Development of a novel bio-organic fertilizer for the removal of atrazine in soil

Abstract

The accumulation of atrazine in farmland is prone to cause phytotoxicity to kinds of sensitive crops, such as soybean. In addition, some kinds of agricultural solid wastes have long been considered as the important non-point pollution source. The aim of this experiment was to investigate the feasibility of removing atrazine from soil and alleviating the stress of atrazine on the growth of soybean by application a novel bio-organic fertilizer developed by agricultural solid wastes, such as cow manure organic fertilizer, biochar and poly-(γ-glutamic acid), as well as an atrazine-degrading strain Arthrobacter sp. DNS10. Sixteen potential bio-organic fertilizer formulations were designed by D-optimal mixture design of Design Expert software and atrazine-removal ability was selected to single out the optimal formulation. As a result, the optimal formulation of bio-organic fertilizer (named as DNBF10) was produced by the cow manure organic fertilizer 76.20%, biochar 4.46%, poly-(γ-glutamic acid) 8.63% (m/m) and the number of Arthrobacter sp. DNS10 with 0.91 × 108 CFU/g. The atrazine removal percentage of DNBF10 for the atrazine in soil with the initial atrazine concentration 15.26 ± 0.49 mg/kg was 95.05% after 10 days' application with DNBF10 at the adding dosage of 5 mg/kg (relative to the dry weight of the soil). Furthermore, pot experiment results suggest that the growth of soybean seedlings in the soil (initial atrazine was 8.14 ± 0.16 mg/kg) that adding both of DNBF10 (25%) and chemical fertilizer (75%) were better than those of the treatment only adding chemical fertilizer (100%) under the same nutrient addition level. All the results indicate that the application of DNBF10 was a new alternative to reuse the typical agricultural solid wastes, as well as to reduce the harm caused by residual atrazine to soybean.