Antioxidants in organic manures can facilitate exoenzyme activities in herbicide treated farm soil

This is the authors' abstract. We don't add key points for this paper.

Herbicide application in farm soil invariably impacts non-target biota including the microbes. Herbicides inhibit microbial exoenzyme activities, crucial for the decomposition of organics and release of nutrients. It was hypothesised that increasing the antioxidant level in soil through organic amendments could reduce the toxicity of the herbicide pretilachlor on soil microbial activity. This study reports the effects of organic amendments with farmyard manure (FYM-T1), poultry manure (PM-T2) and vermimanure (VM-T3) at recommended doses on the activities of the exoenzymes, invertase, amylase and cellulase in farm soils pre-treated with the herbicide pretilachlor. Significant spikes in percent organic carbon (OC), total antioxidant capacity (TAC) and activities of the exoenzymes were observed in amended soils relative to control. The percent soil OC was maximum in T1 (2.63 ) followed by T3 (2.28 ) at 120 h. T3 indicated the maximum amylase (0.27 mg glucose/gsoil/h), cellulase (0.26 mg glucose/gsoil/h), invertase (0.39 mg glucose/gsoil/h) activities and soil TAC (1.03 Mm Trolox/cm3/g soil) at 168 h. A significant positive correlation between % OC, TAC and exoenzyme activities was observed. TAC and invertase proved to be the most responsive markers. It was concluded that selective organic amendments of soil could significantly enhance soil antioxidant level, and reduce herbicide induced stress on soil microbiota with an increase in exoenzyme secretion.