MANURING 47 
the trees, do not plough deep in places where your 
ploughshare would be likely to encounter the roots of 
your trees. Four inches is quite deep enough close to 
the rows, though farther away you may, of course, 
plough deeper. 
You may continue to grow crops in between the trees 
until such time as the roots of adjacent trees and the 
spread of their branches nearly meet. As a broad rule, 
it may be taken that the roots reach as far away from 
the trunk of the tree as its branches spread. 
Manvrine.—An orchard in good trim, with the trees 
healthy and vigorous, and bearing well, but not too 
heavily, should be manured every second year, either by 
applying farmyard manure or by ploughing in a cover crop 
of green manure and letting it rot in the ground. Orchard 
trees need principally three manurial elements : nitrogen, 
which promotes the vegetable growth of wood and foliage ; 
potash, which supplies nutriment to the fruit, giving it 
quality, colour, and flavour ; and phosphoric acid, which 
puts its virtue into the buds and seeds. Farmyard 
manure furnishes all these elements in about the right 
proportions, and in a condition in which the roots can 
readily absorb what they want. A good cover crop 
ploughed in in the spring is almost equally efficacious. 
But it may chance that the trees need more of one or 
other of the three ingredients than these manures naturally 
supply. In that case they must be supplemented or 
replaced by artificial manures in varying proportions as 
the trees appear to need them. If you apply artificial 
manures only, a full dressing of each of the three elements 
would, as a genera! rule, require per acre : nitrate of soda, 
