50 FERTILIZERS 



alkaline effect of the potash salt. Lime carbonate or 

 gypsum or common table salt might have produced 

 the same effect. 



GENERAL PRINCIPLES. 



73. In a general way, both phosphoric acid and 

 potash influence the quality and fineness of the fruit, 

 while nitrogen produces the vegetable tissue, such as 

 the skin and pulp of fruit, and leaves and bark of 

 trees. The juice and seed and smoothness and the 

 number of the fruits, and earliness, can be increased 

 by phosphoric acid and potash . The size and coarse- 

 ness and large growth and late maturity can be 

 secured by the excessive use of nitrogen. These effects 

 are noticeable only when there is an excess of one 

 element and a deficiency of the others. 



AVOIDING PURCHASES OF UNNECESSARY FERTILIZERS. 



74. Knowing the specific effect of the three essen- 

 tial plant foods, as just stated, and by observing the 

 condition of an orchard, a grower may frequently 

 avoid the purchase of unnecessary plant food. 



Bottom lands are usually rich in nitrogen. Sandy 

 soils are apt to lack potash. Clay soils usually con- 

 tain much potash, etc. Coarse, thick-rind fruit, with 

 deep green color of leaves and a too vigorous growth 

 may indicate that nitrogen could profitably be 

 omitted one season, or used very lightly. An over 

 abundance of smooth fruit on yellow trees of slow 

 growth may indicate an excess of phosphoric acid 

 for the nitrogen present, or a lack of nitrogen. Iron 

 is as essential as nitrogen to green leaves and stems, 

 so yellow foliage may, in rare cases, be caused by the 

 absence of iron as well as nitrogen. The amount of 

 iron necessary for green foliage is so small, that lack 



