Effect of different organic amendments and fertigation on growth, yield, quality of watermelon (Citrullus lanatus Thunb.) and soil properties of Theri land (Red sand dune) of southern Tamil Nadu

The present investigation was carried out at Sattankulam taluk, Thoothukudi district of Tamil Nadu, India to study the effect of different organic amendments with recommended dose of fertilizers on growth and yield of watermelon and physic-chemical properties of Theri soil (red sand dunes) during the year 2019 and 2020. The experiment was laid out in Randomized Block Design with Factorial concept (FRBD). In all there were three factors as organic amendments with 6 treatment combinations for each factor, which were assigned at random in each plots with three replications. The recommended dose of fertilizers in treatments were two levels as 75 and 100 percent. Among the treatment combinations, the tank silt application @ 100 t ha^-1 with 100 percent recommended fertilizer as 200:100:100 kg of NPK ha^-1 through fertigation at 7 days interval (A1N5) produced maximum number of branches (10.67), longest vine (362.0 cm), number of fruits plant^-1 (2.57), weight of fruit (5.27 kg), fruit yield (68.77 t ha^-1), maximum content of total soluble solid (10.94%), ascorbic acid (8.07 mg 100 g^-1) and improved the physic-chemical properties viz., particle density (2.45 Mg m^-3), bulk density (1.31 Mg m^-3), percent pore space (48.33%), pH (6.58), EC (0.35 dSm^-1) and organic carbon content (0.52%).