Evaluation of Major Soil Nutrients After the Application of Microbial-Inoculated Acidified Biochar Pellets Using a Sigmoid Function

This experiment aimed to investigate nutrient dynamics in soil and compare plant growth responses after treatment with acidified biochar pellets inoculated with microorganisms during Kimchi cabbage cultivation, using a sigmoid function model. The treatments included the following: Control–only guano application; ABPM 27 (Pseudomonas fluorescens 22BCO027); and ABPM 86 (Bacillus megaterium 22BCO086). Guano and biochar pellets were applied at 320 kg ha−1, based on the recommended nitrogen application rate for cabbage cultivation. The results showed that the cumulative NO3-N and P2O5 in the ABPM 27 treatment were 27.7% and 12.1% higher, respectively, compared with the control. The maximum cumulative K was not significantly different (p > 0.05) between the treatments. The cumulative NH4-N and NO3-N were well fitted (R2 > 0.824) to the sigmoid curves, while the cumulative P2O5 and K were well described with the linear function (R2 > 0.970) regardless of treatment. The highest yield was 77.4 tonnes ha−1 under the ABPM 27 treatment. Therefore, the ABPM 27 treatment is strongly recommended for enhancing cabbage yield in organic farming due to its high capacity for accumulating NO3-N and P2O5.