Irrigation scheduling strategies for horticultural field crops under limited water availability.

摘要

Horticultural field crops are the main cash crops in most irrigation projects in Tunisia. They are often cropped in rotation with cereals and fodder crops. However, very irregular precipitation and river runoff occurs, thus, the amount of water available for irrigation varies, and in drought years there is a very reduced water supply. These conditions require the development of irrigation scheduling strategies to minimize the water demand with low impacts on yields. The irrigation scheduling modelISAREG, validated for field crops in two locations in Tunisia, Cherfech in the north and Hendi-Zitoun in the centre, was used for the simulation of different irrigation scheduling alternatives for tomato and potato crops in Siliana (central Tunisia). Alternatives are evaluated through the combined use of indicators relative to the reduction in demand for irrigation water, soil water use, corresponding yield reduction and farmers' income reduction. The paper presents the main results for different probabilities of net irrigation demand in combination with typified water availability limitations during the crop season. The applicability of deficit irrigation for horticultural crops is discussed.