Wisconsin State Agricultural Society. 119 
service to the plant in building up its structure, but it is not essen¬ 
tial that it should do so, and doubtless with much farm-yard man¬ 
ure this is but a secondary office, its indirect benefit being much 
the greater. 
Secondly. Manure improves the texture of heavy soils, rendering 
them “light” loose and porous, diminishing their tenacity and so 
accomplishing the ends that are often sought only by stirring the 
soil with implements of tillage. This is a most important function 
of manure when applied to heavy clay soils. 
By the thorough incorporation of decomposing organic matter in 
such a soil, its tenacity is destroyed, it is no longer hard and 
“lumpy,” yielding to the plow with the greatest difficulty, but is 
friable, and is readily stirred in tilling. 
Thirdly. Manures benefit soils by the decomposition of the or¬ 
ganic matter of which they are composed within the soil, thus 
furnishing where it is needed an abundant supply of carbonic acid 
gas, which acts as a powerful solvent upon the mineral constitu¬ 
ents, disintegrating them and setting free material needed by the 
plant in building up its structure. 
Boussingault and Leroy as quoted by Johnson in “How Crops 
Feed,” found that while the ordinary air contained but six parts of 
carbonic acid gas in ten thousand, air from the surface soil of a for¬ 
est contained 130 parts, that from the surface soil of a pasture con¬ 
tained 270 parts and that from a newly manured sandy field, during 
wet weather, contained 1413 parts of this gas. 
The solvent power of carbonic acid is shown in the natural 
waters which have become charged with it in passing through the 
soil and have in consequence taken up considerable quantities of 
mineral matter. This dissolved mineral matter is again deposited 
when the carbonic acid is slowly driven off by heat, as is shown in 
the coating in a tea kettle, or when it escapes spontaneously, when 
exposed to the air, by which method, beds of bog-iron ore are 
formed, and large deposits of carbonate of lime are made. Then, 
with such a great increase of this solvent of minerals, as is shown 
by the above figures, we should expect the disintegration of soils to 
be rapidly hastened by the decomposition of manure in their midst. 
This, then, is a very important function performed by manure, 
and so far as it alone applies, shows the increased benefit to be 
gained by adding the manure to the land in a green state, allowing 
