Irrigation scheduling through on-farm demonstration

Sugarcane farmers will now benefit from the use of  real-time irrigation advice on sugarcane production using a crop model, weather data and telecommunication ‘The study funded by the Water Research Commission (WRC) provides simple, practical and useful advice to farmers using state-of-the-art technology such as crop models and weather stations, and provides farmers with the benefits of irrigation scheduling through on-farm demonstration’ says Dr Andrew Sanewe ,  WRC research manager responsible for the study .

The South African Sugarcane Research Institute (SASRI) has developed a system that provides farmers with access to the power of modern technological advances without the need to learn how to operate. The MyCanesim system comprises: A database of model inputs and outputs; A sugarcane model (Canesim) that simulates the recent, current and future water balance, crop status and yield for a number of positions in a field; An irrigation scheduling and advice module and an Internet-based user interface for advisors and extension staff to enter and edit field, crop and irrigation system data. During this project the MyCanesim system was successfully improved by developing and implementing a user-friendly, web-based graphical user interface that allows users to set up simulation runs, manipulate simulation input data and view various system reports (including irrigation advice). ‘A control module was created to allow for the smooth operation and monitoring of the MyCanesim system’ says Dr Sanewe. It allows the system administrator to activate or deactivate schemes and fields listed for batch running, to edit key field input variables such as cell numbers and harvest dates, to edit historic irrigation schedules and to manage advice dissemination.’ A facility was also developed that enabled farmers to send a blank SMS reply to the MyCanesim system when they chose not to, or could not, follow advice. The reply is automatically interpreted in the context of the specific advice and then used to adjust assumed irrigation records used as simulation input’ he adds.

‘With the full implementation of the system on the Pongola small-scale irrigation scheme, subscription to the service grew from 10% in 2005 to 87% in 2008’ says Dr Sanewe. ‘The project helped extension staff and farmers gain a much better understanding of the important factors that determine the crop water balance and how irrigation can be scheduled to impact positively on productivity and sustainability’ he adds. 

Farmers can obtain a positive net benefit from the 'advice only' service. The benefit of the more costly 'advice plus monitoring' is more doubtful. ‘The users were involved in the design and implementation and the system complexity was hidden from users which contributed to quick and wide adoption of the technology’ says Dr Sanewe. It was also shown that there is no need to scale down on technology when providing decision support for small-scale farmers. Significant direct monetary benefits are possible, provided the specific prerequisites are in place. An advisory service that provides real time irrigation scheduling advice based on weather data could be implemented on other sugarcane irrigation schemes, provided that specific constraints are addressed.

The WRC report No. 1577/01/09 provides recommendations for the successful implementation of the system. A copy is available on request at the Publications Office -email  orders@wrc.org.za  or Tel : 012 330 9015.