Release test of N, P, and K of complete slow release fertilizer (PUKAP JESTRO-1) and its effect on the growth of young siam citrus (Citrus nobilis Lour.)

Abstract

Abstract The research aimed to study the release of N, P, K elements from slow release complete fertilizer (PUKAP JESTRO-1) and its effect on the growth of Siam citrus in a high density planting system (HDP). The release test of PUKAP JESTRO-1 was carried out in a laboratory, where the remaining N, P, K content in fertilizer was measured periodically. The influence test of PUKAP JESTRO-1, which compared with conventional fertilizer in the form of a single fertilizer and NPK compound fertilizer, was carried out on a 1-month old Siam citrus planted on Grumusol (vertisol). The study used randomized block design with 5 treatments and 3 replications, namely 400 g/plant/year mixed fertilizer (200 g Urea + 150 g SP36 + 50 g KCl); 200 g/plant/year PUKAP JESTRO-1; 300 g/plant/year PUKAP JESTRO-1; 400 g/plant/year PUKAP JESTRO-1; 400 g/plant/year NPK YaraMila (16-16-16). The experimental results showed that PUKAP JESTRO-1 released N, P, and K until the fourth, tenth, and eighth week respectively. Application of PUKAP JESTRO-1 at 25% lower dosages produced better plant height compared to mixed fertilizer applications but did not significantly increase leaf N, P, and K levels due to the effect of dilution of elements in plant tissue.