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Humans live in a world of sound. Many sounds are quite pleasant and persons who are not hearing impaired enjoy hearing voices, music, and many sounds of nature. People often listen for sounds that could warn of danger or the malfunctioning of equipment. Individuals have differing abilities to detect sound of varying intensities and frequencies, and differ as well in their personal tolerance of and appreciation of sound.

Measuring distance and angles with simple instruments are two of the most common surveying procedures used in agriculture. Even though the instruments may be simple, a sufficient level of accuracy for many measuring jobs can be achieved with practice and careful work. In this chapter, you will become acquainted with the basic methods and techniques of measuring distances. The layout and measurement of angles is covered in Chapter 13.

The layout and measurement of angles are very important parts of agricultural surveying. In this section, you will learn, using simple tools and procedures, three indirect methods that can be used to lay out a perpendicular (90°) angle and one method that can be used to lay out or measure any angle between 0° and 90°. These procedures are useful in planning buildings and fences and in determining the corner angles of irregular-shaped tracts, fields, and/or smaller areas.

From earliest times there was a need to mark and describe the boundaries of parcels of land. It is recorded that in about 1400 B.C. Egypt developed a system to reestablish land boundaries after each flood. The need to accurately establish and describe land boundaries has persisted to this day. To transfer ownership one must be able to describe what land is being considered, and where it is located. In the United States, a unique description for each parcel of land is required to collect property taxes. Three primary systems are used in the United States to define land boundaries and locations. These are metes and bounds, block and lot, and the Public Land Survey System (PLSS) commonly called the rectangular systems.

Leveling is the process of determining the elevation of points on, above or below the surface of the earth. Many different types of surveys can be used depending on the desired results. Differential and profile leveling are two surveying methods that are very useful for agricultural and horticultural projects. They are both useful for planning and layout of projects. For planning purposes they are used to provide the information needed to develop the maps, charts, and drawings necessary to lay out buildings, roads, drains, etc. They can also be used for layout. Layout is used to establish the boundaries, lines, and elevation for the construction of those structures. Differential and profile leveling rank next to the measurement of distance in importance as a surveying technique. The following chapter will discuss the terms, equipment, and procedures for two types of leveling.

The weather is the largest uncontrolled variable, as well as the most unpredictable variable, in the production of agricultural products. Agricultural production is based on the growth of plants, and those plants require an optimum environment for maximum production. However, maximum production is seldom realized in the natural environment because the weather seldom matches the needs of plants. Whenever the real environment is significantly different from the optimum, plants are stressed, and production is reduced. The major limiting factor is water. An understanding of the mechanisms of the weather will improve the decision-making process for activities such as cutting hay, irrigating, harvesting, and tillage. Better decisions mean increased productivity for any agricultural enterprise. This chapter will discuss the pressure systems that influence the weather, the hydrologic cycle, and a few of the characteristics of rainfall and runoff.

In the previous chapter it was determined that runoff occurs whenever the rainfall intensity exceeds the infiltration rate. In many situations it is important to be able to determine the volume of water that will run off an area and/or the maximum rate of runoff. The volume of runoff is used to size drainage structures and water impoundments. One of the uses of the peak rate is to size drainage ways, culverts, and bridges. The peak rate can be easily visualized if the flow rate is plotted in the form of a hydrograph. A hydrograph plots the runoff rate for a watershed versus time. A watershed is a drainage basin where all of the water that runs off passes through one point, Figure 17.1.

Soil is a complex, constantly changing resource. It affects the life of plants and thereby all animals, and it is affected by plants and animals. Soil is the primary medium of growth for plants. It supplies nutrients, water, and a place to anchor roots. Soil has an economic value and therefore any that is lost from production is an economic loss. The topsoil has the most value because it is the primary source of nutrients, chemicals, seeds, water-holding capacity, and organic matter. Soil is formed and destroyed by erosion. In this chapter soil development, destruction, and conservation will be discussed.

The most limiting and most variable environmental factor affecting the productivity of plants is water. Whenever adequate water is not available, farmers have always tried to irrigate their crops. Irrigationwater has always been in short supply, but it is becoming a scarce commodity inmany regions. Even where it is available, pumping and/or transportation costs have increased dramatically in many locations. Today the profitability of irrigated agriculture is dependent of efficient use of water. The effective and efficient use of irrigation is dependent on four factors.

The term biological products describe all of the food, feed, and fiber produced by agriculture. These products include everything from fruits and vegetables to grain, hay, and cotton. Although the diversity of agricultural production is too broad to be totally covered in this text, the following sections will discuss some of the principles involved in the handling, drying, and storage of these products.