8 April, 1907.] Drainage and Irrigation. 207 



though probably not excessive, the average addition to the i)erennial crops, 

 such as fruit trees, being about 24 inches net, i.e., without allowing for 

 water seeping from the distributary channels. Considering that there are 

 many light showers which do not get into the sub-soil, the result of such 

 heavy watering is equivalent to being in a zone of rainfall of about 40 

 inches per annum. Hence the raising of the water-table to within a few 

 feet of the surface, injury to the growth of the trees, and the necessitv for 

 sub-soil drainage. 



In the fruit-growing areas in the south, pipe draining is becoming more 

 and more the rule, whether a limited amount of irrigation is practised or 

 whether the natural rainfall alone is relied upon. Fruit trees show more 

 quickly than any other crop the injurious effects of a shallow " water- 

 table." In the Goulburn Valley, it will not be long ere drainage will Ije 

 compulsorily resorted to by the orchardists. Already the warnings are 

 being given. The evil day is being staved off by good cultivation, bv 

 " liming," and bv careful and economical use of water. Even where, as at 

 Pendigo, only comparatively small additions of water are made bv the 

 irrigators, the season just past — one of rainfall much beyond the average 

 — has shown the need for drainage. man\ trees having either died or 

 received a severe set-back. 



So far, these remarks have dealt almost wholly with fruit trees, which 

 receive considerable attention, much cultivation, and — most important — 

 are watered by furrows and not li\ flooding. The case with regard to 

 flooding irrigation is more marked. The almost invariable practice is to 

 water all cereal crops, lucerne, and grasses by flooding. Apart from the 

 injurious effects of submerging to a greater or less extent the growing 

 plant, and pre\'enting the natural processes of atmospheric action — 

 markedly injurious under the high temperatures characteristic of our sum- 

 mer season — the inadequate preparation of the land calls for the applica- 

 tion of a great excess of water to parts in order to cause the water to 

 reach the higher lands. Consequentlv, the sub-soil is filled with water, 

 and, especially where a " plough-pan " exists — as is usually the case in old 

 cultivation ground — becomes water-logged and sour. The soil bacteria 

 are deprived of their revivifying oxygen ; their beneficial effects cease par- 

 tially ox wholly, and the soil becomes "adobe" or "brick." The sub- 

 soil loses largely its capacity to retain moisture in its capillary or useful 

 state, owing to the small particles cohering to form larger ones ; within ten 

 days or so, the crop shows signs of distress, and another watering — as 

 wasteful as the previous — is required. Small wonder need be felt when 

 assertions are heard that the life of lucerne is not more than five vears — 

 at other times, eight years is the statement — and that at the end of such 

 a period, replanting is necessary. The crv that " irrigation does not 

 pav " is justified by the results achieved under such methods. 



It is not, of course, claimed that drainage, and drainage alone, will 

 prove the sovereign remedy for all ills attendant upon irrigation. Far 

 from it. Drainage is, however, a first essential, and the irrigationist em- 

 ploving or introducing drainage will rarely be found deficient in other 

 respects. For orchard lands, and for like crops where the capital value 

 of the producing land is high, there is nothing to excel the tile or agricul- 

 tural pipe system. Its cost is high, as much as £^6 or jQ'] per acre, 

 though its general adoption should lead to the establishment of tile- 

 making works in the locality, and consequent cheapening of the tiles. 

 Besides, a complete system is necessary for trees and vines, it is a matter 



