More than 60 per cent of irrigation water is wasted

Islamabad : Irrigated agriculture in Pakistan consumes 93 per cent of the available water resources whereas more than 60 per cent of irrigation water is lost during the conveyance and application in the field. The major reason for application losses is the lack of knowledge about irrigation scheduling.

These facts are discussed in detail in the latest research report titled “Water Requirements of Major Crops in the Central Punjab” published by Pakistan Council of Research in Water Resources (PCRWR).

Conducted by Zamir Ahmed Soomro, Muhammad Ashraf, Khuram Ejaz and Ahmad Zeeshan Bhatti, the report says that due to lack of knowledge on irrigation scheduling, farmers either under or over irrigate their fields resulting into loss of yield, low water and fertilizer-use efficiencies.

The report highlights the fact that for proper irrigation scheduling, knowledge of crop water requirements (CWR) is essential. Crop water requirements can be determined using empirical methods or Lysimeter set ups. The report is synthesis of the research done on CWR of major crops in Central Punjab during the last three decades at Lahore.

It mentions that Pakistan has one of the largest irrigation systems in the world comprising three major reservoirs with a design capacity of about 20 billion cubic meters (BCM), 23 barrages, head works and Siphons, 45 main irrigation canals irrigating about 17 million hector (Mha) of land. Irrigated agriculture consumes 93 per cent of the available water resources. Irrigation is used on 80 per cent of all arable land and produces almost 90 per cent of all food and fibre requirements.

However, the research mentions that this system is subject to a number of issues such as increased population, urbanizations, industrialization, inadequate storage and sediment in existing water resources and overall low system efficiency. The overall efficiency is generally less than 40 per cent. For example, out of 142 BCM of water available at the canal head works, hardly 55 BCM is being used and remaining 87 BCM (61 per cent) is lost during conveyance through canals, distributors, minors and watercourses and during application in the field.

The report points out due to lack of knowledge about irrigation scheduling, farmers keep on applying water even when the crop does not need that. This is not only the wastage of water but also wastage of precious nutrients that are leached down with access water.

The PCRWR determined crop water requirement of major crops including wheat, rice, sugarcane, sunflower, berseem, sorghum, and maize (local and hybrid) in the central Punjab using drainage-type Lysimeter located at Lahore. The researchers measured total evapotranspiration (ET) and average crop coefficient of the selected crop. The determined crop water requirements indicate that there is enormous potential for water saving if it is applied according to crop’s requirement.