187
|
|
|
Quantity of nitrates formed in the soils of fallow fields
|
188
|
|
|
Position of nitrates depends on season
|
188
|
|
|
Nitrates in drainage-waters
|
188
|
|
|
Amount produced at different times of year
|
189
|
|
|
Nitrification of manures
|
190
|
|
|
Ammonia salts most easily nitrifiable
|
191
|
|
|
Sulphate of ammonia the most easily nitrifiable manure
|
191
|
|
|
Rate of nitrification of other manures
|
192
|
|
|
Soils best suited for nitrification
|
192
|
|
|
Absence of nitrification in forest-soils
|
193
|
|
|
Important bearing of nitrification on agricultural practice
|
193
|
|
|
Desirable to have soil covered with vegetation
|
194
|
|
|
Permanent pasture most economical condition of soil
|
194
|
|
|
Nitrification and rotation of crops
|
195
|
|
|
|
APPENDIX TO CHAPTER IV.
|
|
NOTE
|
|
I.
|
Old theories of nitrification
|
196
|
|
II.
|
Nitrification takes place in solutions devoid of organic matter
|
196
|
|
III.
|
Oxidising power of micro-organisms in soils
|
197
|
|
IV.
|
Effect of urine on nitrification in soils
|
197
|
|
V.
|
Solution used by Professor Frankland in cultivating nitrificative micro-organisms
|
198
|
|
VI.
|
Experiments by Boussingault on rate of nitrification
|
198
|
|
VII.
|
Nitrogen as nitrates in Rothamsted soils after bare fallow in lb. per acre
|
198
|
|
|
|
CHAPTER V.—POSITION OF PHOSPHORIC ACID IN AGRICULTURE.
|
|
Occurrence of phosphoric acid in nature
|
199
|
|
Mineral sources of phosphoric acid
|
200
|
|
Apatite and phosphorite
|
200
|
|
Coprolites
|
201
|
|
Occurrence of phosphoric acid in guanos
|
202
|
|
Universal occurrence in common rocks
|
202
|
|
Occurrence in the soil
|
203
|
|
Condition in which phosphoric acid occurs in the soil
|
203
|
|
Occurrence in plants
|
204
|
|
Occurrence in animals
|
205
|
|
Sources of loss of phosphoric acid in agriculture
|
205
|
|
Loss of phosphoric acid by drainage
|
206
|
|
Artificial sources of loss of phosphoric acid
|
206
|
|
Amount of phosphoric acid removed in milk
|
207
|
|
Loss of phosphoric acid in treatment of farmyard manure
|
208
|
|
Loss of phosphoric acid in sewage
|
208
|
|
Sources of artificial gain of phosphoric acid
|
208
|
|
|
|
APPENDIX TO CHAPTER V.
|
|
NOTE
|
|
I.
|
Composition of apatite (Voelcker)
|
210
|
|
II.
|
Percentage of phosphoric acid in the commoner rocks
|
211
|
|
|
|
CHAPTER VI.—POSITION OF POTASH IN AGRICULTURE.
|
|
Potash of less importance than phosphoric acid
|
212
|
|
Occurrence of potash
|
213
|
|
Felspar and other potash minerals
|
213
|
|
Stassfurt salts
|
214
|
|
Occurrence of saltpetre
|
215
|
|
Occurrence of potash in the soil
|
215
|
