Soil Quality Assessment of Salinized Farmland Neighboring a Chinese Oil Exploitation Area

Abstract

Industrial intensification in salinized areas poses a risk of farmland soil degradation. Limited research has been carried out on comprehensive assessment of both soil fertility and polycyclic aromatic hydrocarbon (PAH) contamination. In this study, we performed a soil quality assessment to consider soil fertility and PAH contamination, with quantification of 13 indicators of soil physicochemical and biological properties and 16 PAHs in the Yellow River Delta (YRD) of China. The soil fertility level in this area was moderate according to the minimum data set (MDS), which consisted of pH, soil organic carbon (SOC), microbial quotient, total nitrogen, phosphorus, potassium, sand, and salinity level. Soil salinity was identified as the primary limiting factor in the study area. In addition, according to the Nemerow pollution index (NPI), the farmland soils were seriously contaminated by PAHs. Comprehensive assessment revealed that the soil quality belonged to moderate to low grades. Pearson correlation analysis showed that the soil quality index scores had significantly negative correlation with the NPI (p < 0.01) and significantly positive correlation with the soil fertility index (p < 0.05). This study demonstrates that pollution control and fertility improvement (e.g., soil salinity, SOC, nitrogen, and phosphorus) are crucial in managing soil quality of salinized farmlands neighboring an oil exploitation area in the YRD. The results will help different stakeholders to better understand the status of soil quality and the importance of pollution remediation in the YRD.