SOILS FERTILIZERS, 



819 



calcium and niagiicsiuni caiiioiiatcs, pliosphoric acid (0.1 to 0.25 per cent), and 

 |totash(0.4 to O.G per cent). The soils vary mainly in texture and structure, 

 tliese variations causing tbem to differ widely in their behavior toward alkali 

 under irrigation. 



Flooding is the connnon method of irrigation ('mph)yed. A study of the 

 effect of rtoodiug upon the movement of alkali in soils of different physical 

 properties led to the following conclusions: (1) Flooding of the heavy, fine- 

 grained soils may be practiced for a long time without danger of rise of alkali, 

 l)Ut the amount of water used should be sufficient to thoroughly saturate the 

 whole area, and the soil should be cultivated and planted as soon as the condi- 

 tion of the surface soil permits. (2) To avoid rise of alkali in flooding light 

 sandy soils the water must be supplied in abundance and rapidly and irrigation 

 must be confined to small areas at a time. Measures must also be taken to de- 

 crease the loss of water through evaporation. (3) Thorough drainage is nec- 

 essary to prevent rise of alkali in the soils of this region under irrigation. 



What processes go on in fallow soils? Ulrich (B^uliUiig'fi Laiidir. Zty., 

 55 {liWd), Ao. G, pp. 200-215: ahs. in ('< iilbl Bakt. [etc.], 2. Abt., 11 (1<)0(!). 

 No. i7-/,s', p. 572). — The active physical, chemical, and bacteriologicaU-proc- 

 esses which go on in fallow soils are discussed. 



Effects of shading on soil conditions, J. B. Stewart ( U. 8. Dept. Agr., 

 Bur. Soils Bill. .W. jiji. I!i. jiis. ). fins. 7). — This bulletin reports the I'esults of 

 observations on temperature, soil moisture, humidity of the air, and wind 

 movement inside and outside of a shelter tent for tobacco during the period 

 froni .Tune 13 to August 1, 1905, and the results are discussed with reference 

 to the influence of the conditions inside the tent on the growth of tobacco. The 

 studi(>s are of the same general nature as those recently reported by the 

 Pennsylvania Station (E. S. R., 18, p. 211). The main results are summarized 

 in the following table: 



Temperature, .soil moisture, and relative huniiditi/, inside and outside of tent. 



The following conclusions are drawn : 



"(1) The soil retains more moisture, which is of es])ecial imiiortance during 

 the dry periods. The inside soil is then always closer to the optimum water 

 content. Because the soil is not subject to the packing due to alternate wetting 

 and drying, it remains in better physical condition. 



"(2) The temperature of the atmosphere is made slightly warmer, which 

 brings the temperature closer to the optimum growing temperature. An even 

 greater effect is, however, perhaps due to the fact that there is less variation 

 in the temperature, which is generally recognized to be of much importance. 



"(3) The relative humidity of the atmosphere is greatly increased. In 

 addition to its effect on soil and atniosi)beric conditions it has an influence on 

 jilant growth. ... 



"(4) The velocity of the wind is much reduced, which decreases evaporation, 

 and is of importance in the i)reservation of tlie plants, for they are not whi|)ped. 

 bruised, or blown down. 



