much a benevolent Government might contribute towards alleviating its financial effects, but rather as an evil which

’ restricts the best efforts of ■ a farmer to make the best I use of his land. r The following informai tkm has been' obtained from the experimental proi grammes studying the ini fluence of irrigation on potential production at Winchmore. In a study for which 16 years data are available pasture production on an unirrigated area has varied from 26501 b dry matter per acre to 78601 b. Thus there is nearly a threefold difference between the poorest and the best year. The variation from the average production of 54001 b per acre is plus or minus 49 per cent. A measure of the effect of drought during these years can be obtained by ■ comparing this production with that measured in the same way from irrigated pastures. The average yield of irrigated pastures was 10,600 d.m. ranging from 9420 to 11,890. The difference from the

f average in this case is t plus or minus 12 per cent. The average response to ir- ■ rigation was 97 per cent, I ranging from 40 per cent in 1962-63 to 289 per cent in ■ 1955-56. It should be noted that in ■ the wettest season studied i there was still a 40<per cent i increase resulting from irrii gation. It can be concluded I from this ' then ‘ that ■ “drought” in Canterbury is a normal but greatly fluctuating hazard which has to be faced.

This article is by Mr W. R. Lobb, superintendent of •the Winchmore Irrigation Research Station.

Similar data, but generally over shorter periods are available for a number of crops. For example in 88 comparisons between irrigated and non-irrigated lucerne, average dry matter yields were 96781 b for irrigated and 65591 b for non-irrigated treatments. With potatoes results from six years experiments have given an average increase of 86 per cent from 7.9 to 14.7 tons per acre. In some seasons the yields of non-irrigated crops have been extremely poor. In 1963-64 for example the variety Katahdin yielded three tons without irrigation; this was increased to 14.3 tons or by 343 per cent with irrigation. Four years results with wheat have given an average response of 46 per cent. Wheat, as with many other crops, is sensitive to drought at particular stages, and the biggest response was to irrigation in a very dry November—l 72 per cent. From two years results with peas for processing it is obvious that variety and planting date will have a considerable influence on the degree of response. In 1969-70 the late varieties Greenfeast and Victory

freezer gave a response of only 5.6 per cent from 5580 to 58901b/acre. This response of 3101 b was probably not significant. However, for William Massey yields were increased from 4590 to 70001 b or 53 per cent. Over two :; seasons with six. different crops the average increase was 23 per cent. These examples are sufficient to indicate the poten- j Jials available, remember-1 s ing that many areas have t- much less favourable rain-J ■- falls and more favourable | soils than those at Winch-1 a more. • i Perhaps the most import-I ant benefits of water to an j i irrigation farm are: that! 1 production from pastures] t and stock is predictable,' | j that wlthin-year and be-..| 1 tween-year fluctuations are | t minimal, that crop yields | s are reliable, that a greater! - intensity of cropping can« > be undertaken and that as I a consequence a lower cost § and simplified system of | * farming can be undertaken. | The year just past re-J corded a notable milestone a for irrigation development! in Canterbury. On the five | schemes operated by the * , Ministry of Works die area prepared for borderdyke ■ irrigation exceeded the > 50,000 acre mark. ■ The Department of Agriculture has been associ- • ated with the development I of some 3500 acres in areas , stretching from Hawke’s ■ Bay to the Rangitata. In North Otago the Waitaki I County scheme has' borderdyked some 6500 acres as a 1 forerunner to the major i Lower Waitaki scheme. This latter scheme and i the Glenavy-Morven scheme i in the North side of the river will usher in some ■ 70,000 acres for further de- | velopment ■ Not only is the interest 1 in irrigtaion broadening but there have been some quite 1 significant changes related to the use of water and the development of farming irrigation systems. Since the gradual establishment of a semi-automatic system for water distribution on farms and its acceptance as a practical system about four years ago, some 15,000 acres have been equipped for this type of control. Local enterprise has im- , proved the equipment and i new developments in elec- i ironies offer possibilities of i further sophisticated sys- ;

terns, at a cost. The initial costs are so insignificant that even the substantial increases in improved systerns make them attractive if compared with other items of farm mechanisation. It is considered too, that these systems are well in advance of anything offering overseas. In recent years much more water is used on crops and more sprinkler systems are being installed each year. A recent Ministry of Works survey showed that in 1969-70, 24.6 per cent of the borderdyked area in the Ashburton - Lyndhurst scheme was in crop to be irrigated. Thirty-eight per cent of the area commanded by 90 sprinkler plants in the district was also in crop. There has been an intensification of the research programme involving sprinkler systems and crop production studies in the last two years. The interest in water conservation, distribution and use has quickened in the last year and the operations of a Water Allocation Council have done much to make people aware of the import-

ance of water to their livelihood. Nowhere would the impact of this be more apparent than in Canterbury. It is to be hoped that the people of the Ashburton

County will recognise the importance of water to the future development of the area not only for agriculture, but for the many beneficial uses to which it must be put.