MICHIGAN ACADEMY OF SCIENCE. 
37 
Two soils are here offered by way of illustrating the reasons or some 
of the reasons at least for the foregoing conclusions . 
These two soils were taken from adjacent fields. In appearance they 
are very similar — practically identical. They did not appear so 18 
years ago: That year the soil numbered 1 produced 42 bushels of wheat 
per acre, last year it produced 18 bushels per acre. Eighteen years 
ago the soil numbered 2 produced 12 bushels of wheat per acre, last 
year it produced 36 bushels per acre. Eighteen years ago the soil 
numbered 2 was called a “blow” sand. At the present time it does not 
blow. Its moisture condition does not permit it. When the present 
owner purchased this land 19 years ago he was laughed at for his 
alleged folly. He had faith in the soil however, and in his ability to 
make it a profitable soil and his faith has been abundantly rewarded. 
The transformation has been brought about without the use of 
mineral fertilizers. The owner has read, observed and thought. 
He has practiced care in the selection and use of tools. 
He has followed a fairly careful rotation of crops — one in which clover 
formed an important part. 
He has grown one “money crop” each year — wheat, or potatoes or 
beans. 
He has built up a dairy herd in addition to keeping other live stock, 
and has exercised fair care -in husbanding and applying the manures 
produced on the farm. 
In other words he has followed a fairly rational system of soil man- 
agement (practice). 
The farm from which the soil numbered 1 was taken has been rented 
during the greater part of the period. Further comment is hardly nec- 
essary. 
Two important facts are before us. First: The larger part of Mich- 
igan soils are producing abnormally low yields and in not a few cases 
negatively profitable yields. Second : In a goodly number of cases 
soils producing very low and even unprofitable yields have been trans- 
formed into highly productive soils, and that without the addition of 
mineral fertilizers. In general the transformation has been accom- 
plished by means similar to those applied to the soil numbered 2 above. 
We ask then what are the causes of this lowering of yields? 
Are they chemical, physical or biological, and whatever the direct 
cause, may it be due indirectly, the soil physicist will ask, to the failure 
of the soil to function normally physically and if so how great is the de- 
parture from normal ? • 
Is the departure measurable? 
If measureable, how far does the departure affect 
chemical changes, 
the abundance and activity of life forms, 
solutions, 
surface tension, 
osmosis, 
transpiration, and 
deposits and retention of the by-products of plants 
and how far do any of these become causes as well as effects? 
