Does higher ratio of wheat straw addition decrease PAHs degradation in PAHs-contaminated paddy soils and PAHs...

Area of Science:

• Environmental Science
• Soil Science
• Agricultural Science

Background:

• Limited research exists on polycyclic aromatic hydrocarbons (PAHs) degradation in paddy soils following straw incorporation.
• Polycyclic aromatic hydrocarbons (PAHs) pose risks to soil and crop health.

Purpose of the Study:

• To investigate the effects of varying wheat straw application rates and types on PAHs degradation in contaminated paddy soils.
• To assess the impact of straw returning on PAHs accumulation in rice plants.

Main Methods:

• Incubation experiments were performed to measure PAHs degradation rates.
• Pot trials were conducted to quantify PAHs accumulation in rice.
• Bacterial community diversity and functional genes involved in PAHs degradation were analyzed.

Main Results:

• A threshold effect of straw returning on PAHs degradation was observed, with peak degradation at 0.8% wheat straw.
• Pretreated straw (PS) enhanced PAHs degradation compared to conventional straw (CS), but also increased PAHs in rice due to higher dissolved organic carbon (DOC).
• Optimal straw application (1%) reduced PAHs in rice by enhancing rhizosphere degradation and microbial activity.

Conclusions:

• The amount and method of straw returning significantly influence PAHs degradation in paddy soils and their uptake by rice.
• Pretreated straw shows potential for enhancing PAHs degradation, but careful management is needed to mitigate increased PAHs accumulation in crops.
• Optimizing straw application strategies can improve soil remediation of PAHs in agricultural systems.