Aircraft specifically designed or adapted from a general utility airframe for use in agriculture and forestry and for control of insect vectors of human, animal, and plant diseases. Agricultural aircraft (Fig. 1) have become an indispensable tool for high-productivity agriculture and have contributed to the worldwide crop production revolution that began in the second half of the 20th century. See also: Agricultural engineering; Agricultural science (plant); Agricultural soil and crop practices; Agriculture; Aircraft; Aviation; General aviation

The science of chemical compositions and changes involved in the production, protection, and use of crops and livestock. As a basic science, agricultural chemistry (see figure) embraces, in addition to test-tube chemistry, all the life processes through which humans obtain food and fiber for themselves and feed for their animals. As an applied science or technology, it is directed toward control of those processes to increase yields, improve quality, and reduce costs. One important branch of agricultural chemistry, specifically chemurgy, is concerned chiefly with utilization of agricultural products as chemical raw materials. See also: Agricultural science (animal); Agricultural science (plant); Agricultural soil and crop practices; Agriculture; Animal feeds; Chemistry; Fiber crops; Food; Food science

A discipline concerned with solving the engineering problems of providing food and fiber for the people of the world. The problems dealt with by agricultural engineering include designing agricultural machinery to work the soil and harvest crops, as well as developing water supplies for agriculture and systems for irrigating and draining land where necessary. Agricultural engineers design buildings in which to house animals or store grains. These engineers also work on myriad problems of processing, packaging, transporting, and distributing the food and fiber products. In these ways, agricultural engineering combines the disciplines of mechanical, civil, electrical, and chemical engineering with a basic understanding of biological sciences, agricultural practices, and available applicable technologies (see illustration). Concern for the properties of agricultural materials and the way the materials influence engineering designs also characterizes the agricultural engineering approach. See also: Agriculture; Engineering

Mechanized systems of food and fiber production used in agriculture. The mechanized systems comprising agricultural machinery are utilized in numerous aspects of agriculture, including the initial tillage of the soil (Fig. 1), planting, cultural practices during the growing season, protection from pests, harvesting, conditioning, livestock feeding, and delivery for processing. The use of hydraulic power, which offers the advantages of being easily controlled and automated, made possible highly specialized mechanisms to perform intricate operations. Modern technology has been used to increase the precision needed in modern agriculture, with examples including lasers for laying out fields for surface irrigation systems; microprocessors for sensing and controlling intricate operations, such as controlling feed mixtures for dairy cows and grading fruits and vegetables; and electronic devices in the automation of many harvesters. See also: Agricultural engineering; Agricultural science (animal); Agricultural science (plant); Agricultural soil and crop practices; Agriculture; Dairy machinery; Hydraulics; Laser; Microprocessor

A branch of meteorology that examines the effects and impacts of weather and climate on crops, rangeland, livestock, and various agricultural operations. Agricultural meteorology, or agrometeorology, addresses topics that often require an understanding of biological, physical, and social sciences. The field studies processes that occur from the soil depths where the deepest plant roots grow to the atmospheric levels where seeds, spores, pollen, and insects may be found (see illustration). Agricultural meteorologists characteristically interact with scientists from many disciplines. See also: Agriculture; Meteorology

The pure and applied science that is concerned with botany and management of crop and ornamental plants for utilization by humankind. As it relates to plants, agricultural science concerns itself with the application of scientific methods to agriculture (Fig. 1), including the cultivation of land and the farming of crops. Crop plants include those grown and used directly for food, feed, or fiber, such as cereal grains, soybeans, citrus, and cotton; those converted biologically to products of utility, such as forage plants, hops, and mulberry; and those used for medicinal or special products, such as digitalis, opium poppy, coffee, and cinnamon. In addition, many plant products, including crambe oil and rubber, are used in industry, especially in cases where synthetic products have not been satisfactory. Ornamental plants are cultured for their aesthetic value. See also: Agricultural engineering; Agricultural soil and crop practices; Agriculture; Agroecosystem; Agronomy; Farm crops; Floriculture; Horticultural crops; Ornamental plants

The art and science of crop and livestock production. In its broadest sense, agriculture comprises the entire range of technologies associated with the production of useful products from plants and animals, including soil cultivation, crop and livestock management (see illustration), and the activities of processing and marketing. The term agribusiness has been coined to include all the technologies that mesh in the total inputs and outputs of the farming sector. In this light, agriculture encompasses the whole range of economic activities involved in manufacturing and distributing the industrial inputs used in farming; the farm production of crops, animals, and animal products; the processing of these materials into finished products; and the provision of products at a time and place demanded by consumers. See also: Agricultural science (animal); Agricultural science (plant); Food manufacturing

A model for the functioning of an agricultural system, with all inputs and outputs. An ecosystem may be as small as a set of microbial interactions that take place on the surface of roots, or as large as the globe. An agroecosystem may be at the level of the individual plant–soil–microorganism system, at the level of crops or herds of domesticated animals (Fig. 1), at the level of farms or agricultural landscapes, or at the level of entire agricultural economies. See also: Agriculture; Ecosystem

The science and study of crops and soils. Agronomy is the umbrella term for a number of technical research and teaching activities (see illustration): crop physiology and management, soil science, plant breeding, and weed management frequently are included in agronomy; soil science may be treated separately; and vegetable and fruit crops generally are not included. Thus, agronomy refers to extensive field cultivation of plant species for human food, livestock and poultry feed, fibers, oils, and certain industrial products. See also: Agriculture

The cultivation of freshwater and marine species for human purposes. Aquaculture, or aquatic farming, is concerned with the raising of animals and the harvesting of plants in freshwater and marine environments (Fig. 1). In other words, it is the aquatic equivalent of land-based agriculture. When marine species are involved, aquaculture is often referred to as mariculture. The concept of aquaculture is not new, having begun in China about 4000 years ago, and the practice of fish culture there has been handed down through the generations. Today, aquaculture is a modern, multidisciplinary technology. Overall, aquaculture accounts for approximately half of the world's production of fish and shellfish, according to the Food and Agriculture Organization of the United Nations. See also: Agricultural science (animal); Agricultural science (plant); Agriculture; Fisheries ecology; Marine conservation; Marine ecology; Marine fisheries