Integrated evaluation of greenhouse gas emissions (CO2, CH4, N2O) from two farming systems in southern Germany

Abstract Agricultural practices contribute to emissions of the greenhouse gases CO2, CH4 and N2O. The aim of this study was to determine and discuss the aggregate greenhouse gas emission (CO2, CH4 and N2O) from two different farming systems in southern Germany. Farm A consisted of 30.4 ha fields (mean fertilization rate 188 kg N per ha), 1.8 ha meadows, 12.4 ha set-aside land and 28.6 adult beef steers (year-round indoor stock keeping). Farm B followed the principles of organic farming (neither synthetic fertilizers nor pesticides were used) and it consisted of 31.3 ha fields, 7 ha meadows, 18.2 ha pasture, 5.5 ha set-aside land and a herd of 35.6 adult cattle (grazing period 6 months). The integrated assessment of greenhouse gas emissions included those from fields, pasture, cattle, cattle waste management, fertilizer production and consumption of fossil fuels. Soil N2O emissions were estimated from 25 year-round measurements on differently managed fields. Expressed per hectare farm area, the aggregate emission of greenhouse gases was 4.2 and 3.0 Mg CO2 equivalents for farms A and B, respectively. Nitrous oxide emissions (mainly from soils) contributed the major part (about 60%) of total greenhouse gas emissions in both farming systems. Methane emissions (mainly from cattle and cattle waste management) were approximately 25% and CO2 emissions were lowest (circa 15%). Mean emissions related to crop production (emissions from fields, fertilizer production, and the consumption of fossil fuels for field management and drying of crops) was 4.4 and 3.2 Mg CO2 equivalents per hectare field area for farms A and B, respectively. On average, 2.53% of total N input by synthetic N fertilizers, organic fertilizers and crop residues were emitted as N2O–N. Total annual emissions per cattle unit (live weight of 500 kg) from enteric fermentation and storage of cattle waste were about 25% higher for farm A (1.6 Mg CO2 equivalents) than farm B (1.3 Mg CO2 equivalents). Taken together, these results indicated that conversion from conventional to organic farming led to reduced emissions per hectare, but yield-related emissions were not reduced.

[1]  K. Kramer,et al.  Total greenhouse gas emissions related to the Dutch crop production system , 1999 .

[2]  K. Isermann Agriculture's share in the emission of trace gases affecting the climate and some cause-oriented proposals for sufficiently reducing this share. , 1994, Environmental pollution.

[3]  A. Bouwman Direct emission of nitrous oxide from agricultural soils , 1996, Nutrient Cycling in Agroecosystems.

[4]  Keith A. Smith,et al.  Nitrous oxide emissions from intensive agricultural systems: Variations between crops and seasons, key driving variables, and mean emission factors , 1999 .

[5]  J. Munch,et al.  Effect of crop-specific field management and N fertilization on N2O emissions from a fine-loamy soil , 2001, Nutrient Cycling in Agroecosystems.

[6]  G. Velthof,et al.  Nitrous oxide emissions from grazed grassland , 1997 .

[7]  A. Lind,et al.  Loss of Nitrous Oxide from Animal Manure in Dungheaps , 1993 .

[8]  R. Isermann,et al.  Food production and consumption in Germany: N flows and N emissions , 1998, Nutrient Cycling in Agroecosystems.

[9]  Agricultural Ecosystem Effects on Trace Gases and Global Climate Change , 1993 .

[10]  Jürgen Augustin,et al.  Automated Gas Chromatographic System for Rapid Analysis of the Atmospheric Trace Gases Methane, Carbon Dioxide, and Nitrous Oxide , 1997 .

[11]  Friedrich Beese,et al.  Seasonal variation of N2O and CH4 fluxes in differently managed arable soils in southern Germany , 1995 .

[12]  R. Ruser,et al.  Nitrous oxide emissions from arable soils in Germany — An evaluation of six long‐term field experiments , 2000 .

[13]  J. Stone Climate change 1995: The science of climate change. Contribution of working group I to the second assessment report of the intergovernmental panel on climate change , 1997 .

[14]  A. Bouwman,et al.  Influence of cattle wastes on nitrous oxide and methane fluxes in pasture land , 1996 .

[15]  G. Velthof,et al.  Denitrification in nitric-acid-treated cattle slurry during storage , 1993 .

[16]  Carolien Kroeze,et al.  Closing the global atmospheric N2O budget: nitrous oxide emissions through the agricultural nitrogen cycle. (OECD/IPCC/IEA Phase II Development of IPCC Guidelines for National Greenhouse Gas Inventories). , 1997 .

[17]  Ewald Schnug,et al.  Nitrous oxide release from arable soil: Importance of N-fertilization, crops and temporal variation , 1998 .

[18]  A. F. Mackenzie,et al.  Nitrous oxide emission in three years as affected by tillage, corn-soybean-alfalfa rotations, and nitrogen fertilization , 1998 .

[19]  A. Mosier,et al.  Contributions of agroecosystems to global climate change , 1993 .

[20]  F. Beese,et al.  Effects of Sugarbeet Residues on Soil Redox Potential and Nitrous Oxide Emission , 1995 .

[21]  C. Wagner-Riddle,et al.  Estimates of nitrous oxide emissions from agricultural fields over 28 months , 1997 .