Jan. 2, I9SO Relation of Moisture in Substrata to Salt Balance 365 



From a comparison of the three diagrams of figure i it is at once 

 apparent that there is a marked degree of similiarity between the dia- 

 grams with respect to the locations of the areas of good growth. Out 

 of a group of nine cultures in each series giving high yield values, five 

 are corresponding cultures of the three series and are included in the 

 areas marking good growth in each of the three diagrams. These five 

 cultures are R4C4, R5C2, R5C3, R6C2, and R6C3. The two cultures 

 R7C1 and R7C2 are also included in the group of high-yielding cultures 

 in both series B and C, as is indicated on the diagrams representing 

 these two series. 



The highest average dry-weight yields obtained from series A and 

 from series B were produced by corresponding cultures (R5C2) of the 

 two series. The highest average relative yield obtained from series C 

 was that produced by culture R5C3. It is to be noted, however, that 

 during the two experimental periods of this series cultures R5C2 and 

 R5C3 produced corresponding dry-weight yields which were nearly equal 

 in value, so that the average absolute yield from the former was some- 

 what higher than that from the latter, while the average relative yield 

 from the latter was slightly higher than that of the former. 



A careful comparison of the diagrams of the three yields with reference 

 to the location of the high-producing cultures brings out the fact that 

 these areas approach more closely to the apex of the triangle and recede 

 correspondingly from the base as the moisture content of the cultures 

 in the different series is' increased. Thus, in series A, which was main- 

 tained at a moisture content of 40 per cent of the water-retaining capacity 

 of the sand, the areas of high yields lie mainly in a central region of the 

 triangle between the second row of cultures from the base and the third 

 row from the apex. In series B, which had a 60 per cent moisture con- 

 tent, the area of high yields is centrally located, mainly between rows 

 4 and 7. While this area has receded considerably from the base of 

 the triangle toward the apex as compared with the areas of high yields 

 in series A, it does not extend entirely to the apex and just touches the 

 left margin at culture R7C1. In series C, which had an 80 per cent 

 moisture content, the area of high yields has receded still farther from 

 the base of the triangle and extends entirely to the apex, bordering on 

 both right and left margins. 



From the foregoing facts it is at once clear that the differences in the 

 degrees of moisture employed in the cultures of these 3 series had no 

 apparent influence upon the physiological salt balance of the culture 

 producing maximum yields of tops, since the salt proportions and the 

 total concentrations of the soil (sand) solutions of the highest-yielding 

 cultures of these series were approximately the same, and since the 

 cultures occupied the same relative positions in their respective series 

 with reference to the yields produced, as is indicated in Table I and on 

 the diagrams of figure i. The fact that out of each of the 3 groups 



