PLANT NUTRIENTS AND THEIR ABSORPTION 



119 



Table 13. — Highest Amount of Alkali in Which Fruit Trees Were Found 



Unaffected 



{After Lo ughridge^'^^) 



(Pounds per acre in 4 feet depth) 



Loughridge^^^ makes the following comments on these data: "The amount 

 tolerated depends largely upon the distribution of the several salts in the vertical 

 soil column, the injury being most severe in the surface foot, where under the 

 influence of the unfortunate practice of surface irrigation the feeding rootlets 

 are usually found. It is therefore important that in alkali regions such methods 

 of culture and irrigation should be followed as to encourage deep rooting on the 

 part of crops. 



"The amount tolerated varies with the variety of the same plant, as shown 

 in the grape." For instance, Flame Tokay is reported as "not growing" with a 

 total of 24,320 pounds of alkali^in the surface 4 feet per acre while Trousseau is 

 reported as thrifty in the presence of 31,360 pounds, though the sal soda content 

 of the Flame Tokay soil was somewhat higher but still well within the general 

 tolerance limit of the grape for this salt. 



"The amount of alkali tolerated by the various cultures varies with the 

 nature of the soil. It is lowest in heavy clay soils and fine-grained soils, in 

 which the downward movement of plant roots is restricted; and highest in loam 

 and sandy soils, in which the roots have freedom of penetration." 



Injuries jrom Excessive Fertilization. — It is evident that continued 

 application of fertilizer such as sodium nitrate may produce concentra- 

 tions that are harmful. 



In discussing experiments with citrus trees Kelly and Thomas^"^ state: 

 "While the growth of the trees was notably stimulated by sodium nitrate during 

 the first few years of the experiment, and healthy, normal appearing trees were 

 produced, since that time excessive mottle leaf has appeared on every tree in 

 this plot. The mottling here became so severe during the past 2 or 3 years as 

 to render the trees wholly unprofitable. No marketable fruit whatever is now 

 produced by these trees." 



