INDIVIDUAL ELEMENTS 159 



Seeds usually contain less than fruits, from 1 to 2 per cent., but walnuts have 

 been recorded as having 2.25 ])er cent., cocoanuts 8.39 per cent, and dates 9.03 

 per cent.^' 



Though sodium is regarded as unessential for the growth of very many 

 plants, investigations with turnips, radishes, beets, cucumbers, buckwheat, 

 oats, potatoes and a number of other crop plants, indicate that this 

 element can partially replace potassium when the latter is not present in 

 amounts sufficient for good growth. ^^ "In the field, however, more 

 potassium was removed in the larger crops which usually resulted when 

 sodium was increased in connection with an insufficient amount of 

 potassium, and this was in spite of the fact that sodium frequently de- 

 creased the percentage of potassium in the crop. A portion of the bene- 

 fits arising from the use of sodium in the field is, therefore, attributable to 

 indirect action, but the solution work indicates that also direct beneficial 

 effects were probably obtained in the field. "^^ 



Probably this function of sodium is of little direct importance in the 

 deciduous fruit plantation, since it is very seldom that a lack of potassium 

 is a limiting factor; however, it is at least a matter of interest. 



Chlorine. — Chlorine occurs in many plants, but seldom in large amounts except 

 in salt marsh plants. In leaves the amount varies from 25 per cent, of the total 

 ash to mere traces. The chlorine content of bark ash is low, certain records in 

 the pear showing 1.7 per cent., in the apple 0.33 per cent, and in the grape 0.4 

 per cent.^ The chlorine content of wood ash is even less, being 0.31 per cent, in 

 the pear, 0.255 per cent, in the apple and 0.02 per cent, in the grape. ^"^ The 

 chlorine content of fruits is more variable, but never very great. 



Table 57. — The Chlorine Content of Fruits" 

 (In percentages of total ash) 



Pineapple Trace Plum . 38 



Banana 2.69 Orange 2.35 



Fig 0.83 Olive 0.16 



Seeds usually have 0.5 to 1.5 per cent, of chlorine in the ash, but the amount 

 present varies greatly. Walnuts and almonds have mere traces. Other records 

 are: for chestnuts, 0.52 per cent, of the ash, for grape seeds, 0.27 per cent, and for 

 the cocoanut, which grows on the sea-shore, 13.42 per cent.^'* 



There is no definite relation between the amount of sodium and the amount 

 of chlorine a tissue contains. 



It would appear from the preceding statements that no benefit would 

 be derived from the chlorine in fertilizers carrying this element. Com- 

 mon salt has often been suggested as having possible value as a fertilizer 

 and has been tried in a limited way. So far as records are available they 

 indicate that it is of no value for deciduous or for most other fruit trees. 

 However, greatly increased yields of the mango have been reported in the 

 province of Bombay, India, from applying 10 pounds to the tree and 



