were used in the corn planter, the number of grains dropped at one time varied from one to six grains, the planter dropping three grains to the hill sixty-six times out of a hundred. When only the middle grains of the ear were used, the planter dropped two grains eight times and three grains ninety-two times to each hundred hills. Since uniformity of stand is essential to maximum yield, it is therefore good practice to discard the largest of the butt and the smallest of the tip grains. It is also found that in order to secure uniformity of stand it is essential to select ears having grains of uniform size. It was found that when long and short grains were mixed together, the planter dropped three grains seventy-five times out of one hundred; while when planted separately with proper plates for each, the planter dropped three short grains ninety-five times out of one hundred and three long grains ninety-two times out of one hundred.

XII.

MAIZE.

I. CLIMATE.

274. Limited Distribution.-That there is a wide difference in distribution of maize as compared with other cereals is shown in the following table giving average production in million bushels by continents for five years, 1898-1902 inclusive:

The fact that sixty-six per cent of all the maize raised in the United States is grown in seven maize surplus States-Ohio, Indiana, Illinois, Iowa, Missouri, Nebraska and Kansas-is a further indication of its limited distribution. It is this limited distribution, coupled with the fact that maize will produce about twice the food nutrients of any of our other cereals per acre, that makes lands especially adapted to the culture of maize command relatively high prices.

275. Causes Limiting Distribution.-Among the causes limiting successful cultivation are temperature and sunshine, rainfall and physiographical features, including soil. It is only when these several factors are properly combined that the culture of

maize becomes commercially successful. The absence of any one may limit successful production. If, for example, the area between the 70° and 80° July isotherm be followed around the world in the northern latitude, it will be found that throughout the larger part of its course the rainfall is insufficient at those times of the year when it is most needed by the maize plant;

Variation in amount and distribution of normal monthly rainfall, see map (276). For May, June, July and August, total normal rainfall is: Lincoln, Nebraska, 15.7 inches; Tuscola, Illinois, 14.4 inches; Columbus, Ohio, 13.2 inches; Western England, 10.7 inches: Middle Germany, 8.6 inches; Southeast Russia, 7.2 inches.1 The great maize belt lies between the longitudes of Columbus, Ohio (83° 0' W. Long.), and Lincoln, Nebraska (96° 45′ W. Long.).

or, where the rainfall is sufficient, physiographical fea.ures prevent the culture of maize on a large scale.

The so-called "corn belt" of the United States appears to have the best combination of temperature, sunshine, rainfall, soil and topography for the production of maize of any considerable area in the world.

1 Rainfalls for Lincoln, Tuscola and Columbus are from twenty-five-year averages of the United States Weather Bureau. The European figures are from Davis' Elementary Meteorology.

276. Influence of Temperature.-It is the temperature during the maize growing months of May to September inclusive, rather than the average annual temperature, that influences the production of maize. It is not only the temperature of air and soil as expressed by the thermometer, but also the sunshine, the influence of which is not fully expressed by thermometric readings. Brewer1 has shown that fifty-five per cent of the maize crop of 1879 in the United States was grown between July isotherms 75° and

Map showing area in Northern Hemisphere between July isotherms, 70° and 80° F., indicating suitable temperature for the production of malze. Note rainfall in chart (275).

80° F. and thirtythree per cent between 70° and 75° F., making a total of eighty-eight per cent between July isotherms 70° F.

to 80° F.

It is difficult to

give precise limits to an influence which is one of several absolutely necessary. Beale has compared the yield of maize with the temperature in each of the nine leading maize producing States, viz., Ohio, Indiana, Kentucky, Tennessee, Illinois, Iowa, Missouri, Nebraska and Kansas, during the five months May to September inclusive for sixteen years. No relation in these favored States could be traced between yield per acre and temperature.

Temperature is well known to influence maturity and may thus, indirectly at least, affect yield of merchantable grain, especially in regions near the northern limit of successful culture. The New York State Station 3 compares the soil temperature with yield in crops of different maturity, as follows:

1 Tenth Census U. S., Vol. Agr.

2 H. G. Beale: Thesis, B. S. Degree, Ohio State University, 1902.

N. Y. Rpt. (Geneva) 1886, p. 39.

277. Influence of Climate Upon Habit of Growth.—There is greater variation in the habit of growth of the maize plant than

in

any other cereal. These variations within any one of the five types of maize seem to be correlated with the climatic conditions as indicated by the great variation in size and in the time of maturity in northern as compared with southern latitudes.

The growing season for maize varies in different sections of the United States from ninety to 160 days and varieties exist which are adapted to these different growing periods. In general it may be said that as we go north or south of a given latitude a variety becomes one day later or earlier for each ten miles of travel, the altitude remaining the same. That is to say, a variety which ripens two weeks before a killing frost in a given locality would only barely ripen if taken 140 miles farther north, the altitude remaining the same. Care should be taken, therefore, in selecting new varieties, to get them from the same latitude. If obtained from much farther north they may ripen too early and consequently be too small. If obtained much farther south, they may not ripen.

Size and period of growth are also influenced by moisture. Under conditions of favorable water supply, the plant continues to grow, while a deficiency will reduce growth and hasten ripening.

278. Influence of Climate Upon Varieties. Whether the environment was a cause of variation or whether selection, it is probable