.221 Reading the weather map. .2211 Characteristics and movement. 2213 Tropical and extratropical storms. .223 Forecasting. .224 Seasonal forecasts. .225 Local weather signs. 23 Forecast centers. 24 Daily forecasts. .28 Shippers' forecasts. to abolegi .281 Description.ous edinew 1000 I .282 Utilization. 3 Special warnings. lolqontdue ban in 89 .322 Distribution of warnings. Bold .33 Frost and alfalfa seed. .351 Damage to crops and livestock. .361 Forecasting for navigation. .37 Hurricane and storm warnings. I .371 Tropical storms. moliosisa 190 .372 Distribution of warnings.n .373 High winds. .gola 10 gadus. .38 Fire weather warnings (forests). .381 Conditions favorable for fires. .382 Distribution of warnings. an .39 Miscellaneous. Frost protection for fruit. .40 General. enobela Inol .41 Principles of protection.alb bas .411 Conserving heat.vasado vils .412 Stirring the air. atogen alde .413 Adding heat. 82-1-01--1...W .4 Frost protection for fruit-Continued. Retarding radiation. .5 .42 .421 Covering trees. .422 Smudging. Fuel. 4221 .423 Effectiveness of smudging. .43 Principles of air mixing. .431 Air-stirring machines. 432 Effectiveness. .44 Heaters. .45 .46 .49 .441 Material and construction. .443 Number of heaters required. .445 Caring for heaters. .446 Effectiveness of heating. Effectiveness of different protective measures. .451 .452 .453 .454 .455 .456 Value of cover crops. Temperature surveys. .461 Number and location of stations. .462 Importance of local temperature data, .4631 Different portions of the same orchard. Miscellaneous. Weather and crop services. .50 General. .51 Daily cotton and grain region services. .52 Districts. .521 Number and areas covered. .53 District centers. .531 Locations. .532 Number and distribution of substations. .533 Weather bulletin issued. .5331 Distribution. .534 Bulletins issued at subcenters. .54 Weekly range and cattle service. .541 Cattle-region districts. .5411 Number and areas covered. .542 Data collected. .543 .544 Bulletins issued. .5431 Distribution. Summer range. .545 Winter range. 55 Weekly weather and crop service. .551 Section centers. .5511 Number and locations. .5512 Collection of data. .5513 Cooperative observers and correspondents. .552 Weather and crop bulletins. .5 Weather and crop services-Continued. .56 Weekly cotton, and corn and wheat region bul .561 letins. Character. .562 Where published. .59 Miscellaneous. Climatological service. .6 Reporting stations. .611 .612 Cooperative observers. .613 Number and distribution of cooperative sta tions. Section centers. 621 Location. Current meteorological publications. .62 .63 631 .632 .633 Station monthly and annual reports., Annual State summaries. .634 Annual report, Chief of Weather Bureau. .635 .636 .637 Meteorological tables, weekly weather and crop Daily weather maps and weather bulletins.. .639 Summaries of past weather records by sections. .64 Snow reports. .641 Snow in western mountains and irrigation. .69 Miscellaneous. .7 Climatic tables. 9 .70 General. .79 Miscellaneous. Miscellaneous. .99 Bibliography of meteorology and climatology. $. WEATHER WEATHER AND CROPS Many things affect the farmer in his work, but the weather is usually of greatest concern to him, on account of its direct influence on farm work and crop growth. There are numerous weather risks that the farmer has to take. Either continued wet weather or drought may interfere with planting and cultivation or damage crops during the growing season. Frost in a single night may seriously harm or completely destroy growing plants, or hail in a few minutes lay waste a promising yield. The weather influence begins with the preparation of the soil for planting, and does not terminate until the crop is safely garnered. During this entire time the farmer is, so to speak, at the mercy of the weather. In a study of the relation of climate to agriculture two general divisions of farm land may be made, on a basis (1) of moisture alone and (2) of temperature and moisture combined. In the first division, agriculture is considered from the standpoint of the general suitability of the land for growing crops of any kind without the employment of special methods, such as so-called dry farming, or by artificially supplying moisture by irrigation; the other subdivides the larger areas more or less specifically by crops, such as the Corn Belt, the Cotton Belt, and other similar groupings. Geographic Distribution of Crops Corn. This is a sun-loving, warm-weather crop, in general thriving best where summer rainfall is ample and the nights as well as the days are warm. The principal producing sections in the United States have a frostless season of at least 140 days, a mean summer temperature of 70° to 80° F., and an annual precipitation between 25 and 50 inches. July usually is the most critical month, when growth has reached the tasseling and earforming stage and ample moisture is necessary. Wheat. This crop is best suited to temperate regions having a growing season of at least 90 days and moderate rainfall. It is most extensively cultivated where the annual precipitation is less than 30 inches. There are two general varieties of wheat, the winter variety being best suited to sections where the normal winter temperature (December-February) is above 20° F., and the spring variety where the winters are normally colder, with light snowfall. Oats. This crop thrives best in cool, moist climates. It requires moderately low temperatures, especially when the heads are developing and filling. In warmer climates oats is a winter crop. Rye. This is a typical cool-weather crop. It can be sown late in fall, and will grow where the winters are too cold for wheat. Barley. This crop has a short period of growth, and consequently can be produced where the growing season is too short for corn. The temperature range of barley is wider than for any other cereal. Buckwheat. This crop grows best where the summers are cool and moist; the mean summer temperature should not be much over 70° F. for best results. U. S. D. A.-10-1-26° Grain Sorghums.-These crops are more or less drought resistant and are best suited to a dry, hot, and sunshiny climate, such as prevails in the southern Great Plains area. Potatoes.-Because of their cool-weather requirements, potatoes make their best development in the northern and western parts of the United States, where the mean annual temperature is between 40° and 50° F. and the mean for July not over 70°. In the warmer climates potatoes should be grown in the cooler season of the year, to escape the unfavorable warm summer weather. Cotton. This crop is of tropical origin and requires a mean summer temperature of about 78° F. and a frostfree season of about 200 days in length. The growth of cotton is limited more by temperature than by rainfall, the annual precipitation varying in the Cotton Belt from about 25 to 50 inches. Cotton requires abundant sunshine and only a moderate degree of moisture, In the central and eastern portions of the belt the cotton erop is frequently damaged by too much moisture, and in the more western portion by summer droughts. Rainfall and Types of Farming The amount of moisture required by crops for their best development varies for different localities and for different crops. The minimum quantity of rainfall needed under favorable seasonal distribution for ordinary farming methods of diversified cropping is usually considered to be from 15 to 20 inches annually. Modifying influences which must be taken into account are (1) soil texture as affecting its moisture-retaining qualities, (2) temperature conditions, and (3) rate of evaporation. In general, crops can be grown with a smaller quantity of rainfall in cooler climates than in warmer regions. Considered as to its moisture in relation to agriculture, the United States may be divided into an eastern and a western half. Broadly speaking, 15 inches of annual rainfall may be regarded as the minimum precipitation required for ordinary farming in the more northern portions of the United States, 20 inches in the central, and 25 inches in southern sections. These minimum quantities occur along the one hundred and first meridian. In the transition zones between the humid East and the semiarid West crops more or less drought resistant, such as the grain sorghums, usually do best in the warmer regions, and the hardier grain crops, such as wheat, in the cooler. T Temperature and Crops Wheat and oats thrive with lower temperature 'than does corn, which in turn requires less warmth than cotton. Thus some crops may not only be planted earlier in spring than others, but can be grown in cooler climates. Spring wheat may be seeded in cooler weather than any other major spring crop. Seeding usually begins in the Dakotas and in Nebraska when the normal daily temperature rises to 37° F., and in Minnesota and Wisconsin at 40°. Next in thermal order comes spring oats, the seeding of which may begin when the normal daily temperature rises to 43. Early potato planting begins, as a rule, at 45°, and corn at 55°. The cornplanting date in any locality corresponds closely to the average date of last killing frost in spring. Cotton planting should not begin until the normal daily temperature rises to about 63°. The date on which this temperature is reached corresponds closely to the latest date in spring on which killing frost has occurred. |