Where manure is not available or where it
cannot be applied in sufficient amounts, commercial fertilizers may be
resorted to, after they have been experimentally tested out.
Leguminous cover crops are the best source of nitrogen, as has been
indicated, but where these do
not grow well, or in seasons when they
have for some reason failed, nitrate of soda or dried blood are good
substitutes. From two hundred to three hundred pounds of one or the
other of these may be applied broadcast in the spring soon after
growth is well started and all danger of its being checked by frost or
cold weather is past. It is well to apply the nitrate of soda in two
applications a few weeks apart, especially on soils which are leachy
and in wet seasons, as part of the nitrogen may leach away if all is
applied at once. These should be thoroughly worked into the soil with
a spring-tooth harrow.
To supply the other two elements, from two hundred to four hundred
pounds of treated rock phosphate or basic slag for the phosphoric
acid, and the same amount of sulphate of potash for the potash, should
be applied at any time in the early part of the season, preferably
just before a light rain, and worked into the soil as before.
Home-made wood ashes are a good source of both these elements, and
especially of the potash. They cannot be purchased economically in any
quantity, but on the general farm there could be no better way to
utilize the wood ashes made around the place than by applying them two
or three bushels to a full grown tree every year or two. Wood ashes
are also a good source of lime, being about one-third calcium oxide.
Thus a large amount of available plant food will be supplied to the
tree, and where it is needed should result not only in better wood
growth but in the formation of vigorous leaf and fruit buds for the
Lime is not usually considered as a fertilizer except on soils
actually deficient in it. But it will usually be advisable to apply
from one thousand five hundred to two thousand pounds of fresh burned
lime or its equivalent, in order to correct any natural soil acidity,
to hasten the decay of organic material, to increase the activity of
the soil bacteria, and to improve the physical condition of the soil
by floculating the soil particles and helping to break up lumpy soils.
Lime also helps to liberate plant food by recombining it with certain
other elements in the soil. All these effects make a more congenial
medium for the leguminous crops to grow in, and it is frequently
advisable to use lime for this purpose alone. After this first heavy
application about 800 pounds of lime should be applied per acre every
four or five years.
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