22 EXPERIMENT STATION RECORD. 



the in-ocUiction of grass; and cliemlcal examinations of certain Rhode Island 

 soils. 



Natal soils, E. R. Sawer (In Cedara Memoirs on South African Agriculture. 

 Pletcrmaritzburg: Govt., 1000, vol. 1, pp. 7-50, figs. 3).— This article, which 

 forms part of an elaborate memoir on South African agriculture dealing with 

 the cereals in South Africa, discusses the geology, formation, composition and 

 fertilizer requirements, bacteriological activities, and tillage of typical soils of 

 Natal. As regards origin, the soils are mainly of two classes, granitic and 

 calcareous, the former class being by far the larger. 



The low productive capacity and the especially small content of available 

 phosphoric acid in certain of the soils ai*e attributed to deficiency of certain 

 kinds of bacterial activity in the soils. On the other hand, the organisms which 

 fix and transform nitrogen appear to be quite active. The importance of thor- 

 ough tillage to improve the physical condition of the soils is particularly em- 

 phasized. 



Analyses of 4 representative hillside soils at Cedara showed that on an 

 average each acre-foot of these soils contains 7,776 lbs. of nitrogen. 5,398 lbs. of 

 phosphoric acid. 6,195 lbs. of potash, and 2.301 lbs. of lime, of which only 174 lbs. 

 of phosphoric acid and 478 lbs. of potash are citrate soluble, and only 7 and 

 30 lbs., respectively, available for crops grown in the field as shown by practical 

 tests. The soils showed an acidity which would require 8.584 lbs. of lime per 

 acre to neutralize. 



In plat experiments on the 4 soils the results showed marked differences in 

 favor of the types containing the higher percentages of fine material. The 

 yields were doubled or trebled on all 4 soils by the use of superphosphate, slag, 

 bone dust, and mixtures of lime and complete fertilizer or lime and superphos- 

 phate. Applications of lime alone produced little effect. The action of basic 

 slag and bone meal was less affected by the texture of the soil than that of 

 superphosphate. The latter gave its best results only on fine soil. Basic slag 

 was especially effective on clay soils on account of the excess of lime in the slag. 



Studies of the absorptive power and capillary rise of water in soils of differ- 

 ent types are reported, showing that these properties are dependent upon and 

 controlled by the size and distribution of the soil particles. 



Studies of the accumulation of soluble salts in these soils showed " something 

 of a gradation downwai'ds in the contents of saline matter, which points to the 

 influence of capillary matter accompanied by a concentration on the surface 

 due to evaporation of the water of solution. . . . Very little of the soluble 

 matter obtained was found to be of value to the plant ; at the most only a trace 

 of phosphoric acid was obtainable from the filtrate, a minute quantity of potash, 

 and smaller quantities of lime and magnesia. Sodium as carbonate, chlorid, 

 and sulphate predominated in the majority of cases." 



The absorptive power of the soils for soluble salts \yas studied by passing 

 dilute solutions of monocalcium phosphate, magnesium sulphate, calcium nitrate, 

 and potassium sulphate through columns of soil a foot in depth. On an average 

 92.5 per cent of the phosphoric acid was retained. 60.1 per cent of lime, 55.8 

 per cent of magnesia, 24 per cent of potash, 23.6 per cent of nitrogen, and 11.7 

 per cent of sulphuric acid. 



Examinations of 12 samples of typical tea garden soils of the coast region 

 showed the most marked characteristics of these soils to be a deficiency of 

 humus and of phosphoric acid. The water-holding capacity of these soils was 

 dependent in part upon the size of the soil particles but to a greater extent 

 upon the amount of organic matter present. 



In view of the fact that the soils of Natal as of other parts of South Africa 

 are deficient in phosphoric acid and certain of the alluvial soils are deficient in 



