SOILS FERTILIZERS. 823 



cent of the water-soluble phosphates into Insoluble or, as measured by these 

 solvents, into unavailable form. Where lime was mixed, with equal quantities 

 of iron or aluminum hydroxids, the fixation of phosphoric acid was not so 

 great, as 57 per cent was available, showing that a part combined with lime. 

 Where calcium and magnesium carbonates were used as a fixing agent the 

 resulting compounds were completely dissolved and would have to be classed 

 as available." 



The weights of the crop produced in the pot experiments indicated " that 

 iron and aluminum do not fix the phosphoric acid in forms unavailable to the 

 wheat plant. As a part of the phosphoric acid was available in the iron and 

 aluminum compounds, as shown by the solvents, and as 0.6 gm. of phosphoric 

 acid was added to each pot, which would be more than could be removed by 

 the wheat, a second crop was grown, using oats, without the addition of more 

 phosphates. . . . The second crop of oats shows practically the same results 

 as the first crop of wheat, that is, the iron and aluminum compounds produce 

 more plant growth than the calcium compounds, and are more available. . . . 

 The corn experiments from the first and second crops confirmed the results 

 obtained with wheat and oats and indicate that the solvents used by chemists 

 to determine the availability of phosphoric acid, when applied to the products 

 of fixation or reversion of phosphates by iron and aluminum, do not represent, 

 in any way, their true availability, and can not be correlated with what the 

 plant can or can not assimilate." 



The conditions of soil climate in relation to the nitrogen and soluble 

 phosphoric acid of the soil, R. Perotti {Rend. Soc. Chim. ItaL, 2. ser., 2 

 (1910), pp. 143-I48). — The relation of climatic conditions in the soil to the 

 decomposition of organic matter and the formation of humus, and its influence 

 upon the nitrogen supply, bacterial activity, and availability of mineral con- 

 stituents of the soil, are briefly discussed in this article. 



The influence of lime and humus on the mechanical and physical proper- 

 ties of clay, loam, and sandy soils, W. Thaer {GeJcront. Preisschr. Univ. 

 Gottingen, 1910, pp. IJ/h ; Jour. Landiv., 59 {1911), Nos. 1, pp. 9-57; 2, pp. 101- 

 135; abs. in Jour. Cliem. Soc. [London], 100 {1911), No. 585, II, pp. 6-'i8, 6-i9; 

 Ztschr. Angeio. Cheni., 24 {1911), No. 37, p. 1776). — In investigations here re- 

 ported it was found that the calcium of soils was in combination with carbon 

 dioxid and colloidal acids and in case of humus sand also in combination with 

 strong mineral acids. The addition of lime to the soils resulted in a precipita- 

 tion of colloids, in an increase of permeability and water-holding power, and in a 

 decrease in shrinkage on drying. 



As regards permeability, the action of lime on the humus colloids and the clay 

 colloids was the same, but it decreased swelling of the former while it increased 

 the permeability of the clay colloids. The effect of the action of lime on both 

 humus colloids and other colloids was to increase ease of cultivation of the soil. 

 In case of humus soils the addition of lime was especially favorable to nitrogen 

 fixation and nitrification. 



The methods of investigating the soluble soil colloids are described. 



Soil evaporation, G. H. True {Nevada Sta. Bui. 73i, pp. 32, 33). — In exper- 

 iments with jacketed tanks sunk in the soil and given surface irrigation equal 

 to a depth of 6 in., " the average loss of moisture for the tanks not cultivated 

 was equal to a depth of 1.71 in. over the whole surface, and that from the 

 cultivated tanks 1.3 in., the loss by evaporation being decreased 24 per cent as 

 result of cultivation." 



In another s( Mes of experiments " two tanks were irrigated by surface flood- 

 ing to a depth of 6 in., two given the same amount of water applied in furrows 

 17732°— No. 9—12 3 



