Humus, Fertilizers, Lime and Fertilizer Inspection 
Dr. H. J. Wheeler, Boston, Mass. 
HUMUS 
Before entering upon a discussion of 
fertilizers and their use, it is of first im¬ 
portance to speak of humus; since, if the 
soil is not adequately supplied with hu¬ 
mus, plants cannot make their best 
growth, neither can fertilizers exert their 
maximum effect. 
What is needed in Florida soils is not 
organic matter which has reached the 
most advanced stage of decomposition, but 
rather organic matter in the various stages 
of decomposition. I have known soils ex¬ 
ceedingly rich in organic matter, a large 
part of which had decomposed to such an 
extent and was in such a state that it 
could be dissolved from the soil by treat¬ 
ment with ammonia water; and yet these 
same soils were very unproductive be¬ 
cause of the need of organic matter in the 
earlier stages of decomposition. In gen¬ 
eral it is probably safe to state that the 
richer the plants are in protein, the chief 
nitrogenous constituent, the more quickly 
they decompose. On this account many 
of the non-legumes decompose rather 
more slowly and furnish organic matter 
in the various stages of decomposition for 
a longer time than the legumes do. 
Young and tender legumes decay very 
rapidly. In fact, they act almost as quick¬ 
ly as sources of available ammonia for 
plants as do certain of the well recognized 
organic materials, such as tankage and 
cottonseed meal. 
I recall experiments made several years 
ago, in which I grew the perennial flat 
pea for two or three years on the same 
land and then turned the crop under and 
sowed barley. The barley was much bet¬ 
ter than it was on adjoining land where 
flat peas had not been grown previously, 
and the crop appeared to be abundantly 
supplied with nitrogen. The next year, 
however, there was no appreciable in¬ 
crease in the crop where flat peas had 
been turned under a year before as com¬ 
pared with the plot where no flat peas 
had been grown. This showed that the 
nitrogen contained in the flat peas had 
practically all been utilized by the crop 
which followed or that it had been trans¬ 
formed into nitrates which had leached 
away. 
For crops or plants which may be in¬ 
jured by the presence of too much nitro¬ 
gen, particularly toward the close of or 
just following the rainy season, it might 
be better in some cases to use non-le¬ 
gumes as cover crops, rather than le¬ 
gumes. It is generally recognized, that 
certain crops or plants are more affected 
by various diseases if the plants are over¬ 
fertilized with ammonia at certain stages 
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