No. 6. 



DEPARTMENT OF AGRICULTURE. 



381 



TABLE VI. FERTILIZER ELEMENTS ON YIELD, COLOR, SIZE AND 



GROWTH 



(Calculated Percents of Benefit,) 



Experiments 215, 216 and 220. 



Yield. 



1906-11. 



1911. 



Nitrates in combination, .. 



Nitrates alone, 



Phosphates in combination 



Phosphates alone, 



"Floats" alone^ 



Potash in combination, _-. 



Complete fertilizer, 



Manure, 



Lime alone, 



PerCt. 



41.7 



30.0 



15.4 



—7.4 



—18.8 



15.2 



68.8 



101.— 



—12.0 



PerCt. 

 18.05 

 39.10 

 9.35 

 —7.37 

 6.4 

 12.80 

 65.7 

 221.90 

 15.1— 



Color. 



190&-11. 



Per Ct. 



—12.35 



—16.00 



—1.56 



2.80 



7.70 



6.55 



—16.00 



—9.90 



.8 



Size. 



1908-11. 1907-11 



Per Ct. \ 



-1.67 



. —6.23 



.925 



—1.21 



—1.92 



5.67 



4.30 1 



4.73 



—1.05 



Growth. 



PerCt. 



14.83 



18.33 



.62 



.52 



—6.00 



2.71 



19.10 



24.70 



3.1 



In general, these tables corroborate and extend the deductions 

 obtained from those already considered. The addition of the results 

 from the other experiments have reduced the apparent benefits 

 somewhat and the relative values of certain materials are also slight- 

 ly changed. We have included the results of the first year in the 

 yields of Table V, which also reduces the apparent benefits, since 

 the fertilizers had not yet had time to operate. Even at that, how- 

 ever, we see that the yields during the 4-year period have been 

 nearly doubled by the addition of nitrates, in experiments 33G, 338 

 and .339 and with the same material they have been increased by 

 41 per cent, in the younger experiments of Table VI. 



Phosphates, when used in combination with nitrogen or in a com 

 plete fertilizer, maintain their position as the next limiter after 

 nitrogen, though they are closely pressed by potash in Table VT. On 

 the other hand, neither acid phosphates nor "floats" nor lime, when 

 used alone, have shown any consistent benefits on yield thus far. 

 Their apparently negative influences on yield may be smoothed out 

 in time, as indicated by some of the results of the past year. There 

 is some evidence, however, that certain of these negatives really in- 

 dicate a toxic action that is manifested only under certain condi- 

 tions, but we have not yet carried this far enough for definite state 

 ments. 



The important advantage shown by manure, especially in Table 

 VI, is doubtless largely due to the very full crops on the manure 

 j>lots of those experiments during the past year, which was rather 

 of an off year for the similar plots receiving complete fertilizer. 

 The better moisture conservation under the manure and the larger 

 amounts of plant food carried in it also probably account for a part 

 of the superiority. In general, however, we do not find any im- 

 portant superiority in manure over a proper commercial fertilizer, 

 reifher in actual nor net increases. Manure is undoubtedly a -lafe 

 and valuable material to apply in orchards, when it can l)e satis- 

 factorily obtained in sufficient amounts. But with very few ex- 

 ceptions, thus far in our experiments as a whole, wherever manure 

 has given important increases, these increases have been approached 

 or surpassed by a proper commercial fertilizer. 



