354 VALUATION AND PURCHASE [chap. 



manures arc adjusted to the various crops in the 

 rotation, and partly because it is generally advisable to 

 apply the nitrogenous fertilisers as top dressings at a 

 later period than the phosphatic or potassic manures. 



One other question of valuation and price comes 

 into play in connection with fertilisers, and that is the 

 value of the residues left behind in the soil after one or 

 more crops have been grown. The provisions of the 

 Agricultural Holdings Act of 1900 award the tenant 

 compensation for any unexhausted fertility he has 

 brought to and leaves behind on the holding, A 

 tenant, for example, who has given his grass land a 

 dressing of 10 cwts. per acre of basic slag and then 

 leaves his farm within the following two years will by 

 no means have rcajxrd the full benefit the land has 

 derived from its treatment On the other hand, a 

 tenant who has used nitrate of soda to grow his last 

 crop of oats or wheat, and then sells the grain pro- 

 duced, will have obtained all that the manure can 

 return ; no nitrogen will be left behind in the soil for 

 the benefit of the succeeding tenant. 



It is thus necessary to consider each fertiliser 

 separately and attach some value to the residue left 

 behind after one or two crops have been grown since 

 its application. It cannot, however, be said that proper 

 data exist for the compilation of such a scale of com- 

 pensation ; it is not sufficient to estimate what propor- 

 tion of the fertilising materials that have been applied 

 the crop may be expected to remove, and then assume 

 that the remainder is available for future crops. 

 Experiments already (juoted will have served to 

 show that residues of slow-acting fertilisers, such as 

 farmyard manures and shoddy, are very far from being 

 wholly recovered even after such long intervals of time 

 as would render any compensation quite out of the 



