Abstract

SINGER, A., GEISSELER, D., LUDWIG, B.
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Biol. Fertil. Soils 47, 249-259 (2011).

The objective of this study was to examine the effects of soil moisture, irrigation pattern, and temperature on gaseous and leaching losses of carbon (C) and nitrogen (N) from soils amended with biogas slurry (BS). Undisturbed soil cores were amended with BS (33 kg N ^ha-1) and incubated at 13.5degreesC and 23.5degreesC under continuous irrigation (2 mm ^day-1) or cycles of strong irrigation and partial drying (every 6 weeks, 1 week with 12 mm ^day-1). During the 6 weeks after BS application, on average, 30% and 3.8% of the C and N applied with BS were emitted as carbon dioxide (_CO2) and nitrous oxide (_N2O), respectively. Across all treatments, a temperature increase of 10degreesC increased _N2Oand_CO2 emissions by a factor of 3.7 and 1.7, respectively. The irrigation pattern strongly affected the temporal production of_CO2 and _N2Obut had no significant effect on the cumulative production. Nitrogen was predominantly lost in the form of nitrate (_NO3-⁾. On average, 16% of the N applied was lost as _NO3-^. Nitrate leaching was significantly increased at the higher temperature (P<0.01), while the irrigation pattern had no effect (P=0.63). Our results show that the C and N turnovers were strongly affected by BS application and soil temperature whereas irrigation pattern had only minor effects. A considerable proportion of the C and N in BS were readily available for soil microorganisms.