718 kxpkrtment stattox record. - 



"The average acid-soluble matter decreases steadily on the surface and more 

 rapidly in the dee[)er layers, espeiially during the summer months. . . . 



" It will further be noticed that the apparent loss from all the plats except- 

 ing the slaked lime and unmanured ones (where there is a slight gain) is very 

 much greater than can be explained by the ash removed by the crop. To what 

 extent these apparent losses are real ones, and to what extent they are due to 

 decreases in solubility, to increases in absorptive power, or to changes in dis- 

 tribution, must be reserved for further investigation. As far as they go they 

 seem to show that the fine alluvial, sandy rivei"-flat soils widely cultivated in 

 many parts of Victoria appear to be pec-uliaily liable to exhaustion under the 

 action of all chemical manures excepting slaked lime." 



Relations between the properties of soils and the assimilation of food by 

 plants, J. KiiXK;. E. ("oppknratii. and .1. IlASKXBAr>tKK (Landir. ^'ers. Stat., 

 66 {1901), Ao. 6. pp. J,01-.',61. fig. 1 : abs. in ('hem. Zrnthl., 1907. II. Xo. 9. p. 

 725; Chem. Ztg.. 31 (1907), Xo. .J.S. Rcpcrt. Xo. J-i, p. ,l')0 ; .Jour, fhcui. Soc. 

 [London], 92 (1907). Xo. .53S. II, pp. 6'-'/~. 6-}S). — In continuation of previous 

 investigations of similar character (E. S. R., 17, pp. 121, 1138) the authors 

 report chemical and physical studies of G typical soils (sand, loamy sand, loam, 

 calcareous, clay, and shale) to determine if jiossible in this way the relation 

 between the physical and chemical properties of the soils and their content of 

 plant food as measured l)y treatment with various solvents (strong sulithuric 

 acid, hydrofluoric acid. 10 per cent hydrochloric acid, dilute organic acids, 

 ammonium citrate, G per cent ammonia, water under pressure, and water 

 charged with carborr dioxid), and shown by their productiveness as tested in 

 experiments with oats, rye. peas, and potatoes grown on the soils in pots and 

 large boxes. 



The 6 soils varied widely in plant-food content and in physical properties, but 

 although the amount of plant f<iod dissolved by the different solvents was very 

 variable the relative solubility was. contrary to previous results with other soils, 

 much the same for individual solvents and soils.' For determination of easily 

 soluble potash, lime, and magnesia, therefore, one may use with equal safety 

 weak solutions of either citric acid, ammonium citrate, ammonium chlorid, 

 acetic acid, and carbonated water. Ten jier cent ammonium chlorid is too 

 strong, a 1 per cent solution being suflicientl.v strong. Two per cent solutions of 

 citric acid and ammonium citi'ate are each considered well suite<l to determina- 

 tion of available phosi»horic acid, but the first is preferred. 



The plant food, especially the jiotash. dissolved by treatment of the soil with 

 steam under a jtressure of 5 atmospheres is considered to approximate more 

 closely that taken up by f>lants than the amount dissolved by mineral solvents. 



A new property of soils which is described is the power of withdrawing oxygen 

 from hydrogen peroxid. This power is attributed in tlie first place to enzym 

 action, since the reaction is known to occur with enzyms and the catalytic power 

 is destroyed by treatment with substances known to be jxjisonous to enzyms. 

 Accompanying this action of enzyms, however, is the colloidal action of man- 

 ganese and iron oxids, etc. The influence of these oxids in withdrawing oxygen 

 from hydrogen peroxid is only temi)orarily checked by hydrocyanic acid. 



In all of the 6 soils except a clay soil rich in manganese oxid the catalytic 

 actioti st<»od in almost <lirect relation to the humys content. 



The growth of plants and the consequent assimilation of plant food from the 

 soil appeared to depend not only uixtn the amount of soluble plant food present, 

 but also upon the moisture and the depth of the food-supplying soil layer to the 

 extent that the crop yield as well as the absorption of plant food uniformly in- 

 creases with the water content of the soil u\) to GO ]ier cent of the water-holding 

 capacity of the soil and with the depth of the soil layer up to 30 eui. 



