ISHS Acta Horticulturae 278: Symposium on Scheduling of Irrigation for Vegetable Crops under Field Condition
USE OF SIMULATION MODELS FOR DEVELOPING INDICATIVE IRRIGATION SCHEDULES AND EVALUATING PREVAILING IRRIGATION PRACTICES |
| Author: | M. Smith |
| Abstract:
To stabilize and increase agricultural production large investments have been made in irrigation infrastructures both in developed and developing countries. Of the total agricultural area of the world 15% is presently irrigated, contributing to an estimated 35% of agricultural production. Although horticulture, both fruit and vegetables, covers a modest area compared to the total area (5%), its economic and nutritional value is of much more importance. Horticultural production techniques are more complex and an adequate and timely water supply is a first condition to optimize production. Although only 30% of the world vegetable area is irrigated, 50% of total production is irrigated and it is expected that by the year 2000 approximately 63 percent of vegetable production will be irrigated. Adequate irrigation techniques for vegetable production is an essential condition to achieve the potential yield levels under irrigation. Production figures for vegetables show clearly the technological gap between developed and developing countries. Not only technologies but in particular also the management and operation of the irrigation system play a decisive role in the production increase and the preservation of resources and environment. Irrigation scheduling is an important means to achieve better water management. Irrigation scheduling techniques introduced with success in developing countries use in general direct or indirect soil moisture measurements (tensiometers, water budget methods) as a base for timing of irrigations. In third world countries such techniques can often not yet be applied on a practical scale as small farm holdings and different socio-economic conditions would not permit application of costly and sophisticated devices and complex data processing for each irrigated field unit. To achieve nevertheless a better watering of crops, simple and practical guidelines need to be given which take into account not only the water use by the crops but also the field irrigation method and water supply system. The FAO irrigation management model developed for and tested in a number of FAO field projects allows the development of indicative irrigation schedules from average climatic and agricultural field data, taking into account the specific irrigation management conditions of the irrigated crop. Furthermore, the model allows the assessment of efficiency of prevailing irrigation practices in terms of water efficiency and yield reductions from readily available and obtained field data. From the information, improved irrigation practices can be recommended. | |
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