Irrigation Of Crops To Be Studied

Press, Volume CVI, Issue 31071, 28 May 1966, Page 9

Irrigation Of Crops To Be Studied

The Department of Agriculture’s irrigation research station at Winchmore is to embark this autumn on experiments on the irrigation of crops. A 27-acre farmlet is to be used for this project, which is likely to be a longterm one with the aim of developing a cropping rotation that will fit into a practical farming system.

i In announcing this development this week the superini tendent of the station, Mr W. R. Lobb, said that while there was a place for irrigati ing crops on farms which were still only partially irrigated, it was his feeling that the totally-irrigated grass farm producing only animal : products could be the easiest (to run and could be the best proposition from an economic (point of view at present.

Mr Lobb said that the rea(son irrigation of crops had ' not been given more atten(tion in the early stages of I irrigation research was that (the light soils were at that Itime at a fairly low stocking (level and their best potential , was in producing animal products from pasture. The demands of the export markets had also more or less governed this course, with cropping being of less significance because of its obvious limitations in providing for internal demands. The result was that the experimental programme had been based largely on the many factors involved in the growing and utilising of irrigated pasture. These investigations had now been carried to the stage and analysed to a degree where a reasonable amount of practical information was available, and with the increasing demand for crop products some investgiation was needed into the growing of crops, especially since the production potential had risen over the irrigable areas. There was also another factor which demanded that consideration should be given to irrigation of crops at this stage. With the advent of automatic grassland irrigation the design of the race system might introduce some difficulty for application of irrigation to crops, so that before developments proceeded too far it was necessary to examine the distribution of water over a range of crops so that modifications could be

made to Improve irrigation of cropping land. To this end it was necessary to establish a reasonable farm rotation with a series of crops being grown on land which had had adequate periods in pasture—this was necessary to enable the investigations to have a reasonable degree of application on the farm. It was therefore considered that a small farmlet should be established on which a crop rotation could be practised to enable a limited range of crops to be examined over a period of time. Over the last five years potatoes had been investigated in detail under irrigation and this crop would be retained in the system on the farmlet until such time as an adequate rotation had been developed to enable other crops to be examined. In the first instance it was intended that wheat would be included in the rotation and other cash crops might also be brought into the system until a rotation using about a third of the unit for cropping was developed.

This Autumn Mr Lobb said a start was being made on the farmlet this autumn but it would be a number of years before a complete rotation had been developed. The area had been all in grass the year before last Apart from wheat other crops that might be looked into were peas, barley and linseed. Small seeds could noi be included as the unit would not be big enough for this purpose. Apart from cash crops, and this could include small seeds, Mr Lobb said the range of cropping in Canterbury at pre sent was fairly limited. Some fodder crops had already been shown to have considerable yield increases with water, but the extent of these could well be reduced by the use of irrigated pasture. But if markets were available it was possible that there could be fuller development of special crops for processing on the better soils in the irrigable areas.

In examining yields on the farmlet Mr Lobb said it would not be possible at the same time to look at irrigation efficiency in the shape of distribution of water and it was hoped to obtain the co-oper-ation of crop irrigators in the area to look at these factors. Mr Lobb said it seemed that yields of crops would benefit most from irrigation where they were spring sown and the crops made all of their vegetative growth in the drier periods. It was desirable, therefore, that both winter and spring sown wheat should be considered as wheat seemed to be the crop with the greatest demand and the most stable price structure. The irrigation of crops could involve a number of treatments and it was obviously difficult to design these because of the unpredictable distribution of the rainfall, so until an investigation programme had been established over a number of years it could be difficult to make accurate predictions. To begin with soil moisture deficits would be used to determine when irrigation should be applied to a crop. Although crops were likely to require less irrigation than grass and this might be thought to Indicate that irrigation of crops was more economical in the use of water, Mr Lobb said it was likely that reduced efficiency in application of water and

increased labour needed in applying the water to crops could reduce this advantage. A number of people were now irrigating crops, he said, and quite a lot of this was being done on soils where there did not need to be any substantial land preparation. How efficient this was in the use of water was not known. It was satisfactory while water was available in adequate quantities, but if it happened that water was being utilised to the full it might be found that this was an inefficient form of water use and consideration would have to be given to the more efficient use of water.

Good Responses Some people had had very good responses from irrigating crops and it was intended to be guided by what they had done in the irrigation treatments that would be applied at Winchmore.

Mr Lobb said he anticipated that something would come out of these investigations almost Immediately in the way of responses to water, but to get a pattern of what happened over a number of years this investigation would have to go on for a long time. But where the full potential for grass production could be developed with irrigation and a low cost system for the whole of the farm could be adopted, it was likely that a totally irrigated grass farm producing animal produce only would be the easiest to operate and would possibly be the most economic, said Mr Lobb.