Effect of biochar and mineral fertilizer integration on growth and nutrient dynamics of rice varieties under dry direct-seeded conditions
The increasing need for food, which results from fast population growth, requires agricultural methods that can produce more crops while protecting soil health. Biochar has become an effective soil enhancer that boosts soil fertility and nutrient retention while increasing crop productivity. The study examined the effects of nutrient management with biochar on the growth performance of direct-seeded rice in the Bagamoyo irrigation project during the cropping period of 2025. The split-plot design was used with three replicates and a split-plot ANOVA and linear mixed effect models to assess the integration of biochar and NPK from maize straw in three rice varieties (TXD 306, TANRICE 1, and KHAODUCKMALL) under multi-season conditions, with a p<0.05 mean separation and a Tukey HSD. The study results demonstrate that biochar application constituted the only element that produced a statistically significant impact on crop height at harvest level measurement (p = 0.0135), while all other factors, including variety and their interactions, showed no significant impact. The two most important factors for sample discrimination were Fe and Zn, while TN and K followed behind. The PCA results showed that PC1 explained most of the variation through its strong links to Fe and Zn and TN, while PC2 showed primary connections to P and K and Mn. The biplot showed three distinct clusters, which scientists identified with 95 confidence with confidence ellipses. The 50% biochar plus 50% NPK treatment outperformed the control and sole fertilizer treatments because it produced taller plants, although the varieties showed minor differences in their plant response. The study results show that biochar combined with mineral fertilizer produced greater tiller manure yields when compared to the control treatment. The results demonstrate that combining biochar with inorganic fertilizers enhances rice growth and productivity in drought-prone direct-seeding conditions while also improving soil fertility management.