No. 1, February, 1921] ' SOIL SCIENCE 71 



grass; (2) 12 per cent, and grows wheat and barley; (3) 14 per cent, growing barley, (4) and (5) 

 17 per cent; (6) 31 per cent, and (7) 13 per cent. The lighter soils grow principally rye and 

 oats. The value of such a map is discussed. — W. N. Sparhawk. 



462. Parker, F. W., and E. Truog. The relation between the calcium and the nitrogen 

 content of plants and the function of calcium. Soil Sci. 10: 49-56. Fig. 1. 1920. — See Bot. 

 Absts. 7, Entry 406. 



463. Roberts, George, and A. E. Ewan. I. Report on soil experiment fields. II. 

 Maintenance of fertility. Kentucky Agric. Exp. Sta. Bull. 228:89-131. 1920.— Results are 

 reported from eight experiments fields on as many different soil areas of the state, ranging 

 over periods of four to nine years. The requirements for phosphorus, potassium, nitrogen, 

 and limestone were determined, and a comparison was made of acid phosphate and rock 

 phosphate on limed and unlimed soil. The rotation employed in most cases is corn, soy 

 beans, wheat, and clover. None of the treatments give any material increase in crops on 

 the Lexington field, representing the highly phosphatic soils of the Central Blue Grass region. 

 On all the soils represented by the other fields, limestone and phosphates give very large 

 increases. The returns from potassium salts in connection with phosphates or in connection 

 with phosphates and limestone give little or no increase in yields. Nitrate of soda gives prac- 

 tically no increase for corn, but gives small or medium increases for wheat and tobacco. In 

 the comparison of acid phosphate and rock phosphate at the average annual rate of 200 

 pounds per acre of 16 per cent acid phosphate and 400 pounds per acre of 32 per cent rock 

 phosphate, the rock phosphate has generally given the larger increases on unlimed ground, 

 while the acid phosphate has generally given the larger increases on limed ground. — George 

 Roberts. 



464. Robinson, C. S. The determination of carbon dioxide in water-soluble carbonates. 

 Soil Sci. 10: 41-47. Fig. 1. 19'20. — A description is given of precautions used and modifi- 

 cations in the apparatus made in determining the carbon dioxide content of limestones, marls, 

 and soils by Van Slyke's titrometric and gasometric methods. — W. J. Bobbins. 



465. Schollenberger, C. H. Organic phosphorus content of Ohio soils. Soil Sci. 10: 

 127-141. Fig. 1. 1920. — The relation of the organic phosphorus content of twelve soils in 

 relation to other soil constituents is reported. Virgin soil samples are richer in total phos- 

 phorus than cultivated soils of the same type, and the organic phosphorus contents stand in 

 the same order as the contents of total phosphorus. From average data one-third of the 

 phosphorus in the surface and one-fifth in the subsurface is organic. Organic phosphorus is 

 probably not of a high order of availability. — W. J. Bobbins. 



466. Thornber, H. Cover crops, tillage and commercial fertilizers. Better Fruit 15^: 5, 

 20-22. Aug., 1920. 



467. Thorne, Charles E. Carriers of nitrogen in fertilizers. Soil Sci. 9: 487-494. 1920. 

 — Field experiments since 1894-5 with cereals and clover or potatoes and clover rotations 

 fertilized w'ith sodium nitrate," linseed meal, dried blood, ammonium sulfate, and tankage 

 show in 40 comparisons with but 2 exceptions that sodium nitrate has produced the largest 

 yield. The same is true of a tobacco-wheat-clover rotation except on limed land, where the 

 yields from the ammonium sulphate slightly exceed those from sodium nitrate — W. J. 

 Bobbins. 



MOISTURE RELATIONS 



468. Cunningham, Brysson. Rainfall and drainage. [Rev. of: Craster, J. E. E. Esti- 

 mating river flow from rainfall records (Engineering. Jan. 2, 1920). Nature 105: 42. 1920.] — 

 Craster finds the proportion of run-off to rainfall varies in both England and America from 

 33 to 67 per cent. That not less than 1 mm. (0.04 inch) of rainfall is required to wet vegeta- 

 tion and surface of ploughed land; this being lost by evaporation after every rain. Percola- 

 tion may be estimated roughly at not less than 10 per cent. Mentions also data on 

 transpiration. — 0. A. Stevens. 



