Vol. XIV. No. 343. 



THE 4.GKICULTURAL NEWS 





RECENT WORK IN SOIL CHEMISTRY. 



Three numbers of the Journal >i A i K •■'"'■ 



for Septembei and I tecembei (191 t) ;n d March i 1915 

 pectively, have been received, and the following notes have 



been abstracted, containing interes inf< n icern 



ing the latesl wort thai has done in England in 



d to the bigger problems of soil chemistry. In mak- 

 ing this selection it has been endea von I ir in mind 

 the possible application ol the results in a general way in the 

 West Indies. 



The soil solution and the urinei il constituents ol the 

 soil is the subject of an important paper by Mr. A. D. II. ill, 



Dr. Brenchley, and Miss Underw I. The soils of fields at 



Rothamsted which have been under cultivation in one crop 

 for a large number of years were examined, and the work 

 included the growth of plants in soil water obtained from 

 the samples. It is concluded that the composition of the 

 natural snil solution as regards phosphoric acid and potash is 

 qoI constant, and varies with the composition of the soil and 

 its past manurial history. The growth of a plant is largely 

 influenced by the concentration of the nutritive solution, 



irrespective of the total amount ol plant f 1 available. 



On norma] cultivated soils the growth of crops like wheat 

 and bailey, even when repeated for sixty years in succession 

 does not leave behind in the soil specific toxic substances 

 which have an injurious effect upon the growth of the same 

 or other plants in that soil. 



Another important piece of investigation in the second 

 number of the journal referred to, deals with the evaporation 

 of water from soil. Mr. !'•. A. Keen, the author, has found 

 that the evaporation of water from soil fractions like sand 

 and silt, an 1 from China clay as well as from ignited -oil, is 

 a relatively simple phenomenon: but the evaporation from 



soil is mon mplex, something being present which operates 



in making the relation between the soil and the soil water oi 

 a different and closer nature than in the case of sand. The- 

 effect is not due to soluble humus, and it i.s concluded 

 that the phenomenon is principally due to the colloidal prop- 

 erties of clay. The rate curves for soil evaporation are exam 

 ined mathematically in this paper, and it is thought that 

 a second factor must be taken into consideration, namely, the 

 effect on evaporation of the decreasing water surface in 

 the soil. 



One of thi' chief lines of research conducted at Kotham- 

 sted is the 3tudy of soil gases, and Mr. Appleyard in 

 collaboration with Dr. Russell publishes a lengthy and 

 important | ia per on the subject in the March number of the 

 journal. The free air in the spores of the soil to a depth of 



6 inches is very similar in composition to the atmospheric 

 air, but it differs in two respects: it contains more carbon 



dioxide anil correspondingly less oxygen, and it shows 

 greater fluctuation in composition. The dissolved ail' in the 

 soil consists mainly of carbon dioxide. Fluctuations in 

 composition of the free soil air are mainly due to fluctuations 

 in the rate of biochemical change in the soil: and these 



fluctuations are seasonal. Grassland usually contains more 

 carbon dioxide and less oxygen than arable land, but we cannot 

 attribute the difference to the crop owing to the large differ 



ences in soil differences 1 conditions. There is no evidence 



to show that the crop increases tic percentage o| carbon 

 dioxide in the soil, and such weather conditions as barometric 



pressure, wind velocity, variations in temperature from the 

 mean, small rainfall, etc., seem to have but little influence on 



■il atmosphere. 



One of the most interesting contributions to the same 

 number of this journal is a paper on soil protozoa by 



Mi \n.lre\\ Cunningham. This paper was prepared 

 ad was published in ' i< i manj last * ■ but 



could be | 'in sd in England owing to the war. 



was republished in the Journal oj Agricullui 

 Duringthe lasl yearortwo, particularly in Am ^sell's 



discovery of soil protozoa as a fan., rot fertility 



subjected I nsiderable i i iticism. It is inten 



Cunningham's paper, ba ed on research in Gern nj i ; i 

 Professor Lohnis, support iclusions of bussed. 



Stated at the end of the paper: 'the reduction in Ki i 

 numbers in the soils inoculated with protozoa is vet I 



and lies well outside the limits of experimental error, lie- 

 conclusion may safely lie drawn, therefore, that the limiting 

 factor or at least one limiting factor (of Russi H and 



Hutchinson) has 1 n n ulated into the sterilized I I 



has produced its effects on the numbers of bacteria. . . . 

 Large numbers of protozoa were observed in thi 



Used for inoculation and these organisms were cultivated once 



re on soil extract from the soils which showed low bacterial 



counts. And as it has been shown that the protOZi N 



capable of reducing the numbers of bacteria in solutions, it 



appears justifiable to consider them as the limitii 



in soils.' 



The Value of Soil Analysis. -The following is the 

 advice given by Dr. E. J. Russell in the Journal of the Board 

 of Agriculture (May 1915), in regard to the value of soil 

 analysis to the farmer: — 



'The farmer who wishes to derive the maximum 

 assistance from soil analysis must bear the following points 

 in mind: — 



'1. The simplest problem for the expert is to compare 

 soils, and, therefore, the chances of success are greatest when 

 a soil survey has been made, or when some similar soil has 

 been under proper field experiments. 



"J. The object of the analysis is to furnish information, 

 but no one has the time, even if he had the power, to set out 

 all that he can discover about a particular sample of soil. 

 The farmer must, therefore, arrange to go over the land with 

 the expert and discuss on the spot the various points on 

 which information is desired; the necessary samples cm\ then 

 be drawn with the proper tools, and with all due precautions. 



'.'5. Finally, it should be remembered that the problem 

 is very difficult indeed when no satisfactory standards exist, 

 and where the expert has not made a personal inspection; so 

 much balancing of probabilities has to be done that no 

 expert can give more than a general opinion or do more than 

 submit two or three alternative schemes for consideration 

 and trial.' 



Cable advices from the Federated Malay States Govern 

 ment to the Malay States Information Agency state that the 

 export of rubber from the federated Malay States for the 

 month of March last amounted to 3,418 tons, as compared 

 with 3,41 1 tons in February, making the total for the three 

 months 10,302 tons, as against 7,32 I tons, in the correspond 

 ing period of li)l+. {Chamber of Commerce .Inn, mil, 

 May 1915.) 



An American consular report states that the production 

 of cacao in the Guayaquil district of EcuadoF amounted to 

 92,213,874 lb., the value, at an average price of l'i centavos 

 (SOOTS) per It.., being $7,192,682. The 1913 crop was 

 85,908,495 ft., valued at#7,452,014 The lowei prices in 



1!UI were due to the European war. Returns fort] ther 



parts of the Republic have not been received from the 

 customs office, but they will not materially increase the above 

 figures. (Chamber oi Commerce Journal, May 1915.) 



