No. 4.] SOIL FERTILITY. L39 



improve the physical condition of the soil. A strenuous 

 advocate of the position taken in Bulletin No. 22 said to me 

 that he would use all the farm manures possible on the soil 

 of Long Island, which is notably light and over many areas 

 is of a very low degree o'f fertility ; but this advocate of the 

 dominance of soil physics declared he would not use such 

 maimres because of the nitrogen, phosphoric acid and potash 

 which they contain, but because they consist largely of 

 organic matter. For myself, I am not prepared to abandon 

 the old theories of feeding plants. Indeed, there is little 

 reason for forsaking some of the fundamentals of plant nutri- 

 tion as we now understand them. Who has not seen the 

 roots of a plant centring around a bone which has been 

 buried in the soil. Is this because of a better soil texture? 

 What intensely luxuriant growth is induced where the car- 

 cass of an animal has been buried ! Is this due to better 

 water supply, finer texture of the soil, or any other condi- 

 tion excepting that of an over-abundant supply of plant food ? 

 What marked etfects follow the application of nitrate of soda 

 to a field of wheat, not only increasing very materially the 

 growth of straw, but causing a much darker foliage ! Have 

 two or three hundred pounds of nitrate of soda so materially 

 modified the water supply or the physical conditions of an 

 acre of land as to cause this marked result? We have all 

 of us noticed that where the old-fashioned and somewhat 

 irrational method of dropping a handful of fertilizer in a hill 

 of corn or potatoes has prevailed, spots of luxuriant growth 

 have been seen in the grass field for several successive years. 

 Are these merely spots of favorable soil texture and water 

 supply? Is it fair to say that in the Lawes and Gilbert's 

 notable experiments the decreasing yield of wheat on the 

 umnanured plots and the persistent or increased produc- 

 tion on those which have received commercial fei-tilizers are 

 wholly due to a nu)dificati<)n of physical conditions? Is the 

 fertility of farms which have been well managed and well 

 fertilized due wholly to a deference, conscious or uncon- 

 scious, to the principles of soil physics, and is the sterility 

 of the farm which we call exhausted wholly a matter of water 

 supply and soil texture and temperature? To conclude that 

 in till these instances Avliidi T have numtioncd the su])ply of 



