98 THE CLOVER CROP. 



which our system of rotation farming is based. At the 

 same time, we must recollect that the clovers require a 

 larger proportion of lime than most of our other " Farm 

 Crops," and that if. this be not present naturally in the 

 soil, it is desirable that it should be added to it in the 

 form of some calcareous application. For this purpose 

 gypsum (sulphate of lime) is very commonly used, and 

 generally with very satisfactory results. 



The proper place for clover in the rotation is between 

 two straw crops, and this place it almost invariably 

 occupies. This practice, which in itself is based upon 

 sound principles, would admit of no question or com- 

 ment were the clover cultivated in the rotation as a 

 separate crop. Such, however, is very rarely indeed the 

 case. In well-nigh every instance it is accompanied by 

 other plants rye-grass most Commonly differing from 

 it widely in botanical characters, and belonging, indeed, 

 to the same " order" to which both the preceding and suc- 

 ceeding straw crops belong thus ignoring in every way 

 the principles upon which a rotation of crops is based, 

 and neutralizing to a great extent the good we are taught 

 to expect from a change of crops judiciously arranged. 

 The evils resulting from a continuous cultivation of the 

 same crops on the same ground are known practically to 

 every one. We find that under ordinary circumstances not 

 only does the produce diminish every year, but that the 

 health and vigour of the plants are also affected, and that 

 the injuries they sustain from their insect enemies become 

 more serious, as the insects infesting the crops are thus pre- 

 served from the crop of one year to that of the next. Thanks 

 to chemistry, we now can understand clearly some of the 

 causes why such effects should be produced. Investigations 

 into the analytical composition of our various cultivated 

 plants show that all plants belonging to the same natural 

 order take the Graminece, for instance possess a great 



