8 BULLETIN 1418, U. 8. DEPARTMENT OF AGRICULTURE 
EFFECT ON SEED YIELDS 
Not much work has been done to determine the effect of acid 
phosphate on seed production, but preliminary tests indicate that 
its use in this connection will prove nearly as beneficial as it has on 
the hay crop. In 1925 a crop of seed was taken from the plots that 
were harvested for hay in 1923 and 1924. As the plots had passed 
through two whole seasons and part of another, they were beginning 
to decline, and the effects on seed yields of the various fertilizers ap- 
plied in 1923 had undoubtedly diminished. Furthermore, the seed 
yields in this test were materially reduced by considerable shattering 
as a result of three wind-driven rains that occurred between cutting 
and threshing. The results, however, are presented in Table 3, since 
they are believed to be indicative of what may be expected. 
TABLE 3.—Alfalfa seed yields from various fertilizer treatments at the United States 
Yuma Field Station, Bard, Calif., in 1925 
[Fertilizers applied in 1923] 
Seed yields (pounds) 
Fertilizer treatment and rate per acre Siwy Increase 
er 4- or de- 
acre plat Per acre crease (—) 
per acre 
16 per’cent‘acid phosphate (250 pounds) 22-22-2222. = ee 21.5 86. 0 18.0 
WO CKe Sere visser cere ES NR ei a a rn rere 17.0 68.0 ([2 2 ore 
16 per cent acid phosphate (250 pounds in the spring and 250 pounds in the 
PA) hs a PSs ES eas PE eee Ad ee ee ee ena ot eee 24.5 98. 0 42.0 
Cee kes ea Se kee Fe ei ee A Ce oe ea ee a 14.0 56.0: [esp ass 
16 per cent acid phosphate (500 pounds) -_-------------------------------- 12.5 50. 0 —14.0 
cK ay sige ye re Se So lps Dh I at eee i Bie Sen ee ee 16.0 642072325 ses 
44 per cent acid phosphate (182 pounds) ---------------------------------- 20. 0 80. 0 36. 0 
(heck sctevte. Hate Sel yt ee ee Sept til > Pee eee epee eee 11.0 44-0 |2 3 
16 per cent acid phosphate (750 pounds) -___------------------------------ 36. 2 144.8 58. 8 
Check i233 tenet A oat as eS cee ek are Ee eta eee ena 21.5 86:0{|- Sree 
Manure (12 tons) plus 16 per cent acid phosphate (250 pounds) ___-_------ ae B60 102. 0 
(SY Gh Ce aS a Se ng en RN ae Ye a ibe SOs is aa ae 
Manure; (i2:C0ns) 22052255 a oe ee Se ee ee 59. 0 236. 0 36. 0 
sheck2 Soe ee Se ee a es eee ee eee ee 50. 0 2002 0' Sarees 
Texas eulfsulphur’(200pounds)=25 = 222 =e ee ee ee ee ee 29.5 118.0 —4.0 
Checks Se ers as Se oe ee eS ce ee ee 30. 5 22:05 eee 
‘Roroystl phure(200 Wounds) = Sse a ee ee ee 22. 5 90. 0 14.0 
@hieck 22-28 ts See Fe eee PES ST Pe SEE eae Poe eee ree 19.0 76:08)2325-2 2S = 
Toro sulphur (209 pounds) plus 16 per cent acid phosphate (250 pounds) __ a 5 32. Qs see 
: . 5 2. On) Sa eee 
@hHeek 228 LPF eee eS Ea are cee a ee ote gee ee eee eee ee 
Although the seed yields as given in Table 3 are rather low in all 
cases, the beneficial results from applications of acid phosphate are 
very marked. All plots receiving acid phosphate yielded more than 
the accompanying checks, with the exception of a plot receiving an 
application of 500 pounds of acid phosphate per acre, which showed 
an actual falling off. Other factors, however, enter in to explain this 
apparent discrepancy. The highest yields were obtained from the 
plots receiving manure and acid phosphate. This is not surprising, 
since the effects of manure would naturally be expected to be apparent 
longer than the more soluble commercial fertilizers. The benefits 
from the use of acid phosphate undoubtedly would have been much 
more marked if a seed crop had been removed the first or second year 
after the fertilizers were applied. Sulphur had no effect on seed yields. 
In 1922 one demonstration plot receiving 275 pounds of 16 per cent 
acid phosphate per acre yielded at the rate of 481 pounds of seed 
per acre, whereas the check plot yielded at the rate of 181 pounds 
