34 BULLETIN" 1082, U. S. DEPARTMENT OF AGRICULTURE. 
perfect bulb coats in the merchantable sizes when dug. The plant- 
ing was on newly cleared cut-over Whatcom silt loam which had 
received an application of 12 loads to the acre of half-rotted stable 
manure in May previous to planting in August and one crop of rye 
turned under. The size of the bulbs under these conditions was 
very much larger than normal, measuring fully 13 centimeters as 
against 9 or 10 centimeters under low fertility and 10 to 11 centime- 
ters for the optimum. 
THE SOURCE OF THE FERTILITY. 
One thing above all others should be impressed upon the American 
tulip grower, i. e., that cow dung is not the only source of fertility 
that can safely be used; indeed, in fertile soil with good cover crops 
no animal manure may be necessary. 
Stable manure from which the "fire" has gone seems to be as good 
as any fertilizer. Sheep manure gives good results, and bone meal 
can not be surpassed, but it is too expensive for liberal use. 
The nature of the soil will have a great deal to do with the kind of 
fertility demanded. On our heavy silt loams humus is needed to 
give porosity and tilth and opportunity for percolation of water, 
which these soils do not naturally have. 
To put the matter tersely, the crop is no more exacting in the 
nature and origin of its required fertility than any other farm crop. 
It demands plenty of it, but is not particular as to its source, which 
means, as in other farming operations, that the grower will resort to 
whatever source of fertility is available to him. Commercial fer- 
tilizers can best be supplemented by cover crops and other means 
of adding humus. 
DISPOSAL OF CROP RESIDUES. 
As with many other horticultural crops, care should be exercised 
in the handling of the refuse from tulip-bulb production. This 
should not be burned or otherwise wasted, but should be handled so 
as to avoid its use on land which is to grow tulips or other bulbs, as 
an added precaution against the spread and accumulation of the 
spores of fungi which cause diseases. This is a very important 
matter and should not be overlooked. 
This debris, made up largely of stems and leaves hoed off the beds 
at digging time, flowers cut off before the petals drop, old coats, and 
imperfect, rotted, and undersized bulblets, cleaned out of the stock 
during the time it is in the bulb house, should be composted and 
thoroughly rotted before being used on any ground; otherwise the 
bulbs will come up as weeds in other crops and be a source of annoy- 
ance and loss indefinitely. There are few weeds more persistent in 
cultivated fields than tulips which have been left undug or plowed in 
with unrotted compost. 
