SOILS. 17 



nor have they served as a prelmle to thr funeral of tlie method, as some have 

 thought; they encouraged, on the contrary, the most legitimate hopes of success in 

 the struggle undertaken for protection against hail." 



The mechanism and causation of hot waves, H. ]M. Waits {Jour. Franklin 

 Inst., 153 {1902), No. 4, PP- 2S5-39S, Jiy^. 3). 



SOILS. 



Sixth annual report for the year 1900 of the Agricultural Experiment 

 Station of Ploti {Sic. liap. An. Sta. K.rpt. Atjron. Plot//, 1900, pp. XXIV'Jr334, pis. 

 •2, ilgtiis. 3). — The report consists of separate reports of the experiment field, the 

 chemical laboratory, the meteorological station, the vineyard, and of vegetation 

 experiments, together with introductory articles by the founder and the editor-in- 

 chief. The report is in the Russian language, but contains a French resume of the 

 work in the chemical laboratory (p. .5). (See also Field crops, jx 29.) 



Report, of the e.rperhnent field. — In experiments on the dependence of the temperature 

 of the soil on the plant covering, one part of a small plat was planted to oats, while 

 the other was left without a crop. Observations were made with 4 thermometers, of 

 which 2 were placed under the plant on the surface of the soil and at a depth of 0.1 

 meter respectively, while the other 2 were similarly placed on the part without a 

 crop. The experiments showed that the difference in temperature on the surface of 

 the soil reached up to 15.4° C. and at a depth of 0.1 up to 7°. 



In a study of the humidity of the soil in dependence on the kinds of fallow, the 

 depth of plowing, and the plant covering determinations of humidity were made, as in 

 previous years, on the green fertilized fallow of the four-course rotation, plowed to a 

 depth of 7 in., on the black April and May fallows of the nine-course rotation, plowed 

 to a depth of 7 and 10.5 in., and on an unplowed field. The results are summed up as 

 follows: (1) The black fallow stands first in the matter of accumulating moisture, 

 fields plowed in April next, while the fields plowed in May occupy the last place; 

 (2) the loss of moisture during the winter, spring, and summer is greater on black 

 fallow than on ground plowed in April or May; (3) the general amount of water 

 stored up in the fields plowed in April was nearly the same as in those plowed in 

 the fall, but as regards the yield the former exceed the latter; (4) deep plowing gave 

 better results than shallow, except during the summer, when the influence of the 

 plants reverses the conditions. 



Vegetation experiments. — The comparative fertility of the different soil horizons was 

 studied by taking samples of soil on which barley had grown to 3 different depths, 

 from the surface to 10.5 in., 10.5 in. to 17.5 in., 17.5 in. to 24.5 in. Analysis showed 

 that the soil at the lowest depth (sul)arable soil) was richer than the arable layer in 

 all constituents except phosphoric acid. In the intermediate layer or horizon the 

 amounts of potash, lime, and magnesia were larger than in the upper or arable layer, 

 wliile the amounts of humus, nitrogen, and phosphoric acid were less. In pot 

 experiments with the soil of these three horizons the yield of oats on the soil of the 

 arable layer was much larger than in the other cases. This is explained by the fact 

 that only the upper layer of soil has a sutHcient supply of assimilable phosphoric 

 acid. Assimilable nitrogen is distributed throughout the soil layers, and deep-rooted 

 plants can secure all of this constituent which they require, even when the surface 

 soil is somewhat deficient in nitrogen. 



In the experiments with oats in the arable soil layer described above the amount 

 of water evaporated daily from the soil receiving different fertilizers was determined 

 throughout the whole period of vegetation. The results show that large crops were 

 accompanied V)y larger absolute losses of water, although the relative amounts of 

 water evaporated decreased. The increase of the yield in these experiments depended 



