Risk of Soil Recontamination Due to UsingEleusine coracanaandPanicum maximumStraw After Phytoremediation of Picloram

Abstract

This study aimed to evaluate the herbicidal activity of picloram on the biomass of the remediation plants Eleusine coracana and Panicum maximum after cultivation in a soil contaminated with this herbicide. These species were grown in three soils, differentiated based on texture (clayish, middle, and sandy, with 460, 250, and 40 g kg(-1) of the clay, respectively), previously contaminated with picloram (0, 80, and 160 g ha(-1)). After 90 days, the plants were harvested and an extract was produced by maceration of leaves and stems of these plants. It was applied to pots containing washed sand, comprising a bioassay in a growth chamber using soybean as a bioindicator for picloram. Soil and plant samples were analyzed by HPLC. The results showed the presence of picloram or metabolites with herbicidal activity in the shoots of E. coracana and P. maximum at phytotoxic levels with regard to soybean plants, indicating that they work only as phytoextractors and that the presence of straw on the soil surface can promote recontamination within the area. It is not recommended to cultivate species susceptible to picloram in areas where it was reported remediation by E. indica and P. maximum and still present residues of these species.

Sulfentrazone Phytoremediation Under Field Conditions

“…This reduction indicates that phytoremediation may shorten the time required before an area becomes available for the cultivation of said species (NASCIMENTO et al, 2015), which can lead to greater optimization of land use, with greater economic returns for agricultural activity.…”

The residues of Canavalia ensiformis and Crotalaria juncea after phytoremediation in soil contaminated with sulfentrazone do not result in soil recontamination

“…crop yield, indicating that the stubble permanence on the soil surface does not promote recontamination of the area. On the other hand, Nascimento et al (2015) detected the presence of the herbicide picloram in the leaf extract from Panicum maximum cv. Tanzania and Eleusine coracana (finger millet) at phytotoxic levels for soybean plants, which forces the biomass removal of these grasses from the area in question, limiting the phytoremediation for this herbicide.…”

“…In cases such as that of the picloram herbicide, phytoextraction and consequent phytoaculation implies in phytotoxicity to sensitive species cultivated on the stubble containing this herbicide, which invalidates its reuse and makes the application of phytoremediation harder (Nascimento et al, 2015). However, regarding the sulfentrazone, with the obtained results by the bioassay, we can infer that it is possible to keep the green manure stubble in the phytoremediated area (Figures 2, 3 and 4 and Tables 2, 3 and 4), agreeing with the results found by Procópio et al (2007) about the reuse of the biomass from the Stizolobium aterrimum and C. ensiformis species, regarding the herbicide trifloxysulfuron-sodium.…”

Influência da matéria orgânica na fitorremediação de solo contaminado com sulfentrazone

“…However, in situations where the contamination already occurred, corrective or remedial measures must be taken. In the light of this, researches have been conducted in the last few years, with greater emphasis on the use of species that are able to remove and/or degrade xenobiotics from the soil (Madalão et al, 2013;Nascimento et al, 2015); they highlighted phytoremediation, which consists of the ability that some plant species have to accelerate the removal of toxic compounds, such as herbicides, from the environment (soil and water), promoting its decontamination (Cunningham et al, 1996).…”