Objective By analyzing the spatial distribution characteristics of soil nutrients and rice yields in paddy fields of Fujian Province and identifying their key influencing factors, this study aimed to provide an important reference for rational fertilization management in paddy fields.

Method Data were obtained from the Fertilizer Reduction and Efficiency Improvement Project of Fujian Province, with a total of 6,803 topsoil samples (0-20 cm) and rice yield data collected during 2015-2019. Geostatistical methods were employed to analyze the spatial distribution characteristics of soil nutrients and rice yield. Additionally, this study quantified the effects of different natural conditions (elevation, annual average rainfall) and subgroups of paddy soil on soil available nitrogen (AN), phosphorus (AP) and potassium (AK) nutrients, pH and organic matter (SOM). It also comprehensively evaluated the soil fertility of paddy fields and analyzed the correlation between the integrated fertility index(IFI) and yield.

Results In the paddy soils, the mean values of pH, SOM, AN, AP and AK were 4.81, 31.4 g kg⁻¹, 152.7 mg kg⁻¹, 32.7 mg kg⁻¹ and 79.4 mg kg⁻¹ in Fujian Province, respectively. The paddy soil was generally acidic. Meanwhile, 51% of paddy soil showed pH < 4.5 and the proportions of soils with very low levels of SOM (< 15 g kg⁻¹), AN (< 60 mg kg⁻¹), AP (< 10 mg kg⁻¹) and AK (< 80 mg kg⁻¹) were 5.57%, 2.64%, 42.2% and 25.6%, respectively. The average IFI of paddy soil was 0.66, and the percentages in levels 1-5 were 16.6% (0.8 < IFI ≤ 1), 51.2% (0.6 < IFI ≤ 0.8), 29.2% (0.4 < IFI ≤ 0.6), 2.99% (0.2 < IFI ≤ 0.4) and 0.04% (0 < IFI ≤ 0.2), respectively. The mean rice yield was 5.12 t hm⁻², mostly ranging between 4 and 6 t hm⁻². AN and SOM contents were higher in the northwest and lower in the southeast, while AP and pH showed lower values in the north and higher in the southeast. AK exhibited higher concentrations in the central region and lower levels along the periphery. Rice yield generally showed lower values in the north and higher in the south, whereas the IFI displayed the opposite pattern. Paddy soil subgroups, elevation and precipitation were the factors influencing soil nutrient contents. Soil pH, SOM and AN were significantly positively correlated with elevation and mean annual rainfall, whereas AP and AK were significantly negatively correlated with mean annual rainfall.

Conclusion Overall, paddy soils in Fujian Province exhibited relatively high fertility. Meanwhile, above Class-2 fertility levels were mainly concentrated in eastern and northern regions. However, the paddy soils were acidic and relatively rich in N, P and K, indicating that moderate reduction in fertilizer inputs was necessary. Additionally, the application of soil amendments to ameliorate acidity was recommended to prevent resource waste and minimize environmental pollution.