154 CALIFORNIA FRUITS: HOW TO GROW THEM 



chaser to choose his fertilizers and to make his determination to use 

 them only after careful deliberation and with great discrimination. 

 The advice of the agricultural experiment station should always be 

 sought in such matters, since their experience has been broad 

 enough even without definite scientific basis, to constitute a more 

 reliable' guide in such matters than the experience of the individual 

 orchardist or vineyardist. 



The elements essential to plants are sold in fertilizers on what 

 is known as the "unit basis." A unit in this connotation is the 

 equivalence of one per cent of a ton. Thus, if nitrate of soda is sold, 

 with nitrogen, at a $4 a unit, it means that for every 20 pounds (or 

 1 per cent) of nitrogen which a ton contains, we pay $4. If nitrate 

 of soda contains 15 per cent of nitrogen, the fertilizer sells at 4 

 times 15 or $60 per ton. Such simple calculation will readily make 

 clear to the grower the basis upon which he purchases his fertilizers. 



DOES IT PAY TO USE FERTILIZERS? 



It should be clear from the foregoing discussion that this ques- 

 tion, which is so frequently asked, cannot be answered without much 

 reservation and qualification. From practical experience and such 

 excellent evidence as that furnished by Professor Stewart at the 

 Pennsylvania Experiment Station in working with apple orchards, 

 there can be no question that fertilization of orchard soils is profit- 

 able under some conditions. But we must also remember that under 

 somewhat similar conditions at the New York Experiment Station 

 at Geneva, Professor Hedrick was unable to obtain evidence that 

 fertilizers pay, while under the totally different conditions of Cali- 

 fornia, we could not expect either set of results to apply. Both of 

 the investigators just named are doubtless correct, each for his own 

 set of conditions, and this emphasizes the importance of the testing 

 of fertilizers in every orchard and vineyard to determine the best 

 practice for it, until such time as our scientific experiments may 

 yield us something less empirical. The only orchard experiment in 

 fertilization which we have in California which is at all usable as 

 a guide is that carried on at the Citrus Experiment Station at River- 

 side for the past ten years or more. That teaches us that nitro- 

 genous fertilizers on that piece of land make a considerable increase 

 in tree growth and fruit production, but has not demonstrated that 

 it pays to fertilize even at that. It shows us very little, if any, 

 effects from phosphatic and potassic fertilizers, and it has proved 

 the injurious effects to that soil, under those conditions, of nitrate of 

 soda. But the results obtained there, meager as they are, are not 

 even applicable to any other piece of land necessarily. This em- 

 phasizes again the point of view advanced with regard to the neces- 

 sity of fertilizer trials in every vineyard and orchard. 



Above and in addition to all, it should be borne in mind, always, 

 that fertilizers are merely supplementary measures for eking out 

 directly and indirectly the necessary supply of the essential plant 

 food elements in the soil. They constitute very little alone, but they 



