DEPARTMENT OF AGRICULTURAL ENGINEERING AHMADU BELLO UNIVERSITY ZARIA: A TIME-BASED STRESS-DAY INDEX CONCEPT FOR IRRIGATION SCHEDULING

DEPARTMENT OF AGRICULTURAL ENGINEERING AHMADU BELLO UNIVERSITY ZARIA: A TIME-BASED STRESS-DAY INDEX CONCEPT FOR IRRIGATION SCHEDULING

Abstract:

A time-based concept which provides a quantitative means for estimating the plant water stress imposed on a crop during its growing season to provide a criterion for characterising the need for irrigation is presented, based on the stress -Day Index (SDI) concept. Wheat (Triticum aestivum L.) was used as the experimental crop, at the Ahmadu Bello University Farm during the 1991/92 irrigation season. The Time-based concept was evaluated by comparing; (1) estimates of plant-based plant water deficits corresponding to specified time intervals at different crop growth stages; (2) the values of water used efficiencies from the time-based concept for irrigation scheduling with results obtained from a conventional irrigation scheduling approach; and (3) Estimating the Correlation Coefficient between seasonal crop water stress and grain yield from the time-based concept. The results indicated that the time-based form of characterising plant water deficit is less effective with regards to the definition of crop susceptibilities to water deficits as a function of the timing of occurance of the deficit. However, using the time-based concept for irrigation scheduling, an increase of 20.5 per cent in water use efficincy was obtained over that of the conventional approach to irrigation scheduling.

DEPARTMENT OF AGRICULTURAL ENGINEERING AHMADU BELLO UNIVERSITY ZARIA: A TIME-BASED STRESS-DAY INDEX CONCEPT FOR IRRIGATION SCHEDULING