17 
ROTATIONS. 
The practice of some primitive system or other of rotating crops 
has apparently been followed from the very earliest times, and 
men have adopted the principle from their first attempts at 
growing cultivated crops. In Bible history, which is our oldest 
authentic record, we find the idea inculcated in the Mosaic laws, 
and what was practically a crude seven-years’ rotation was laid 
down as one of the rules of that dispensation. 
Coming down to classical times we find the idea enlarged 
on by the Roman and other writers — Virgil, Columella, Ovid, 
and several others giving instructions and references regarding 
the practice very frequently. Later on, in Saxon times, we 
meet with a sort of three-course shift — two corn crops and a 
bare fallow — practised on the small patches of arable land near 
the village settlements or homesteads in the days when little or 
nothing was known about manuring, when fallow crops were 
unknown, and only the natural fertility of the soil was 
depended on. 
The practical foundation of the system of rotating crops is 
the experience of generations of farmers including those of the 
present day, that if the same crop is repeated on the same 
field for even two years in succession the yield may deteriorate 
independently of season, cultivation, or any other circumstance, 
while if the repetition is continued the resultant crops, with 
some species of plants, will become worse and worse. 
Per contra , it has been found that if the successive crops are 
different the yield is better, and that, in the case of certain 
plants, the greater the number of yeai’S that is allowed to elapse 
before growing the same crop a second time on a given field 
the better are the results. This was the broad outstanding fact 
known to farmers since the earliest times from practical 
experience ; but it is only within the last century or so that 
we began to inquire into the reason why of this state of 
matters, and to understand when and how rotations might 
be followed, or modified, or departed from altogether, as 
circumstances allowed. 
The old restrictions in farm leases binding a tenant to a 
certain course of cropping and a certain method of using the 
crop were founded on the idea that a farm must be self- 
supporting manurially, and thus all fodder and roots were to 
he consumed at home to make manure for future crops. The 
discovery of so many varied forms of artificial manures and 
VOL. 69. 0 
