Agriculture belongs to the major sources of the trace gases nitrous oxide (N2O) and methane (CH4). However, little is known about the contribution of the increasing area of organically managed arable soils in organic farming systems to the greenhouse gas emissions.
The objective of our study was the quantification of the in-situ N2O- and CH4- emissions in common organic crop cultivation without livestock. In comparison to this control variant, we focused on the manuring effect of fermented herbal organic matter on the emissions (biogas variant). The straw of the crops and the growth of the intercrops were harvested, fermented in a biogas reactor and applied as fertilizer on the field when the nutrient demand of the crops occurred.
The results obtained in 2003/2004 in winter wheat generally revealed a low level of N2O emissions and indicated reduced losses (458 g N ha-1 yr-1) of the soil in the biogas variant compared to the control variant (770 g N ha-1 yr-1). Measurements of the CH4 fluxes showed a slightly decreased CH4 uptake rate in the biogas variant
(484 g C ha-1 yr-1) in comparison to the control variant (591 g C ha-1 yr-1)
