104 
Ploughing-ia Green Crops. 
dry climate.) Or ajjain it may depend on the quantity of tops, 
which varies considerably as a j^eneral rule, an increased rainfall 
producin": a greater weight of tops : the quantity is likewise 
greater when early storing is practised. I find the average 
weight of tops left by a good crop of mangold or swedes to be 
about 4 tons per acre when taken up during the early part of 
November. 
Where potatoes are much cultivated, the haulm or top should 
invariably be returned to the soil, either by being ploughed-in or 
by adding it to the manure-heap, as in vine-growing districts the 
prunings of the vines are always returned to the roots of the trees. 
1 have frequently noticed the more observant and industrious of 
our cottagers carefully collecting and at once digging-in the tops 
of their early-lifted crops of potatoes, in order to supply food for 
the succeeding crop of cabbages or brocoli, which on well- 
managed cottage gardens generally follow an early-lifted crop 
of potatoes. Of green-manures, that have been partially 
consumed on the land, the most familiar in practice are clover- 
stubble, pastured-seeds, rape or coleseed, rye, vetches, <Scc. 
These, when partially returned to the soil in their green state, 
produce a double effect, as they act both chemically and 
mechanically — chemically, as on decomposition they form food 
for a new race of plants ; mechanically, as in strong clays they 
increase the porosity of the soil, and by allowing the air to per- 
meate more freely heighten the temperature, whilst on light 
sandy land the roots bind the soil together, imparting firmness 
and tenacity. All who are practically acquainted with the 
management of light lands know the difficulty and uncertainty 
of growing a good crop of wheat when the previous crop of clover 
has failed ; whilst on every class of soils the wheat-crop is greatly 
benefited by the ploughing-in of a good crop of clover or grass, 
particularly where early ploughing is practised. On light land 
furrow or wheel pressing is beneficial, and the land should remain 
a considerable time after ploughing before the seed is deposited, 
otherwise the vegetable acids which are formed during the earlier 
stages of the decomposition of the green-manure prove injurious 
to and often endanger the life of the young plants. Experience 
and observation confirm me in the opinion that to this cause may 
be traced the failure of or thinning of the young wheats. 
On a light-land farm, managed on the five-course system with 
barley following wheat, we have for several years adopted the 
practice of mowing or cutting the wheat by machine, and as soon 
after harvest as circumstances would permit, the land was autumn- 
cultivated and thoroughly cleaned from weeds. If the horses can 
be spared from preparing the clover-layers for the wheat-crop, the 
land is at once ploughed and sown thickly with common turnip- 
