xxxn 



THE ESSENTIALS OF AGRICULTURE 



North Dakota Experiment Station, 1 59 

 Northern states, planting corn in, 150 

 Nurse crops, 196 



Oak, the, 43, 63, 281 



Oats, 38, 60, 86, no, 116, 118, 119, 

 169 ff., 196, 340, 34i, 346, 3 6 5> 3 6 7 

 393, 405, 427, 429 ; water drawn 

 from soil by, 29 ; food used by, 73 ; 

 in rotation, 86 ; oats and dry farm- 

 ing, 131 ; introduction of, 169; re- 

 gions of growth of, 169 ; cultivation 

 of, 170; harvesting, 170; used as 

 a nurse crop, 196, 208-209; smut 

 of, 293-294 



Ohio, corn in, 135, 140; wheat in, 

 1 60; sugar beets in, 237; tobacco 

 in, 244, 245, 246 



Ohio Experiment Station, 97 



Oil engines, 45 O ~454 



Oil meal, 341 



Oil of tar, 281 



Oklahoma, corn in, 149; wheat in, 

 1 60; sorghums in, 227; mules pro- 

 duced in, 338 



Olive oil, 328 



Olives, 9, 263 



Onions, 9, 38, 46, 53 



Oranges, 35, 262 ff. 



Orchard, sprayers for, 318 



Orchards, 262 ff. ; origin of the apple, 

 262-263 ; orchard regions of the 

 United States, 263-264; climate, 

 264; soils, 264-265 ; sites, 265-266; 

 air drainage, 266-267 ; bodies of 

 water, 267 ; preparing the land, 267 ; 

 varieties to plant, 267 ; planting, 

 268-269; shaping the top, 269; 

 pruning for open form, 270 ; prun- 

 ing for pyramidal form, 270-271 ; 

 making trees bear fruit, 271-272; 

 orchard cultivation, 272-274 ; when 

 to pick fruit, 274-275 



Oregon, wheat in, 161; alfalfa in, 

 210; vetch in, 220 



Oregon Agricultural College, 420 



Organic matter, 25 



Osage orange, 43 



Osmotic pressure, 27 



Overproduction, 5 



Oxygen, 25, 31, 33 



Oyster shells, 425, 427 



Paddock, W., 277 

 Palestine, wheat in, 166 



Palladius, quoted, 204 



Palms, 266 



Parasites, 287-289 



Parasitic insects, 308-309, 422-424 



Paris green, 314-315 



Parsnips, 38, 231 



Pastures, 365, 368, 404-405 ; in rota- 

 tion, 86 



Pasturing. See Grasses 



Pawpaws, 63 



Peaches, 9, 35, 44, 262 ff. ; brown rot 

 of, 289, 292 ; leaf curl of, 292 ; scab 

 of, 292 



Peanuts, 328, 404, 405 



Pears, 9, 35, 26jff.\ blight of, 288, 

 289-290 



Peas, 14-1 5, 25, 38, 62, 403, 404, 429 ; 

 water drawn from soil by, 29 



Pennsylvania, wheat in, 160; rye in, 

 172; cattle in, 385; swine in, 



39? 



Persia, alfalfa in, 210; peaches in, 

 262 



Pheasants. See Poultry 



Philippines, the, rice in, 173; sugar 

 cane in, 237 



Phosphate rock, 105 



Phosphates, 97-98 



Phosphatic fertilizers, 103-105 



Phosphorus, 25, 33, 72 ff., 92, 94, 116, 

 118-119, 184, 231, 327 



Pigeons. See Poultry 



Pigweed, water drawn from soil by, 

 29 



Pines, 63, 280-281 



Pit silos, 258 



Pitch, 281 



Plant diseases, 186-187, 287 ff. ; due 

 to parasitic plants, 287-288 ; bac- 

 teria, 288 ; fungi, 288-289 ; control 

 by pruning, 289-290 ; control by 

 crop rotations, 290-291 ; control by 

 spraying, 291-292 ; apple blotch, 

 292 ; control by seed disinfection, 

 293 ; preventive treatment of smut, 

 294-295 ; control by growth of re- 

 sistant varieties, 295-296; sanita- 

 tion and quarantine, 297 



Plant food in soil, 72 ff.; important 

 elements in, 72; available and un- 

 available, 72-73 ; amount used, 73- 

 74; amount in soils, 74; amount 

 available in a season, 75; how po- 

 tassium and phosphorus are made 

 available, 75-76; how nitrogen is 



