MANURES AND FERTILIZERS. 59 
lizers upon it, although stable manure is some- 
times used. Deep, black prairie soils of the 
new West do not as yet need additional plant 
food, although the time is soon coming when 
they will. Again there are alluvial river 
bottoms subject to annual overflows which so 
enrich them that artificial fertilization is un- 
necessary, for such bottoms grow large, fine 
crops of corn year after year. In the Eastern, 
Middle, and Southern States, however, soils 
have become impoverished by constant crop- 
ping, and each year enough plant food should 
be returned to them to keep them highly pro- 
ductive. 
It is safe to say that the only way to deter- 
mine certainly what manure or fertilizer is 
best suited to one’s land is to experiment on it 
on a simple, practical basis. 
Stable manure is alwaysa standard material 
for enriching the land, and it is suited to the 
needs of all classes of crops and all kinds of 
soils. Its effect is more lasting than the read- 
ily soluble commercial fertilizer. Since 1883 
an experimeut has been in progress at the ex- 
periment station at Purdue University to de- 
termine how long stable manure will continue 
to affect the yield of succeeding crops. The 
plat set apart for this experiment has been pro- 
ducing corn continuously since 1879. To cer- 
tain plats in the series fresh horse manure was 
