SOILS FERTILIZERS. 219 



of plant roialions throws lif,'lit on sovcral important phases of the subje<-t. ami 

 incidentally strengthens the eolian hypothesis." 



The influence of geology on horticulture, C. H. Hooper {Jour. Roy. Hart. 

 Soc. [London], 3', {J!H)ii), Xo. S, pp. .VJ'i-.'iW, pL 1, figs. //).— This article dis- 

 cusses the relation of surface geology and the character of the soil to the 

 growth of different plants, more particularly fruit-producing plants, in dilVerent 

 parts of the British Isles. Itather definite relations of this kind are traced. 



Bibliography of North American geology for 1906 and 1907, with subject 

 index, F. B. Weeks and J. M. Nickles (U. »S'. <!col. t^urvcy Bui. 372, pp. 317).— 

 A bibliography of soils is included. 



The waste from soil erosion in the South, W. W. Ashe { Avici: Kcr. of 

 Reviews, 39 {J!)09), No. J,, pp. .',3D-.'iJi3, figs. J).— Attention is called to the large 

 loss from this source. It is stated that more than 5,0(»().UU() acres of land in 

 the upland regions of tlie South which were once cultivated are now idle 

 mainly as a result of soil exhaustion and erosion. Clean culture and removal 

 of forest growth tend to increase floods and consequent erosion. Terracing 

 and reforesting are I'eferred to as means of reducing the injurious effects of 

 the erosion. Considerable areas of exhausted and washed lauds have been 

 partly reclaimed by natural reforesting. In the author's opinion " it would 

 be possible to reduce the jireseiit erosion from farm lands one-half with an 

 enormous saving to the nation." 



The conservation of soil moisture, W. MacDonald (Agi: Gaz. N. 8. Wales, 

 20 {1909), Ao. -), pp. 333-339). — This is a summary of conditions essential to 

 the conservation of moisture in dry land farming. 



The water requirements of crops with special reference to tropical condi- 

 tions, P. Vageler {Tropcnpflanzcv, 13 {1909), Nos. 3, pp. 103-113; .), pp. 160- 

 17.'i). — A rather complete discussion of this subject. 



The chemistry of heated and of partially sterilized soils, S. V. Pickering 

 {(1(11(1. Cliroii., 3. set:, .'/.5 {1909), A'o. I Hid, p. 275). — This is a brief summary of 

 recent progress in imestigations on this subject. 



Comparative soil temperature study of two plats differently treated, 

 B. E. Brown {Pennsylvania Sta. Rpt. 1908, pp. 93-102, j^ls. 3, fig. /).— Observa- 

 tions by means of recording thermographs on the temperature variations on a 

 very productive and a less productive plat which had been used in long 

 continued fertilizer experiments are reported. 



" During the jieriod wheat was on the ground, in 1907, the low yielding plat 

 recorded the higher temperature. During the winter 1907-8 the high yielding 

 plat maintained the higher temperature. Again in 1908, with clover and tim- 

 othy growing the low-yielding plat recorded the higher temperature. Moisture 

 determinations were made on the two plats. [The] i)]at producing greater 

 crops, usually ran higher in moisture. Greater amounts of water-soluble nitro- 

 gen and potassium were recovered from the plat recording the higher temper- 

 ature during the growing season. The amounts of calcium and phosphorus 

 recoveral)le were about the same from each i)lat. The plat recording the higher 

 temperature during the growing season produces lower yields." 



Investigations on the action of sulphurous acid on soils, E. Haseluokf 

 {Interndt. I'liylopath. Diciisl { licigalie Ztsriir. I'flanzcnkrnnlc), 1 {1908), No. 3, 

 pp. 73-91, pis. 2). — In coiniection with a study of the injurious effect of smoke 

 and fumes, pot experiments were made with beans and barley to determine the 

 action o£ sulphurous acid when used at the rate of 14.90 gm. to each S kg. of 

 soil, the acid being drawn through the soil in Aarying amounts at intervals 

 during the growth of the plants. Experiments were made with soils free from 

 c(»pper and with those containing various copper salts supplying 0.25 to 0.0 per 

 cent of copper oxid. 



