The quality of irrigation water has a significant impact on crop yield, degradation of soil, pollution of groundwater, and operation and life of irrigation systems. It also interacts with soil and its chemical and physical constituents. In irrigation engineering, water quality is evaluated by considering physical and chemical characteristics of water, but biological characteristics may also be important if wastewater is used for irrigation. This chapter discusses water quality from an agricultural irrigation viewpoint.

Sprinkler irrigation is becoming popular these days all over the world, especially because water is becoming scarce for meeting agricultural needs fully, and demands on water resources are growing from other competing sectors, such as industry, energy generation, waste disposal, domestic, and so on. The objective of this chapter is to discuss different aspects of sprinkler irrigation.

Irrigation of crops and drainage of excess water have both positive and negative environmental consequences. Irrigation return flows degrade the quality of receiving streamflow as they transport pollutants. Although return flows cannot be entirely eliminated, they can be reduced by appropriate water management and improved conveyance and delivery systems. This chapter briefly discusses the importance of return flows and the pollutants transported by them.

For irrigation management and maintenance, it is necessary to determine the volume of water that is applied to the field and the rate at which water is applied. Measurement devices are therefore included in irrigation systems. This chapter discusses different methods and devices that are commonly employed for determining flow rates and volume in agricultural irrigation.

Drainage is the orderly removal of excess water from the soil surface as well as the soil profile or root zone. It directs the removal in a manner such that it does not erode the soil and damage crops. By so doing it provides a suitable environment for the maximization of plant growth, keeping in mind financial constraints. The objective of this chapter is to present rudiments of agricultural drainage.

Design of a farm irrigation system entails both technical and nontechnical considerations. It is an integration of principles borrowed from agriculture, meteorology, hydrology, hydraulics, irrigation, and drainage engineering as well as economic, environmental, and management sciences. This chapter provides a snapshot of the steps involved in designing a farm irrigation system.

Irrigation is vital for productive agriculture and consequent food and nutritional security. However, irrigation requirements are fundamentally impacted by climate, soil, and the crops to be irrigated. They are also impacted by the source, availability, and quality of water. Providing a snapshot of irrigation worldwide as well as in the United States, this chapter discusses the organization of the book, irrigation practices, and environmental concerns arising due to irrigation, and is concluded with a reflection on the future of irrigation.

Crops are grown in certain types of soils, that is, not all soils are suitable for growing all crops and some crops can be grown in only certain types of soils. Irrigation of crops significantly depends on the type of soil. Soil is fundamental to our biosphere and requires proper management. This chapter discusses the basic soil properties that are relevant to crops and farm irrigation.

Irrigated agriculture is vital for food security. Irrigation systems that make it possible are usually designed with the long-term objective that they are economically sustainable, although that is not always the case in many developing countries. This chapter visits fundamental concepts needed for analyzing benefits and costs, which in the long term define the benefit–cost ratio.

When an agricultural field is irrigated, the common thought is that it should be irrigated efficiently so that crop yield is maximized. Does it mean that irrigation efficiency should be maximized? Is maximum efficiency desirable under all circumstances? How does irrigation efficiency relate to the type and design of the irrigation system? Should irrigation efficiency be entirely based on the amount of water consumed by plants? Before addressing these and related questions, we must first address the question: What is meant by efficient irrigation or irrigation efficiency? This chapter discusses the concept of irrigation efficiency and related aspects.

Groundwater is of vital importance for agricultural irrigation. In almost all countries, a significant portion of irrigation water is derived from groundwater using wells. In developing countries where farm holdings are small, one well may suffice but a number of wells are used in large farms. This chapter discusses rudimentary aspects of groundwater and wells from the perspective of irrigation. Although the material covered in the chapter is based on gross simplifications, it has been found to be useful nonetheless for irrigation purposes.

Channels are a vital part of irrigation systems. They are the link between the source of water and the irrigation field. Channels used in irrigation systems can be either erodible or non-erodible, or earthen or lined. Flow in channels is governed by the principles of hydraulics. This chapter discusses rudimentary aspects of hydraulics and the design of open channels.

Pumps are an integral part of many agricultural irrigation systems. A pump is used to lift groundwater to the ground surface, raise water from a lower elevation to a higher elevation, transport water, overcome friction, or generate pressure for the operation of sprinkler and trickle irrigation systems. This chapter discusses rudimentary aspects of pumps and their operation and selection.