SOIL EXHAUSTION AND ROTATION OF CROPS. 171 



tions which just maintain them without much gain or loss of 

 live weight, the daily urine usually contains rather more ni- 

 trogen than the dung. Sometimes the nitrogen of the dung 

 exceeds that of the urine, but while all the nitrogen of the 

 urine is adapted for immediate use as plant food, much of 

 that in the dung is comparatively inert. The urine contains 

 also more alkalies than the dung, but the dung usually con- 

 tains all the phosphoric acid and most of the lime. 



Measured by assimilable nitrogen or by alkalies, the liquids 

 are much tlie best ; measured by phosphates, the dung is 

 most valuable. Practically, however, we cannot make a sharp 

 separation. The solids nearly always absorb a good portion of 

 the liquids. 



I think I have now gone over about the ground that I con- 

 templated. At least, we have approached pretty near the 

 hour for dinner. With regard to the question about the im- 

 provement of pastures, there are a variety of ways in which 

 the land can be saved from being useless. One of the most 

 practical methods is to put on a top-dressing of some sort. 

 The fact that moss grows there indicates that the soil is get- 

 ting a little too moist, and it is a question whether plants will 

 do well unless that moist condition of the soil is somewhat 

 broken up. If those fields admitted of nnder-drainage, and 

 it did not cost too much, tliat would be an effectual remedy 

 against moss ; you would never see that again. My excellent 

 friend, Mr. Blakcslee, whispers to me, " Put on a flock of 

 sheep! " and that is also an excellent prescription. 



Mr. . We can't do it ; the dogs kill them. 



Prof. Johnson. . The treatment which the gentleman sug- 

 gests who asked the question, has nothing against it theoreti- 

 cally, and the fact that it has succeeded elsewhere shows it 

 must be a good plan. There is no reason why such land 

 should not grow into great value. If clover could be brought 

 in it would probably raise the land in a couple of years to the 

 productiveness that it had forty years ago, by simply bring- 

 ing up the materials which the roots of other plants cannot 

 get at. Probably any application containing lime or sulphate 

 of lime, leached aslies, oyster-shell lime, or any thing of that 



