818 EXPERIMENT STATION RECORD. 



" The cost of producing such fertilizer, including pressing the sludge, drying, 

 grinding, and bagging, will vary somewhat with the size of the plant and 

 quantity produced, but should not cost over $1.75 per ton at any plant producing 

 10 tons or more per day." 



SOILS— FERTILIZERS. 



What the States are doing toward the conservation and improvement of 

 soil fertility, T. N. Carver (Orig. Commun. S. Intcnmt. Cong. AppL Chem. 

 [Washington and New York], 24 (1912), Sect. Xlb, pp. Jt1-5~, fig. 1). — This is 

 an address delivered before the Eighth International Congress of Applied Chem- 

 istry in which the author gives an account of the activities of the various States 

 in the promotion of irrigation and drainage work, the prevention of soil erosion 

 by forestation and other means, and the direct improvement and conservation 

 of the fertility of the soil by scientific methods of culture. 



The author maintains that " the only legitimate purpose of soil improvement 

 and conservation is to increase the product per man, and a larger product per 

 acre is desirable only when it gives us a larger product per man." It is a thing 

 to be shuimed " if it is to be secured by those forms of intensive culture which 

 are forced upon overpopulated coimtries where labor is abundant and cheap 

 and laud scarce and dear." Judged by the standard of utilizing labor so as 

 to secure the largest income per man or per family, and thus to live upon as 

 high an economic plane as possible, " our system of agi'icultural education makes 

 an excellent showing as compared with that of other countries, though there is 

 much to be done yet." 



Recent advances in agricultural science. — The fertility of the soil, A. D. 

 Hall {London: Roy. Inst. Great Brit., 1912, pp. 9; Nature [London], 89 (1912), 

 No. 2231,, pp. 61,8-651; Set. Amer. Sup., 71, (1912), No. 1\920, pp. 21,6, 2.^7).— This 

 is an address delivered before the Royal Institution of Great Britain in which 

 the author outlines three stages in the development of the agriculture of a 

 country, namely, (1) the period of exploitation, (2) the conservative period, 

 and (3) the period of intensive agriculture, illustrating each by farming 

 systems in vogue in different countries and tracing the inner history of these 

 three stages of agriculture by the records of certain experimental plats at 

 Rothamsted. 



It is shown that in maintaining the level of intensive production the losses, 

 particularly that of niti'ogen, due to bacteria in the soil, are increased out of 

 all proportion until there is i-ecovered in the crop only about one-fourth of the 

 nitrogen applied in the manure. Hence, there must be returned to the soil not 

 merely the nitrogen contained in the extra amount of crop produced but several 

 times that amount to repair the waste, and still greater amounts when the fer- 

 tility and the production are increased. 



In the author's opinion, therefore, the important problem in intensive agricul- 

 ture to-day is the reduction of this waste of nitrogen due to bacterial action. 

 He points out, on the basis of the work of Russell and Hutchinson at Rotham- 

 sted (E. S. R., 22, p. 121), that by putting the soil through various processes 

 of partial sterilization, such as heating or treatment with antiseptics like 

 chloroform or toluene, " we can eliminate certain organisms which keep in 

 check the useful bacteria in the soil, that is, the bacteria which break down 

 the nitrogen compounds to the state of ammonia, a form assimilable by 

 plants. ... At present the processes have not been extended to the open field, 

 but progress is being made in that direction, and give some promise of a 

 method by which ultimately the unseen fauna and flora of the soil will be 

 domesticated, the useful races encouraged, and the noxious repressed." 



