Impact of tillage intensity on carbon and nitrogen pools in surface and sub‐surface soils of three long‐term field experiments

Abstract

Summary Management options such as the intensity of tillage are known to influence the turnover dynamics of soil organic matter. However, less information is available about the influence of the tillage intensity on individual soil organic matter pools with different turnover dynamics in surface as compared with sub‐surface soils. This study aimed to analyse the impact of no tillage (NT), reduced tillage (RT) and conventional tillage (CT) on labile, intermediate and stable carbon (C) and nitrogen (N) pools in surface and sub‐surface soils. We took surface and sub‐surface soil samples from the three tillage systems in three long‐term field experiments in Germany. The labile, intermediate and stable C and N pool sizes were determined by using the combined application of a decomposition experiment and a physical‐chemical separation procedure. For the surface soils, we found larger stocks of the labile C and N pool under NT and RT (C, 1.7 and 1.3 t ha−1; N, 180 and 160 kg ha−1) than with CT (C, 0.5 t ha−1; N, 60 kg ha−1). In contrast, we found significantly larger stocks of the labile C pool under CT (2.7 t ha−1) than with NT and RT (2 t ha−1) for the sub‐surface soils. The intermediate pool accounted for 75–84% of the soil organic C and total N stocks. However, the stocks of the intermediate N and C pools were only distinctly larger for NT than for CT in the surface soils. The stocks of the stable C and N pools were not affected by the tillage intensity but were positively correlated with the stocks of the clay‐size fraction and oxalate soluble aluminum, indicating a strong influence of site‐specific mineral characteristics on the size of these pools. Our results indicate soil depth‐specific variations in the response of organic matter pools to tillage of different intensity. This means that the potential benefits of decreasing tillage intensity with respect to soil functions that are closely related to organic matter dynamics have to be evaluated separately for surface and sub‐surface soils.

Long term effect of legume intensified crop rotations and tillage practices on productivity and profitability of maize vis-a-vis soil fertility in North-Western Indo-Gangetic Plains of India

“…In contrast, CA practices (ZT and PB) have been reported to reduce the losses of SOC by reducing their oxidation through minimizing the physical manipulation of soil. The stratification of TSC under CA has also been reported by several others researchers (Baker et al, 2007;Kaiser et al, 2014). The legume intensified maize based crop rotations also had significant (P<0.05) effect on TSC upto 30 cm soil depth only.…”

Impact of legume intensified crop rotations and tillage practices on maize productivity vis-à-vis C and N dynamics of a sandy loam soil in north-western Indo-Gangetic Plains of India

“…In contrast, CA practices (ZT and PB) have been reported to reduce the losses of carbon and nitrogen by reducing their oxidation through minimizing the physical manipulation of soil which ultimately resulted in higher TSN in CA compared to CT. The stratification of TSN under CA has also been reported by several others researchers (Baker et al, 2007;Kaiser et al, 2014). The legume intensified maize based crop rotations also had significant (P<0.05) effect on TSC upto 30 cm soil depth only ( ratio of legume residue facilitate their decomposition (Congreves et al, 2015).…”

“…PB-MCS plots registered 35.02% (0-15 cm) and 31.13% (15-30 cm) higher SOC stocks compared to CT-MMuMb and CT-MMS. The higher SOC stocks of soil due to legume inclusion and their residue retention in different cereal based systems were also reported by Kaiser et al (2014). The higher carbon stock with MCS crop rotations was might be due higher addition of easily decomposable crop residue due to overall higher biomass production over other crop rotations.…”

Water-extractable organic matter and its fluorescence fractions in response to minimum tillage and organic farming in a Cambisol

“…Higher contents of SOC and TN in MT at upper soil could be attributed to the fact that MT reduces the mineralization of SOM [14] and improves the physical protection of SOM via reducing the disruption of soil aggregates and avoiding physical access of SOM by microbes [56] compared with conventional tillage. Furthermore, crop residues accumulate in the upper layer of soil, while plowing tillage incorporates crop residues into the whole tillage horizon of soil more uniformly resulting in dilution effects of C and N [57,58]. When the two soil depths were considered, the effect of MT was negative, this being perhaps because of dilution effect in deeper soil part.…”