394. ReEpoRT OF THE CHEMIST OF THE 
organisms in soils. These effects may be grouped under three 
general divisions: (1) Promotion of the decomposition of or- 
ganic matter, including the process of nitrification; (2) making 
conditions favorable for the nitrogen-gathering organisms asso- 
ciated with leguminous plants; and (3) favoring the growth 
of those soil organisms that utilize atmospheric nitrogen inde- 
pendently of other plants. 
The presence of lime compounds, especially quicklime and 
slaked lime, hasten the conversion of organic matter into 
humus, with the changing of the nitrogen into nitrates. Or- 
ganic matter in decomposing produces acids quite freely, which 
may render a soil acid when they are allowed to accumulate 
without being neutralized. In the presence of the neutralizing 
forms of lime, these acids are converted into neutral lime com- 
pounds and soil acidity prevented. Nitrifying and nitrogen- 
gathering organisms do not grow satisfactorily in acid soils 
but appear to require for their best development a neutral or 
slightly alkaline condition. When applied in excessive quan- 
tities, quicklime and caustic lime hasten the decomposition 
of organic matter by direct chemical action. By applying these 
forms of lime too frequently or in too large quantities, it is 
possible to exhaust the supply of humus rapidly, unless un- 
usual methods of supplying humus are utilized. 
PHYSICAL EFFECTS. 
Chemical changes produced in soils by lime compounds result 
in producing physical changes. In general, it may be said that 
lime compounds lighten heavy soils and compact light soils. 
Clay soils are made less sticky, more crumbly, and more easily 
cultivated; water passes through them more readily and, in 
general, such a soil becomes a more congenial place for the 
erowth of plant roots. On sandy soils, lime compounds tend 
to act like cement in holding the soil particles together, thus 
enabling them to hold water more tenaciously. 
