compared with the plat continuously in maize without fertilizer was 2.6 bushels per acre.1

285. Maintaining the Crop Producing Power of the Soil.The use of stable manure and the rotation of crops in connection with stock raising are the chief means of keeping the land in good condition to grow maize. Maize is not an exhaustive crop because (1) it removes from the soil comparatively small quantities of soil elements for food produced; (2) it produces large quantities of organic matter which when fed to live-stock makes large quantities of organic manure to return to the soil; (3) the intercultural tillage is doubtless beneficial, although this has not been as fully demonstrated as the expression of Jethro Tull,"Tillage is manure,"-might indicate.

The Indiana Station manured for two years a series of alternate plats which had grown maize continuously for five years with fresh horse manure amounting for two years to about fifty tons per acre. No manure was used before or since. During twelve years the average yield was nearly ten bushels per acre more on the manured than on the unmanured plats and on the last year of the period was nearly five bushels greater.

286. Influence of Organic Matter.-Stable manure is more frequently applied to land intended for maize than to any other. Grass and clover are usually followed by maize. One reason why stable manure is found generally beneficial for maize is that it supplies organic matter, which when in proper condition may modify the water content of the soil. Instances are known where no influence whatever was obtained from the use of large quantities of commercial fertilizers, but where the use of stable manure increased the crop. The Wisconsin Station found that while the total amount of water in the upper six feet of soil was essentially equal in both manured and unmanured

1 Ill. Bul. 42, p. 177.

8 Ind. Bul. 55, p. 29.

ground,1 yet there was a marked difference in the distribution of it, the upper three feet of the manured ground being decidedly more moist than the unmanured. This may have been due to one or more of four reasons:

(1) The increased vegetable matter in the soil may cause more of the rainfall to be absorbed and allow less to run off the surface.

(2) Less water may be evaporated from such a soil, as indicated by laboratory experiments.

(3) The water may drain off into subterranean channels less rapidly.

(4) More water may be brought up from below by capillary attraction.

It is not unlikely that all four of these causes operated to produce the observed results.

287. Application of Stable Manure.-The amount of stable manure per acre may vary from ten to twenty tons. Where feasible, an ideal method is to apply the stable manure to the meadow in August and plow land late in the fall for the next spring's planting. For practical reasons, however, the manure is usually hauled in winter and spring and the manured land is then spring plowed. When hauling manure in the winter, care should be taken not to haul when the land will be seriously injured from puddling, and not to spread manure on top of a considerable thickness of snow lest it should run off suddenly and carry the manure with it. Well rotted manure will bring the most immediate results and the largest yield per acre, but hauling manure before much decay has taken place causes it to go farther, since there is considerable loss through decay. In regions or seasons of deficient rainfall the application of unrotted manure may cause a reduction in yield. The moisture in the soil being insufficient to cause decay, the undecayed organic

1 After making a correction for water used in producing the increased yield of maize upon the manured portion.

matter makes the soil drier, while if it had rotted either before or after being put on the soil, it would have increased the soil moisture. (286) The system of piling manure in the field and subsequently spreading it, while having the merit of securing substantially uniform distribution per acre, has fallen into disuse. It was found to be wasteful of labor and if the piles were left to stand for a considerable time, to cause unequal local distribution of the fertilizing elements. The manure is now usually spread from the wagon with a fork, or spread by means of a manure spreader. The latter are quite satisfactory so far as their work is concerned, but the amount of work required of a spreader is such as to cause those at present manufactured to lack durability.

288. The Use of Commercial Fertilizers for the production of maize has been the subject of field experimentation in at least twenty-six stations, principally in regions east of the Mississippi River. Many of these stations have found but very small increases from the use of commercial fertilizers, and most of them have not found profitable returns, especially west of the Alleghany Mountains. Practically all agree that the maize plant does not respond as readily to the use of commercial fertilizers as do the smaller cereals which are sown broadcast and thus have so many more plants to the acre, and which grow during a cooler portion of the year.

Where the soil requires it, from twenty to sixty pounds of phosphoric acid and from five to twenty pounds of nitrogen may be applied to the acre. Generally speaking, however, the best practice will be found to consist in relying upon the overturned sod and stable manure, with lime where needed to grow the maize and applying the commercial fertilizers to the wheat both to increase the yield of the latter and to promote the new seeding..

289. Relative Importance of Fertilizing Constituents.-The behavior of maize towards the different constituents of fertilizers

appears to be much the same as that of wheat. (121) In fact, so far as the cereals are concerned, the influence of the several ingredients of commercial fertilizers appears to be more dependent upon the soil than upon the crop. The following table gives the average yield of maize cut green for silage during fourteen years at Ottawa, Canada, when grown continuously on the same plats:1

Fertilizers applied each year from 1888 to 1898 or 1899. No fertilizer used since. Clover sown in 1900 in place of maize and plowed under in May before maize was planted.

290. Methods of Applying Fertilizers.-While commercial fertilizers may be applied broadcast, this method is not generally advisable. Some maize planters have fertilizer attachments which apply the fertilizer with the seed. Where a wheat drill is used for drilling maize, it is a common practice to drill the fertilizer through the hoes on each side of the hoes drilling the maize, thus placing the fertilizer in the soil seven inches on each side of the maize row. (305)

291. Influence of Season on Efficiency of Fertilizers.—At the Illinois Station where maize was raised continuously for twenty years on manured and unmanured plats (284) in certain seasons of deficient rainfall the unmanured plat gave greater yield than that receiving annually stable manure. At the Indiana Station 2 both stable manure and commercial fertilizers used continuously for five years gave the best yields during seasons of high rainfall 1 Canadian Experimental Farms Rpt. 1902, p. 34

2 Ind. Bul. 55, p. 29.

and the least returns during a season of low rainfall, the commercial fertilizer causing a decrease in yield. Other things equal, the best results from the use of fertilizers may be expected in regions or seasons of high rainfall.

292. The Use of Lime. In those sections where lime is used, it is generally applied to land intended for maize, this appearing to be the best place in the rotation for its application. Wheeler has reported, however, that the use of lime may be injurious to the growth of maize where the nitrogen in the soil is principally in the form of nitrates, but where the soil is very sour and nitrates are not employed its use immediately before this crop may prove of great service.1 In ordinary rotation the lime would be applied to sod land, although sometimes applied to oat stubble, or even maize stubble, where maize follows maize. Usually the best results follow its use upon sod land of rather long standing.

Calcium lime (CaO) is generally used and is to be preferred, although magnesian lime (MgO) is also used to a considerable extent with apparently satisfactory results. Besides increasing the per cent of calcium in the soil, lime makes adhesive soils more friable and granular, perhaps by causing a rearrangement and cementing together of the soil grains; makes sandy soil more retentive to organic matter; corrects the acidity of the soil in case any exists, thus creating a favorable condition for the growth of nitrifying organisms; may make potassium and phosphorus more available; hastens decomposition of organic matter; and while making the nitrogen in organic matter more available, may cause a more rapid loss of total nitrogen ;-there is an old proverb, "Lime enriches the father but beggars the son." Where it is necessary to use lime, it should be accompanied by a liberal use of stable manure.

293. Indications of Need of Lime.—The need of lime may be 1 R. I. Bul. 46, p. 95.