140 Principles of Plant Culture. 
° 
Secrion V. THe Puant as AFFECTED BY UNFAVORABLE 
Foop SuprLy 
A— By ExcesstvE Foop 
249. We saw (62) that water is the most important con- 
stituent of plant food, and we have already considered (Sec- 
tion III) the plant as affected by water supply. But a 
proper supply of the other essential food constituents is only 
second in importance to that of water. 
Excessive food is not the extreme that we have most to 
fear, since natural soils are very rarely excessively fertile, 
and we can only make them so by costly methods. Indeed, 
nearly all the constituents of plant food may be present in 
excess of the plant’s requirements without working harm. 
Nitrogen, however, which, aside from water, is the most 
potent food constituent, must be used with some discretion. 
250. Excessive Nitrogen Stimulates Growth at the 
expense of flowers, seed and fruit. In crops grown for these 
parts, therefore, fertilizers rich in nitrogen must be used 
with caution. Apple, pear and quince orchards, liberally 
manured with such fertilizers, produce an excessive, over- 
succulent growth of wood, that is subject to blight and 
winter injury, and forms comparatively few fruit buds. 
Grain under similar conditions forms long, weak straw, 
with poorly-filled heads. Grape vines on over-manured 
ground produce excessive wood with few and late-ripening 
bunches. 
There is little danger of over-manuring, however, with crops 
grown for parts other than fruit or seed, so long as stable 
manures are used. But the more concentrated animal ma- 
nures, as those from poultry and the hog; the chemical 
