Agriculture is the process of producing food, feed, fiber and other desired products by the cultivation of certain plants and the raising of domesticated animals (livestock). The practice of agriculture is also known as farming, while scientists, inventors and others devoted to improving farming methods and implements are also said to be engaged in agriculture.
The uppermost soil horizon (topsoil) made up of a mixture of organic material (up to 30% humus) and minerals. The A-horizon becomes coarser as you move downward due to the water washing through the soil and carrying away the fine particles.
Rotary drilling using high-velocity air insertead of conventional drilling mud. It is unsuitable where significant volumes of water may be encountered or where natural gas may create an explosive mixture.
Reference: R.L. Bates & J.A. Jackson, DICTIONARY OF GEOLOGICAL TERMS, Third Edition, American Geological Institute, 1983.
A large body of air that has similar horizontal temperature and moisture characteristics.An air mass, by definition, is a large dome of air which has similar horizontal temperature and moisture characteristics. Often, a front separates two different air masses. Fronts are very narrow zones of transition. In other words, temperatures can change dramatically with short horizontal distances near fronts. Fronts are usually anywhere from 10 kilometers to hundreds of kilometers wide, while air masses can be thousands of kilometers wide.
A body of air whose temperature and humidity characteristics remain relatively constant over a horizontal distance of hundreds to thousands of kilometers. Air masses develop their climatic characteristics by remaining stationary over a source region for a number of days. Air masses are classified according to their temperature and humidity characteristics.