320 QUEENSLAND AGRICULTURAL JOURNAL. [1 May, 1902. 
drain pipes serving also for irrigation purposes :—“ The late Isaac Terwilliger 
performed the initiatory work in inventing or adopting a plan of sub-irrigation 
and drainage in one that is responsible for the present development of the 
cultivation of lettuce and celery on a large scale. His method was to econ- 
struct a cement pipe, with a proportion of charcoal, sparks, or cinders, which at 
that time was a waste from the locomotives. This gave a porous pipe, pervious 
in or out; so when the soil was dry the pipes were filled from the artesian 
wells, and when the opposite condition occurred outlets were opened and the 
pipes received water from the soil. 
“But the new trick of the drainage and basins leaves nothing more to 
be desired, for by it an absolute control of water in the soil is had. This 
system needs some explanation. In the first place the ground is very nearly 
level, the incline being only 2 or 3 inches to the 100 feet. Suppose a 
flowing well on the upper side of the field. From thata 3-inch tile is laid along 
the summit, at a depth of 18 inches: This tile enters at the bottom of one 
side of a basin of wood or brick, and leaves the other side in the same manner. 
These basins are placed usually 20 feet apart, and from each a parallel drain 
originates. ‘These parallel drains are also supplied with basins through which 
the water might freely flow for a partition rising nearly, not quite, to the 
surface. When it is desired to saturate the soil, as for instance as a prepara- 
tion for transplanting, the water is made to flow over this partition. In that 
case the water level is raised in the soil above this point. On the other hand, 
if it is desired to dry the ground, or after a heavy rain to carry off the surplus, 
a plug is removed at the base of the partition, and the water passes through 
‘the bottom of the basin. 
“All the parallel drains are supplied with basins at distances of 40 to 
60 or more feet where the surface is nearly level; or closer than that if the 
incline is considerable. One can see that any particular portion or the whole 
place can be dried or saturated at will.” 
I have already told you of the great irrigation works now being carried 
on on Mr. Gibson’s sugar plantation at Bingera, near Bundaberg, and [ should 
advise you to watch this expensive experiment, and note the result.* You will 
prepay be astonished at the increased yield of cane which irrigation, com- 
ined with special manuring, will bring about. 
One thing more before I conclude this chapter on irrigation. Waters 
that are very alkaline are highly injurious to vegetation if constantly supplied 
to plants. The alkali gradually accumulates on the surface as the water 
evaporates, and infallibly destroys the crop. You can easily prove this by 
making even a weak solution of chloride of sodium (common salt), magnesia, | 
soda, or any other alkali. Take a large flower-pot or box of healthy plants, 
and whenever you water them do it with this alkaline water. You will see 
that at every succeeding drying of the surface the alkaline deposit will increase. 
on the surface, and by and by the root-crowns of the plants will rot, and the ~ 
plants themselves will wither and die. Water containing much iron is algo 
unsuitable for irrigation purposes. 
In the 8th Lesson of the 1st Primer, I gave you a few reasons why 
some land should be irrigated. Those were: To increase the crops; to supply the 
want of moisture; to supply the extra moisture some plants, such as rice,’ 
require ; to get early crops; to supply plant food which water contains. sl 
To these you may add that irrigation sweetens the soil and destroys 
noxious weeds, such as moss, rushes, sedges, and many low forms of plants 
which thrive on the acids and other products of chemical action which are; 
prejudicial to farm crops. By irrigation these acids are washed away into the 
drains, and the abovenamed weeds, no longer having their natural food, shrivel , 
up and die, whilst the plants of economic value thrive in the warmed and. 
sweetened soil and yield abundant crops. ; 
* Since this was written, the results show ‘a crop of 60 tons of cane per acre, equal to over 
7 tons of sugar or £80 per acre. 
