Horticultural Crops - Understanding the Basics - Water Management

Table of Contents

1. Irrigation
2. Drainage
3. Nutrient Management

Good quality water is needed for spraying, irrigation and household use. Horticultural crops tend to be very sensitive to moisture levels. Often, it seems there are only two levels - too much moisture and not enough. Irrigation and drainage are best management practices for many horticultural crops. Adequate moisture reduces plant stress and helps prevent disease.

Irrigation

Irrigation must be applied properly to be cost-effective and to prevent harm to the environment. When irrigating:

• Know your soil type and its capacity to hold water.
• Know when moisture is critical to your crop.
• Use a scheduling method such as a tensiometer or the evapotranspiration model.
• Be aware of the weather forecast.
• Monitor the system when it is operating. Breakdowns cost money and waste crop inputs.
• Reduce losses from evaporation. When applying water, avoid the heat of the day. Apply on cloudy days and when wind speed is low.
• Keep good field records.
• Monitor for disease.
• If removing more than 50,000 litres (10,000 gallons) a day from a water source, get a permit from the Ministry of the Environment.

When properly used, irrigation is an effective management tool. There are a number of publications available that can provide you with more detail on equipment and scheduling.

Figure 1. A rain gauge is an important tool in water management. Keeping accurate rainfall records will help in scheduling irrigation.

Figure 2. Reduce water loss when using overhead irrigation – avoid the heat of day, apply on cloudy days and when wind speed is low.

Drainage

Drainage is critical to production of horticultural crops. Poor drainage adds stress to plants and makes them more prone to pests.

• Ensure drainage is adequate. Repair or replace tiles that do not work.
• Protect tile outlets to prevent damage to ditchbanks (see the book on Field Crop Production for details).
• Use a header tile to reduce the number of outlets entering a ditch, where possible. This will help prevent ditch damage and reduce loss of field areas to slumping.

Figure 3. Diagram of undrained land: free water level drops significantly from mid-June to mid-August.

Figure 4. Diagram of drained land: free water level remains fairly constant through the summer.

Good drainage is critical to the production of horticultural crops. Poor drainage does not encourage deep root growth, making the plants more prone to drought stress.

Nutrient Management

Good use of nutrient management will improve both your production and the environment. Cost-effective application will produce the best yield potential while minimizing costs. In turn, this helps reduce nutrients lost to the soil through leaching and water erosion.

Soil testing is an important first step. Soil test results will give you a base on which to analyze soil needs. Also do tissue tests, if available for your crop. This shows what plant nutrient levels are at that point in time, as opposed to what is available in the soil. This is particularly important for perennial crops.

Record keeping of soil and tissue tests will help track trends. Include observations on crop growth, yield, quality and weather conditions during the growing season.

Application of nutrients varies from crop to crop. For more details, check the sections on specific crops in following sections and the listing of OMAFRA publications.

Figure 5. Soil testing is important. Make sure the sample represents the field.

A few general best management practices include:

• If possible, use split applications of nitrogen to reduce the possibility of loss by leaching. This will also increase management and application costs and may not be suited to all crops.
• Keep soil healthy so that root systems will be most effective in using nutrients.
• If nutrients are left after a crop harvest, use cover crops to hold them for the next crop.

To be competitive, horticultural crop growers have to produce high quality products efficiently. To be sustainable, soil and water resources must be protected and conserved. Best management practices need to be chosen and adapted to suit each farm operation.        

Horticultural Crop Production