622 EXPERIMENT STATION RECORD. 



nitrate formation in five typical soils " to compare nitrification in these types 

 kept in a greenhouse with a definite water content and, in the same types, 

 when kept outdoors exposed to the usual temperature and rainfaU ; to measure 

 the i"ate of nitrification in these same soils with 0.2 per cent of ammonium 

 sulphate added; to note the effect of sand and lime on the accumulation of 

 nitrates in clay soils; to study the nitrate-holding power of these soils in pro- 

 tected and unprotected series. 



"All of the soil types tested show a marked nitrate-accumulating power when 

 kept under glass. This gain is greater with certain soils than with others. The 

 percentage of the total nitrogen converted into nitrates is unusually high. 



" The rate of nitrification as measured by the conversion of ammonium sul- 

 phate into nitrate is different in the various types of soil. Here Appomattox 

 Chocolate is first, and in the descending scale, Norfolk, Blacksburg, Albemarle, 

 and Appomattox Light. 



" Sand increases the rate of nitrate formation in the two types of clay soil 

 used in this experiment. 



"Applications of lime cause an enormous increase in the rate of nitrification. 

 The total amount of nitrate formed during one year in these soils treated with 

 lime is more than is possible from the ammonium sulphate alone. 



" When nitrates are added in large quantities as sodium nitrate to protected 

 soils there is almost no loss from denitrification. provided the moisture content 

 does not exceed one-half total saturation capacity." 



The use of forest humus in agriculture, P. Eheenbebg and F. Bahb (In 

 FesUchrift, zum sicbzigsfen Geburtstage von Jacob Esscr. Berlin, WIS, pp. 137- 

 171; Jour. Landw., 61 {19 IS), No. 3, pp. 325-359).— Pine and beech leaf mold 

 was tested in fresh condition in pot experiments on sandy and loam soils with 

 and without addition of lime and other fertilizer constituents. 



The results showed that leaf mold was injurious to plants on soils poor in 

 lime unless accompanied by applications of lime. The fertilizing value of the 

 nitrogen of the raw pine leaf humus and even of the partially decomposed 

 mold was very small, being only about 14 to 16 per cent of that of manure. 

 The nitrogen of the beech leaf mold was slightly more efl5cient than that of the 

 pine leaf mold. The beneficial effect of adding lime was thought to be due to 

 improvement of the physical properties of the soil and not to its effect on the 

 assimilation of nitrogen. 



Report of the physiologist, O. Loew (Porto Rico Sta. Rpt. 1912, pp. 13-17). — 

 This deals principally with protozoan life and mineral nutrients in Porto Rican 

 soils. The infusorium most frequently found was Colpoda cvcullus. This was 

 found " not only in moderately alkaline soils but even in very acid and stiff 

 clay soils in which not a single other protozoan species could be detected." 



A marked characteristic of tropical soils as distinguished from those of more 

 northern climates is an intense red color " partly due to a higher degree of 

 chemical disintegration, whereby the ferric silicates are further split into the 

 brown ferric hydrate and silica, and the former is further changed to red ferric 

 oxid, and partly to the frequent absence of humus, which would impart a dark 

 color to the originally red soil. In some tropical countries the changes by dis- 

 integration go much farther and lead to the rather sterile laterite. The ab- 

 sence of humus forms a second characteristic of tropical soils." A third char- 

 acteristic is the increjised loss of lime caused by the rains at high temperature; 

 in consequence of which there is an excess of magnesia over lime in the soils. 

 A further characteristic is the unusually frequent acidity of soils. 



It is suggested that anemia and other physiological disturbances frequently 

 observed in Porto Rico are due in part to a deficiency of lime in the food prod- 

 ucts, especially rice, grown there. 



