502 THE MONTHLY BULLETIN. 



Effect of the Use of Potash, Nitrogen and Phosphoric Acid. 



The first of the experiments to which I will call your attention has 

 been conducted for the past six years In; one of our largest lemon com- 

 panies. There are eight plats in this experiment containing approxi- 

 mately six acres each. The purpose of the test was to estimate, if 

 possible, the tendency resulting from the addition of an excess of each 

 one of the three so-called "essentials," potash, nitrogen, and phosphoric 

 acid, and also to test the value of the so-ealled "simples" versus mixed 

 commercial fertilizers. All of these plats have had a certain amount of 

 nitrogen added and part of the time all of them have had manure added. 

 The first plat has had only manure at the average annual rate of nearly 

 twenty-five tons per acre. I would call the attention especially of those 

 who are afraid of barnyard manure to this plat. With the exception 

 of one year when there was considerable frost damage, the plat has 

 produced as much fruit of as good a grade as any of the other plats. 

 Three of the eight plats have had no potash added, while other plats 

 have had from one half pound to three pounds per tree per year. There 

 is no evidence either in the quality or quantity of the fruit to show that 

 this potash has been of advantage. The addition of phosphoric acid has 

 varied from one pound to four pounds per tree per year without appre- 

 ciable difference in the crop. Two of the plats located side by side have 

 been treated exactly the same except that one derived its phosphoric 

 acid from superphosphate and the other from bone meal. This experi- 

 ment so far shows no resulting difference in the two sources. 



Other Experiments With Different Amounts of Fertilizers. 



A second experiment in an entirely different district, on a radically 

 different soil, and in this case with oranges, brings out somewhat the 

 same points. In this experiment there were ten plats, one fertilized 

 with blood alone, one with nitrate of soda alone, four with complete 

 fertilizers of different formulas, one with nitrogen derived from vetch, 

 one with nitrogen derived from a summer crop of cow peas, one with 

 superphosphate alone and one with superphosphate and potassium 

 sulphate. There were no plats to which nothing was added. Taking 

 the two plats to which no nitrogen was added as a basis, and comparing 

 the figures of the four years' yield, it appears that the average produc- 

 tion on the two plats to which nitrogen had been added by means of 

 cover crops was increased by eight per cent, while the average of the 

 six plats to which commercial nitrogen in some form had been added 

 showed an increase of sixteen per cent. Records were not kept of the 

 grade of fruit on the various plats, Init no differences were observed in 

 any case. 



The Value of Potash. 



A third experiment conducted in a grove near Pomona on a soil quite 

 different from either of these considered above, was designed simply to 

 show the value of potash. This orchard is at present about twenty 



