Major Divisions of Agricultural Sciences

The agricultural sciences can be divided into six groups.

1- Soil and Water Sciences

2- Plant Sciences

3- Animal Sciences

4- Food Sciences and Other Post-Harvest Technologies

5- Agricultural Engineering

6- Agricultural Economics

1- Soil and Water Sciences

Soil and Water Sciences deal with the geological generation of soil,  soil and water physics and chemistry, and all other factors relevant to soil fertility. Soil science began with the formulation of the theory of humus in 1809. A generation later, Liebig introduced experimental sciences, including a theory of the supply of soil with mineral nutrients. In the 20th century, a general theory of soil fertility developed, embracing soil cultivation, the enrichment of soil with humus and nutrients, and the preparation of soil in accordance with crop demands. Water regulation, principally, drainage and irrigation, was also included. 

Soil and water research have made possible the use of all classes of land in more effective ways, while the control of soil erosion and deterioration has made other advances even more striking. Because the amount of water available for plant growth is one of the major limiting factors in crop production, improved tillage and terracing practices have been devised to conserve soil moisture, and soil-management and land-use practices have been developed to increase the infiltration of snow, rain, and irrigation water, thereby reducing losses caused by runoff.

2- Plant Sciences

The Plant sciences include applied plant physiology, nutrition, ecology, breeding and genetics, pathology, and weed science, as well as crop management. They deal primarily with two major types of crops:

I- Those that represent direct human food such as cereals, vegetables, fruits, and nuts.

II- Those that serve as feed and forage for food, companion, laboratory, and recreational animals.

Special branches of these sciences have been developed to deal with each of the numerous classes of plant crops e.g, arable crops, vegetables, small fruits, citrus fruits and other tree fruits, and flowers and other ornamental plants.

3- Animal Sciences

In modern civilizations, people rely on meat, milk, and eggs as major sources of numerous nutrients. To satisfy this demand, sheep, goats, cattle, chickens, ducks, geese, and turkeys are produced on farms all over the world. The animal sciences comprise applied animal physiology, nutrition, breeding and genetics, ecology and ethology, and livestock and poultry management. In addition, diseases of food animals are the focus of many veterinary scientists.

4- Food Sciences and Other Post-Harvest Technologies

A group of sciences and technologies underlie the processing, storage, distribution, and marketing of agricultural commodities and by-products. Modern post-harvest technology help provides inexpensive and various food supplies for consumers meets the demands of a variety of industrial users, and even creates replacements for fossil fuels. Research having particular significance to post-harvest technology includes genetic engineering techniques that increase the efficiency of various chemical and biological processes and fermentation for converting biomass to feedstock and for use in producing chemicals that can replace petroleum-based products.

5- Agricultural Engineering

Agricultural Engineering includes appropriate areas of mechanical, electric, environmental, and civil engineering, construction technology, hydraulics, and soil mechanics,. Agricultural production presents many engineering problems and opportunities. Agricultural operations, such as soil conservation and preparation, crop cultivation and harvesting, animal production, and commodities transportation, processing, packaging, and storage, are precision operations involving large tonnages, heavy power, and critical factors of time and place. Facilities designed to aid farm operations help farmworkers to minimize the time and energy requirements of routine jobs. Four primary branches have developed within agricultural engineering, based on the problems encountered: farm power and machinery engineering, farm structures engineering, soil and water control engineering, and electric power and processing engineering.

6- Agricultural Economics

The field of Agricultural Economics includes agricultural finance, policy, marketing: farm and agribusiness management, rural sociology, and agricultural law.