26 CALIFORNIA CITRUS CULTURE. 



neglected. Stable fertilizer should be used in generous proportions, 

 with scarcely any limit in the case 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 

 Horticultural Commission, Vol. I, No. 9, page 424.) Dr. Hilgard urges 

 also 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 

 in 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 be 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 living 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 

 nitric 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. 



