56 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 
organic matter, which would aid in rendering the less soluble phos- 
phate more effective. The conditions, therefore, were much more 
favorable to the water soluble phosphates than to raw ground rock. 
The results of the other long-time experiment published in this 
same report! cover a period of seven years. This second experi- 
ment was conducted on a larger scale than that just described and © 
had two objects in view: First, to determine the possibility of main- 
taining soil fertility by the use of commercial] fertilizers, and second, 
to determine the comparative value of raw rock phosphate and acid 
phosphate. 
A 10-acre field, the soil of which was a clay loam and excellent 
grass land, was selected for this experiment, and divided into four 3 
plots vf 24 acres each. For two years (1888 and 1889) no fertilizers A 
whatever were apphed to any of the plots, grass being grown in 
order to determine their relative natural fertility. Fertilizers were __ 
«pplied only once during the seven years of the experiment (in 3 
1890), sv the results after that year show in a measure the residual — 
effects of the various fertilizer treatments. 
The results of this experiment are given below in Table XXX. 
TABLE XXX..—Results obtained on plots of two and one-half acres each, in the 
growing of various crops (1888-1894). 
1888-89 | 18901 1891 1892 1893 1894 
Appli- |) 0) 2 24) 4) ae a, ee 
cation 
Fertilizer. per '| Barley | 6 ats. | Barle Sum- Oats, 
acre Hay.! and Total. ha ¥>| mer 
peas Y- | tilled. | matter.2 
Eee nS ————EE 
Loads. | Pounds.| Pounds.| Pounds.| Pounds.| Pownds.| Pounds. 
Stablenmsnurgs onc ones ieee scoenesans 20 2, 542 2, 208 3, 818 3, 444 | on coQenne 1, 894 
Pounds 
Ground South Carolina ruck..........- 1, 000 ry 
Ammontum sulphate... 002020] Te lf 2418] 72.) 298] 33924)... 2,453 
iPotassimm Ghlornidessccece sc emacn soar 100 ; 
ACID HOSPNALCtees masse estes aa steee 500 : 
Ammonium sulphate... 2201) Tgp 2082 | 1422] 2,972] 1,980)... 7 
Potassium Chlorides. -c-e g. eae sae - 100 
INOMMSTUTeS-seo == aS 5 Soq0éqscoKd0s66dcd|caccdoaac 2,510 1,118 2, 480 TOL: |Pacoceeee 957 
1 Fertilizer applied in 1890 only. 
: 2 Oats were cut before maturing and used for silage. 
The indications are that the plot which was afterwards treated 
with acid phosphate was naturally less fertile than the other plots 
of the experiment field. Contrary to what one would expect the raw 
rock phosphate was apparently as effective as acid phosphate during __ 
the first year of its application, yet the following year (if the ap- 
parent relative natural fertility of the two plots be taken into con- 
sideration) the acid-phosphate plot appeared to greater advantage . 
1Idem., p. 28-32. 
