339 



"Human manure is the most highly prized, although a friend told me that 

 the manure from silk worms was even more valuable. Dog manure, pig 

 manure, cow manure, and water buffalo manure are prized in about this order." 



Thus do the people of China follow the products of the land to 

 the place of consumption and return to the soil every possible 

 recoverable residue, and to this are added a large use of legume 

 crops and applications of muck, marl, lime, etc., and silt deposits 

 on overflowed or irrigated lands. 



The following quotations from circular letters from Doctor Al- 

 fred M. Peter, Head of the Division of Agricultural Chemistry of 

 the Kentucky University Agricultural Experiment Station, will 

 be of interest to the student (see also pages 263-267, Vol. i, 

 Journal of Industrial and Engineering Chemistry, April, 1909): 



"LEXINGTON, KY., January 21, 1909. 



''DEAR SIR: 



" In a 'Hearing before the Committee on Agriculture of the House of Repre- 

 sentatives,' 1908, Doctors Whitney and Cameron of the Bureau of Soils have 

 made statements to the effect that the recent teachings of the Bureau in regard 

 to soil fertility are generally accepted throughout this country and Europe, and 

 that they are being widely taught in the Agricultural Colleges of this country. 

 The teachings referred to, with which you are, no doubt, familiar, may be sum- 

 marized in the following statements: 



" i. That all soils contain enough mineral plant food in available form for 

 maximum crops, and that this supply will be indefinitely maintained. 



" 2. That the real cause of infertility is the accumulation in the soil of poison- 

 ous excreta from plant roots. 



"3. That it is not ever necessary to add fertilizers for the purpose of increas- 

 ing the plant food in the soil, the good effect of fertilizers being due to their 

 power of neutralizing or destroying these toxic substances or their activity. 



" 4. That soil fertility can be maintained indefinitely by practicing a system 

 of rotation by which a crop is grown each year that is not injured by the ex- 

 creta of the preceding crop. 



" In order to ascertain just how extensively these views are accepted and taught 

 in our Agricultural Colleges and Experiment Stations, the writer is sending 

 this letter to professors of agriculture, agronomists, and agricultural chemists in 

 all such institutions on the "Organization Lists." It is proposed to publish a 

 summary of the data obtained, without giving names of institutions or individ- 

 uals. Will you kindly assist by telling me whether or not these views are ac- 

 cepted and taught by you or your institution, or by referring this letter to some 

 one who will give me an authoritative answer ? 



" Yours very truly, 

 (Signed) "ALFRED M. PETER." 



