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The value of the latter will depend largely upon the needs of the soil and the character of the manure used.
111. CULTURAL METHODS. 126. Time of Plowing.—It is generally conceded to be good practice to plow for winter wheat as early as practicable after the previous crop has been removed. This allows the soil to become compact before the seed is sown, prevents weeds from going to seed, and conserves the soil moisture by preventing the growth of vegetation, by the pulverization of the surface soil and by enabling more of the rainfall to be absorbed. In this connection the pulverization of the surface after each heavy rainfall, preferably with a spring tooth harrow, is extremely desirable in order to prevent surface evaporation.
The experiment made by the Oklahoma Station is a fair illustration of what may be expected in the drier climates or the drier seasons of the more humid sections. Plats were plowed on July 19th, August 15th and September 11th. The early plowed plat turned up moist and mellow; the medium plowed somewhat dry and lumpy, while the late plowed plat was weedy, turned up lumpy and was dry to the full depth of plowing. Disking, harrowing and rolling was necessary to the extent that it was estimated that about eight times as much labor was put on it as woulá have been necessary had the ground been plowed when moist. All sections were seeded September 15th. In the early plowed plat germination was prompt and growth good. On the late plowed portion many plants suffered from iack of moisture; the following summer the crop matured later, was more seriously affected by blight, and the grain was more shrivelled. The following yields were obtained: .. Date of plowing
Yield per acre, bu July 19 · · · · · · · 31.3 August 15 . .
September 11 . . . . . . 15.3 i Okla. Bul. 47 (1900), pp. 26-48.
The results of Utah, North Dakota and Minnesota in plowing in fall and spring for spring wheat are only slightly in favor of the fall plowing so far as yield is concerned, but early fall plowing is generally advocated by these stations in the interest of weed and insect destruction and more economical farm management. In Manitoba, spring plowing has given better results than fall plowing, while summer fallowing has given better results than either.1
127. Depth of Plowing.–Generally speaking, plowing less than four inches or more than eight inches deep has not been found desirable. Within and even beyond these extremes the depth of plowing should vary with the character of the soil and the subsoil, but no specific rules can be laid down. In all cases the variation in yield due to depth of plowing has been slight. Subsoiling has not been found economical by any experiment station reporting results, and in some cases the yield has been reduced.
128. Preparing Seed Bed Without Plowing.-It is a common practice on the friable loam soils of the Mississippi Valley to
driil winter wheat without plowing on land which has just produced a crop of maize. In many instances the wheat is drilled in the standing maize without any previous preparation, by drawing a five-hoe drili between the rows.
Where the land is weedy the drill Five-hoe grain drill. Hoes may be
is sometimes preceded by a harrow drawn by one horse. In this case
the soil has the proper surface pulverization from the cultivation of the maize and is compact below. Afterward, at the proper time, the maize is husked. In the winter or spring, when the ground and stalks are frozen, the
Can. Expt. Farms Rpt. 1899.
stalks are broken off by drawing a heavy drag over the surfacean old railroad rail being frequently used for this purpose. In many cases—and this practice is growing—the maize is cut and shocked before the proper time to sow the wheat. Then the wheat is sown as in the standing maize, or the more common practice on the heavier soils is to cut out the maize stubs with a disk harrow and harrow down with some suitable levelling instrument, preferably a spring tooth harrow. These methods make it possible to follow maize with winter wheat and the expense of putting in the wheat is small. It is thought also that the stalks are some protection to the wheat at times in preventing the snow from drifting off the wheat. The effect of this practice upon yield is hardly subject to determination experimentally except where the maize is cut before seeding. The experiments which have been made under the latter conditions indicate that the relative yield will depend upon the character of the soil. Where the soil is mellow and light, it should not be plowed; where it is heavy clay, plowing will be found desirable. In the latter case rotation is generally such that wheat does not follow maize.
In the spring wheat region, land that has previously been in oats or wheat is sometimes prepared without plowing, by using a disk harrow or similar instrument. Minnesota · found disking as good as plowing on burned stubble field; while North Dakota found that plowing gave the best results. Among the objects to be attained in preparing the seed bed are the prevention of the growth of weeds and the conservation of the soil moisture, and whichever method most nearly accomplishes these results will probably be best. Plowing is not necessary for root penetration in the friable soils of the spring wheat region.
129. Time of Sowing. — The proper time to sow wheat depends upon climatic conditions, the fertility of the soil, the preparation of the seed bed, the liability to injury from the Hessian fly, and perhaps slightly upon variety.
1 Minn. Bul. 46 & N. Dak. Bol sa
It is possible to sow later as we go south, and necessary to sow earlier as we go north. When sown too late, the wheat has not sufficient vitality to stand the cold weather. When sown too early, its growth is so rank and succulent as to be injured by freezing. Experiments indicate the best average time of seeding in Ohio, Indiana and Illinois on the fortieth parallel to be about two weeks earlier than in Tennessee upon the thirty-sixth parallel ; while the results at Columbus, Ohio, on the fortieth parallel and Wooster on the forty-first parallel indicate a difference of about one week. Doubtless differences in the fertility of the soil as well as temperature and rainfall have affected the results.
In some localities, early sown wheat is subject to attack from the Hessian fly. When such attacks are imminent, they may be avoided, by concerted action among the farmers of a neighborhood, by later sowing, especially if delayed until there is a killing frost, and also by sowing early some strips of wheat where the Hessian flies will congrecate, and may be destroyed by plowing under the wheat. Generally speaking, delay until killing frosts occur is too late for the best growth of wheat in the fall, except on fertile soils. Where it is necessary, therefore, to delay the seeding of wheat to escape the ravages of the Hessian fly, the seed bed should be put in the best possible condition both as to fertility and physical properties.
The results of the various stations show clearly that there is no best time for any given locality. Some seasons quite early sowing gave the largest yield, while other seasons late seeding gave the best results. Very much depends upon the season prior to and after seeding. It may be said as a general rule, although late sowing is often as good as early sowing, it is seldom better, while early sowing is often better than late sowing. The more fertile the soil, the later the seeding may be done with safety, as the rich soil produces the growth needed in a shorter time. Wheat often suffers in the fall from lack of rainfall. It is seldom injured from an excess of rainfall. As the time and manner of preparing the seed bed materially affects the moisture of the soil, the preparation of the seed bed may have a decided influence upon the time of sowing. The earlier and better the seed bed is prepared the later the seeding is permissible. On the fortieth parallel at an altitude of 500 to 1,000 feet, winter wheat should be sown generally about September 20th, with variations of a week either way, depending upon various factors indicated above.
While obviously not as many factors enter into the time of seeding of spring wheat as winter wheat, climatic and seasonal variations necessitate as wide variations perhaps in the former as in the latter. It may be laid down as a general rule that spring wheat should be sown as early as the ground can be got in fit condition for seeding. In both North Dakota and Minnesota the earlier sown spring wheats gave best results, while in Utah a medium date gave the best yields. Delay of two or more weeks in sowing caused marked losses where conditions were those of Ontario and Quebec. In other provinces the loss from delay in sowing was less marked. Seeding should be finished by May ist in Ontario and Quebec, and in other provinces fron: May 15th to 25th. 1
130. Depth of Sowing.–This will vary with the kind of soil, the moisture, and the levelness and the firmness of the seed bed. Wheat may be sown deeper in a sandy soil than in a clay soil. It is necessary to sow deeper in a dry than in a wet soil. Variations in rainfall often materially modify the depth of seeding. It is reasonably well established that, under ordinary conditions, the nearer the seed is covered with one inch of moist soil, the better. An uneven and cloddy soil would require that some be planted deeper than is desirable
Cent. Expt. Farm, Canada, Bul. 21.