On Rotations of Crops. 381 



advantages, it was found, that wheat could not be grown 

 with success, on light lands, every other year, for any length 

 of time. After practising it for fourteen years, the result 

 was, that though by the force of manure, abundance of straw 

 could be grown every other year, yet the wheat was light 

 and unproductive. Instead of the second crop of wheat, 

 therefore, oats were preferred (* 6 ). 



The rotation of four crops, adopted near Edinburgh, 

 namely, 1. Potatoes ; 2. Wheat ; 3. Clover ; and, 4. Oats, 

 is a very productive one, but is only calculated for the 

 neighbourhood of great towns, where there is an ample 

 command of manure, of a superior quality, and a demand 

 for potatoes. It appears from the experience of that neigh- 

 bourhood, that there cannot be a better preparation for 

 wheat than potatoes, nor one more valuable in respect to 

 produce, and that the crop of clover afterwards, is abun- 

 dant (** ' ). It has been objected to that system, that potatoes, 

 instead of enriching, rather exhaust the soil, and tend to 

 render the ground so loose and open, as to endanger the 

 crop of wheat being thrown out of the ground during the 

 frosty season. But the practice is attended with this ad- 

 vantage, that the crop is less apt to suffer from the rust, the 

 injurious strength of the dung being exhausted by the po 

 tatoe crop, and that by rolling, the risk of the crop being 

 thrown out, may be prevented. 



In regard to the practice of raising one, and in some cases, 

 two crops of wheat in the four years' rotation, Mr Blaikie 

 remarks, that growing so exhausting a crop as wheat so fre- 

 quently, can only be successfully adopted, where the land 

 is of a superior quality, and adjoins large towns, whence 

 street dung can always be had in abundance, and at a rea- 

 sonable rate ; but on inferior land, where that means of re- 

 storation is wanting, ought never to be attempted. Street dung 

 is certainly the best restorative to over-cropped land, for it 

 contains more of the elements of food for plants, than any 

 other manure in common use. Copious dressings of farm- 

 yard dung, will force abundance of straw, but will not re- 

 store over-cropped land to such a state of fertility, so as to 

 be productive of grain ; whereas street dung, under similar 

 circumstances, produces both straw and corn in abundance. 



Five Years? Rotation. Rotations of jive crops, have in many 

 cases been recommended, both for strong and light lands. 



The following system has been long practised in the neigh- 

 bourhood of Glasgow : 1. Potatoes ; 2. Wheat ; 3. Grass ; 



