CALIFORNIA FRUITS: HOW TO GROW TIIIOM 



beneficial, mechanically, on clay soils, in the same way that fine 

 sand would be. 



The chief supplies of potash salts are now brought from Ger- 

 many and are in the hands of local dealers, but there are exten- 

 sive deposits in Utah, New Mexico, and elsewhere in the interior, 

 which can be employed when railroads make them available. 



NITROGEN 



Nitrogen ministers directly to the vegetative activity of the 

 plant and is a wonderful stimulant of wood growth and foliage. 

 Supplies of this substance can be had from animal manures, which 

 will be considered later. The effect of stable manure upon the 

 soil and the plant is notably strengthening and restorative. For 

 this reason money and effort are often well expended in securing 

 it even beyond the cost of the equivalent of the plant food which 

 it contains. Another natural form of nitrogen in cover crops or 

 green manures will be discussed presently. Of commercial forms 

 of nitrogen, tankage and dried blood are highly esteemed for 

 orchard use, and there is large use also of Chile saltpeter, which 

 contains about sixteen per cent of nitrogen, in immediately avail- 

 able form. From one hundred and fifty to two hundred pounds 

 per acre is the usual application. Sulphate of ammonia is another 

 available source of nitrogen obtainable in commerce ; a good com- 

 mercial article contains twenty per cent and over of nitrogen. It 

 does not, however, act quite as rapidly as the Chile saltpeter. A 

 suggestion of caution in the use of nitrogenous manures will be 

 given presently. 



LIME, GYPSUM AND MARL 



Lime is another substance usually abundant in California soils, 

 but still often desirable as an application. This is, notably, the 

 case on our heavy clays or adobes, where, as has already been men- 

 tioned in another connection, the use of lime as a top dressing, 

 at the rate of six hundred to one thousand pounds to the acre, 

 not only makes the heavy soil more friable, but acts upon and 

 makes available the large amount of organic matter which such 

 soils usually contain. Lime also renders inorganic materials more 

 available for plant food, corrects acidity, and may destroy insects 

 and fungi. Application of lime is also desirable after applications 

 of barn-yard manure have been made for several years; and it is 

 especially valuable wherever, in alluvial soils rich in vegetable mat- 

 ter, there is an excessive growth of wood and leaf. Usually light 

 soils are not materially benefited by the use of lime. 



Ground limestone is sometimes proposed as a fertilizer, and 

 has even been offered on the market, It is insoluble and inert 



