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in combinations in Canada for six years, it was found that the influence upon yield of grain was in order just given from greatest to least. (404) In Ohio, on the fortieth parallel, the yield of grain for five years when grown continuously on unfertilized soil was as follows:
393. Influence of Climate Upon Physical Properties of Oats.—
The physical properties of oats seem to be readily affected by climate. The Southern varieties are larger but less dense, less plump, often of a dirty dun color, with long awns, while the Northern grown varieties have shorter, smoother grains, with short awns or awnless. The fact that short, plump, smooth, heavy grains have the largest market value has led to the importation of varieties from Scotland, Norway and Sweden. To what extent these variations are due to selection and to what extent to environment has not been clearly proven; but the Ohio Station has found that during ten years' experiments with seventy-one varieties, the weight per bushel has decreased while the yield per acre has apparently increased.* The Oklahoma Station compared fifty varieties of Southern grown seed with thirty-four varieties of Northern grown seed and obtained slightly larger yields of grain and straw from Southern grown varieties.3 On the other hand, the Ontario Agricultural College
1 For purpose of computation, average December farm price for decade 18901S99 was used.
a Ohio Bui. 139, p. 45.
3 Okla. Bui . 16 (1895), p. 36.
and the Missouri Station have been exchanging seed oats yearly, and the results have shown in general that the Missouri grown oats have produced the largest yield of grain, and that the Ontario seed produced grain of the best quality when grown in Ontario.1
394. Need of Water.—It has already been shown that the water requirement of oats may be large. (391) This has been confirmed by King, who reports the water requirement of a pound of dry matter in oats to be 504 pounds; of barley, 464 pounds; and of maize, 277 pounds.2 To this must be added the fact that the growth of oats is very rapid and the amount of straw relatively large. The daily demand for water during the period of most rapid growth for each pound of grain produced is high. The amount of water required for irrigating oats in Western States is estimated at about one and three-quarters feet, distributed between May 22 and August 20.*
II. SOIL AND ITS AMENDMENTS.
395. Soil.—The character of the soil upon which oats are sown is of less importance than any other cereal, with the possible exception of buckwheat. Almost any tillable soil brings a fair crop if climatic conditions and cultural methods are suitable. It is on this account, and because oats are liable to lodge on fertile soils, that they are sown on the poorer soils and on soils in the most exhausted state of fertility. The oat does best, however, on relatively moist soils.
396. Rotation.—The oat appears less influenced by rotation with grass and clover than either wheat or maize. The Indiana Station has grown maize, wheat and oats continuously or in alternation one with another for fifteen years, in comparison with the same crops in rotation with grass and clover on
1 Ont. Agr. Col. and Expt. Farms Rpt. 1903, p. 122.
2 Physics of Agriculture, p. 139.
t U. S. Dept. of Agr., O. E. S. Bui. 119.
ardjacent plats. The average per cent of gain from rotation with clover and grass has been: wheat, fifty; maize, twentytwo; and oats, nineteen.1 In the American systems of rotation oats usually follow maize. The following may be recommended: For winter wheat sections: maize, one year; oats, one year; winter wheat, one year; timothy and common red clover, one or two years. (119) For sections specially adapted to maize and not to wheat: maize, two years; oats, one year; timothy and clover, one to three years, depending upon live stock kept. (283) For Southern States: maize and cowpeas, one year; oats, followed by cowpeas harvested for hay, one year; cotton, one or two years. In the first year of this rotation, the cowpeas grown between the rows of maize may be harvested for grain. It has been shown that a rotation including cowpeas greatly increased the subsequent yield of oats.' In Arkansas it has been found possible to raise a profitable crop of peas after removing a crop of oats, in time to seed to oats again in the fall. When the stubble was plowed under, the subsequent yield of oats was considerably increased, and when the vines also were plowed under, the increased yield of oats was greater than that caused by the application of 400 pounds of a complete commercial fertilizer per acre.8
397. The Influence of Fertilizers.—Fertilizers are seldom applied to the oat crop, both because they are apt to grow too rank and because it usually pays better to apply the manure to some other crop.4 Oats, however, respond very readily to an application of fertilizers when applied where needed, as shown in various rotations where light and heavy applications of stable manure and commercial fertilizers were used continuously for ten years.5
1 Ind. Rpt. 1895, p. 38.
2 Ala. Bui. 9_5, p. 157. 8 Ark. Bui. 66.
* Ohio Bui. 134, p. 91. 5 Ind. Bui. 88.
Where oats follow maize which has had an application of stable manure and precede wheat which is to have an application of commercial fertilizers, ordinarily no soil amendment will be required for oats. Where land is seeded to grass and clover with oats, an application of commercial fertilizer may be desirable. Where commercial fertilizers are used, the kind, quantity and method of application will be similar to that for wheat. (122, 123) The relative importance of the several fertilizing constituents is also similar. (121) The Georgia Station recommends the following for Southern conditions: acid phosphate, 200 pounds; muriate of potash, fifty pounds; nitrate of soda, twenty-five pounds; cotton seed meal, 200 pounds to be sown with fall oats, and seventy-five pounds of nitrate of soda to be applied in the spring.1 At the Pennsylvania Station during twenty years lime increased the straw when used alone or in connection with stable manure, but when used alone caused a decrease in yield of grain.2 The Rhode Island Station found a marked increase in yield of green fodder by the use of lime.8
III. CULTURAL METHODS.
398. Seed Bed.—It is not customary to prepare the seed bed so deep for oats as for wheat, rye, barley or maize. In the North Central States many acres are sown on maize land without plowing. The oats are sown broadcast on the unprepared land and covered with a maize cultivator (312) or disk harrow (299) or similar instrument. Sometimes the unplowed land is cultivated once before sowing the oats and then cultivated once or twice afterwards. Good crops are grown in this way, as shown in the table on page 297, but very much depends upon the nature of the soil, and something upon the season:
Where soil is naturally compact, as shown at Pennsylvania Station, plowing gives better results. Sometimes oats are sown on the uncultivated surface and the land plowed, turning the oats under three or four inches deep. A medium compact seed bed appears to give better results than one either very loose or very compact. While as in other cereals no marked differences are found between fall and spring plowing directly, yet because it enables earlier seeding in the spring and facilitates spring work, fall plowing is to be recommended in most instances.
399. After Treatment.—Rolling either before or after oats are up has not materially influenced the yield, although it is often good practice on account of subsequent use of harvesting machinery, particularly if land has been seeded to grass. Where a hard crust has formed after sowing, harrowing or even rolling may serve to break this crust. If land is rolled when too wet, it may so pack the soil as to prevent proper air ventilation and retard germination. The Wisconsin Station has shown that the temperature of a rolled soil may be higher than one that has not been rolled, and the percentage of moisture