[shutt-burwash] "ALKALI" CONTENT OF SOILS 67 



dark streaks of organic matter, no visible efflorescence on drying; 

 "C," yellow-grey clay, damp and plastic, no efflorescence on drying; 

 *'D," brownish-grey sand with very little clay, moist, dries into 

 friable masses. 



The essential alkali of this group is sodium sulphate, which in 

 "A" (0'-0-0'-5) reaches a concentration of -75 percent — an amount 

 when present in the surface soil which evidently approaches the limit 

 of endurance for the crop in question. It is possible, however, that 

 the influence of the sodium sulphate in "A" has been somewhat 

 accentuated by the small percentage of magnesium sulphate present. 



It is interesting to compare this group with Group 1688, Series X. 

 In the latter an impregnation of • 8 per cent sodium sulphate at a depth 

 of -5 to 1-5 feet — the surface soil "A" containing only -23 per cent — 

 apparently does not affect the crop. In the group under consideration 

 a concentration of • 75 per cent sodium sulphate in the first • 5 feet soil 

 is evidently as much as the crop can endure. It is also of interest to 

 note that in the soil below "A" of this group (No. 1695) the alkali 

 falls off to almost negligible amounts. 



Group 1694. No growth; soil entirely bare. Nature of soil: 

 "A" black clay loam with considerable organic matter, wet, air-dries 

 to hard masses with marked effloresence; "B" plastic clay with sand 

 and silt, wet; "C" sand and clay, slightly plastic, wet; "D" almost 

 pure sand. 



The saline content, consisting of sodium sulphate, magnesium 

 sulphate and calcium sulphate, is largely concentrated towards the 

 surface. Sodium sulphate in "A" far exceeds the limit of endurance 

 and the high percentage of magnesium sulphate present would un- 

 doubtedly increase its toxicity. 



Vetch and Rye 



Series XIII. Lot 27, 476, Summerland, B.C. 



The samples of this series were collected in a field about 4 miles 

 southwest of Summerland, Okanagan Valley, B.C. The area had been 

 under irrigation for several years. At the time of inspection a certain 

 number of bare spots showing alkali were in evidence. On a part of 

 the field the crop was very meagre, but over a considerable proportion 

 of the area it was quite good. An orchard occupied this area, but the 

 trees had succumbed on the alkali spots. The soil on the surface is a 

 dark brown loam, well supplied with vegetable matter and is underlaid 

 by a mixture of sand and silt. Hardpan occurs at a depth of 22 to 28 

 inches. This lot (27-476) furnished groups examined in this investi- 

 gation in 1917 (crop: onions) and in 1918 (crop: oats). 



