820 EXPEEIMENT STATION EECOED. 



for short periods only. Tliere is an intimate connection between the moisture 

 content and the numbers of bacteria, the most striking exception being in 

 winter when the germ content increases if the soil is well frozen, but decreases 

 after a thaw. 



In comparing the productive and unproductive plats, no type of bacteria found 

 frequently in one soil was lacking in the other, and during the winter the total 

 numbers of bacteria were higher in the more compact and less productive soil. 

 The quantitative difference between the two soils lay wholly in the group of 

 slow-growing organisms, and rapid liquefiers were often fewer in the less 

 productive soil. 



"At the end of the experiment the relative numbers of liquefiers had de- 

 creased and those of slow growers had increased in the less productive plat; 

 while in the other plat this tendency had been almost unnoticeable." 



A classification of the organisms and a bibliography of related works are 

 appended. 



The rational improvement of Cumberland Plateau soils, C. A. Mooers 

 (Tennessee Sta. Bill. 101 (1913), pp. 99-138, figs. 6).— This bulletin, a continu- 

 ation of work previously reported (E. S. R., 26, p. 422), points out the special 

 plant food needs of the Cumberland Plateau soils which are mainly fine sandy 

 loams deficient in lime and phosphoric acid, and reports 6 years' experiments to 

 determine as far as possible, how much fertilizer to use on different crops in 

 order to get the best practical results. Acid phosphate, muriate of potash, 

 sodium nitrate, and cotton-seed meal are recommended as being the most 

 profitable sources of plant food for general use. The importance of green 

 manuring, soil Inoculation, and crop rotation is pointed out as is also the 

 relation of the potato crop to soil improvement. 



The results of crop fertilization experiments were as follows: Fertilization 

 of potatoes with 1,500 lbs. per acre of a mixture of 1, 6, and 8 parts, respec- 

 tively, of muriate of potash, acid phosphate, and cotton-seed meal was on the 

 average more profitable than 750 lbs. per acre of the same mixture. Sodium 

 nitrate was only slightly more efiicient for potatoes than cotton-seed meal. 

 Fertilization of potatoes with manure showed the necessity of reinforcing the 

 manure particularly with phosphoric acid. The best time for applying sodium 

 nitrate to corn and potatoes was found to be at an early stage of growth for 

 both crops. Acid phosphate alone in moderate quantity was as profitable for 

 corn "as any other material or combination of materials of equal money 

 value." A light manuring, supplemented by acid phosphate, is recommended 

 for com, and acid phosphate for a green manure or pasture crop which is to be 

 followed by corn. Only a very light application of potash salt was needed for 

 corn. The use of sodium nitrate was not generally profitable for corn. How- 

 ever, the results of tests of different fertilizer combinations " seems to justify 

 the use of a complete fertilizer for corn on very poor soils like these." 



On soils similar to the Plateau soils acid phosphate and sodium nitrate with 

 a small amount of muriate of potash gave profitable results with millet. The 

 general requirements for success with alfalfa, red, white, crimson, and alsike 

 clovers, Lespedeza, melilotus, cowpeas, soy beans, Canadian field peas, spring 

 oats, peanuts, small grains, grasses, buckwheat, and sorghum on these soils 

 appear to be liming and phosphating, although some require soil inoculation, 

 sodium nitrate, and manuring. 



A list of crop rotations is suggested, including 5 and 4-year rotations for 

 general farming and 3 and 4-year rotations for potato growing accompanied by 

 a table to serve as a guide during the establishment of the 5-year general 

 farming rotation. 



