Field Crops

John H. Martin.

Climate, rather than soil, is the chief factor in determining where most field crops are adapted. Crop plants with fine, fibrous roots, including wheat, oats, and barley, are best suited to medium or heavy soils.

Plants with thicker roots, such as corn, alfalfa, and sugar beets, succeed well on sandy loam soils but also are well adapted to heavy soils.

Crops like grain sorghum often produce high yields on heavy soils in wet seasons in the drier regions but may fail on heavy soils in a dry year, when fair crops are obtained on sandy soils.

Soils that are high in nitrogen are unsuitable for small grains because excessive nitrogen encourages lodging and the development of rust and delays maturity. Those adverse effects, which seldom occur in other crops, such as sorghum and corn, can be avoided to some extent in small grains by applying phosphorus and potash.

The soil type has only a minor role in determining the adaptation of different varieties of a given crop, except as it affects the abundance of soil moisture or nitrogen. Differences in soil moisture, as influenced by local topography, however, may determine the best variety to be grown. Quick-maturing varieties having small plants thus may be best suited to rolling uplands, and larger and later varieties are best for rich bottom lands.

CEREAL OR GRAIN CROPS include barley, buckwheat, corn, grain sorghum, oats, rice, rye, and wheat.

Barley (Hordeum vulgare) requires a well-drained sandy loam to clay, which has a reaction of pH 6 to 8.5 and is 2.5 to 8 feet deep. It is very tolerant to salinity. It is more tolerant to sandy soil texture but less tolerant to acidity than are wheat and oats.

Buckwheat (Fagopyrum esculentum) needs a sandy loam to clay or drained marshland (pH 4.5 to 7.5) 2 to 4 feet deep. It is suited to infertile soils, especially those low in available phosphorus, and is very tolerant of acidity.

Corn (Zea mays) grows in well-drained, sandy to clay loam of a pH of 5.5 to 8 and 2 to 8 feet deep. Good fertility is essential for high yields, especially when corn is grown in thick stands. Corn responds well to abundant nitrogen. Calcareous soils are likely to be deficient in available potash and phosphorus.

Grain sorghum (Sorghum vulgare) requires well-drained sandy to clay soils 3 to 8 feet deep and having a pH of 5 to 8.5. It tolerates salinity. In semiarid regions it succeeds best on silt loam or clay loam soils in the wetter years and on sandy soils in dry years. Lighter soils provide better water infiltration and reduced vegetative growth, which lessens injury from drought.

Oats (Avena sativa and A. byzantina) grow in well-drained, fine sandy loam to clay, which has a pH of 5 to 8.5 and is 2.5 to 8 feet deep. Excessive soil nitrates favor lodging, and sometimes enough are absorbed by the plants to make oats hay poisonous to livestock.

Manganese deficiency sometimes is evident in oats grown on peat soils.

Rice (Oryza sativa) grows in loam to heavy clay (adobe) that has a retentive subsoil and a reaction of pH 4.5 to 7-5 and is 2 to 3 feet deep. The soil must be wet or flooded. It is sensitive to salinity in excess of 500 grains per gallon of water. The potash requirement is low, but abundant ammonium nitrogen is essential to high yields.

Rye (Secale cereale) is more tolerant of sandy soils than is wheat, oats, and barley. Rye grows in sand to clay soil of pH 4.5 to 8.5 and 3 to 8 feet deep.

Wheat (Triticum species) prefers well-drained silt loam or clay loam but will grow in fine sandy loam to clay pH 5 to 8.5; depth 2.5 to 8 feet. It requires balanced fertility and ample available nitrates to produce grain of high protein content.

FIBER CROPS include cotton, hemp, ramie, broomcorn, and flax.

Cotton (Gossypium hirsutum and G. barbadense) grows in soils that are sand to heavy clay, deep and well drained, reasonably high in organic matter, and pH 5.2 to 8 in reaction. Its indeterminate fruiting habit permits it to mature the number of bolls that can be supported by the extent of vegetative growth. Limited nitrogen reduces both total growth and yield. Deficiencies of potash cause extreme earliness and premature defoliation. Phosphorus is necessary for adequate maturity.

Hemp (Cannabis sativa) requires well-drained loam, silt loam, or clay loam; pH 5 to 7; 3 to 6 feet deep.

Ramie (Boehmeria nivea) grows in loam or muck, pH 5 to 7 in reaction, and 2 to 4 feet deep. Abundant fertility is necessary for successive heavy crops through the season.

Broomcorn (Sorghum vulgare): See Grain sorghum.

SUGAR CROPS include sugar beet, sugarcane, and sorgo.

Sugar beet (Beta vulgaris) grows in deep clay to silt loam, or sometimes fine sandy loam or muck, alkaline to slightly acid, well drained, and free from hardpan. It is very tolerant of salinity. It requires ample available phosphorus and responds to abundant nitrogen. It is sensitive to boron deficiency and to manganese deficiency on slightly alkaline soils in the Great Lakes region.

Sugarcane (Saccharum officinarum) needs loam, clay loam, or muck, including calcareous soils and soils derived from volcanic ash. Sandy loams require more moisture and fertilizers. The pH should be 5 to 8. Depth should be 1.5 to 5 feet, but the shallower soils are suitable only if moisture and fertility are abundant. Muck soils require applications of mineral fertilizers, except nitrogen, and usually such trace elements as iron, manganese, and copper.

sorgo (sweet sorghum) (Sorghum vulgare) grows in well-drained sand to clay loam pH 5 to 8.5, and depth 3 to 8 feet. Excessive nitrogen results in sorgo sirup of low quality.

AMONG THE OIL CROPS are castorbean, flax, mustard, mint, safflower, and sesame.

castorbean (Ricinus communis) grows in sandy loam to loam, 3 to 5 feet deep and pH 5 to 8 in reaction. It is not tolerant of drought during flowering.

Flax (Linum usitatissimum) grows in well-drained loam to clay loam pH 5 to 8 for seedflax and pH 5 to 7 for fiber flax. Alkaline soils are assumed to be unfavorable for the production of good linen fibers.

Yellow mustard (Brassica alba) requires fine sandy loam to clay. Brown mustard (B. juncea) grows in sandy loam. The reaction is pH 6 to 8. A soil depth of 3 to 5 feet is needed.

Mint (Mentha piperita and M. spicata) grows in sandy loam, loam, or muck of pH 6 to 7.5. It needs a constant supply of soil moisture.

Safflower (Carthamus tinctorius) grows in well-drained sandy loam to clay of pH 5 to 8 and a depth of 3 to 5 feet. It tolerates salinity.

Sesame (Sesamum indicum) needs well-drained sandy loam to clay loam, 3 to 5 feet in depth and pH 6 to 8.5 in reaction. It stands medium drought.

MISCELLANEOUS CROPS include hops and guayule.

Hops (Humulus lupulus) grow on deep, sandy, well-drained loam to loam soil,

6 to 8 in pH. Soil moisture must be adequate. Soils of high salinity are unsuitable.

Guayule (Parthenium argentatum), a rubber crop, needs deep sand to sandy loam, 5 to 8.5 in pH. It does not tolerate salinity. It is highly tolerant to drought after the plants are established because the roots may penetrate to a depth of 25 to 30 feet.