212 EXPERIMENT STATION RECORD. [Vol.36 



The organic phosphorus of soil, R. S, Potteb and T. H. Benton {Soil Sci., 

 2 {J 916), No. 3, pp. 291-298). — A method proposed for determining the total 

 organic phosphorus content of soil is described, and experiments conducted at 

 the Iowa Experiment Station on the content of organic phosphorus in a fallow 

 orchard soil are reported. 



It was found that " while the method can not be said to give an absolute 

 knowledge of the organic phosphorus content of soil, it at least gives compara- 

 tive results. ... As a result ot the work done so far, it can be definitely 

 stated that a large part of the r hosphorus of the soil is organic in nature." 



A list of 18 references to literature bearing on the subject is appended. 



The effects of certain organic compounds on plant growth, M. J. Funchess 

 {Alabama Col. Sta. Bui. 191 {1916), pp. 103-132, pis. 8).— Two years' pot cul- 

 ture experiments with oats and corn are reported to determine whether the 

 results obtained by adding fertilizers and lime and certain organic compounds, 

 including coumarin, vanillin, pyridin, quinolin, dihydroxystearic acid, and 

 pyrogallol, to heavy, sticky red clay, unproductive sandy soil, and to productive 

 and unproductive sandy loam soils at rates of 100, 250, 500, and 1,000 parts 

 per million of dry soil would parallel those obtained in solution cultures. 



It was found that lime, carbon black, and pyrogallol, which have been shown 

 to remove the toxic properties of a poor soil extract, were unable to increase 

 the crop yield when added to the poor soils used. " On the other hand, the 

 addition to soils of such toxic compounds as vanillin, coumarin, dyhydroxy- 

 stearic acid, pyridin, or quinolin, failed to increase greatly the infertility of 

 the infertile soils used. The application of such compounds in ratios as great 

 as 1,000 parts per million of dry soil decreased the yields in some cases where 

 the crop was planted on the same day that these heavy applications were made. 

 But when these compounds had been in the soil for a few months . . , little 

 or no toxic effects were to be found. Indeed, the nitrogenous compounds had 

 a beneficial effect in all cases reported, though there was evidence that 

 these may be harmful for a short time after the applications are made. This 

 constitutes good evidence that rapid chemical or biochemical transformation 

 of these compounds into beneficial or inert forms occurs in unsterilized soils 

 under the conditions of these experiments. Slight injury to oats was apparent 

 in most of the heavy treatments of pyridin and quinolin during the first weeks 

 of growth ; but this injurious action disappeared, and the pots so treated usu- 

 ally produced crops which compared favorably with those produced by the 

 nitrate-treated pots." 

 The addition of potassium and phosphorus greatly increased the beneficial 

 effects of pyridin and quinolin. This action is not regarded as an antitoxic 

 action, as these two mineral elements greatly increased the effect of asparagin, 

 nucleic acid, and sodium nitrate, none of which is toxic to plants. 



It is pointed out further that " had these experiments been terminated when 

 the plants were only 15 days old . . . both pyridin and quinolin would have 

 been found to be harmful, while . . . vanillin and coumarin would have been 

 recorded not injurious. Neither of the latter showed injury to oats during the 

 first few days of growth ; only in the later stages could their effect be noted, 

 and that effect was a simple retardation of growth." 



The results show " that solution culture and soil culture experiments fail to 

 agree," and the author concludes that " soil fertility problems can not be solved 

 by means of short-time solution culture studies." 



Physiological balance of nutrient solutions for plants in sand cultures, 

 A. G. McCall {Soil Sci., 2 {1916). No. 3, pp. 207-254, pi. 1, figs. S).— Experi- 

 ments conducted at the Maryland Experiment Station are reported on the rela- 

 tive growth rates of young winter wheat seedlings when grown in a substratum 



