THE PLANT 



35 



more plants is nicely counterpoised by the loss in the 

 later stages through having too many roots in the soil. 



'16.0008.000 4.000 

 I32JOOO 



Holes per acre 



1.000 



Infinity 



FIG. 6. EFFECT OF SPACING ON YIELD. 



These curves are generalized from experimental data obtained at Giza 

 in 1912 (see Phil. Trans. Roy. Soc., 1915, for the full account). 



The tall vertical line on the left marks the extreme limit, or " infinite den- 

 sity," when the seed would be so thickly planted as to give no yield 

 at all. 



The maximum total yield is obtained at the conventional Egyptian spacing 

 of about 14,000 holes to the acre, with two plants in each hole. 



The employment of one plant in each hole lessens the total yield by about 

 10 per cent, (dotted line) in any spacing. 



At wider spacings than 1,000 plants per acre the yield is directly propor- 

 tional to the number of plants. 



The first few flowers to open are directly proportional to the number of 

 plants on the area, unless the spacing is extremely dense; thus, the 

 first picking (dash line) is at its largest with a closer spacing than that 

 which gives the maximum total yield. 



The curves here drawn apply to fairly symmetrical spacings, such as the 

 ideal and Egyptian ones in Fig. 5, opposite. Any departure from sym- 

 metry, as in the U.S.A. arrangement, diminishes the yield, other things 

 being equal. The difference between the total yields with Egyptian 

 and U.S.A. arrangements, but with the same number of holes per acre, 

 is about as 5 : 4. This is shown graphically to the left of the diagram, 

 where the black top of the column represents the advantage of the 

 hand-cultivated Egyptian system over the American one. 



It being agreed that the larger the volume of soil avail- 

 able, the better it is for the plant, and lateral extension 



