Biofilm biofertilizer manipulates toxic heavy metals and micronutrients in the soil-plant systems in Sri Lanka to produce high-quality rice: a sign of ecosystem intelligence

Abstract

Abstract High toxic heavy metals (THM) and low micronutrient contents in rice grains affect adversely on human health. Here we investigated the potential of using biofilm biofertilizer (BFBF) in managing THM and micronutrients in rice by conducting field experiments that compared BFBF practice with the chemical fertilizer (CF) alone practice in Sri Lanka. Bioaccumulation and translocation factors were evaluated to assess the THM and micronutrient distribution in soil-plant systems. The human health risk was also estimated. The BFBF practice showed a significant reduction in estimated daily intakes of the THM like As, Co, Cd, and Cr compared to the CF practice, thus decreasing hazard quotient (HQ) and hazard index (HI) values for lowering health risk. In the CF practice, the translocation of As from panicle to rice seed was significantly increased, and As in rice seeds is reported to exceed the safe level in some cases in Sri Lanka. On the contrary, reduced translocation of As, and increased translocation of Cr within the safe level to rice seeds with the BFBF application were observed, implying a sign of intelligence in the paddy ecosystem. Interestingly, the HI had been kept below the threshold value by significantly reducing the HQ values of each THM, only in the BFBF practice. These results highlight the role of increased microbial diversity and abundance induced by the BFBF, in mitigating the health risks and enhancing the sustainability of the soil-plant system, a clear sign of ecosystem intelligence.