1917] SOILS — PEETILIZEES. 629 



Tlie presence of calcium carbonate and of ammoniuin sulphate at the rate of 

 0.05 grn. of nitrogen per kilogram of soil promoted the decomposition of sugar. 

 Small amounts of nitric niti'ogen (0.05 gm. of nitrogen. In the form of sodium 

 nitrate, per liilogram) also increased the liberation of carbon dioxid except in 

 a nutritive solution in which 0.1 per cent sodium nitrate exercised an inhibiting 

 effect. Potassium sulphate increased the liberation of carbon dloxid in some 

 soils and decreased it in others. 



These results are taken to indicate that the effect of phosphoric acid is 

 differently influenced by the addition of nitrogenous and potassic compounds 

 according to the nature of the soil, any quantitative variation in one as a rule 

 modifying the action of the other. 



The potash question and g'eneral farm crops, A. W. Blaib {Neto Jersey 

 Stas. Circ. 67 (1911), pp. S-7).— It Is stated in this circular that with the ex- 

 ception of the very sandy sections of the State, New Jersey soils contain a fair 

 supply of potash which has been derived from the original rocks and glaciated 

 materials. The greater part of this potash is unavailable and, on the basis of 

 work at the station, the incorporation of organic matter, deep plowing, thor- 

 ough cultivation, and liming are recommended for setting some of it free. 



Potash in New Zealand and other countries, P, Q. Morgan (Jour. Agr, [New 

 Zeal], 14 {1911), No. 4, pp. 257-273). — This article gives general information 

 concerning the present potash situation, possible sources of potash, and methods 

 for rendering potash available to the farmer, with special reference to New 

 Zealand conditions. Some of the natural sources of potash recommended for 

 use by farmers in New Zealand are calcareous clay stones, glauconitic rocks, 

 and calcareous green sandstone. 



A discussion concerning the rational use of lime on the farm (Bui. N. C. 

 Dept. Agr., S8 {1917), No. 1, pp. 22). — This circular gives information on the 

 selection, purchase, and use of lime for agricultural purposes. 



Notes on humus, huniogen, and its accessory plant food substances, A. 

 Stead {So. African Jour. Sci., IS {1917), No. 6, pp. 239-250). — This is a review 

 of the work of others on the soil humus question, special attention being given 

 to the Bottomley bacterized peat process. 



The plant food materials in the leaves of forest trees, P. Serex, jb. (Jour. 

 Amer. Chem. Sac, 39 {1917), No. 6, pp. i2S6-i2P6).— Experiments conducted to 

 determine the plant food constituents of the leaves of the chestnut, sugar maple, 

 and white oak at the beginning of their activity In spring and at the end of 

 their growth in the fall are reported. 



It was found that " the leaves collected In the spring show a higher content 

 of nitrogen and potash than those collected in the fall from the same trees. 

 The phosphoric acid content varies with the species of tree and also with the 

 .section of the tree from which the leaves were obtained. The lowest amount 

 of nitrogen and phosphoric acid occurred in those leaves collected from trees 

 grown upon a clay soil. The highest content of nitrogen, phosphoric acid, and 

 potash occurred in those leaves collected from trees grown upon the Holyoke 

 stony loam and Wethersfield loam. The leaves from the upper branches of the 

 maple and oak have a higher content of nitrogen, phosphoric acid, and potash 

 in the majority of cases than those taken tmm the lower branches. In the 

 case of the chestnut the reverse appears to be true, the leaves from the lower 

 branches having the larger amount of nitrogen, phosphoric acid, and potash, 

 with some exceptions, than those removed from the upper branches. The esti- 

 mated theoretical cash value of a ton of leaves calculated upon a 20 per cent 

 mol8ttir« basis varies from $3 to $6.50, depending upon the kind of leaves and 

 npon what portion of the tree they were grown. The cost of collecting 

 and handling would probably be greater than the value of the leaves, thua 



