SOILS FERTILIZEKS. 719 



Large applications of water-solulilt' fertilizer salts as well as harmful sj'.lts 

 retard plant growth. 



A definite relation betwe«Mi physical properties of soils and plant growth has 

 not yet been worked out in these exiierinients. The soils have not been suffi- 

 ciently long under uniform treatment for this purpose. 



The effect of nitrate of soda on the properties of soils, Kkl'gek (Bl. 

 Zuckcrriihcnbau, /-J (1907), Ao. 17, pp. 265-270). — The injurious effect of nitrate 

 of soda and other sodium salts on the physical properties of soils is attributed 

 to the formation of sodium carbonate in the soil. It is recommended that as 

 far as possible such salts be used only on crops which do not split up the salts, 

 leaving the sodium residue in the soil, but take up both the sodium and the acid 

 radicle. The crops which do this most completely include most of the cereals 

 and beets. On the other hand mustard, potatoes, and oats split up the sodium 

 compounds and leave the larger part of the soda in the soil. 



The utilization of raw phosphate in connection with green manuring, 

 S. DE Gbazia (Staz. Spei: Ayr. Itul.. ',0 (1907), Xo. 1, pp. 5-'i-66; abs. in Chcm. 

 Zentb!., 1907. II, A'o. 12, p. 1011). — Experiments are reported from which the 

 conclusion is drawn that green manuring with leguminous and cruciferous 

 plants increases the availability of the ithosphoric acid of the soil and of insol- 

 uble phosphates applied to the soil, the strongly acid root juices rendering the 

 phosphates soluiile. The literature of this subject is reviewed. 



The phosphoric acid requirements of red clover in relation to the assimi- 

 lation of this substance, and clover sickness of soils, K. K. Gedeoiz (Zhur. 

 Opiiitn. Agron. [Russ. Jour. Expt. Landic], S (1907), Xo. 1, pp. 39-6.5; ahs. in 

 Centbl. Bakt. [etc.], 2. Abt., 19 (1907), No. 10-12, p. 3.'/3).— The experiments 

 reported by the author show that both clover and flax in their earliest periods 

 of development require large amounts of soluble phosphoric acid. Oats and 

 to a greater extent mustard showed smaller refpiirements for soluble phosphoric 

 acid in the soil, although their content of phosphoric acid was greater than that 

 of clover and flax. The conclusion is reached that clover sickness is probably 

 due more frequently to a deficiency of soluble j^hosphoric acid in the soil than 

 to a lack of potash, which is usually assigned as the cause of this condition, 

 although the author does not deny that a deficiency of potash may sometimes 

 be the cause of clover sickness. 



Studies on humus formation, III, S. Suzuki (Bui. Col. Agr., Tokyo Imp. 

 Univ., 7 (1907). \ o. ',. pp. 513-529). — This is an account of a continuation of 

 studies on this subject (E. S. R., 19, p. 419), the results of the series of studies 

 being summarized as follows : 



" These inve.stigations show that the nitrogen in the humus is not present as 

 amino compounds, but chiefly as a kind of protein which may be connected more 

 or less intimately with the black substances. In n)y former communication the 

 observation was mentioned that not only starch but also proteins are blackened 

 by the humification process. This, however, does not exclude that some of 

 the protein is derived from soil bacteria, while another part from the decaying 

 roots. It seems that during the humification process certain atomic groups in 

 the protein molecule are considerably changed or also oxidized away and this 

 becomes thus less suited as food for bacteria and mold fungi. 



"According to this result, the writer is inclined to believe that Udransky's 

 artificial nitrogenous humic acid ° would naturally differ from that of the 

 natural one, because the protein-like substance or several kinds of amino acids 

 would not be formed when a mixture of glucose and urea is treated with boiU 

 ing hydrochloric acid. 



<»Ztschr. Physiol. Chem., 12 (18SS), p. 42. 



