reduce area planted. Reducing irrigation below the level required for best production can reduce yield and quality of vegetable crops greatly. No advantage is gained in trying to spread a given water supply over too large an area. When irrigation water is in short supply, it may be necessary to take some land out of production or stop irrigating some fields. If you have a choice, plant the most productive land.

Select less sensitive crops and cultivars. Commercial growers weigh economic factors heavily in selecting crops. However, during periods of anticipated drought, water requirements assume increased importance. Certain and crops and cultivars are less sensitive to shorter periods of water stress than others. These are not necessarily the highest yielding selections and may not have greatest market demand. Short season: cultivars also can require less water.

Preplant irrigation benefits many vegetable crops by building Subsurface soil moisture and promoting a deeper root system. Avoid over irrigation, which wastes water and can leach fertilizer and chemicals into groundwater supplies.

Established the proper plant stand. Rapid emergence and a uniform plant stand make the most efficient use of soil moisture. Wet soil exposed to sunlight has greater evaporation loss than does soil shaded by a crop.

Once a full canopy has developed, differences in evapotransporation per area due to plant population are negligible.

Consider transplants. Proper germination and emergence in the field require careful water management. Often, less water can be used and more precise control can be obtained by using transplants. However, once in the field, transplanted crops generally develop shallower root systems than direct seeded crops and may require more frequent irrigation.

Use mulches and row covers. Mulches and plastic or spunbonded row covers will increase temperatures for more rapid plant growth. Mulches also can save water by reducing surface evaporation.

Improve irrigation scheduling. Good irrigation scheduling is essential for all irrigation systems if growers are to apply the correct amount of water at the correct time. Irrigation scheduling requires careful attention to soil moisture, climate, and crop growth. The use of tensiometers or moisture blocks can increase the precision of irrigation scheduling.

Maintain proper soil structure and fertility. Proper soil structure permits optimum infiltration and water holding. Proper soil fertility encourages the best plant growth and use of available soil moisture. Adopting tillage methods, such as minimum or no tillage, that maintaining or enhance soil organic matter will improve the water holding capacity of droughty soils. Not all vegetable crops lend themselves to minimum tillage or no tillage systems.

Maintain good plant health. Insect and deceased damage restrict the growth and water use efficiency of vegetable crops, reducing both yield and quality. Maintaining good plant health is especially important in regard to diseases classified as wilts, which reduce the ability of the crop to absorb and translocate water. Plant parasitic nematodes damage or stunt the development of plant roots, thereby worsening drought damage. Good nematode control is essential for healthy root systems.

Careful attention to irrigation is always an essential part of vegetable/turf production and will playoff through improve crop quality, a more reliable product and greater profit. As production costs rise, so does the need to safeguard investments in seed, fertilizer, labour, and land, against losses resulting from weather conditions.

From: Co-Operative Extension Service, Purdue University
West Lafayette, IN U.S.A.