6 BULLETIN 1418, U. S. DEPARTMENT OF AGRICULTURE 
TaBLe 2.—Alfalfa yields from various fertilizer treatments at the United States 
Yuma Field Station, Bard, Calif., in 1923 and 1924—Continued 
SUMMARY OF INCREASE OR DECREASE IN YIELDS OF ALFALFA FROM FERTILIZED, AS COMPARED 
WITH UNFERTILIZED PLOTS 
[Acid phosphate figured at $38 per ton for 16 per cent, $70 per ton for 44 per cent, manure at $1 per ton, 
and sulphur at 5 cents per pound] 
Increase per acre (tons) Approxi- 
mate cost 
Fertilizer treatment and rate per acre of ferti- 
lizer per 
1923 1924 Total ae 
16 per cent acid phosphate (250 pounds) _---___.-____-_-_-_-____ 0. 800 2. 390 3. 196 $4. 75 
16 per cent acid phosphate (250 pounds in the spring and 250 
pounds inthe fall)? -— os ee ee ee . 732 3. 520 4, 252 9. 50 
16 per cent acid phosphate (500 pounds) -------------------____- 1. 304 2. 450 3. 754 9. 50 
44 per cent acid phosphate (182 pounds) ----------------------_- 1. 050 3. 100 4.150 6. 37 
16 per cent acid phosphate (750 pounds) ---__------------------- 1. 672 4. 980 6. 652 14, 25 
Manure (12 tons) plus 16 per cent acid phosphate (250 pounds) _- 1. 372 4. 550 5. 922 16. 75 
Manure ((12'‘tons) 2252 2: = S8s. see ee eee - 420 2. 740 3. 150 12. 00 
‘Lexas culf:sulphur (200-pounds)_.- === eee —. 060 . 390 . 330 10. 00 
Torosulphur:(200) pounds) 222 ee eee —. 320 . 426 . 106 10. 00 
Toro sulphur (200 pounds) plus 16 per cent acid phosphate (250 : 
pounds) 2s he oe ie 8 ee Se ee et ee ee ae 1. 240 1. 378 2. 618 14. 75 
It is apparent that the effects of the manure are somewhat more 
lasting than those of acid phosphate, and while sufficient to justify 
its use where available on the farm, especially as it does not cost the 
farmer anything other than getting it on the land, the returns will 
not warrant much cash outlay for the manure. 
Fic. 1—Comparative yields of alfalfa in the Yuma Valley on plots treated with acid phosphate 
(1 and 3) and on untreated plots (2 and 4) 
In line with previous tests, wherever sulphur was appued there 
was a slight decrease in yield, as compared with the checks the first 
year and a slight increase the second year. These differences, how- 
ever, are not great enough to be significant. Sulphur combined 
with acid phosphate gave an appreciable increase, though considerably 
less than where the same quantity of acid phosphate was applied 
alone. 
The cost of 16 per cent acid phosphate is about $38 per ton, that 
of the 44 per cent acid phosphate $70 per ton f. 0. b. Yuma, and that 
of sulphur is 5 cents per pound. No attempt has been made to 
assign any value to the manure other than the cost of hauling and 
