*13.6.1 Conventional methods of irrigation*

This method involves hand irrigation. A farmer brings water to farming areas by hand, with the aid of livestock, or from wells or canals. Depending on the localization strategy. The main advantage of this technique is its affordability. Its effectiveness is nonetheless minimal due to the uneven dispersion of water. Additionally, there is a substantial chance of water loss. Examples of typical systems are the chain pump, the lever system, and the pulley system. The most popular and commonly used of these is the pump system.

#### *13.6.2 Modern methods of irrigation*

The current technique compensates for the limitations of previous methods and so aids in proper water consumption. The significance of irrigation may be described as follows:

Agriculture suffers from insufficient and unpredictable rainfall. Droughts and famines are caused by insufficient rainfall. Irrigation improves efficiency even in areas with minimal rainfall. The productivity of irrigated land is higher than unirrigated land. Multiple cropping is not feasible in Pakistan because the rainy season varies by area. However, the climate allows for agriculture all year. In most areas of the region, irrigation infrastructure allows for the cultivation of more than one crop. Irrigation has contributed to the cultivation of the majority of the fallow land. Irrigation has helped to maintain productivity and yield levels. Irrigation enhances the availability of water supply for crops, which boosts farmer income.

GRAVITY OR SURFACE IRRIGATION. Suitability of Surface Irrigation Methods


#### **14. Irrigation resource constraints and climate change**

Freshwater availability has an impact on almost all social and environmental elements of climate and demographic change, and also their implications for sustainability. Water scarcity is already a significant problem in many parts of the globe and is predicted to get worse as the population increases, the nutrition quantity is demanded, temperatures are rising, and rainfall pattern change. It also affects energy projects, anthropogenic water usage, and ecological use.

The world's freshwater resources are under tremendous pressure due to population growth, changing land uses brought on by agricultural development, and deforestation [26]. The future availability of freshwater for industrial use, agricultural production, and human consumption become more uncertain as global climate change intensifies. Depending on greenhouse emissions, the predicted range of global temperatures is comparable to 1980–1999 even by end of the 21st century anywhere between 1.1 and 6.4°C [27].

The size and sign of potential impacts are still up for debate, and the extent of predicted precipitation changes varies substantially relying on geographical region and spatial extent [28]. Even in certain locations where mean precipitation is expected to decrease, daily heavy precipitation occurrences are likely to increase [27]. Even though atmospheric CO2 seems to have the potential to increase photosynthesis by close to 30%, such changes are anticipated to have a greater negative impact on


*1\*Ball is formed by squeezing a handful of soil very firmly.*

*Source: https://sanangelo.tamu.edu/extension/agronomy/agronomy-publications/how-to-estimate-soil-mois ture-by-feel/*

**Table 2.**

*Guide for judging how much moisture is available for crops.*

agricultural output [29]. The impact of climate change on agriculture water usage especially changes in net irrigation demands, demand, and agricultural water consumption has been the subject of several studies (**Table 2**).

#### **15. Irrigation scheduling**

It is the ability with which the farmer decides the amount and time of irrigation. It includes the Time of irrigation when irrigation is needed, Amount of irrigation (how much water should be applied?). What should be the response of the crop (seed yield or forage yield) to the irrigation applied? There are two alternative aims for scheduling irrigation. 1 For achieving maximum output per unit of land area 2.For Maximizing land area utilized in crop production.

#### **15.1 Methods of irrigation scheduling**

Fixed interval application: In the warabandi system there is a fixed interval for irrigation application.

Apply irrigation when your neighbor is doing so. A visual sign of crop-based upon their experience farmers apply irrigation when they observe the sign of starvation of water, it is only descriptive. The determination of moisture content of the soil: Gravimetric method, Gypsum block method, Tensiometer method and Neutron probe method.

#### **15.2 Irrigation scheduling benefits**

It enables the farmer to plan a water rotation schedule between fields to lessen agricultural water stress and boost yields. For the farmer, it cuts the cost of labor and water. Because it collects surface runoff, fertilizer costs are reduced. It raises net profits by enhancing agricultural quality and productivity. Water logging risk is decreased. It helps to control problems with root zone salinity. Using the "saved" water to irrigate non-cash crops, creates additional revenue.

#### **15.3 Strategies for irrigation scheduling**

#### *15.3.1 Certain*

Climate variables that have been measured; Average soil parameters were measured. Irrigation water quality. The amount of water used and when it was used Irrigation technique and a few crop parameters (crop height, development stage, DAP, LAI, root depth).

#### *15.3.2 Uncertain*

Reference evapotranspiration and Kc values are estimated. Estimation of crop water needs. Crop water uptake pattern, and crop response function to shortfall irrigation and/or excessive salt accumulation.

Irrigation Scheduling Approaches, Fixed Scheduling, Flexible Scheduling, and Flexible Scheduling Incorporating Rainfall are the three types of irrigation scheduling. Each category is described in detail below.


*Sustainable Irrigation Management for Higher Yield DOI: http://dx.doi.org/10.5772/intechopen.107153*
