51. Similar variations of plant parts may be
observed as a direct result of varying the amount of available
water. In general then, it may be said that the roots of dry-farm
crops are well developed; the parts above ground somewhat dwarfed;
the proportion of seed to straw high, and the proportion of meat or
nutritive materials in the plant parts likewise high.
The water in dry-farm crops
One of the constant constituents of all plants and plant parts is
water. Hay, flour, and starch contain comparatively large quantities
of water, which can be removed only by heat. The water in green
plants is often very large. In young lucern, for instance, it
reaches 85 per cent, and in young peas nearly 90 per cent, or more
than is found in good cow's milk. The water so held by plants has no
nutritive value above ordinary water. It is, therefore, profitable
for the consumer to buy dry foods. In this particular, again,
dry-farm crops have a distinct advantage: During growth there is not
perhaps a great difference in the water content of plants, due to
climatic differences, but after harvest the drying-out process goes
on much more completely in dry-farm than in humid districts.
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