It will be seen from a study of various soil types cited that the value of a soil for trucking purposes is determined largely by its texture. The value of a soil for very early truck depends mainly upon the amount and size of sand. That is, coarse sand is a "quick" soil, because it is well drained and dries out and consequently warms up very early in the spring, and makes early planting possible. Again, the coarse sands are warmer during the entire period of growth, thus hastening early maturity. Such soils require a large amount of vegetable matter. Liberal fertilizing and irrigation are usually a great advantage. The medium sands are not quite so early, but are more productive and somewhat more retentive of moisture and plant food. The fine sands are often our best trucking soils. Although not quite so early as the coarse and the medium sands, they are usually more productive. The silt and the clay soils are often valuable for late crops, and the maintenance of fertility is less expensive on the heavier types.
The soils of the most important trucking regions of the United States contain considerable sand. The advantages of sand in soils for vegetables may be enumerated as follows: (1) The land warms up earlier in the spring and maintains a higher temperature than heavy soils do; (2) fertilizers act more quickly; (3) tillage may begin earlier in the spring and continue later in the fall; (4) tillage is less expensive; (5) tillage may begin sooner after rains; (6) transplanting is facilitated; (7) the harvesting of many crops is facilitated; (8) soils do not become so hard and compact when harvesting crops, especially when the ground is wet; (9) sand lends itself to irrigation because the water is quickly absorbed; (10) the root crops are smoother, better formed and have fewer fibrous roots; (11) many crops require less work in cleaning and preparing for market.
Other things being equal, the smaller the particles the greater is the absorptive power of the soil. Silty soils suffer less from drouth than sandy soils; hence it is more important to be prepared to irrigate the sandy types. The production of large crops of high quality requires a constant and abundant supply of moisture, and the ability to meet the needs of the growing crop determines the value of a soil to a great extent for trucking purposes. A well drained subsoil is important, and yet it should have strong capillary action. The depth of the water table is an important factor in relation to soil moisture. In small areas of trucking soils it is within a few feet of the surface and such soils are highly valued for gardening purposes.
Good drainage is essential to every garden crop. Some vegetables stand wet soils better than others, but no crop thrives in a water-logged soil. Good drainage is especially important for early truck, hence the value of the coarser sands to supply early markets. Artificial drainage is a profitable investment on many soils devoted to commercial gardening.
While it is necessary to have an adequate supply of available plant food, the physical composition of the soil is of much greater importance than the chemical. It is a simple matter to supply fertilizers, but practically impossible to make good truck soils out of some types. Manure or green crops may be used with the utmost freedom. Although these greatly improve the heavier types, they will not make ideal soils for garden crops. The proper chemical composition of truck soils, however, is important and this matter should receive the most careful consideration. See Chapter VII (Commercial Fertilizers) on the use of fertilizers.
Soils differ greatly in their adaptation to various crops. Late cabbage, for example, succeeds on very heavy soils, while the lighter types produce good early cabbage. Lima beans do best on sandy soils, while field beans prefer the heavier types. These illustrations simply serve as examples. More definite information is given in Chapter XXI (Cultural Directions. Artichoke, Asparagus), which is devoted to the culture of various classes of vegetables.