360 
experience and is based largely upon the results of field fertilizer tests. 
However, a chemical analysis of a soil is often of great benefit in studying 
problems of soil fertility. 
It is generally recognized that the removal of plant food by crops is 
not the only factor which may change the composition of a cultivated soil. 
The agencies of wind and water play a very great part in effecting changes. 
Insects, worms and animals often work through the soil and subsoil, caus- 
ing variations and intermixtures. ‘The crops themselves bring up from 
below quite a little plant food and deposit it near the surface in the decay- 
ing roots and stubble. In spite of the fact that the tendency of nature is 
to build up and replenish the fertiliy of soil, there is no question but that 
the destructive system of cultivation that has been followed by the farm- 
ers of this country has more than counter-balanced hature’s tendency to 
upbuild, and as a consequence the soil has become more or less depleted. 
It is believed that the analyses presented in this paper show what chemical 
changes have been effected in the average soil of Indiana by cropping it 
for from sixty to eighty years. 
TABLE I. 
Analisis of Composite (81) Virgin and Cropped Soils. 
Virgin Virgin | Cropped | Cropped 
MATERIAL. Soil. | Subsoil. | Soil. | Subsoil. 
Insoluble silica, ete............. separ oy de 88.49% 87.30% 89.59% | 86.37% 
Potash (K2O) (Acid soluble) .26 36 23 34 
Soda (Na2QO) (Acid soluble)... . is : : .20 .20 sali 21 
Lime (CaO) (Acid soluble)... .. eae as 43 34 43 51 
Magnesia (MgO) (Acid soluble). . ; bak .41 60 40 60 
Manganese oxid (Mn304) (Acid soluble)................... 14 08 07 09 
Ferric oxid (Fe.O3) (Acid soluble). Alumina (AloO;) 
(Acid soluble)......... vive reac se Se ; 5.03 8.01 5.31 | 8.60 
Phosphoric acid (P2O5) (Acid soluble)........... teh oe Az 07 ll 07 
Sulphur trioxid (SO3) (Acid soluble)............... e206 05 06 04 
VG EVUTeart RU GO rr te there oa Sate een a oe eisrari eerie re terots a 5.28 3.20 3.88 3.25 
ADONIS LAN tea nai ella NE eet eae CoN, QAR Sis ie at aera pedemeed [pel Ut Yer 7 100.21 100.22 100.08 
FROLAUMITOMGI. Artin otesc deve bap taaamb ite. eee enter ca aes 18 .07 13 06 
Total potash (K2O).......... oe OR Pee 1.83 1.88 1.94 1.92 
PT OUGIRPULEFEUE Pee ie, ect c0b cise ee eri eM eel tee otis ete 1.98 60 1.04 40 
Aeidhumusinss cde: sted: RO een e erracdooe money. 1.16 44 .84 48 
