l66 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



express amounts of certain substances present having an important effect on 

 crop production. Such methods are best when used for purposes of comparison, 

 and the question as to whether a soil analysis is worth conducting depends 

 largely on the possibility of comparing it with a similar soil whose capabilities 

 are known. 



In at least three distinct cases useful help can be given by the soil expert : 

 (i) Where a grower wishes to know if he has a reasonable chance of obtaining 

 results from experiments on similar soils, such as addition of lime, phosphates, 

 or potash. The expert cannot be absolutely certain, but the chances are that 

 he comes out right. (2) Where a grower wishes to adopt some system of cropping 

 or soil treatment known to give good results elsewhere in the locality. Here 

 examination may reveal some vital difference not obvious to casual inspection. 

 If the grower is made aware of the difference he can make his plans accordingly. 

 (3) Where a man wishes for complete information as to soil on a new farm or 

 estate. Here chemists, physicists, and bacteriologists could each say much 

 without exhausting the subject. In such a case the expert should be consulted 

 on the spot, and a selection made and plans discussed. An expert may be able 

 to point out marked differences in the soil from that where a proposed scheme 

 of cropping was known to be a success. 



The problem becomes very difficult when the expert gets away from com- 

 parison, and a good deal of balancing of probabilities becomes necessary — always 

 a delicate business and likely to miscarry. It is therefore better for the expert 

 not to give more than a general opinion, and to submit two or three alternative 

 schemes for consideration and trial. — G. C. G. 



Soil Constituents, Some Organic. By Edmund C. Shorey (U.S.A. Dep. Agr., 

 Bur. Soils, Bull. 88, Jan. 1913). — The question of the existence of organic 

 phosphorus compounds has now been settled, in the affirmative, by the isola- 

 tion of the nucleic acids. Fifteen new organic compounds have been isolated, 

 and a description of their properties is given. — C. P. C. 



Soil Temperature and some of the most important Factors influencing it, An 

 Investigation on. By Geo. J. Boujoucos (U.S.A. Exp. Stn., Mich., Tech. 

 Bull. 17, Feb. 1 91 3 ; 54 figures). — The figures and data are very interesting 

 and valuable. Colour is shown to have no effect on radiation, but very con- 

 siderable on the amount of heat absorbed. 



Horse manure gave the greatest increase in soil temperature, cow manure 

 intermediate, sheep manure least. 



A salt solution had a marked effect on the raising or lowering of soil tempera- 

 ture, according to the density of the solution added. The quantity of organic 

 matter present or added influenced temperature markedly, the soil containing 

 the greatest amount thawed slowest, but held a higher average temperature 

 throughout the whole year. — C. P. C. 



Soil, The Atmosphere of the. By E. J. Russell and A. Appleyard (Jour. Agr. 

 Sci. vol. vii. pt. 1, pp. 1-48, March 1915 ; figs.). — The remarkable relationships 

 existing between micro-organisms of the soil and the growth of plants have 

 given rise to numerous researches on the bacteria, fungi, and protozoa of the soil. 

 In order that further advances in our knowledge of these organisms may be 

 made, it is recognized that it is necessary to discover the conditions under which 

 life in the soil goes on. The present paper is a contribution to this preliminary 

 work. 



The top six inches of the soil was selected as proper for the experimental 

 work, although there is in fact but slight variation throughout the first twelve 

 inches. Different surface soils were examined, some being under a crop, others 

 bare, some manured, others unmanured. Minor fluctuations in composition 

 were shown, but the broad conclusions are true of all the types selected. 



The total pore space is about one third of the total volume of the soil ; from 

 10 to 20 per cent, of this space is occupied by soil air, the remainder being 

 occupied by water. The soil air contains oxygen, nitrogen, and carbon dioxide. 

 In composition it is generally similar to the ordinary atmosphere, but contains 

 less oxygen, more carbon dioxide, and, usually, more nitrogen, the differences 

 being due to the absorption of oxygen and the evolution of carbon dioxide by the 

 inhabitants of the soil. Diffusion is constantly tending to make the proportions 

 in soil air and in ordinary air equal. The absolute differences are small. For 

 example, the average composition of soil air from arable land was oxygen 20-6 

 per cent., nitrogen 79*2 per cent., carbon dioxide -25 per cent., but taking relative 



