THE IRRIGATION AGE. 



41 



MISTAKES OF FARMERS IN IRRIGATION WORK 



Professor T. H. Cherry, one of Australia's lead- 

 ing irrigation experts, has recently published in the 

 Agricultural Gazette of New South Wales an inter- 

 esting article" on the effect of careless irrigating. 



It is applicable in many ways to our own over- 

 irrigated sections. He writes as follows : 



If the reasons for such failures as have been 

 made by fruit-growing irrigationists in Australia to 

 make their properties payable propositions were 

 sought out and tabulated, the "misuse of water" 

 would be found if not the principal one, at all events 

 high up on the list. There are in most of our irri- 

 gation areas fruit-blocks, some of them abandoned, 

 that are known as "wet blocks" ; these blocks have 

 become water-logged through injudicious irrigating 

 or insufficient drainage, or both. In one of them, 

 seepage starting in a spot where surplus water has 

 been allowed to accumulate, its progress marked by 

 dead and dying vines and fruit trees, slowly spreads 

 right over the block, and perhaps to others adjoin- 

 ing, if stringent measures are not taken to check it. 

 In many of these blocks deep shafts have been sunk, 

 sometimes with success and sometimes without, in 

 the hope of finding a sand-drift, perhaps 100 feet 

 beneath the surface, by which the surplus moisture 

 may be drained away. 



This trouble is nearly always avoidable, even 

 on land where the natural drainage is poor, by the 

 even distribution of water in sufficient, but not more 

 than sufficient, quantities, and by proper attention 

 to cultivation. Mistakes, no doubt, were made in 

 the laying out of many "wet blocks" mistakes 

 against which the reader already has been warned 

 which have made the land difficult or impossible 

 to irrigate properly ; but there are many "wet 

 blocks" the spoiling of which has been due to care- 

 less watering pure and simple. 



It must not be thought that irrigation is all 

 done on the surface, or that it is finished when the 

 water has been cut off from the head-ditch, and has 

 ceased to flow in the furrows ; the water may be 

 moving underground for days afterwards, and this 

 movement should be studied by noting the differ- 

 ence in the amount absorbed in different parts of 

 the farm and the time it takes to irrigate them, by 

 sinking holes before and after irrigation. 



There are patches of land which will take, ap- 

 parently, almost any quantity of water, where water 

 will simply pass through the soil and lodge some- 

 where else ; there are others, notably in Mallee coun- 

 try, where though the soil may be perfectly dry, 

 water will run for hours in a furrow without pene- 

 trating more than a couple of inches; and others 

 again which will hold the water for a period, after 

 which it will suddenly disappear, where if a 3-foot 

 hole is sunk a fortnight after an irrigation a foot of 

 water will rise in the bottom of it, while in a similar 

 one dug a week later the ground may be found 

 almost dry. The irrigationist must, therefore, study 

 each block individually, and learn to irrigate it in 

 such a way that every part will get the water it 

 requires, and no more. A "wet" block may be cured 



as a rule by means of draining tiles, or in places 

 where there is no possibility of surface drainage by 

 sinking a shaft to a sand drift in the manner indi- 

 cated above; but a good many "wet" blocks might 

 be cured simply by the careful and judicious use of 

 water and by thorough cultivation. If it is evident 

 that a patch of ground is getting water below the 

 surface which was intended for other parts of the 

 block, it should be given less on the surface, i. e., 

 given only one irrigation while other parts get two 

 or three, and in some cases, left unirrigated alto- 

 gether. If such a patch shows near the head-ditch 

 or midway down the rows it will be necessary to get 

 water past it to irrigate the land at the far end of 

 the rows. This may be done by making a small 

 temporary earth ditch of one of the furrows higher 

 up the block, from the head ditch to a point past 

 the wet patch (or better still, by laying removable 

 lengths of 6-inch down-piping on the same block), 

 and taking the water from that point across the 

 furrows as required. 



Where there is a patch of ground which, owing 

 either to the steepness of its grade or to that 

 "greasy" quality to be found in places where mallee 

 and certain other trees have grown, will not absorb 

 a sufficient quantity of water if irrigated in the 

 ordinary way, the number of furrows may be in- 

 creased ; and if there is a limestone patch which will 

 take an excessive amount of water, the number of 

 furrows may be diminished. 



The more furrows there are the more the sur- 

 face of the ground is exposed to the water, and the 

 more quickly it will absorb it; and conversely the 

 fewer furrows there are in a piece of land, the longer 

 it will take to water it. Applying this simple fact 

 will considerably aid in the even distribution of 

 water. 



In the settlements on the Murray, where the 

 water-supply is obtained by pumping, an irrigation 

 once started proceeds from necessity day and night 

 until it is finished. The disadvantages of irrigating 

 at night are obvious, but where land has been well 

 laid out for irrigation by the furrow system, and 

 irrigators understand their business, the advan- 

 tages outweigh them. Continuous irrigation is the 

 more economical as regards both the quantity of 

 water used, and labor in distributing it, but what 

 concerns the settler still more is that, if he has a 

 continuous stream of water on a block, he is much 

 better able to judge when the land has had sufficient 

 water and is saved a lot of trouble in the regulation 

 of it. Difficult or badly laid out portions should be 

 finished in daylight, but there should be no diffi- 

 culty in the irrigation of blocks well laid out on 

 the furrow system at night time if the head ditches 

 are in good order, the stream regular, and the boxes 

 properly set. 



The frequency with which lucerne should be 



irrigated depends altogether on the amount of sun 



heat available to it. In cool cloudy weather when 



it grows but slowly, lucerne does not use much 



(Continued on page 42) 



