2G2 On the Modifications of the Four-Course Rotation, S^-c. 
turnips, does suggest the desirability of cultivating a variety of 
green and root crops. 
There can be no doubt that, with our improved implements, 
autumn cultivation and artificial manures, a crop of turnips may 
be f/roirn on any land, however stiff, ])rovided it has first been 
thoroughly drained ; but the damage sometimes done in wet 
seasons by the treading of sheep in feeding off, or by the carts 
and horses, when the crop is drawn, seems at present to limit 
the breadth that can be profitably cultivated on such soils. 
Both rape and tares are extensively substituted for a portion 
•of the turnip-crop, and on manv soils with decided benefit. The 
former can generally be fed off before the land has become very 
wet, whilst early sown vetches afford a most valuable supply of 
green food, either for mowing or folding, after the turnips are 
■consumed, at a time of year when keep is often very scarce. 
I observe that the cultivation of mangold wurzel is steadily 
increasing throughout the country. It produces a greater weight 
per acre than any other of our root-crops ; and, according to the 
analyses published by Professor Johnston, contains about 15 per 
cent, of solid matter, Avhilst the turnip contains only about 12 
per cent. It is true that from being sown a month earlier than 
swedes, mangold requires an extra hoeing ; and that the fact of 
its not bearing frost entails an additional expense in getting it 
in ; but against this may l)e set its exemption from fingers and 
toes and mildew ; and on deep soils, where the treading of sheep 
is not beneficial, it will be found desirable to grow as much as 
can be readily drawn off and secured before the early frosts. 
On chalk and limestone soils, white mustard is not an unusual 
green crop. I have found it very useful for late autumn keep, 
sowing it as an extra crop on a wheat stubble, which may be 
raised by a Bentall or scarifier. Many persons recommend 
ploughing it in as a preparation for turnips, but experience on 
this point is very conflicting. In some cases great benefit has 
Tesulted to the succeeding crop, whilst in others there has been 
no perceptible difference. I am inclined to think that the effect 
of a green crop ploughed in, depends very much upon the 
amount of vegetable matter which the soil contains at the time,* 
and that on most soils feeding off is the most economical plan. 
By turning to account the choice afforded between the fore- 
going and other crops, and by ploughing up and cleaning as 
* The mechanical effect must not be overlooked. In this respect, a green crop 
ploughed in will exert a greater influence, whether for good or barm, than a 
dressing of fresh farmyard-manure. A good result may be anticipated on stiff 
soils if mustard is ploughed in in the autumn, and barley sown the following 
spring ; whereas, if wheat sowing follows iiiiniediately on the ploughing, frost 
may injure the wheat- plant in consequence of the open state of the land. — P. H. F. 
