Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

Despite of various chemical properties of greenhouse soils producing watermelon, the standard fertigation guideline suggests a method of supplying a uniform amount of fertilizer per week. To determine the optimal application rate of fertilizer for watermelon in nutrient-rich soils when using a fertigation system, we grew watermelons twice in spring and summer with four different application rates of fertilizer: 0.5 (NPK 0.5), 1.0 (NPK 1.0), 1.5 (NPK 1.5), and 2.0 times the standard guideline (NPK 2.0). The biomass production (dry weight) and nutrient uptake were not different between treatment groups in both production seasons. The yield of watermelon was significantly decreased in the NPK 2.0 treatment, whereas it was significantly increased in the NPK 0.5 treatment. Based on our observations, we suggest the recommended fertilizer application rates for watermelon in nutrient-rich soils under a fertigation system are 47.8(N)-15.4(P₂O₅)-88.1(K₂O) kg ha^-1 at spring and 77.3-15.6-115.8 at summer. Further studies are needed to subdivide standard fertilization methods with soil nutrient status for customized nutrient management in fertigation systems.

Fruit yield of watermelon were significantly low when treated with twice of the standard application rate (NPK 2.0) in soil containing high nutrients. In the summer period, the maximum yield was shown at half times of the standard application rate (NPK 0.5).