May, 1920] SOIL SCIENCE 257 



nitrate. Other cultures were conducted in sand, with the addition of sterilized (boiled J 

 extracts of the soils, together with nutrient salts. — Sulphur and sulphates enhanced growth. 

 These effects in the sand cultures are attributed to direct effects of sulphur a mpoundfl upon 

 the plants. Clover responded most, having increased nitrogen content and developmenl of 

 roots and nodules where sulphur and sulphates were applied. The hi ter effects are ascribed 

 to stimulation of nitrogen-fixing bacteria. Alfalfa from field plots to which sulphur bad been 

 applied contained more nitrogen and organic compounds of sulphur than that from control 

 plots. The former also contained inorganic sulphates, while the latter contained none. — 

 W. E. Tottingham. 



1771. Pethtbbidoe, G. H. Investigations on potato diseases. Jour. Dept. Agric. Ire- 

 land 19: 271-292. Fig. 1-2. 1919. 



1772. Pescott, Edward E. The Australian flora from an ornamental aspect. Jbur. 

 Dept. Agric. Victoria 17: 360-364. PI. 4- 1919— See Bot. Absts. 3, Entry 2279. 



1773. Pickering, Spencer. The action of one crop on another. Jour. Roy. Hortic. Soc. 

 43 : 372-380. Fig. 54-59. 1919.— The author points out that the growth of plants in soil pro- 

 duces a toxic substance which appears to have a deleterious effect on vegetation. This con- 

 dition is brought about by the decomposition of organic matter, and, since most of the or- 

 ganic matter comes from plant growth, it is natural to suppose that more toxin will be found 

 where plants are growing than where they are not; thus the toxic effect of one plant on an- 

 other. He goes on to point out that the toxic effect produced is only temporary and that the 

 toxin is later changed into plant food. — The growth of grass around fruit trees produces a 

 toxic effect which is detrimental to the trees. The effect varies under different conditions, 

 but experiments indicate that the effect was independent of the age of the tree. — Heating the 

 soil caused a temporary increase of toxicity, though the ultimate growth of plants in heated 

 soil was greater. What the toxic substance is has not yet been ascertained, but it is not 

 dihydroxystearic acid. — /. A. Middleton. 



1774. Powers, W. L. The improvement of marsh land in western Oregon. Oregon Agric. 

 Exp. Sta. Bull. 157. 32 p., fig. 1-24. 1919. — Preliminary surveys indicate that drainage and 

 improvement of most of Oregon's 150,000 acres of marsh land is entirely feasible. Materials, 

 methods and costs for achieving such a result are given. Experiments and successful farm- 

 ing operations in various parts of the state have demonstrated the great value of the land 

 already drained. — E. J. Kraus. 



1775. Shutt, Frank T. The "alkali" content of soils as related to crop growth. Agric. 

 Gaz. Canada 6: 8-15. 1919.— The results of the analysis of five series of soil groups are re- 

 corded, each series consisting of three groups representative of land upon which (1) there 

 was good growth, (2) there was poor growth, the crop being distressed by alkali and (3) there 

 was no growth, due to excess of alkali. The crops studied were western rye grass, native 

 prairie grass, oats, wheat and onions. Soil samples were taken at various intervals to the 

 depth of 5 feet. The per cent of sodium sulphate, magnesium sulphate, calcium sulphate, 

 sodium carbonate, and the total soluble saline content was determined for each sample. The 

 western rye grass soil series was impregnated with white alkali, the chief constituent being 

 sodium sulphate and the limits of toxicity where growth took place, ranged from 0.117 to 0.980 

 per cent depending on the depth of sampling. Native prairie grass showed some growth in 

 much heavier concentration ranging from 0.432 to 1.662 per cent. In the wheat series, the 

 limit of tolerance was indicated by a per cent of 0.123 in the first 6 inches of soil. Below that, 

 the sodium sulphate increased rapidly to 0.701 per cent, and all root extension was inhibited. 

 In the oat and onion series, the soil was heavily impregnated with black "Alkali," the char- 

 acteristic salt of which is sodium carbonate. The concentration of this salt was greater on 

 the surface soil and decreased steadily in the lower samples. The limit of toxicity seemed to 

 be reached in oats at 0.212 per cent and in onions at 0.224 per cent. With the exception of 

 the series upon which wheat was grown, the soils were under irrigation and were located in 



