Respiration response to different tillage intensities in transplanted soil columns

Abstract

Undisturbed soils columns were transplanted from three tillage treatments at four sites in Central Germany to one site to investigate the relations between the CO2 efflux, soil temperature (TS) and volumetric water content (VWC) over one year in an unplanted period and maize (Zea mays L.) planted period. No tillage and grubber, i.e. rigid‑tine cultivator, (10-15 cm) systems contain higher stocks of microbial biomass C (MBC) in comparison with mouldboard ploughing (25-30 cm). This must be due to a reduction in microbial turnover, because higher VWC reduces TS. At 5 cm depth, VWC was lowest with plough tillage throughout the year. At 15 cm depth, VWC was highest with grubber tillage during the planted period. During the unplanted period, mean TS was generally highest with grubber tillage. During the planted period, mean difference in TS increased in the order no tillage < plough < grubber at 5 cm depth and in the order plough < grubber < no-tillage at 15 cm depth. Mean CO2 efflux was 1.12 t C ha−1 in the unplanted and 2.85 t C ha−1 in the planted period. Multiple linear relationships showed that TS and VWC explained 70.4% of the variance in CO2 evolution rates in the unplanted and 37.2% in the planted period. TS effects generally dominated and showed similar regression coefficients in both periods. VWC had smaller effects, which were positive in the unplanted period and negative in the planted period. Significant tillage × TS interactions were observed in the unplanted period and tillage × VWC interactions in the planted period. Interactions were caused by strong positive TS effects with grubber tillage in the unplanted period and by strong negative VWC effects with plough tillage in the planted period. From a soil ecological viewpoint, grubber and no tillage can be recommended, as it improves microbial life conditions.