398 INVESTIGATION BY CULTURE EXPERIMENTS 



nored in planning systems of permanent agriculture. With hay at 

 $15 to $25 a ton, which are common prices near the large Eastern 

 markets, very satisfactory profits may be made by top-dressing 

 timothy meadows with 200 pounds or more of sodium nitrate, or 

 with perhaps 300 pounds each of sodium nitrate, acid phosphate, 

 and kainit. As a rule, smaller applications will give the greater 

 profit for the money invested in fertilizers, but larger amounts may 

 yield still greater profit per acre, especially when the price of hay 

 is $20 or more. 



On the other hand, at the average prices that can be counted on 

 for the Central states, the data from the Rothamsted investigations 

 afford no evidence of profit from the use of commercial nitrogen or 

 potassium salts or acid phosphate or any combination of these ma- 

 terials, for top-dressing permanent meadows. 



ROOT CROPS ON BARN FIELD, ROTHAMSTED 



While some important experiments with turnips were made by 

 Sir John Lawes, even before 1840, the principal individual plot 

 records date from 1845; an d, with the exception of three years 

 when barley was grown without the annual fertilizing (1853- 

 l8 55)> root crops have been grown every year on this part of Barn 

 field. 



These experiments were made more extensive in 1856, as will 

 be seen from Table 71, which gives certain average yields in four 

 periods, from 1845 to 1870, and the detailed records of sugar beets 

 grown on these plots from 1871 to 1875, the last two years without 

 the full yearly application of fertilizers. The last column shows the 

 percentage of sugar in the beets in 1873, which was apparently a 

 normal season and the last in which the fertilizers were applied 

 in full for the sugar beets. From these data, the sugar per acre can 

 be computed, but it should be kept in mind that the yield of beets 

 is given in tons of 2240 pounds and for roots with only the leaves 

 removed. The fertilizers applied were in general the same as those 

 specified in Table 7 1 b. 



It will be seen that the first year sugar beets were ever grown on 

 thisfield the yield varied from 5 .o5tons to 28.90 tons, a fact which 



