Soil respiration after tillage under different fertiliser treatments – implications for modelling and balancing

Tillage-induced short-term soil organic matter turnover and respiration

“…Rochette and Angers, 1999) and can be explained by both the magnitude of the disturbance, i.e. soil comminution, and the fertilisation history of the soil (Fiedler et al, 2015). The smaller relative efflux from BD compared to MF and CL after tillage is remarkable since before tillage the CO 2 fluxes in BD were of the same magnitude as those in MF and exceeded those in CL (Fig.…”

“…The increase in HWN in BD after tillage indicates an increase in easily mineralisable organic N which probably originates from soil biomass and lysates (Ghani et al, 2003;Leinweber et al, 1995) and implies an accelerated microbial turnover of soil organic N. This seems reasonable since the microbial community is able to adjust its structure and activity relatively fast to utilise formerly protected organic matter after exposure due to disruption of aggregates by tillage (Jackson et al, 2003;La Scala et al, 2008). Accordingly, Fiedler et al (2015) observed a short-lived increase in HWC after the first of 2 days of several tillage operations which was not found in the present study. It is possible that we did not detect it because we did not take any soil samples after the first day.…”

“…The soil is a Stagnic Luvisol (IUSS Working Group WRB, 2006) with sandy loam texture (sand: 63 %; silt: 26 %; clay: 11 %) overlying bedrock of till. The topsoil (0-30 cm) has an organic carbon content of 8.5 ± 0.2 mg g −1 (mean ± standard deviation, n = 9), pH of 7.4 ± 0.9 (n = 3) and bulk density of 1.51 ± 0.08 g cm −3 (n = 3), measured according to Fiedler et al (2015). The climate is characterised by maritime influence, with annual averages of 8.8 • C temperature and 557 mm total precipitation for the 30-year period from 1985 to 2014 (Federal State Research Institute for Agriculture and Fisheries Mecklenburg-Western Pomerania (LFA), Germany, personal communication, 2015).…”

“…Research on short-term effects of tillage on SOM has focused largely on CO 2 efflux: several studies have recorded the dynamics of CO 2 efflux immediately after tillage (see Table 5 in Fiedler et al, 2015) and some basic models have been developed that describe correlations between CO 2 efflux and the turnover of soil organic carbon (SOC) after tillage by first-order kinetics (La Scala et al, 2008). Admittedly, these correlations do not causally explain which organic components are mineralised.…”

“…Admittedly, these correlations do not causally explain which organic components are mineralised. Furthermore, SOM-CO 2 efflux relationships are influenced by the type of soil amendment (Fiedler et al, 2015).…”