1 Jaw., 1902.] QUEENSLAND AGRICULTURAL JOURNAL. u 
water per acre. The great trouble with rainfall is that it is not. evenly dis- 
tributed throughout the year. We have alternately in this State a wet and a 
dry season. For the first three months of the year in the North it rains daily 
and nightly; then for nine months there are only occasional rains and thunder- 
storms, and the land becomes parched and dry. Just think what wonderful 
crops we could grow if the rain came only when it was wanted! But then 
such regular rains would not suit every farmer. When one man wants fine 
weather to make hay or to harvest his wheat, another wants rain for his corn, 
or sugar-cane, or sweet potatoes; so that it is much better as it is, and we must 
take the seasons as we find them. 
In artificial irrigation enormous quantities of water are poured over the 
land. To give a hayfield a proper drenching, Professor Storer says that an 
amount of water is used which, if it were spread out evenly, would form a layer 
4 inches deep over the field, and that for 4 acres 86,400 cubic feet are run over 
the land in twenty-four hours, and this is repeated twelve times in the season 
at intervals of a fortnight. Now, there is a little calculation for you to find 
out how many gallons this makes. All you have to do is to reduce the cubic 
feet to cubic inches by multiplying by 1,728, then divide by 2774, because 2773 
cubic inches equal 1 gallon. What is the result? Jive thousand three 
hundred and eighty-five gallons, and this repeated twelve times is equal to 
64,620 gallons. 
With regard to irrigating other crops, such as sugar-cane, wheat, root 
crops, &c., the running of the water over the—surface of the ploughed land 
cannot be practised without injury to the soil, because it puddles it up; and 
when the sun has baked the surface it is so hard that plants do not grow 
properly, and even the water run on afterwards mostly runs off the surface. 
So that some other method has to be adopted. For ploughed land, undergroud 
drainage is necessary. Such underground drainage is done in various ways, 
which I will explain to you in a special chapter on How to Drain. 
Suffice to say here that, by these underground drains, far less water is needed, 
because it is not evaporated so quickly by the sun, the water cannot lie on the 
surface and become stagnant, there are no ditches on the surface, and the soil 
does not become alternately puddled and baked. 
The kind of water used in irrigation is of the greatest importance. Some 
of our bore waters are so impregnated with mineral salts that they would ruin 
the land if applied in quantities. In the case of alkaline waters, the alkaline 
matter accumulates by degrees on the surface, and very soon nothing will grow 
on land irrigated with such water. You may see how true this is by examining 
the alkaline patches on some of the soils on the Darling Downs, where various 
crops have regularly failed to grow. 
Questions on Lesson 9. 
. What is the meaning of Irrraarron ? 
. State the object of irrigation. 
. What is a Raty Gaver? 
. What two things are needed for irrigation ? 
. Under what circumstances would irrigation be too expensive for a 
farmer to undertake ? 
6. In what manner are drainage and irrigation connected ? 
7. Does irrigation supply a crop with anything but water ? 
8. How does water keep life in plants ? 
9. What amount of water is contained in melons, cucumbers, lettuce, grass, 
grain in blossom ? 
10. How many gallons of water per acre are supplied by one inch of rain ? 
11. Why are underground drains employed ? 
12. Explain why you should be particular as to the kind of water you use 
in irrigation. 
13. Are there any waters in Queensland which would be injurious to 
crops ? 
: 14. Which water is best for irrigation purposes? Why? 
OR ON H 
