324 EXPERIMENT STATION RECORD. 



entirely unsuited for the growth of plants because of its acid reaction and lack 

 of soluble humates. When the peat was subjected to the action of certain 

 micro-organisms a large quantity of soluble humates was formed and the peat 

 was rendered alkaline. A water extract of peat thus treated was found to be 

 capable of supplying all the necessary plant food for successful water culture 

 experiments. Tomato seedlings failed to grow in raw peat extract, but grew 

 well, flowered, and produced fruit in extract from the treated peat. Similar 

 results were obtained with buckwheat, radishes, and barley. 



As no trace of nitrate was found in the peat extract the author concludes that 

 the plants draw their supply of nitrogen from the organic forms of nitrogen in 

 the solution. 



Forms of nitrog-en compounds in the soil which are direct sources of 

 nitrog-en for the higher plants, G. A. Rittee {Internat. Mitt. Bodenk., 2 (1912), 

 No. 6, pp. 533-540). — From a review of various investigations it is concluded 

 that where, as in the case of moor soils, there is little or no nitrate formation, 

 ammonia compounds and other soluble nitrogenous substances in the soil supply 

 the demands of the higher plants for nitrogen. 



Conditions affecting' the availability of nitrogen compounds in vegetation 

 experiments, II, J. G. Lipman, A. W. Blair, I. L. Owen, and H. C. McLean 

 (New Jersey 8tas. Bid. 257, pp. 3-45, pis. 6, figs. 7; Ri)t. 1912, j)p. 205-248, pis. 6, 

 figs. 7). — This is an account of a continuation of experiments begun in 1911 

 (E. S. R., 28, pp. 724, 725). 



"All of the experiments were carried out in glazed earthenware pots, hold- 

 ing 20 lbs. of pure quartz sand. To this sand there was added for each pot 4 

 gm. acid phosphate, 2 gm. potassium sulphate, 5 gm. calcium carbonate, 0.5 gm. 

 magnesium sulphate, and 0.25 gm. ferric sulphate. The. pots were kept in the 

 open with a provision for covering with canvas at night and during rainy 

 weather. The moisture was kept at 9 to 10 per cent by weighing the pots from 

 time to time, and replacing the loss thus indicated. Barley was planted in all 

 the pots and was allowed to grow to maturity, or as nearly so as was practical, 

 and was then harvested, dried, and the total dry weight recorded. The sample 

 thus prepared was ground and nitrogen determinations made [to give] the 

 total nitrogen in the crop. The pots were run in duplicate, and all nitrogen 

 determinations were also made in duplicate. . . . One set of pots was always 

 run without the special treatment, as a check." 



Summarizing the results it is stated that " when sand is mixed in varying 

 proportions with shale soil, the yield of dry matter and the percentage of nitro- 

 gen recovered from barley, when nitrate of soda is used, are greater with from 

 10 to 70 per cent of sand than they are with either the pure soil or with higher 

 percentages of sand. The highest point for yield of dry matter and percentage 

 of nitrogen recovered is reached with 40 per cent of sand. 



" The yield of dry matter and the percentage of nitrogen recovered from 

 barley, when dried blood was used, are lower with 40 per cent of sand than 

 with shale soil or with lower percentages of sand. With 50 per cent of sand 

 the yield of dry matter and nitrogen recovered are higher than with 40 per 

 cent. With higher percentages of sand there is a decline in dry matter and 

 percentage of nitrogen recovered, but this decline is much more gradual than 

 it is when nitrate of soda is used. 



"The yield of dry matter in the barley on the check cylinders is not, with 

 any of the dilutions, as great as the yield with nitrate of soda or dried blood. 



"With a residual crop of buckwheat none of the nitrogen of the nitrate of 

 soda was recovered from any of the cylinders having sand mixed with the soil. 

 A small amount was recovered from the shale soil. 



