26 CALIFORNIA CITRUS CULTURE. 
neglected. Stable fertilizer should be used in generous proportions, 
with scarcely any limit in the ease of clay soils. Straw, especially bean 
straw, is particularly valuable. Commercial fertilizers are also to be 
recommended. While the abundance of potash in our California soils 
would seem to sustain Dr. Hilgard’s contention that we need not 
add this element to our soils, yet some of our most intelligent growers 
feel sure that they have secured much advantage in the use of this soil 
element. Dr. Hopkins maintains that limestone, ground coarsly, is 
often more needed than potash. (See The Monthly Bulletin, State 
florticultural Commission, Vol. I, No. 9, page 424.) Dr. Hilgard urges 
algo that the phosphates are likely to be the first fertilizers that will 
be called for by our California citrus orchard soils. It is never safe 
to neglect advice of one so thoroughly informed, and one who has had 
such valuable observation and experience as has had Dr. Hilgard. Dr. 
Hopkins states, as already mentioned, that many soils are more likely 
to be deficient in lime than in potash. The reason for this is, the greater 
solubility of the lime permits it to be washed from the soil. (See The 
Monthly Bulletin, State Commission of Horticulture, Vol. I, No. 9.) It 
makes no difference whether we use rock or bone phosphates, as phos- 
phates are phosphates, whatever their origin. In case either of bone or 
rock, the treated or superphosphates are more readily and quickly avail- 
able, but if the untreated are ground very fine and added to a soil rich 
im organic matter, and if the bone is steamed, they will answer well and 
in time will all be utilized, so that really nothing is lost. The potash 
and phosphates should always he placed deep in the soil. The presence 
of humus insures organic acid, which renders the phosphates available. 
The phosphate slag affords also a cheap and valuable fertilizer, when 
procurable. 
The most costly fertilizing element—nitrogen, so necessary because 
it enters into every hving cell, plant or animal—will be much in evi- 
dence in case we have followed the foregoing advice regarding the use 
of cover crops and stable or barnyard manure. Yet we may find it 
advisable to secure it in more ample quantities. Many use Chili salt- 
petre or nitrate of soda. This in the cool days of early spring brings a 
quick response from all vegetation. It is, indeed, very quickly available 
as it is very readily soluble. For this reason it is quite likely to be 
washed out of the soil and lost. The late Dr. Frank H. King, one of 
our greatest soil chemists and long time professor in the University of 
Wisconsin, urged great caution in the use of this sodium nitrate. The 
nitrie acid is very likely to let go of the soda and unite with some other 
base, and the carbonic acid of the soil will at the same time couple with 
the soda, and thus we will have formed sodium carbonate, the black 
alkali, which, as we know, is a very serious enemy of nearly all plants, 
