Conservation agriculture in its version of permanent raised bed planting with crop residue retention increases yields and
improves soil characteristics, e.g. aggregate distribution, organic matter content, so it remained to be seen how greenhouse
gas emissions and dynamics of C and N might be altered. The objective of this study was to investigate how conservation agriculture
with permanent raised beds, tied ridges, i.e. dykes within the furrows to prevent water run-off, and residue retention affected
greenhouse gas emissions. A field experiment was started in 1999 comparing permanent and conventionally tilled raised beds
with different residue management under rain fed conditions. Soil was characterized and emissions of CH
4, N
2O and CO
2 and dynamics of NH
4
+, NO
2
− and NO
3
− were monitored in a laboratory experiment. The crop and tied ridges had no effect on soil characteristics and dynamics of
C and N. Tilled beds reduced the water holding capacity (WHC) 1.1 times and increased conductivity 1.3 times compared to soil
under nontilled beds with retention of all crop residues. The WHC, organic C, soil microbial biomass and total N were ≥1.1
larger in soil from nontilled beds where the crop residue was retained compared to where it was removed after only 6 years.
The emission of CO
2 was 1.2 times and production of NO
3
− 1.8 times larger in nontilled beds where the crop residue was retained compared to where it was removed. The CO
2 emission was 1.2 times and the emission of N
2O after 1 day 2.3 times larger in soil under tilled beds compared to nontilled beds with full residue retention, while the
increase in concentration of NO
3
− was 0.05 mg N kg
−1 soil in the former and 2.38 in the latter. We found that permanent raised bed planting with crop residue retention decreased
emissions of N
2O and CO
2 compared to soil under conventionally tilled raised beds. Production of NO
3
− is larger in soil with permanent raised bed planting with crop residue retention compared to conventionally tilled raised
beds.
Keywords Conservation agriculture - C and N mineralization - Methane oxidation - Microbial biomass - Nitrous oxide emission - Water content
Responsible Editor: Ute Skiba.