SOILS 49 
vegetables are grown successfully upon the heavier types 
of soils. In the forcing of vegetables sand, and pre- 
sumably fairly coarse sand, is more important than in 
trucking or market gardening. The air spaces between 
the particles are much larger in coarse-grained soils than 
in the fine silts and clays, and for that reason such soils 
are not so solid and compact. As explained by the fol- 
lowing statements, the open, porous character of sandy 
soils makes them peculiarly well adapted to the culture 
of greenhouse vegetables. 
(1) Tillage is less difficult and less expensive than in 
heavy soils. This factor is important in general farming, 
but vastly more important in the handling of greenhouse 
soils, since so much of the work must be done by hand. 
When plows and harrows can be used under glass, texture 
from the tillage standpoint is not so important. 
(2) Sandy soils are well aerated, and this condition 
accelerates chemical activity. In other words, oxidation 
is more rapid in sandy soils, fertilizers act more quickly 
and stable manures decompose and become available 
sooner than in heavy soils. 
(3) Sandy soils are valued for trucking and market 
gardening because they are light and warm, and crops 
mature earlier in them than in heavy soils. The same 
influence exists in the greenhouse, though to a less extent, 
because moisture and temperature conditions are arti- 
ficially controlled. In greenhouse management, time of 
maturity is determined mainly by the date of planting; 
nevertheless, sandy soils are favorable to rapid growth 
and quick maturity. 
(4) It is important for greenhouse soils to dry quickly 
on top after watering, because an excessive amount of 
moisture at the surface is conducive to plant diseases. 
This is especially true in lettuce culture. Surface 
evaporation is most rapid in the coarse sands and slowest 
in the fine silts and clays. 
