Bacillus Consortium Functions to Reduce the Nitrogen-Phosphorus-Potassium Compound Fertilizer Dose in Potted Choy Sum

Abstrak

Increasing the productivity of choy sum (Brassica rapa subsp. chinensis var. parachinensis) can be achieved by using organic and inorganic fertilizers properly. This study aimed to determine the effect of combining NPK 16-16-16 fertilizer with 0,5% Bacillus spp. biofertilizer on the growth and yield of choy sum plants. The study used a randomized block design with six treatments, namely control (P₀), NPK 50 kg/ha (P₁), Bacillus spp. 0.5% (P₂), a combination of Bacillus spp. 0,5% with NPK 50 kg/ha (P₃), a combination of Bacillus spp. 0,5% with NPK 100 kg/ha (P₄), and a combination of Bacillus spp. 0,5% with NPK 150 kg/ha (P₅). Plants treated with Bacillus combined with all NPK doses showed greater plant height, leaf number and width, and stem thickness. Fresh root weight was not affected by the treatment. The combination of Bacillus spp. 0.5% with 50 kg/ha of NPK produced the highest dry weight of 10.9 g, whereas the highest dry root weight was obtained from plants treated with Bacillus at all doses of NPK. The acidity and total N of the planting medium did not change significantly, but available P increased with higher NPK doses rather than Bacillus inoculation. This study shows that Bacillus is an effective biofertilizer as a complementary input that improves plant performance under reduced chemical fertilizer.