in a five year rotation of maize, oats, wheat, each one year, and clover and timothy two years, fertilizer being applied to each of the grain crops:

"When phosphoric acid has been applied alone in superphosphate, 20 per cent of the quantity applied in the fertilizer has been recovered in the crop. When phosphoric acid has been reinforced with potash, there has been a recovery of 27 per cent of the former. When phosphoric acid has been reinforced with nitrogen instead of potash the recovery has reached 38 per cent of the phosphoric acid applied, and when both potash and nitrogen have been added, the recovery of the phosphoric acid has amounted to 46 to 50 per cent."1

Wheat does not appear to be benefited directly by the application of lime. If the soil needs liming, it is best applied to the land prior to planting it to maize.

122. Amount of Fertilizers.—A standard application of fertilizer may be said to be one that furnishes from ten to twenty pounds each of ammonia and potash and from thirty to sixty pounds of phosphoric acid. This can be obtained by applying from 250 to 500 pounds of a commercial fertilizer containing four per cent of ammonia, twelve per cent of available phosphoric acid, and four per cent of potash. This is often referred to as a 4-12-4 fertilizer and is a grade that usually can be found on the market.

The ratio of phosphoric acid to nitrogen and potash should be varied somewhat with state of fertility. With soil quite exhausted through continuous culture the proportion of nitrogen and potash to phosphoric acid should be increased, while with land of higher fertility and with favorable rotation, nitrogen and potash may be reduced. The above figures are at best only general averages.

When it is necessary to apply lime to wheat land, an amount equal to 1,000 to 1,500 pounds of quick or freshly burned lime (CaO) may be applied. When it is water-slaked it will have increased in weight thirty-two per cent (CaO: Ca(HO),::100:132).

1 Ohio Bul. 110 (1899), p. 57.

123. Time and Manner of Applying Commercial Fertilizers.— Commercial fertilizers are applied to wheat lands by sowing broadcast just in front of the wheat drill or by applying at the same time the wheat is drilled by a fertilizer attachment. The latter method is much to be preferred. In some cases an additional application of nitrogen is made to winter wheat by sowing nitrate of soda broadcast in the spring. At the experiment stations it has been customary to apply onefourth of the nitrogen in the fall, often in the form of dried blood, and the rest of the nitrogen in the spring in the form of nitrate of soda, on the theory that if all the nitrogen is applied in the fall in a soluble form, much of it would be lost through drainage during the winter. Where nitrogen is applied in the spring, care should be taken to apply it before the wheat plant has made much growth. (113)

In case lime is used, it should be spread upon the plowed land three or four days before seeding, immediately harrowed in and allowed to remain until all lumps which may be present have slaked, when the ground should be stirred again, preferably with a spring tooth harrow.

124.

Farm Manure.-Farm manure is usually applied to some other crop in the rotation, as maize, rather than directly to the wheat. If applied directly to wheat land, better results will be obtained by applying 200 tons to twenty acres of wheat than by applying the same amount to ten acres. If the preceding crop has been oats, the manure should be spread as soon as possible after the oats are cut and the land plowed. It is desirable that the manure should be well rotted, where rainfall is liable to be deficient. Beginning with a virgin soil, the Central Experiment Farm has found, however, after sixteen years that fresh and well-rotted manure applied in equa weights gave equal yields of grain and straw, while barnyard manure gave considerably higher yields than any form of commercial fertilizers, and about twice the yield of plots not

fertilized. Farm manure may be applied to the land after the wheat is sown, if well rotted, preferably with a manure spreader, if the condition of the land is such as not to be cut up too much with the spreader. Experiments have shown that a ton of stall manure will produce a larger return of wheat than a ton of yard manure.2

Farm manure does not produce as large returns for the fertilizing constituents contained as commercial fertilizers when applied to wheat; nevertheless its lower cost often makes its use profitable. Where there is a limited quantity of farm manure or where both farm manure and commercial fertilizers are used, the best practice usually is to apply the farm manure to land for maize and apply the commercial fertilizers, if deemed desirable, to the land for wheat.

125. Mulching.-Mulching wheat with straw or other material for the purpose of winter protection has not been generally practiced. The Ohio Station has tested the value of mulching for a series of years, and has found no practical benefit from the use of a mulch. In severe seasons the benefit has been very slight, while in mild seasons the mulch has usually been harmful. A heavy mulch was more harmful than a light one. The Tennessee Station obtained about five per cent less yield from a lightly mulched plat than from one which was not mulched.

In exposed situations and localities where there is little snow upon the ground, a light mulch may be beneficial to the wheat. But where there is considerable snow and the temperature more uniform the mulch is pretty certain to do more injury than good. Mulching, however, must not be confused with a top dressing of stable manure for the purpose of adding fertility to the soil.

1 Can. Expt. Farms Rpt. 1903, p. 24.

2 Ohio Bul. 110 (1899), p. 52.

3 Ohio Bul. 82.

4 Tenn. Vol. III, Bul. 2.

The value of the latter will depend largely upon the needs of the soil and the character of the manure used.

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.

1

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 would 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 ack 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:

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

dril 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 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 1 Can. Expt. Farms Rpt. 1899.

Five-hoe grain drill. Hoes may be adjusted to different widths.