3.3 Relationship between GRSP and soil nutrients
Correlation analysis showed that the T-GRSP and EE-GRSP were highly positively correlated with the contents of SOC, TC, TN, and AP but negatively correlated with SIC and PH (P<0.001) (Fig. 2). The redundancy analysis (Fig. 3) results indicated that SOC is the main impact factor for T-GRSP and EE-GRSP. The explains of SOC to the GRSP was 84.8%, and the contribution of SOC to the GRSP was 92.9%. TC was removed since TC and SOC are collinear. Redundancy analysis and linear regression analysis (Fig. 4) showed that SOC, TN, and AP were positively correlated with both T-GRSP and EE-GRSP (P<0.01).