ENGLISH AGRICULTURE. 167 



examining the barley plots which have been continuously 

 manured with superphosphate we find the yield forced up 

 to twenty-two and a half bushels per acre, which contrasts 

 remarkably with seventeen and a half bushels upon the 

 unmanured plots. This is the result on barley. 



In the case of wheat the superphosphate alone increases 

 the yield from thirteen up to sixteen bushels per acre. Just 

 pause for a moment to consider this important point. Why 

 has the superphosphate acted more distinctly in the case of 

 barley than in the case of wheat ? The reason appears to be 

 that the barley occupies the ground for a shorter period, and 

 is a surface feeder, and therefore it is more dependant upon 

 its food being close at hand. In the second place, land in- 

 tended for barley is reduced to a very fine tilth in the 

 month of March or April, and there is not the slightest 

 doubt that the open nature of the seed-bed for barley causes 

 nitrification to go on in a very brisk manner, and therefore 

 enables the barley to seize upon and to appropriate a larger 

 amount of mineral food. This is not the case with wheat. 

 The ground is close and compact in the case of winter-sown 

 wheat, and the application of superphosphate is probably not 

 assisted by that amount of nitrification which we know is so 

 necessary in order to enable the plant to take up mineral 

 constituents from the soil 



Take, in the next place, mineral applications consisting of 

 all the ordinary mineral materials supposed to be necessary 

 for the growth of plants. They are chiefly in the Eothamsted 

 series represented by sulphate of potash, sulphate of soda, 

 sulphate of magnesia, and superphosphate of lime. It is 

 noteworthy that the effect produced by such applications is 

 bat little better than what is obtained by superphosphate 

 alone. Thus you find not only sulphate of potash, sulphate 

 of soda, and sulphate of magnesia produce but little effect 

 over unmanured plots, but likewise that these three sub- 





