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Trial on Watermelon - Guanacaste, Costa Rica

KTS® is a clear, chloride-free solution that features the highest potassium and sulfur content available on the market.

CaTs® is a clear liquid fertilizer containing calcium and sulfur that reduces the harmful eff ects of salt, such as sodium, in the soil, and it can work as a soil amendment.

Year: 2018-2019
Cooperation with: Margie Taylor and Miguel Rojas (Del Monte - Melons Research Department)
Type of application: drip irrigation
Parameters measured: foliar and fruit nutrient contents, gross and net production, waste.
Variety: Crispy Delight
Goal: Evaluate the eff ect of the application of CaTs and KTS on fruit quality and total yield on watermelon crops.


The crop fertilization program was based on the application of water soluble fertilizers through the fertigation system. The quantities of elements applied throughout the crop cycle are shown in the following table.

T1. Control. Farm practice. No applications of CaTs.
T2. Complementary applications (drip irrigation) of:

  • CaTs: 3 l/ha/application at 21, 25, 28, 31 and 34 days after transplanting.
  • KTS: 3 l/ha/application at 31, 37, 43, 56 and 62 days after transplanting.


  • CaTs price given to the grower by the distributor: 2.55 USD/l of product.
    Total liters applied: 15 ha. Total cost of product: 38.25 USD/ha.
  • KTS price given to the grower by the distributor: 3.20 USD/l of product.
    Total liters applied: 15 ha. Total cost of product: 48 USD/ha.
Treatment​Exportable boxes/ha​Box Price​Total Profit/ha
​Dif. total profit Control vs. KTS + CaTs
​Total cost/ha of
KTS + CaTs
​Break-even point
​Net profit/ha with
KTS + CaTs applications
​1 491 ​10 USD ​14 910 USD ​+ 3 470 USD ​86.25 USD
​9 boxes
​+ 3,383.75
​Base fertilization (kg/ha)





KTS + CaTs applications increased the net yield of exportable boxes by 23.27%. The complementary applications of KTS + CaTs to increase the yield and the marketability of the fruit. Break-even point: 9 more boxes and with KTS + CaTs, 347 additional boxes were produced.


KTS CaTs Watermelon Trial Costa Rica 2019.pdf 

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