126 PLANT LIFE ON THE FARM. 



The varying effects of season, according to the nature 

 of the manure employed, suggest also that a variety of 

 manures should be used. In the Kothamsted experiments, 

 it has been shown that the seasons which proved most 

 propitious to the unmanured crops, and to those to which 

 only mineral manures were applied, were not equally so 

 for the crops to which nitrogenous manures were applied ; 

 hence, says Sir J. Lawes, "the best season for land in low 

 condition is not the best for land in high condition." 



The varying effects of manure may be illustrated by a few 

 figures taken from the Kothamsted "memoranda": thus, in 

 the case of wheat, the average produce per acre over 30 

 years, was about 13 bushels on the unmanured plots, as 

 against 35 on highly manured plots (mineral and ammonia 

 salts, and mineral and nitrate respectively), some plots also 

 producing the largest quantities of straw, the nitrate pro- 

 ducing rather more than the ammonia. The quality of the 

 produce of wheat as measured in Ibs. per bushel is not so 

 different, that on the unmanured plots being usually nearly 

 equal to that of the highly manured plots. From this point 

 of view, farmyard manure proved more beneficial than the 

 artificial nitrogenous and mineral manure yielding the 

 largest quantity of grain. The corresponding figures 

 in the case of barley, are 17 and 49 ; the highest produce 

 was with farm-yard manure, and the highest quality with 

 that and with nitrate and minerals, but the largest amount 

 of straw was yielded with a manure containing a large 

 proportion of nitrate of soda with minerals. Of hay, the 

 average produce under like circumstances over 20 years, 

 was 21 cwts. on the unmanured, and 62 cwts. on highly 

 manured plots (mineral and ammonia). 



In like manner, turnips varied from 1 or 2 tons per acre 



