SOIL TEST INFORMATION SHEET NO. V-300

Prepared by Extension Horticulturists Mike Cannon and James Boudreaux

Watermelons and Cantaloupes

1.	Both watermelons and cantaloupes are very sensitive to extremely acid soils.  Production may be affected when soil pH is below 5.0.  When soil pH is below 5.0, soils should be limed.  Apply agricultural limestone to increase pH.  On soils low in magnesium, apply dolomitic limestone.  Apply lime 2 to 6 months before planting.

2.	Apply nitrogen fertilizer in a split application.  Apply 30 to 60 pounds per acre prior to planting.  Sidedress with 30 to 60 pounds of nitrogen when vines begin to run, 3 to 4 weeks after planting.  Watermelon should be sidedressed with 60 to 90 pounds of potassium.

3.	Watermelon quality is normally better when melons are grown in the sandy soils in the upland hill areas of the state.  Watermelons grown on highly fertile alluvial soils often are of low quality and may develop “white heart”.  Reduce nitrogen according to recommendation sheet.

4.	Cantaloupes are not as specific in soil types as watermelons.  Cantaloupes produce over a wider range of soil types, however, quality is determined to a great extent by the amount of moisture received just prior to ripening.

5.	Blossom end rot can result from excess nitrogen, moisture stress, low soil calcium levels or a combination of these factors.  Foliar sprays of calcium nitrate or calcium chloride 95 lbs./100 gals.)  Will help to reduce losses.  Spray at first fruit set.  Make 2 or 3 additional applications at 7-day intervals.  Always apply foliar treatments in the early morning hours to the underside of leaves.  Use 30 to 100 gallons per acre to ensure through coverage.

6.	Watermelons and cantaloupes grown with drip irrigation can be sidedressed by injecting nitrogen fertilizer with the irrigation water.  This process is called fertigation.  Apply 8-10 pounds of nitrogen per acre per week.  Start fertigation 2-3 weeks after planting and continue for 10-12 weeks.

7.	Contact your county agent for additional information and help in your fertilization program.  The agent also receives a copy of this report for the parish office files.