618 EXPERIMENT STATION RECORD. 



Fruit soils in the Sierra foothills, J. W. Nelson (Mo. Bui. Com. Hart. Cal., 4 

 {1915), No. 3, pp. 134-139) .—This article deals briefly with the soils of an area 

 of about 5,000,000 acres in the Sierra foothills of California, the topography of 

 which consists of a series of low broken hills, small narrow valleys, rounded 

 ridges, and moderate to steep slopes along the valley margin. The drainage is 

 good except in small irrigated valleys. 



The soils are prevailingly red in color and have been derived mainly from 

 igneous and metamorphic rocks. It is stated that they are generally fertile 

 and their greatest requirement appears to be organic matter. They are all 

 well supplied with mineral plant food, but the heavier types rank first and are 

 the most durable soils. 



It is also stated that the marked variation in elevation, rainfall, temperature, 

 and soils makes the gi-owth of a wide range of profitable fruits possible in this 

 belt. 



The atmosphere of the soil: Its composition and the causes of variation, 

 E. J. Russell and A. Applet abd {Jour. Agr. 8ci. [England], 7 {1915), No. 1, 

 pp. 1-45, Jigs. 17). — This article, the first of a series, reports investigations of 

 the composition and characteristics of the soil air. 



It was found that the free air in the pores of the soil to a depth of 6 in. is 

 very similar in -composition to the atmospheric air, but differs in that it shows 

 greater fluctuations in composition and contains more carbon dioxid and corre- 

 spondingly less oxygen, the average in 100 volumes being 0.25 volume of carbon 

 dioxid and 20.6 volumes of oxygen against 0.03 volume of carbon dioxid and 

 20.96 volumes of oxygen in atmospheric air. " Usually the sum of the CO2 and 

 oxygen is only slightly less than in atmospheric air, but at periods when nitrates 

 rapidly increase there is a perceptible falling off of oxygen and a still greater 

 one in waterlogged soils." 



In addition, there is another atmosphere dissolved in the water and colloids 

 of soils which consists mainly of carbon dioxid and nitrogen and has practically 

 no oxygen. " The fluctuations in composition of the free soil air are mainly due 

 to fluctuations in the rate of biochemical change in the soil. . . , The rate of 

 biochemical activity attains a maximum value in late spring and again in 

 autumn and minimum values in summer and winter. In autumn the bacteria 

 increase first, then the CO2 rises, and finally the nitrate increases. From 

 November to May . . . the soil temperature . . . appears to be the dominating 

 factor, from May to November . . . the rainfall and to a less extent the soil 

 moisture. . . . 



" It is shown that the dissolved oxygen brought in [in rainfall] is probably a 

 factor of considerable importance in renewing the dissolved soil atmosphere 

 and facilitating biochemical change. ... No evidence could be obtained that 

 the growing crop markedly increases the amount of CO2 in the soil air, and if 

 it gives rise to any great evolution of CO2 in the soil. It apparently exercises a 

 corresponding depressing effect in the activities of soil bacteria. ... As the soil 

 differences are eliminated so the differences in composition of the soil air 

 become less and less. . . . Such weather conditions as barometric pressure, 

 wind velocity, variations in temperature from the mean, small rainfall, etc., 

 seem to have but little effect on the soil atmosphere." 



A manometer method of determining' the capillary pull of soils, "W. A. 

 Cannon {Plant World, 18 {1915), No. 1, pp. 11-13). — An apparatus for de- 

 termining the capillary lift of soils is briefly described. 



It consists essentially of a U-shaped mercury manometer with open ends, a 

 soil container of 500 cc. capacity, and a water reservoir of about 500 cc. ca- 

 pacity. The water reservoir is connected by means of a T-shaped glass tube 



