440 Bulletin 267. 



which resulted from a combination of nitrogen and phosphorus applied 

 in two different quantities, or a combination of phosphorus and potas- 

 sium in the larger quantities. It also appears that the greater net gain 

 resulting from the heavy application of a complete fertilizer, over the 

 application of half the same amount, is not large enough to cover the 

 added cost of application and of harvesting the increase in yield. 

 Other combinations of the three ingredients used in the complete fer- 

 tilizer did not produce so good results as those shown in Table XL 



If the apparent increase in yield per acre (Table XI) for both years 

 of the experiment be contrasted, four of the plats present contradic- 

 tions, while the rest show a fair degree of agreement. Where nitrate 

 of soda alone was applied at the rate of 120 pounds per acre, the increase 

 was much greater in igo8 than during the previous season. The reverse 

 is true of the plat where 240 pounds of nitrate of soda was applied. 

 It must be borne in mind that the two seasons were quite different as 

 regards moisture and temperature during the most critical period of 

 growth. Apparently 120 pounds per acre of nitrate of soda was the 

 more efficient when combined with abundant rains during July and 

 August, while 240 pounds per acre of the same fertilizer produced a 

 much greater net loss under the same conditions. The apparent increase 

 from the plat to which 120 pounds nitrate of soda and 80 pounds muriate 

 of potash were applied, coincides with that from the plat where 120 

 pounds of the nitrate were applied alone. Where 240 pounds acid 

 phosphate and 80 pounds muriate of potash were applied, the resulting 

 increase in yield was less in the favorable season than in the previous 

 unfavorable one. 



It will be noticed that four of the fourteen plats showed a net loss 

 from the use of fertilizers in 1907, while but one net loss appears in the 

 1908 column. 



The best average net gain from a single fertilizer ingredient was 

 obtained by applying 120 pounds per acre of nitrate of soda. The best 

 average net gain from a combined fertilizer was obtained from the 

 application of 240 pounds of nitrate of soda and 480 pounds of acid 

 phosphate per acre. An application of just half these amounts gave 

 an average net gain per acre which might fairly be considered more 

 profitable if the extra cost of applying fertilizers and harvesting a larger 

 crop are to be considered. 



On every one of the fourteen plats recorded in Table XI, the per 

 cent of total weight in tops is higher for the first year than for the year 

 following. 



The effectiveness of applying a fertilizer containing one ingredient 



