Chief among these are the
low forms of life known as bacteria. Many of these, under favorable
conditions, appear to have the power of liberating food from the
insoluble soil grains. Others have the power when settled on the
roots of leguminous or pod-bearing plants to fix nitrogen from the
air and convert it into a form suitable for the need of plants. In
recent years it has been found that other forms of bacteria, the
best known of which is azotobacter, have the power of gathering
nitrogen from the air and combining it for the plant needs without
the presence of leguminous plants. These nitrogen-gathering bacteria
utilize for their life processes the organic matter in the soil,
such as the decaying header stubble, and at the same time enrich the
soil by the addition of combined nitrogen. Now, it so happens that
these important bacteria require a soil somewhat rich in lime, well
aerated and fairly dry and warm. These conditions are all met on the
vast majority of our dry-farm soils, under the system of culture
outlined in this volume. Hall maintains that to the activity of
these bacteria must be ascribed the large quantities of nitrogen
found in many virgin soils and probably the final explanation of the
steady nitrogen supply for dry farms is to be found in the work of
the azatobacter and related forms of low life.
Pages:
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279