100 QUEENSLAND AGRICULTURAL JOURNAL. {L Ave., 1902. 
have to be manured rather heavily, but it is safe to say that not 20,000 acres of 
the cultivated lands of Queensland have ever been manured, and less than that 
area has been irrigated. 
The great drought of 1901-2 had a most disastrous effect: upon the 
Southern and Central sugar plantations, as shown by our illustrations in the 
June issue of this journal, yet the wheat crop was the largest and best for 
quantity, yield per acre, plumpness of grain, and freedom from rust, that has. 
yet been produced in the State. An average of nearly 20 bushels per acre in 
spite of drought surely points to Queensland as being a State pre-eminently 
fitted for cereal-growing. With wheat at 4s. 6d. and 4s. 8d. per bushel, the- 
farmers have every reason to be satisfied with their lot. 
CONSERVATION OF MOISTURE IN THE SOIL. 
{By G. B. Brooks, Manager, State Farm, Biggenden. ] 
The present drought has been the means of impressing more deeply upon. 
farmers, fruit-growers, and others that water is one, if not, the most important 
factor influencing the growth of crops. This is to be seen in the agitation now 
being made in the matter of supplying water to the crops by means of irrigation. 
In the future, irrigation will, no doubt, play a very necessary part in the 
operations of the successful Queensland tarmer. The field to be operated upon - 
is a large one, and many things have to be considered before water can be 
applied by this means to such a vast area. Important as this side of the 
question is, nevertheless there is another which calls for equal consideration. 
This is the conservation of moisture in the soil that Nature supplies in the shape 
of rain. It is true this supply has of late been a poor one, still this makes it 
all the more imperative that we should do our utmost to retain what little we do: 
get. ‘That moisture can be conserved in the soil for some considerable time is. 
no new theory, for we read that in some parts of America good crops of wheat 
can be matured upon an annual rainfall of some 12 to 14 inches. The question 
for us then is: By what means can our soils be made more drought-resistant, 
and to better retain the moisture without being what may be termed water- 
logged and sour? for it has been found that when water in a soil amounts to 
80 per cent. or more of its water-holding capacity it is detrimental to the plants. 
Ordinary plants do best when the water in the soil amounts to from 40 to 60: 
per cent. of the water-holding capacity. The water-holding capacity of a soil 
is the amount of water that a given weight, say 100 Ib., of the soil will contain 
when all the space between the grains of soil is filled with water. or example, 
a cubic foot of a very sandy soil has been found to contain about 40 per cent. 
by volume of air-space; when all this space is filled with water the sand will 
contain four-tenths of a cubic foot of water. A hundred pounds of such soil,. 
when all the space between the grains is filled with water, contains about 20 lb. 
of water. In the same way wheat soil has been found to contain about 314 lb. 
of water in every 100 Ib. of the fully saturated soil. The amount of water in 
this soil most favourable to the growth of wheat is from 40 to 60 per cent. of 
313 |b., or from 123 to 19 lb. per 100. The water-holding capacity of heavy 
clay soils is about 44:2 lb. of water in 100 lb. of saturated soil. The most 
favourable condition for plant growth in such soils is when they contain from 
16 Ib. to 24 1b. of water in 100 lb. of the saturated soil. 
The water-holding power of soils has been given as follows :— 
Sand a ms ... 20 to 25 per cent. 
Clay soil (60 per cent. clay) 40 per cent. 
Clay soil (80 per cent. clay) 61 _,, 
Pure grey clay... WW = 
Loam AD i “en tal 
Garden mould ... ~ :... 89°. ,, 
Humus ... ay wen ere 
