An FAO type crop factor modification to SWB makes inclusion of crops with limited data possible: Example for vegetable crops

Abstract

There is a lack of information on crop water requirements of vegetables in South Africa. Six winter and 10 summer irrigated vegetable species were grown in a field trial at Roodeplaat (Gauteng Province) during the 1996/97 season. The objectives were to determine seasonal water requirements of vegetables and to develop a simple, generic crop, irrigation scheduling model that would not require time-consuming and therefore expensive growth analysis data to determine model parameters. Weather data were recorded with an automatic weather station, canopy cover (C) was measured weekly with a sunfleck ceptometer and soil water with a neutron meter. A simple C-based procedure was used to determine FAO (Food and Agriculture Organisation of the United Nations, Rome, Italy) type basal crop coefficients (Kcb) and growth periods for the following stages: initial, development, midseason and late-season. In addition, initial and maximum rooting depths and crop heights were determined.

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