Abstract:
Objective The aims were to understand the acid-base buffering characteristics of citrus orchard soils and their influencing factors for improving soil acidification.
Method Through field surveys, 67 soil samples from Citrus sinensis orchard were collected then soil acid buffering capacity were analyzed with acid-base titration. Correlation analysis and stepwise regression were employed to explore the relationship between soil acid buffer capacity and its influencing factors.
Result The results showed that the citrus orchard soil was generally acidic (pH 4.90 ± 0.57), with an acid-base buffering capacity (pHBC) of 18.54 ± 3.99 mmol kg−1, indicating sensitivity to acid. Significant differences were observed when soil pH was < 5.0 or ≥5.0. The acid-base buffering capacity showed no significantly difference among different soil types, but the sensitivity to pH change followed the order of krasnozem > paddy soil > purple soil. Pearson correlation analysis revealed that soil acid buffering capacity was significantly negatively correlated with exchangeable acidity, exchangeable hydrogen, and exchangeable aluminum (P < 0.05), while it was significantly positively correlated with organic matter, available potassium, slowly available potassium, exchangeable calcium, exchangeable magnesium, available copper, and available manganese (P < 0.01). Additionally, it showed significant positive correlations with total nitrogen, available iron, and elevation (P < 0.05). Stepwise regression analysis indicated that organic matter, exchangeable calcium, and available potassium collectively explained 57.9% of the variation in acid-base buffering capacity.
Conclusion The acid buffer capacity of soils in Citrus sinensis orchards in Hunan Province closely correlated to soil organic matter and exchangeable base ions, which showed a close linkage to soil pH and soil type. It is recommended to selectively apply organic fertilizers, alkaline soil amendments, or potassium fertilizers based on soil pH, soil type, and fertility levels to moderately enhance soil acid-base buffering capacity, thereby ensuring sustainable orchard utilization.