SOILS FEKTILIZERS. 825 



Fertilizer experiments, C. C. Georgeson {Alaska Stas. Rpt. 1910, pp. 33, 

 3.'f, /f9, 50). — This is a brief account of fertilizer experiments on barley and oats 

 at the Rampart Station. 



" The fertilizers were sodium nitrate, superphosphate, potassium sulphate, and 

 stable manure, each plat being compared with an unfertilized plat seeded with 

 the same variety of grain and in the same manner. The result shows that when 

 the three important elements of plant food are mixed in proper proportion the 

 yield is better under normal conditions than when only one of them is used, 

 and the variations which always occur in field fertilizer experiments also occur 

 here. The important point is that the soil needs fertilization. It has been men- 

 tioned in former reports that whenever the brush and moss and dead vegetation 

 of all kinds which cover the surface have been thoroughly burned then the soil 

 usually yields a large first crop, but whenever, on the other hand, the surface 

 has not been well burned the crop is usually poor [E. S. R., 23, p. 1031. There 

 are two reasons for this; one is that the ashes which result from the burning 

 are a valuable fertilizer in that they furnish plant food immediately available, 

 and the other reason is that when the burning is not well done much of the 

 moss remains, which makes the soil acid, and the acid is a poison to the crop. 

 Now, it has been demonstrated in these experiments that even though there has 

 been a thoi*ough burning, followed by a heavy yield, the fertility which resulted 

 from the added plant food in the ashes soon becomes exhausted, and to continue 

 with good crops fertilizers must be added. 



"Alaska soils are not rich. Frequently statements from travelers and other 

 observers are seen to the effect that the soil must be exceedingly rich in plant 

 food to judge from the height of the grasses and the luxuriance of some of the 

 vegetation, but such a conclusion is not warranted. Grasses will sometimes 

 grow rank on an almost barren gravelly soil because they have plenty of mois- 

 ture and they are adapted to the climate and to the conditions. The virgin soil 

 in the interior is everywhere frozen to an unknown depth or to bedrock. In 

 this state of refrigeration there can be no activity of the organisms which aid 

 in the formation of mold and the manufacture of plant food from the organic 

 matter, and what plant food the soil may hold is in a large degree insoluble, 

 and therefore not available for plants except by a long and slow process of 

 weathering. For this reason the soil soon becomes exhausted, and fertilizers are 

 necessary. 



The law of the minimum and its applications, E. A. Mitscherlich (Landw. 

 Vers. Stat., 15 (1911), No. 3-J,, pp. 231-263; ahs. in Ztschr. Angew. Clicm., 24 

 {1911). No. 37, p. 1776; Chem. ZentU., 1911, II, No. 14, pp. 1056, 1057).— 

 Reviewing the results of pot experiments by Wagner and others, as well as of a 

 series of sand cultures carried out by the author according to the Hellriegel 

 method, the conclusion is reached that the law of the minimum is a logarithmic 

 function and can not be established by fertilizer experiments as ordinarily car- 

 ried out. The more exact sand culture method of Hellriegel is necessary for 

 this purpose. 



The use of artificial and chemical manures [on tea] {Indian Tea Assoc, 

 Sci. Dept. Quart. Jour., 1911, No. 2, pp. 5-14). — This article discusses the ferti- 

 lizing of tea with the various materials available for this purpose in Assam. 



Effect of fresh and well-rotted manure on plant growth — second report, 

 E. B. Fred {Virginia Sta. Rpts. 1909-10, pp. 142-158, pi. 1, figs. 7).— In continu- 

 ation of previous experiments (E. S. R., 21, p. 418) it was found that " denitri- 

 fication is most active when fresh manure is applied just at time of seeding. 

 Very little, if any, harmful effect from denitrification could be observed in the 

 second crop. In a clay soil the second crop seems to have been helped by the 

 addition of fresh manure. In a loam and sand mixed the fresh manure acts 



