Stable manures are universally regarded as the most valuable fertilizing materials for the growing of all classes of vegetables upon all types of soils. This is a very broad statement, but it is not likely to be challenged, since the most successful vegetable growers in all parts of the world place their main dependence upon stable manures. In many instances applications of special fertilizers have a more marked effect for the season or possibly for several seasons, but their long-continued use without additions of vegetable matter to the soil is always disastrous. It is true that examples can be cited of gardening operations that have been conducted for many years without any increase in the supply of vegetable matter, but in all such cases the supply of humus is very large to begin with. Muck soils are often farmed for a long term of years without manure, but even upon these soils stable manures are highly beneficial.
Market gardeners are especially dependent upon the use of stable manure, because there is no interval between crops for the growing of green manures. Near all our large cities immense quantities of manure are used by growers following intensive methods. In trucking or farm gardening, however, growers are learning to rely mainly upon cover crops and green manures, so the demand from this class of producers is not quite so great, perhaps, as a few years ago. But there are many instances of manure being shipped hundreds of miles. One very extensive grower on the eastern shore of Maryland declares that he could not be successful in producing melons and cucumbers without stable manure shipped from Philadelphia and New York.