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11. Increased CO2 fluxes from a sandy Cambisol under agricultural use in the Wendland region, Northern Germany, three years after biochar substrates application.

Author

Polifka, Steven, Wiedner, Katja, and Glaser, Bruno

Subjects
*BIOCHAR, *EXPERIMENTAL agriculture, *ARABLE land, *BIOMASS production, *GAS chromatography
Abstract

Abstract: In recent years, biochar has been discussed as an opportunity for carbon sequestration in arable soils. Field experiments under realistic conditions investigating the CO2 emission from soil after biochar combined with fertilizer additions are scarce. Therefore, we investigated the CO2 emission and its 13C signature after addition of compost, biogas digestate (originating from C4 feedstock) and mineral fertilizer with and without biochar (0, 3, 10, 40 Mg biochar/ha) to a sandy Cambisol in Northern Germany. Biomass residues were pyrolized at ~650°C to obtain biochar with C3 signature. Gas samples were taken biweekly during the growing season using static chambers three years after biochar substrate addition. The CO2 concentration and its δ13C isotope signature were measured using a gas chromatograph coupled to an isotope ratio mass spectrometer. Results showed increased CO2 emission (30%–60%) when high biochar amount (40 Mg/ha) was applied three years ago together with mineral fertilizer and biogas digestate. On average, 59% of the emitted CO2 had a C3 signature (thus, deriving from biochar and/or soil organic matter), independent of the amount of biochar added. In addition, our results clearly demonstrated that only a small amount of released CO2 derived from biochar. The results of this field experiment suggest that biochar most likely stimulates microbial activity in soil leading to increased CO2 emissions derived from soil organic matter and fertilizers mineralization rather than from biochar. Nevertheless, compared to the amount of carbon added by biochar, additional CO2 emission is marginal corroborating the C sequestration potential of biochar. [ABSTRACT FROM AUTHOR]

Published
2018
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12. Effect of biochar fertilizers on amino acid variability of Secale cerealeand Lupinus angustifolius

Author

Wiedner, Katja, Schimpf, Corinna, Polifka, Steven, and Glaser, Bruno

Abstract

Little is known on the effects of biochar on N uptake and amino acid variability in crops such as winter rye and narrow-leafed lupine despite the fact that amino acids are important indicators, for food quality and plant stress. N uptake of both crops showed contrasting results when treated with different biochar fertilizers. Total amino acid contents referred to total nitrogen generally tend to decrease in rye grains in the presence of biochar; whereas lupine seeds were more or less unaffected by biochar combined with mineral fertilizer or compost. In lupine seeds, total amino acid contents significantly increased when biochar was mixed with digestate but decreased when mixed with fermented digestate. Lysine, one of the most limiting amino acids in cereals, reached the recommended value of 4 g kg−1in rye grain for most biochar fertilizers. In lupine seeds, lysine decreased when biochar had been applied but were still in the recommended range when used as animal feed. Proline, an indicator for plant stress, significantly decreased (− 49%) in rye when 2 Mg biochar ha−1was added in combination with mineral fertilizer. In contrast, proline increased when biochar was added to organic (digestate and compost) fertilizers (up to 43%). Further biochar research should focus much more on food quality, which is a key challenge for global food production.

Published
2019
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