1917] SOILS FERTILIZERS. 519 



Availability of potash in certain orthoclase-bearing soils as affected by 

 lime or gypsum, L. J. Bbiggs and J. F. Breazeale (U. S. Dept. Agr., Jotir. Agr. 

 Research, 8 (1917), No. 1, pp. 21-28). — Experiments are reported in which 

 *' samples of pegmatite and orthoclase were collected near Riverside, Cal., repre- 

 senting, respectively, types of the potash-bearing rock and mineral from which 

 many of the citrus soils appear to be derived. These samples were finely ground 

 and shaken for a number of days with aqueous solutions of calcium hydroxid 

 and of calcium sulphate in graduated concentrations. Tlie calcium-hydrate 

 solutions did not modify the solubility of the potassium in either pegmatite or 

 orthoclase. Gypsum solutions depressed the solubility of potassium in orthoclase, 

 the quantity of potash in solution decreasing progressively as the concentration 

 of the calcium sulphate increased. 



" Similar tests were made upon a virgin soil of a granitic type from the 

 experiment station near Riverside, Cal. The solubility of the potash was not 

 measurably different in distilled water and in solutions of calcium hydrate or 

 calcium sulphate. 



"The addition of calcium sulphate to a citrus soil which had been under 

 cultivation for some time and which was more granular and less weathered 

 than the virgin soil decreased the solubility of the potash, 



" The potassium content of wheat seedlings was practically the same when 

 grown (1) in water containing finely ground orthoclase, and (2) in a saturated 

 calcium-sulphate solution containing the same quantity of orthoclase. Similar 

 experiments in which a citrus soil was used instead of orthoclase showed a 

 decreased absorption of potassium by wheat seedlings in the presence of calcium 

 sulphate. 



" The experiments indicate that the availability to plants of the potash in 

 .soils derived from orthoclase-bearing rocks is not increased by the addition of 

 lime or gypsum. In some instances a marked depression of the solubility of the 

 potash in the presence of g:sT)sum was observed." 



Acidity of soils and lime requirements, J. A. Voelcker (Woburn Expt. Sta. 

 Rpt. 1915, pp. U-^S; Jour. Roy. Agr. Soc. England, 76 (1915), pp. 355-357).— 

 The results obtained in these experiments are similar to those obtained in the 

 1914 experiments (E. S. R., 35, p. 324). 



Chalking: A useful improvement for clays overlying the chalk, E. J. Rus- 

 sell (Jour. Bd. Agr. [London], 28 (1916), No. 7, pp. 625-632, pi. 1, fig. J).— This 

 is a brief account of the method and cost of obtaining and using chalk on stony 

 clay soils in the English counties surrounding the city of London, together with 

 n brief review of results showing the effect of chalk on different crops. 



The relation of lime to magnesia in soils, J. A. Voelckeb (Wohurn Expt. 

 Sta. Rpt. 1915, pp. 37-41, pis. 2; Jour. Roy. Agr. Soc. England, 76 (1915), pp. 

 351-355, pis. 2). — Experiments on the effect on wheat of adding caustic lime and 

 calcium carbonate to soils containing an excess of magnesia and of adding 

 caustic magnesia and magnesium carbonate to soils containing an excess of 

 lime are reported. 



In the first case the conclusion was reached that " lime may be added in con- 

 siderable excess of the magnesia present provided it be put on in the form of 

 carbonate of lime and not as caustic lime." In the second case the results were 

 not conclusive. 



Influence of magnesia on wheat, J. A. Voelcker (Wohurn Expt. Sta. Rpt. 

 1915, pp. 17-20; Jour. Roy. Agr. Soc. England, 76 (1915), pp. 33i-3S^).— Experi- 

 ments with wheat on two 1/20-acre plats of soil containing 0.46 per cent 

 of calcium oxid and 0.2S per cent of magnesium oxid, to which ground 

 magnesia was added at the rate of 4 tons per acre, showed that the wheat on 



