322 EXPERIMENT STATIOISr RECORD. 



peas (as green manure), wheat, and clover carried on since 1909 to determine 

 the fertilizer needs of the typical dark brownish-gray silt loam prairie soil of a 

 region formed larj^ely from limestone and shale. Chemical analysis showed the 

 soil to be deficient in nitrogen and humus and somewhat acid in the surface 

 layers, the acidity representing a lime requirement equivalent to about 2,400 lbs. 

 of ground limestone per acre to a depth of 7 in. 



The soil treatments tested consisted of (1) cowpeas; (2) cowpeas and lime- 

 stone; (3) cowpeas, limestone, and bone meal; (4) cowpeas, limestone, bone 

 meal, and muriate of potash; (5) no treatment; (6) manure; (7) manure and 

 rock phosphate; (8) manure, rock phosphate, and limestone. The limestone 

 was used once during the rotation at the rate of 2 tons per acre, bone meal, 

 150 lbs. per acre, and muriate of potash, 50 lbs. per acre, before the corn and 

 wheat, and rock phosphate, 800 lbs. per acre, and barnyard manure, 8 tons per 

 acre, once in the rotation before corn. 



The best average yields of corn were obtained with treatments 7 and 8, the 

 highest average net return with treatment 6. The highest average yield of 

 cowpea hay and the highest net return were with treatment 7. The highest 

 average yield of clover and the highest net return were with treatment 7. The 

 highest yield of wheat and the highest average profit were with treatment 4 

 followed closely by treatments 6 and 7. 



Recommendations are made regarding the handling of this soil, including 

 methods of maintaining the supply of organic matter and the use of phosphates, 

 potash, and lime. It is noted that manure has a high value on this soil and its 

 conservation and use is urged. The practice of sowing covrpeas in the corn at 

 the last cultivation was not usually profitable. It was apparently better to 

 plant in the rows. It is believed that after the content of organic matter in 

 the soil has been made more nearly normal it may be profitable to apply finely 

 ground rock phosiihate in amounts of 1,000 lbs. once in four to six years in 

 connection with manure or green manure. " For corn, where an immediate 

 return is required, it can best be secured by using about 100 lbs. per acre of a 

 mixed fertilizer relatively high in phosphorus, but containing some potash 

 and perhaps a little nitrogen," but it is pointed out that this practice will not 

 build up the soil. With the present condition of the soil a fertilizer containing 

 1 to 2 per cent ammonia, 10 per cent available phosphoric acid, and 4 to 5 per 

 cent water-soluble potash is recommended for corn at the rate of 200 lbs. per 

 acre and for wheat at the rate of 150 to 175 lbs. per acre. 



To what extent do stable manure and green manure affect yields through 

 the carbon dioxid they produce? Boknemann {Mitt. Dcut. Landw. GeseU., 28 

 (WIS), Ao. 31, pp. U3-U5; at)S. in Centhl. Bakt. [etc.], 2. A1)t., 41 {19U), 

 No. 9-10, pp. 290, 291). — In experiments with spinach on a plat of soil con- 

 stantly supplied with carbon dioxid through a buried pipe there was an increase 

 In yield of 12.2 per cent over the crop grown on untreated soil. The possibility 

 of increasing the carbon dioxid supply of soil and thus increasing the yield by 

 means of organic manures is discussed and the need of exact experiments on 

 this subject is pointed out. 



Poultry manures, their treatment and use, W. P. Brooks (Massachusetts 

 8ta. Circ. 36 (1914), pp. ^).— A revision of Circular 22 (E. S. R.. 23. p. 717). 



The oxidation of nitrogen and how cheap nitrates would revolutionize our 

 economic life, W. W. Strong (Science, n. so:. 40 (191^), No. lOJfZ, pp. S99- 

 908; Amer. Jour. Pharm., 87 (1915), No. 1, pp. 29-3^). — The nature of the chemi- 

 cal reactions involved in the oxidation of nitrogen and the inefficiency of the 

 processes used are discussed. 



