Nwawuike, Ifeoma Monica, et al. “Application of Nutrient Index and Multivariate Analysis for Soil Fertility Assessment of Rice Farms in Okigwe, Southeastern Nigeria”. Direct Research Journal of Agriculture and Food Science, vol. 14, no. 2, May 2026, pp. 41-49, https://doi.org/10.26765/DRJAFS16457234.