Sediment removal from eutrophicated shallow lakes may not only be an effective method for lake restoration but also provides the potential for recycling nutrients from sediments to crop production. However, finding a suitable strategy for sustainably reusing the sediment remains a challenge. Therefore, current study focused on the best practices in applying the sediment from a shallow eutrophicated lake to the soil in terms of grass yield, nutrient uptake, and nutrient leaching. During a nine-month lysimeter experiment, 100-cm high columns were filled with six combinations of soil, sediment, and biochar, with or without meat bone meal organic fertilizer. Aboveground biomass, root mass distribution in soil, nutrient concentration, phosphorus (P) uptake of perennial ryegrass (Lolium perenne L.) along with easily soluble nutrients in the growing medium, and leached mineral nitrogen (N) and P levels were measured. Plant growth conditions were improved by sediment additions, as the yield and P uptake of ryegrass nearly doubled in treatments containing sediment compared to the control soil. While the sediment was richer in macro and micronutrients (e.g. P and N) compared to the soil, the leached N and P levels from both treatments were almost equivalent (N < 830 mg m^-2 and P < 3 mg m^-2). In addition, applying a 2-cm layer of biochar between the sediment and soil reduced P and N leaching by 50%. According to the results, applying a 75-cm thick layer of sediments on agricultural sandy loam soils surrounding the lake seems a promising practice for improving plant yield and soil nutrient status without increasing of P and N leaching from soil.

The development of new options to reduce ammonia (NH₃) emissions during slurry manure storage is still required due to the shortcomings of the current technologies. This study aimed to identify to what extent untreated and acid-treated biochar (BC) and pure acids could reduce ammonia nitrogen (NH₃-N) volatilization and increase nitrogen retention in slurry digestate. The NH₃-N emissions were effectively reduced by H₂SO₄ and H₃PO₄ acids, untreated BC when applied mixed into the digestate and acidified BC treatments applied on the surface of the digestate. Acidification increased the specific surface area and number of O-containing surface functional groups of the BC and decreased the pH, alkalinity and the hydrophobic property. Compared to untreated BC, the ability of BC to reduce NH₃-N emissions was greater when it was acidified with H₂SO₄ and applied to the digestate surface. The effect on digestate pH of acidified BC when applied mixed into the digestate was not different, except for H₂O₂, from that of the addition of the respective pure acid to digestate. The total N concentration in digestate was not significantly correlated with NH₃-N emissions. These findings indicate that acidified BC could be an effective conditioner to reduce NH₃-N emissions from slurry digestate storage.

Biochar has been proposed as an amendment that can improve soil conditions, increase harvest yield, and reduce N losses through NO₃⁻ leaching and N₂O emissions. We conducted an experiment to test the hay biochar mitigation effect on N₂O emissions depending on its production temperature. The pot experiment consisted of the soil amendment with three different production temperature biochars (300 °C, 550 °C, 850 °C) alone and in combination with three different organic fertilizers (cattle slurry, slurry digestate, vinasse), in growth chamber conditions. The effects of biochar and fertilizer were both significant, but the interaction biochar:fertilizer was not. The amendment with the three fertilizer types and with the highest production temperature biochar resulted in significantly higher cumulative N₂O fluxes. Biochar did not show a mitigation effect on N₂O emissions when applied with organic fertilizer. Cumulative emissions were higher with biochar addition, with increasing emissions for increasing biochar production temperature. Our results support the idea that biochar cannot be considered as a universal tool for the reduction of N₂O emissions.