EGYPTIAN COTTON AS AFFECTED BY SOIL VARIATIONS. 



19 



small and yellowish green. Each of the three samples consisted of 

 three cores taken about 1 foot apart and to a depth of 4 feet. The 

 soil from all three cores at each successive 1-foot depth was thoroughly 

 mixed together to represent that depth of the boring in question, 

 and upon each of the 12 samples as thus prepared four determina- 

 tions of moisture equivalent were made. 



The electrical resistance of saturated soil from each sample was 

 measured in order to ascertain whether there were significant differ- 

 ences in the salt content of the soil. The high resistances observed 

 in every case made it evident that the effects noted could not be 

 attributed to alkali. On the other hand, the fact that the resistances 

 were much lower at all depths of boring No. 1 than of borings Nos. 

 2 and 3 indicated that a deficiency of nutrient salts at the two latter 

 borings may have been a factor in the poor growth of the plants. 



On several plants in the neighborhood of each boring counts were 

 made of the number of the node on the axis at which the first fruiting 

 branch was retained and of the number of set bolls to the plant. 1 



Table II gives for each of the three borings the wilting coefficient 

 (calculated from the moisture equivalent) and the electrical resist- 

 ance of the soil at successive depths, as well as the average height of 

 the plants, the mean of the numbers of the node bearing the first 

 fruiting branch, and the mean number of bolls per plant. 



Table II. — Relations between the wilting coefficient of the soil and the growth and 

 fruitfulness of Egyptian cotton plants at Bard. Cal., in 1912. 



< The counting was done by Mr. Rowland M. Meade. The importance of retention of the fruiting 

 branches at low nodes on the axis as an indication of fruitfulness is pointed out by Mr. Argyle McLachlan 

 in Bulletin 249, Bureau of Plant Industry, 1912, entitled "The branching habits of Egyptian cotton." 



2 Based upon thoroughly mixed samples of each 1-foot depth, regardless of variations of texture within 

 that depth. The variations are indicated by the following notes: 



Boring No. 1. Soil silty from the surface to a depth of 14 to 20 inches (varying in the several cores), then 

 fine sand, with some admixture of silt at a depth of 24 to 30 inches, then coarse sand from the depth of 30 

 to 48 inches. 



Boring No. 2. First 12 inches much sandier than at boring No. 1. Coarse sand began at a depth of 20 

 to 24 inches and continued to the bottom of the boring (48 inches). 



Boring No. 3. Soil sandy to the surface. Coarse sand began at a depth of about 18 inches and continued 

 to the bottom of the boring. 



[Cir. 112] 



