Alternate furrow irrigation can radically improve water productivity of okra

Alternate furrow irrigation (AFI) is gaining interest as a means of saving water while minimising loss in crop production. Given the potential water savings of AFI, a field experiment was conducted in the Tandojam region of Pakistan by growing okra with AFI and conventional furrow irrigation (CFI) in which every furrow is irrigated. Our results show that total irrigation water applied in the AFI treatment was roughly half (248±2.9mm) that applied to the CFI treatment (497±1.7mm). Despite the very significant reduction in irrigation water used with AFI there was a non-significant (p>0.05) reduction (7.3%) in okra yield. As a result, we also obtained a significantly (p<0.001) higher crop water productivity (CWP) of 5.29±0.1kgm−3 with AFI, which was nearly double the 2.78±0.04kgm−3 obtained with CFI. While this reduction in yield and/or potential income may appear small, it could be critical to the welfare of individual farmers, who may as a result hesitate to make changes from CFI to AFI if they are worse off than farmers who do not adopt AFI. This situation exists because current water charges are based on crop and land area rather than the volume of water being accessed for irrigation. Transitioning from the current crop and land area based method of charging for water to a volumetric method may require investment in irrigation system changes and may take time to accomplish. These are important lessons for other countries, and particularly developing countries who are trying to improve the environmental, social and economic performance of their irrigated systems. We recommend that further studies be carried out using AFI to determine whether similar water savings and flow-on benefits can be achieved across a wide range of cropping systems in arid and semi-arid environments.