296 
Vuriations of the Four-course Si/slem. 
expensive to cultivate of the whole course, and seldom proves 
profitable to the cultivator. 
The nutritive value of the turnip crop varies considerably. 
Taking an average sample, one ton of swedes will not produce 
more than one imperial stone (of 14 lb.) of beef or mutton. 
The cost of production^under the four-course system where farm- 
j^ard manure alone is used would be at least 81. per acre, or 8s. per 
ton. Thus the meat, without the additional cost of labour, 
cannot be produced for less than 7d. per lb. 
The crop is not only the most costly to cultivate, it is also the 
most exhaustive of certain manurial constituents of any in the 
rotation. Formerly roots were fed in excessive quantities, and 
were usually given whole to cattle ; this entailed a considerable 
amount of exertion and expenditure of vital force. These roots, 
containing 90 per cent, of water, threw into the system a 
large volume of fluid at a low temperature, which could only be 
raised to the normal heat of the body by a considerable oxidation 
of carbo-hydrates. 
On light lands, that had long been woi’ked on the four-course 
system, it was well-nigh impossible with our knowledge of the 
subject a quarter of a century ago to grow a crop of broad clover. 
This was chiefly due to the repeated and exhaustive effects of 
the root crops, more particularly where the root crop was drawn 
off. Light lands began to show the injurious results at an 
earlier period, and in a more pronounced form, than the stronger 
and better class of loams. The cultivated grasses grown under 
this system were chiefly confined to the different vai-ieties of 
rye-grass, cocksfoot, and others natural to the soil, but all 
the members of the clover family were erratic and uncertain. 
In some cases the seeds were mown early and grazed during the 
latter part of the summer ; this, next to folding, was the best 
method of management. It prevented the formation of seed 
culms and the production of seed, an exhaustive process where 
the plant was thin and weak and closely grazed during the 
summer months. Considerable loss was entailed on the seed 
layers owing to the necessity of having to break them up in 
September. In the case of the wheat crop on the sandy soils 
the great difficulty was in getting the young plant to stand. 
It generally thinned off during the spring months, and early 
ploughing and drilling on a stale furrow were the best pre- 
ventatives. 
At one time autumn cultivation was much practised on light 
lands. When the soil was left throughout the winter without a 
covering of vegetation, the land suffered in condition from ex- 
posure to the winter rains. Where the weeds were destroyed, 
