TRANSACTIONS OF SECTION M, 659 
(ii.) Some Factors controlling the Growth of Cotton,* 
By H. T. Ferrar, M.A., F.G.S. 
Among the main factors which control the cultivation of cotton on a com- 
mercial basis are :—(1) Temperature, (2) water-supply, (3) soil, (4) labour. 
(1) The cotton-plant is commonly found in those parts of the world which lie 
within thirty degrees of the Equator, but finds its best development in what may 
be described as sub-tropical climatological regions. In Egypt the air-tempera- 
tures which rule at sowing-time are in the neighbourhood of 65° F.; as the plants 
attain maturity the temperatures gradually rise to values of 82° F. and 83° F. 
and fall some 9° or 10° during harvest. 
(2) The water requirements of the crop are equivalent to about 46 inches of 
rainfall, which in Egypt is met by irrigation from perennial canals. The water- 
factor naturally depends upon environment. The methods adopted by the 
Egyptian cultivators were described. 
(3) The volume (depth) of soil available to the roots of the cotton-plant is of 
more importance than its texture or its chemical composition, provided always 
that the soil contains sufficient available plant-foods. In Egypt cotton is grown 
profitably on a soil which in one extreme case is an almost pure sand, and in 
the other extreme an unctuous clay. Diagrams were exhibited showing how a 
high water-table, by reducing the volume of available soil, limits the yield of the 
plant. 
(4) The profits derived from the cultivation of cotton naturally depend upon 
the cost of agriculture. Where the price of labour is high better returns are 
obtained by cultivating the more valuable types of cotton. The higher-grade 
Egyptian cottons grow best in the Delta, while warmer Middle Egypt supplies a 
cotton (Ashmuni) whose fibre is of medium value only. 
The East Coast of Australia would seem to provide the requisite temperatures 
and rainfall necessary for cotton-cultivation, but widespread experiment is 
necessary if it is desired to prove what areas provide suitable soil conditions and 
what is the margin of profit of the husbandman. 
(i1.) Two Maps illustrating the Fertility of Lower Eqypt.* 
By H. T. Ferrar, M.A., F.G.S. 
In an arid country water-supply is the most important factor governing the 
fertility of the soil, and, given a sufficiency of water, the origin or the chemical 
composition of the soil is usually of secondary importance. Evaporation being 
active under arid conditions there isa tendency for salt to accumulate in the soil 
to the detriment of agriculture. In the United States of America much arable 
land has deteriorated owing to the accumulation of salts caused by injudicious 
irrigation, and the next step in Hgypt’s agricultural progress is the provision 
of a widespread and efficient network of drains. 
The programme of this work is now in hand, and, in order to be in a position 
to assess the improvement effected after the improved drainage facilities begin 
to operate, the Egyptian Survey Department was asked to make a survey which 
would record the present condition of the land. A Fertility Map of part of the 
Northern Delta was shown. The map on a scale of 1 : 50,000 is reduced from the 
1: 10,000 field-sheets of Mr. F. E. Frith and myself, which are coloured accord- 
ing to an eye-estimate of the value of the land. The agricultural value has been 
proved to depend upon the salt-content of the soil, and in order to control the 
arbitrary scale adopted frequent soil-samples have been analysed by Mr. F. 
Hughes of the Agricultural Department. The mean salt-content of what we 
have called good land (coloured yellow on the map) is about 0-3 per cent., 
medium land (burnt sienna) about 0:5 per cent., poor land (sepia) 0-8 per cent., 
and barren or uncultivated land (purple) 1 per cent. to 20 per cent. 
On comparing this map with another on the same scale showing the contours 
it is noticeable how the fertility depends upon both absolute and relative levels, 
i.e., upon natural drainage. The good land occurs in the south, aud becomes 
? By permission of the Director-General of the Egyptian Survey Department. 
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