Production of pine sawdust biochar supporting phosphate-solubilizing bacteria as an alternative bioinoculant in Allium cepa L., culture.

We produced and characterised biochar made from Caribbean pine sawdust as raw material. The biochar (BC500) was used as biocompatible support to co-inoculate phosphate solubilizing bacteria (PSB) (BC500/PSB) on Allium cepa L., plants at a greenhouse scale for four months. The three biomaterials study included proximate analysis, elemental analysis, aromaticity analysis, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), adsorption studies at different pH and PSB stability as a function of time. The results indicated that BC500 is suitable as organic support or solid matrix to maintain the viability of PSB able to solubilise P from phosphate rock (PR). The biofertilizer (BC500/PSB) allows increasing germination, seedling growth, nutrient assimilation, and growth of Allium cepa L., because PSB immobilised on BC500 promoted nutrient mobilisation, particularly P, during cultivation of Allium cepa L., at pots scale. The two treatments to evaluate the biofertilizer (BC500/PSB) showed the highest concentrations of total P with 1.25 ± 0.13 and 1.38 ± 0.14 mg bulb-1 in A. cepa L. This work presents the benefits of a new product based on bacteria naturally associated with onion and an organic material (BC500) serving as a bacterial carrier that increases the adsorption area of highly reactive nutrients, reducing their leaching or precipitation with other nutrients and fixation to the solid matrix of the soil.

Influence of Organic Matter in Sorption of the Saflufenacil in Ferralsols.

The saflufenacil herbicide has been applied in the agricultural areas as an efficient alternative for the control of resistant weeds to glyphosate. However, the environmental risks from the use of saflufenacil, especially in tropical soil, is not yet clearly known. We evaluated if the organic matter addition into the soil influences the sorption of saflufenacil in samples of a sandy and clayey texture soils. The sugarbeet was used as a species indicating the presence of saflufenacil in the solution of the substrates. We estimated the required dose of saflufenacil responsible for causing 50% of sugarbeet intoxication (C50) and the sorption ratio (SR) of this herbicide. The addition of organic matter increased the C50 and SR of saflufenacil in both soils. Here it is demonstrated that the soil organic matter content increases saflufenacil sorption in tropical soils and, consequently influences the dose of this herbicide to be applied in pre-emergence of weeds.