Soils: Their Properties, Improvement, Management, and the Problems of Crop Growing and Crop Feeding

abundance acid phosphate acre alfalfa ammonia animals applied available plant food bacteria barnyard better bushels carbon cent clay clover compounds condition contains corn cotton cow peas crop rotation cultivated crop culture dairying decay deep disk drainage earth effect elements fact farm farmer favor feeding fertilizer fertilizing materials field follows forms given grass ground grow growth harrow hence humus inches increase inoculation kainit kind labor land legume leguminous lime live stock loss materials mellow mineral mixed moisture mulch nature nitrate of soda nitrates nitrification nitrifying bacteria nitrogen nitrogen fixation organic matter oxygen phosphoric acid phosphorus plant food plant roots plow poor potash pounds production quantity rain reason rock sand secured seed silt soluble sort spreader stable manure subsoil substances sulphate supply surface theory things tile drain tillage tion tons tubercle vegetable weeds wheat yield