SCIENTIFIC AGRICULTURE. 188 



less, upon the supposition that all the objects accomplished by 

 it, may be also by the application of manures. The proposal 

 to substitute manures, is of course equivalent to an admission 

 that fallow is beneficial to the soil. Now if any change takes 

 place in the soil while lying in fallow, we must first know what 

 that change is before we can determine whether manures will 

 affect the same change : and in order to know this, we must 

 have an exact analysis of the soil, before the fallowing begins, 

 and at the end of its term ; this will show what new elements 

 are formed, and what old ones are decomposed. 



If, tlven, we have a manure which will furnish to the soil all 

 the elements which were formed by chemical action during fal- 

 low ing, it will fulfil the same indication. But in either case, 

 an analysis of the soil is requisite before the fact can be estab- 

 lished : and inasmuch as those who discard fallowing, have 

 made no such analysis, they have made no demonstration of 

 the truth of their position. And until farther facts are de- 

 veloped by chemical experiment, it may be fairly questioned, 

 whether, on all soils, and under all circumstances, fallow can be 

 dispensed with. The benefits to be derived from allowing land 

 to lie in naked fallow are enumerated by Johnston as follows : 



1. In strong clay soils, fallow affords opportunity for destroy- 

 ing weeds, which it is difficult to extirpate while the land is 

 continually bearing crops. 2. The weeds and herbage which 

 spring up during summer, afford an abundant crop for green 

 manure : they should be ploughed under before their seeds 

 ripen. 3. Land which is continually cropped, becomes ex- 

 hausted of certain elements within the depth to which their 

 roots extend. By leaving the soil at rest, the rains which fall 

 and circulate through it, equalize the distribution of the solu- 

 ble substances which it contains. The water which in dry 

 weather, ascends by capillary attraction from below, brings up 

 Baline compounds and deposits them as it evaporates. 4. Some 

 subsoils require to be turned up and exposed to the action of 



