Food for Plants. . 23 



fully iinderstaiid that in all cases where Nitrate has been 

 recommended in large amounts, potash and phosphates 

 should be used also unless the soil already contains 

 amjile supplies of both. 



The most important material used to supply Nitrogen, 

 in the composition of commercial fertilizers is Nitrate of 

 Soda. Nitrate of Soda is particularly adapted for top- 

 dressing during the growing season, and is the quickest 

 acting of all the nitrogenous fertilizers. 



Dried blood, tankage, azotine, fish scrap, castor pom- 

 ace, and cotton-seed meal represent fertilizers where the 

 Nitrogen is only slowly available, and they must be 

 appled in the fall so as to be decomposed and available 

 for the following season. Nitrogen in the form of Ni- 

 trate of Soda is available during the growing and fruit- 

 ing season, possessing, therefore, a decided advantage 

 over all other Nitrogen plant foods. 



Chemical Composition of Soils. 



Sandy soils may be described as soils containing 

 seventy-six (76) per cent, or more of sand. 



Sandy loam is a soil containing seventy-five (75) per 

 cent, less of sand, and a loam is said to be a soil contain- 

 ing forty (40) to fifty-nine (59) per cent, of sand. 



Clay loam runs between twenty-nine (29) to thirty- 

 nine (39) per cent, of sand, and a clay soil would be 

 described as a soil containing about sixty-one (61) per 

 cent, or more of clay, 



A very rich soil may be described as a soil containing 

 2 per cent, of lime and 18.80 per cent, of potash and from 

 .02 to .10 per cent, of sulphuric acid, in the form of sul- 

 phate, and from .10 to .30 per cent, of phosphoric acid, 

 in the form of phosphates, with humus running from 

 1.20 per cent, to 2.20 per cent, and Nitrogen fi'om .20 to 1 

 per cent. 



According to French authorities a good soil would 

 contain .20 per cent, of Nitrogen and .20 per cent, of phos- 

 phoric acid, in the form of phosphates, and .30 per cent, 

 of potash. 



