Potato production in Germany is of two kinds. The crop of the west is grown mainly for table purposes, that of the east mainly for industrial purposes—though naturally much variation to this occurs at times. In eastern Germany there exist vast tracts of light sandy soil of little use for grass or cereal production, but by Potatoes, sometimes distinguished from sweet potatoes as white or Irish potatoes, hold first rank among the vegetables produced in the United States. The average annual production approximates nearly 400,000,000 bu., a per capita production of about four bushels. Americans eat comparatively fewer potatoes than the people of northern Europe, probably because of a greater diversity of other vegetables available to them. Per capita consumption for food is about three bushels. The late or main crop is grown mostly in the States bordering Canada where climate and soil are most favourable. The States leading in production are Minne sota, New York, Maine, Michigan, Wisconsin and Pennsylvania. Every State produces potatoes at some season but the surplus com mercial crop is grown mostly in the above-named States. Idaho, Colorado, California, Florida, South Carolina, New Jersey and Virginia ship many carloads to distant markets when potatoes from the North are scarce. The southern States grow the crop for northern markets in the winter and spring when the temperature is comparatively cool. Potato soils along the Atlantic seaboard are mostly of sandy loam and conduce to early-maturing, bright skinned, high-quality tubers.
grown commercially are mainly those which were originated by pioneer potato breeders 3o to 5o years ago. Some of these are products of hybridization, some were discovered as accidental mutations or "sports"; most of them represent chance seedlings. More recently, a few improved strains have been selected from existing varieties. These are higher yielding and have been given new variety names. The varieties Green Mountain, Norcross and Triumph originated by hybridization ; Pearl and Late Beauty of Hebron by mutation; Early Rose, Early Ohio, Burbank, Beauty of Hebron, Delaware, Sir Walter Raleigh, Carman No. 3, Rural New Yorker No. 2 and Carman No. 1 as chance seedlings ; while Heavyweight and No. 9 are the result of strain selection for high yield. Dr. William Stuart of the United States Department of Agriculture has classified American varieties into 12 groups largely on the basis of tuber characters, season of maturity and blossom colour. These groups are Cobbler, Triumph, Early Michi gan, Rose, Early Ohio, Hebron, Burbank, Green Mountain, Rural, Pearl, Peachblow, and Up-to-Date. Each group is named for the leading variety in it and contains all of the commercially im portant varieties of the respective type which it represents. Stand ard late varieties of great importance are Green Mountain, Sir Walter Raleigh, Carman No. 3, No. 9, Heavyweight, Russet Rural and Burbank. There is also a mid-season variety grown
extensively in Florida, Spalding Rose 4. The most impor tant early varieties are Irish Cobbler, Bliss Triumph, and Early Ohio. Varietal adaptation to regional production is contingent mainly upon climate and market preference. Green Mountain is very susceptible to disease, drought, and high temperature. It is best suited to cool climate and light loamy soil both of which are found in the north-eastern States. When well grown it commands a premium price over all other varieties in Eastern markets. The Cobbler variety is similar in its requirements. Bliss Triumph seems to be more resistant to high temperatures than Cobbler. Varieties of the Rural type are notably resistant to drought and are more resistant to heat and to blight rot than the Green Mountain varieties.
Soils.—Potatoes are usually grown in a rotation series of two or more other crops ; the one preceding is preferably a legume. Type and length of rotation depend on the kind of agriculture practised. In the famous Aroostook County section of Maine, where the potato is the major crop, a three-year rotation of potatoes, oats and clover is used. Clover is considered an ideal crop to precede potatoes because it leaves in the soil an organic residue rich in nitrogen. Alfalfa and sweet clover commonly pre cede potatoes in the rotations used in the central and western States. In most of the New England and Middle Atlantic States, timothy sod containing clover residue is ploughed before potato planting. Frequently, the sod residue is too scanty to be of much benefit to the potato crop. Along the Eastern seaboard, potatoes are commonly grown year after year on the same soil. Little or no stable manure is available, the growers depending on rye or rye and vetch as winter green manure crops to maintain the soil humus supply. In the South, velvet beans, soy beans and cow-peas are used for the same purpose. Rotation is necessary in many sections where the soil reaction is nearly or quite alkaline to avoid infection of the tubers with the common scab disease. In these sections, growers avoid the use of lime and effort is made to use commercial fertilizers which increase soil acidity. Recent soil studies show that the potato thrives best on slightly acid soil. It is advisable to sweeten potato soils only when and to the extent necessary to promote the growth of legumes in the rotation. Friable, well aerated soils rich in humus are best for this crop. Where neces sary to use heavy soils, fall ploughing is advised so that frost action may assist in pulverizing the soil particles. Light soils should be spring ploughed. Stable manure, when used, may be applied previous to ploughing but the manure should be well de composed by potato planting time. Thorough seed-bed prepara tion by harrowing to eliminate weeds is much better than harsh and frequent cultivation during the growing season.