Nitrogen and Gypsum. 159 
open piles, leached by rains, are hardly worth handling. Coal 
ashes are almost devoid of fertilizing properties, though, if finely 
divided, as in the case of coals burning completely, their use is 
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 vegetable activity of the 
plant and is a wonderful stimulant of wood growth and foliage. 
Supplies of this substance can be had from animal manures 
as far as available, but the most convenient, and at present cer- 
tainly the cheapest and most available, source of nitrogen at 
command of the farmer is Chile saltpeter, which contains about 
sixteen per cent of nitrogen, in its most effective form. From 
one hundred and fifty to two hundred pounds per acre is the 
usual dose. Sulphate of ammonia is the other most available 
source of nitrogen obtainable in commerce; a good commercial 
article contains twenty per cent and over of nitrogen. It does 
not, however, act quite as rapidiy as the Chile saltpeter. A sug- 
gestion 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 mentioned 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 matter, 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 ever been offered on the market. It is insoluble and inert 
carbonate of lime, and is not worth the cost of hauling any dis- 
tance. It cannot take the place of burned limestone. 
