Key soil fertility determinants influencing rice yield in Malaysian paddy soils

Soil fertility plays a crucial role in ensuring both the quality and quantity of agricultural crop production. However, determining the optimal parameters for regulating rice growth to enhance yield remains challenging, as the correlation between soil factors and rice yield has not been quantitatively assessed. The present work will examine the relationship between soil fertility and rice yield in Malaysia. A Pearson correlation matrix heatmap was employed to quantitatively evaluate the relationships between soil chemical properties and rice yield of two paddy seed varieties, UiTM 1 and UiTM 5, cultivated across three regions in Perak, Kedah, and Johor. Furthermore, Principal Component Analysis (PCA) was utilised to elucidate the multivariate structure of soil fertility data and identify the dominant factors influencing yield variance. The results revealed that soil pH exhibited a stronger positive correlation with the yield of UiTM 5 (r = 0.66, p < 0.01) compared to UiTM 1 (r = 0.45, p > 0.05). In contrast, aluminium showed a stronger negative correlation with UiTM 5 (r = - 0.87, p < 0.01) than with UiTM 1 (r = - 0.78, p < 0.01), indicating a greater risk of aluminium toxicity in UiTM 5. The PCA identified two main components accounting for 78.2% of the total variance, suggesting that rice yield is strongly associated by the Soil Acidity and Cation Status Factor (PC2) rather than nitrogenous organic fertility alone. Among the five paddy fields studied, location A9 recorded the highest rice yields, with 9.29 mt/ha for UiTM 1 and 9.11 mt/ha for UiTM 5, which aligned with the optimal vector space for pH and cation exchange capacity in the PCA biplot. This superior performance may be attributed to the soil fertility at A9, which falls within the optimal critical range for rice cultivation. The integration of correlation and multivariate analyses demonstrates that managing soil acidity and aluminium toxicity is a critical consideration for optimising productivity. Understanding these relationships provides valuable insights for improving soil management practices and enhancing rice production sustainability in Malaysia.