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SCIENCE 



[N. S. Vol. XXXVI. No. 932 



farm land, and by a large decrease in our 

 exportation of food stuffs; and the fact 

 must be plain that before another decade 

 shall have passed we shall reach the prac- 

 tical limit of our relief in both of these 

 directions. 



Indeed, a most common subject already- 

 discussed in the press and investigated by 

 national, state and city authorities during 

 the last three or four years is the high cost 

 of plain living. 



"With these facts and statistics before us, 

 let us consider the actual results secured 

 from field and laboratory investigations: 



Where wheat has been grown every year 

 since 1844 on Broadbalk Field at Rotham- 

 sted, England, the average yield for fifty- 

 five years has been 12.9 bushels per acre 

 on unfertilized land, 35.5 bushels where 

 heavy annual applications of farm manure 

 have been made, and 37.1 bushels per acre 

 where slightly less plant food has been 

 applied in commercial form. 



Barley grown every year on Hoos Field 

 at Rothamsted has produced, for the same 

 fifty-five years, an average yield of 14.8 

 bushels on unfertilized land, 47.7 bushels 

 with farm manure and 43.9 bushels where 

 much less plant food was applied in com- 

 mercial form. 



Potatoes grown for twenty-six consecu- 

 tive years, also on Hoos Field at Rotham- 

 sted, produced, as an average, 51 bushels 

 per acre on unfertilized land, 178 bushels 

 Avhere farm manure was used (reinforced 

 with acid phosphate during the first seven 

 years), and 203 bushels where plant food 

 was applied in commercial form. The first 

 year of this investigation the unfertilized 

 land produced 144 bushels, land receiving 

 farm manure alone produced 159 bushels 

 and land fertilized with commercial plant 

 food produced 328 bushels per acre. 



Director A. D. Hall, of the Rothamsted 

 Experiment Station, makes the following 



statement on pages 95 and 96 of his book 

 on "The Rothamsted Experiments": 



On the plots receiving farmyard manure, and 

 even on those receiving only a complete artificial 

 manure, the crop was maintained in favorable 

 seasons. No falling-off was observed which could 

 be attributed to the land having become "sick" 

 through the continuous growth of the same crop, 

 or through the accumulation of disease in the soil. 



In commenting upon these same experi- 

 ments, Milton Whitney, Chief of the 

 United States Bureau of Soils, makes the 

 following statement in Farmers' Bulletin 

 No. 257, page 14: 



One of the most interesting instances going to 

 show that toxic substances are formed and that 

 what is poisonous to one crop is not necessarily 

 poisonous or injurious to another is a series of 

 experiments of Lawes and Gilbert- — the growing 

 of potatoes for about fifteen years on the same 

 field. At the end of this period they got the soil 

 into a condition in which it would not grow pota- 

 toes at all. The soil was exhausted, and under the 

 older ideas it was necessarily deficient in some 

 plant food. It seems strange that, under our old 

 ideas of soil fertility, if the soil became exhausted 

 for potatoes, it should grow any other crop, 

 because the usual analysis shows the same con- 

 stituents present in all of our plants, not in the 

 same proportion, but all are present and all neces- 

 sary, so far as we know. This field was planted 

 in barley, and on this experimental plot that had 

 ceased to grow potatoes they got 75 bushels of 

 barley. 



If, now, we turn to the actual records of 

 the Rothamsted experiments we find that 

 the first crop of barley grown after twenty- 

 six years of potatoes was 33.2 bushels per 

 acre on unfertilized land, only 24.8 bushels 

 where minerals alone had been used and 

 the soil depleted of nitrogen by the potato 

 crops, 67 bushels per acre where minerals 

 and nitrogen had been used, and 72.4 bush- 

 els where farm manure had been applied 

 for twenty-six years. We also find in 

 strict harmony with Director Hall's state- 

 ment, that the largest average yield of 

 potatoes from the farm manure plots (3 



