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Publication #SL 278

Crop Water Use and Irrigation Scheduling Guide for North Florida1

Thomas Obreza2

Introduction

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This guide presents average daily water use for 13 north Florida crops that can be used to help schedule irrigation. Knowledge of crop water use and field soil water-holding capacity allows a grower to develop a realistic irrigation schedule that minimizes plant water stress, saves water, and reduces nutrient leaching.

Crop water use as defined in this guide is a combination of evaporation and plant transpiration. Evapotranspiration, abbreviated ET, is the term used to describe these two processes acting together.

Major factors that affect daily crop water use include:

  • Crop type.

  • Crop age.

  • Plant spacing and/or percent ground coverage.

  • Weather or climatic conditions, such as

    1. Amount of sunshine – ET is much greater on a sunny day compared with a cloudy day.

    2. Air temperature – ET increases from winter to spring to summer.

    3. Amount of wind – ET is greater on a windy day compared with a calm day.

    4. Humidity – ET is greater on a dry day compared with a humid day.

The average daily crop water use estimates in this guide were determined by multiplying reference ET by a factor that takes crop type and age into account. Reference ET is the ET rate of a short, healthy, well-watered grass. Depending on crop type, crop factors ranged between 0.2 for emerging plants to 1.2 for actively growing plants with a large canopy volume.

Footnotes

1. This document is SL 278, one of a series of the Soil and Water Science Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date December 2008. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. Thomas Obreza, professor, Soil and Water Science Department; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer, Interim Dean.