indicated (1) by the per cent of lime (CaO) present;1 (2) by the acidity of the soil, which may be determined in quite sour soils by bringing the moist soil into contact with neutral litmus paper under proper precautions; (3) by the excessive adhesiveness of clay soils; (4) by the character of the vegetation, or a change in the characteristic vegetation, or (5) by the persistent failure of certain crops, such as clover and beets. The most satisfactory method, however, of determining the need of lime is by applying it under conditions which make it possible to tell whether there is any increase of crop due to liming.3

294. The Application of Lime.-The equivalent of from one to four tons or from twenty-five to 100 bushels of quick lime (CaO) may be applied to land intended for maize. Ordinarily the amount should not exceed fifty bushels.1 (122)

The freshly burned (quick) lime may be applied directly to the field, where it soon slakes, after which the land may be plowed, care being taken not to plow too deep. Unless it is ground, however, it is difficult to spread quick lime evenly. In order to reduce it to a fine powder the lime may be put in piles of two or three bushels at any convenient time in the fall, where the air, rains and moisture from the soil slake it. Better results will be obtained if the ground is scraped off down to moist soil where the lime is placed and the pile covered with moist soil. If the soil is dry, a half pail of water may be added to each pile. As soon as possible, the piles should be spread with a shovel and the land plowed. Although more laborious, it is better to apply the slaked lime to the plowed land in the spring and

1 For agricultural crops, o.2 per cent is usually considered the minimum requirement. This can be determined only by chemical analysis.

2 R. I. Bul. 46, p. 100.

3 For full discussion on the use of lime, see The Agricultural Use of Lime in Pennsylvania. By Dr. William Frear, 6th Ann. Rpt. Penn. Dept. of Agr. (1900), pp. 193-353

4 The legal weight of a bushel of lime varies in different States from seventy to eighty pounds.

harrow it in. It takes less lime, the lime is nearer the surface, and, if water-slaked in a large pile, it is in a much finer powder. While there is a difference of opinion as to the practical differences between the causticity of quick lime (CaO), water-slaked lime (Ca(HO).), and air-slaked lime (CaCO1), all seem agreed that fineness is a positive advantage. The slaked lime may be spread from a wagon with a shovel, or a manure spreader with lime attachment may be used. Finely ground quick lime is now placed upon the market, and may be applied with a grain drill or a lime spreader.

295. Irrigation.-While alfalfa, wheat, potatoes and many fruits and vegetables have been abundantly raised by irrigation in America, maize has nowhere been extensively grown by this means. The yields of maize in the arid region under irrigation so far as reported do not compare favorably with yields in humid regions without irrigation.

The Wisconsin Station has studied the influence of irrigation in the humid region. During eight years, ending 1901, the average yield of maize silage containing thirty per cent of dry matter was 17.2 tons with irrigation and 12.3 tons without irrigation, on land of moderate fertility. Wherever comparisons were made the increase in grain was greater than the increase in total dry matter. The average amount of water added per year was five inches. King concludes that "well managed irrigation in climates like that of Wisconsin may increase the yield of maize silage 40 to 45 per cent, and that of ear corn from 50 to 60 per cent as a general average." On coarse sandy soils in Wisconsin, water alone produced much better results than stable manure alone, but both together had much the greatest effect.2 In 1902, the yield during a cold wet season without irrigation was greater than on comparable plats in the hot dry season of 1901 with irrigation. It was also found that the yield was greater on land that had not been irrigated the previous year, the reduction being greatest on manured land. 3

1 U. S. Dept. of Agr., O. E. S. Bul. 119, p. 315. 2 U. S. Dept. of Agr., O. E. S. Bul. 119, p. 326. Wis. Rpt. 1902, p. 187

296.

XIII.

MAIZE.

CULTURAL METHODS.

Time of Plowing. The evidence appears conclusive that the question of time of plowing relates to economic farm management rather than to differences in comparative yields. The experimental evidence on the subject of fall and spring plowing is meager and inconclusive. At the Nebraska Sta

tion much better yields of grain were obtained from plowing in September than in April, but no material difference was obtained from plowing in November than April. There are fine clay soils which become during the winter, if fall-plowed, so hard and compact as to make the preparation of a suitable seed bed at planting time a difficult task. Usually, however, the frosts of winter have a mellowing

Single row stalk cutter used for cutting up stalks, where maize follows maize, to prevent stalks from interfering with the operation of the cultivator.

influence and increase the ease of preparing the seed bed. As fall plowing seldom affects the yield adversely, at least, it is generally good farm practice to plow in the fall those areas to which manure is not to be applied during winter and spring. Early plowing in the spring as compared with late plowing tends to conserve the soil moisture both by preventing evaporation of water and by increasing the amount of rainfall held.

1 Neb. Bul. 54

Quiroga has shown that early plowing as compared with late plowing may not only increase the percentage of moisture in the soil and the yield of maize, but that the nitric nitrogen in the soil may be considerably increased. The available nitrogen in parts per million of dry soil was found to be as follows:1

On the other hand, early plowing decreases the amount of organic matter which will be incorporated in the soil if the land is in sod or a cover crop. Where the land is badly infested with perennial weeds, such as the bindweed or morning glory, late plowing destroys the growth already started and gives the maize plant a chance at least to start even. When the land is plowed immediately before planting, it may be at once dragged or rolled and then harrowed and planted while the surface is still fresh and moist. When the plowing is done earlier in the spring the surface requires working at once to prevent it from becoming hard, thus generally increasing the amount of labor to get a good seed bed.

297. Depth of Plowing.-While the variation in the depth of plowing seriously influences the cost of raising maize, since the draft of the plow is nearly proportional to the amount of soil turned, yet the investigations on this subject are quite unsatisfactory. In only one instance has a station reported results on depth of plowing for more than one year upon the same land. Undoubtedly the best depth will vary with the soil, the climate, the season, often with the previous crop grown, and the applica

1 Ohio State University Bul. Series 8, No. 28.

tions made (291); but no rules can be laid down as a guide for general practice. The following table gives the results of trials on widely different soils under widely differing climatic conditions:

In all cases the plowing was done in the spring, except at the New Hampshire Station, when the land was plowed November first. In the first trial at the Illinois Station, in place of the usual intercultural tillage, the weeds were removed by scraping with a sharp hoe with the least possible disturbance of the soil. An adjacent plat, not plowed but disked one inch deep, yielded 56.4 bushels of grain. The land on which this experiment was conducted had not been plowed in two years.

At the Pennsylvania Station a timothy and clover sod was plowed. At the four. inch depth the sod did not cover well and the shallow cultivation (two inches deep) which all plats received did not eradicate the grass on plats plowed only four inches deep.

While in a number of trials satisfactory results have been obtained by plowing four inches deep and less, yet the most generally satisfactory depth, all things considered, would seem to be six inches. As compared with wheat and oats, deep plowing is advisable.

1 All results are in bushels of grain per acre, except in the case of New Hamp shire, where tons of green fodder are given.

? Depths were 3, 5, 7 and 9 inches.

Also subsoiled 6 inches deeper.

• Depths were 3 and 7 inches.