SOILS FERTILIZERS. 221 



These figures show that while the amount of nitrogen contained in the rain 

 water of this region is not very great, it is much larger than that reported from 

 other regions (see above) and is not entirely negligible as a source of plant food 

 in certain years. As was to be expected, liy far the larger proportion of the 

 nitrogen is found in the rain water during the warmer months of the year. 

 Tlie conditions influencing the accumulation of nitric acid and ammonia in the 

 rain water are discussed. 



Chemistry, and the conservation of our water resources, M. T, Bogert 

 (Jour. Franklin Inst., 169 {1910), No. 5, pp. 385-388).—'- The author points out 

 the important bearing that the purity of our water supply has upon its 

 utilization for drinking purposes or in various industries, and the services of 

 the chemist in determining its availability for these purposes. Attention is 

 also called to the serious problem arising in connection with the steadily in- 

 creasing pollution of our streams and tide-waters by sewage, factory waste, and 

 refuse of all kinds, and how chemistry can be of service in the solution of 

 this problem." 



SOILS— FERTILIZERS. 



The fixation of nitrogen in some Colorado soils, W. P. IIeadden (Colorado 

 Sta. Bill. 155, pp. -'iS, figs. 8).— This bulletin records the results of a study of 

 causes of unproductiveness in certain spots on irrigated lands. The barrenness 

 of these spots is popularly attributed to black alkali, but the investigations 

 reported in this bulletin show that it is due to excessive quantities of nitrates. 



■' These nitrates do not come from the soil nor from the shale as frequently 

 assumed but are formed in the soil. 



" The death of many apple trees, some poplars and other shade trees during 

 the season of 1900 was caused by excessive amounts of nitrates in the soil. 

 These nitrates were carried down within the feeding area of the roots by the 

 spring rains and irrigation. The amount of these nitrates accumulated in 

 some of these soils is already very large, amounting to many tons per acre-foot 

 of soil, 100 tons per acre-foot having been indicated by some samples. 



" The agency by which the nitrogen of the air is converted into these nitrates 

 in the soil is a group of micro-organisms possessing the power of converting the 

 nitrogen of the air into nitric acid. These organisms have a very wide distri- 

 bution in our soils and are not always hurtful, but when the conditions of the 

 soil, including moisture, temperature, and the presence of much alkaline earth 

 carbonate, become very favorable they develop so vigorously that they produce 

 the effects recorded in this bulletin. These organisms thrive in some of our 

 best cultivated lands, and some of the anomalies of our agriculture are probably 

 due to them. 



" The very considerable amounts of nitrates found in some of our soils, to- 

 gether with the large areas so enriched, and their wide distribution, suggest the 

 I)robability that the formation of the nitrates of Chile and Peru may have been 

 due to the agency of these organisms." 



A thorough bacteriological study of the subject is in progress. 



Experiments on the influence of sterilization of the soil on the growth of 

 plants and on the soil, K. K. Gedroitz (Tritdui Selsk. Khoz. Khim. Lab. St. 

 Petrrh., 6 (1909), pp. 30'i-SJi2; ahs. in Zhur. Opuitn. Agron. (Rnss. Jour. Expt. 

 Landw.), 10 (1909), No. «, pp. 8Ji6, 8.',7). — Some of the changes in the soil 

 which are caused by sterilization, such as the increase of the solubility and 

 assimil:d)ility of the nutritive substances and the increase of the absorption ca- 

 pacity of the humus, are unqualifiedly useful for the plant. Other changes due 

 to sterilization, on the contrary, may prove to be unfavorable for the growth of 



