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Melon - Irrigation

Soil tension values for different soil textures for use in scheduling drip irrigation, based on various percentages of depletion of available water holding capacity (Field capacity).

Soil Texture 0%
Soil Tension Values (centibars)
Sand, loamy sand 5-10 17-22 25-30
Sandy loam 10-20 22-27 33-40
Loam, silt loam 15-25 25-30 40-50
Clay loam, clay 20-40 35-45 55-65

Melons require regular, uniform watering during the growing season. Water shortages early in the season can limit seed germination, transplant establishment, and vine growth. Inconsistent watering around fruit set can cause misshapen fruits and induce blossom end rot, and affect fruit sizing, flavor, and color development. Over-watering encourages root rots, belly rot on fruits, and can cause cracking. Furrow and drip irrigation is well-suited for melon production and some growers use sprinkler irrigation to aid in stand establishment. Later in the growth of melons, sprinkler irrigation (solid set, wheel lines, and center pivots) can contribute to foliar diseases and may interfere with bee activity, thus reducing fruit set, shape, or size. A small decrease in water after fruits reach mature size can improve fruit quality and flavor

Soil water status should be monitored regularly to maintain consistent soil water. Soil moisture monitoring is easily done with a resistance block such as the Irrometer Watermark sensor. Place sensors at various locations in the field and at several depths in the soil profile to get accurate measurements. Sensors typically express soil water content as a tension reading (centibars) that defines effort required to access available water. Soil texture (clay, loam, sand) influences the soil’s ability to hold water. Soil water monitoring is useful in helping to determine when to irrigate. Field capacity describes a soil at 100% available water-holding capacity after excess water has drained away. Start irrigation for melons at 20-25% when irrigating with drip systems and at 40-50% with furrow or sprinkler systems. Note that irrigation depends on soil type. Other low cost tools and methods to monitor soil water can be found at the ATTRA website.