Effects of Organic Energy Crop Rotations and Fertilisation with the Liquid Digestate Phase on Organic Carbon in the Topsoil

Levin, Karin; Auerswald, K.; Reents, Hans Jürgen; Hülsbergen, Kurt‐Jürgen

doi:10.3390/agronomy11071393

Cited by 11 publications

(20 citation statements)

References 52 publications

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“…The size of topsoil SOC pools increased in all treatments, despite the fact that all aboveground biomass, except for stubbles, was used for biogas production. These observations were recently described for this field trial by Levin et al [ 19 ], who analyzed the change in SOC between 2010 and 2017 for all 10 crop rotations. They found that SOC content increased in 96% of the plots, independent of the type of rotation and the fertilization level.…”

Section: Discussionmentioning

confidence: 52%

“…The perenniality of a crop rotation is therefore considered to be more important with regards to increasing SOC stocks and stabilization efficiency than its crop diversity [ 17 ]. Increasing the perenniality of a crop rotation generally means including ley phases with grasses and/or legumes in crop rotations, which were shown to positively affect carbon sequestration [ 18 , 19 ]. In the future, not only management, but also climate change-induced SOC losses, must be offset to maintain or increase SOC stocks [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

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Perennial Crops Can Compensate for Low Soil Carbon Inputs from Maize in Ley-Arable Systems

Poyda

Levin

Hülsbergen

et al. 2022

Plants

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(1) Background: Soil organic carbon (SOC) in agricultural soils plays a crucial role in mitigating global climate change but also, and maybe more importantly, in soil fertility and thus food security. Therefore, the influence of contrasting cropping systems on SOC not only in the topsoil, but also in the subsoil, needs to be understood. (2) Methods: In this study, we analyzed SOC content and δ13C values from a crop rotation experiment for biogas production, established in southern Germany in 2004. We compared two crop rotations, differing in their proportions of maize (0 vs. 50%) and perennial legume–grass leys as main crops (75 vs. 25%). Maize was cultivated with an undersown white clover. Both rotations had an unfertilized variant and a variant that was fertilized with biogas digestate according to the nutrient demand of crops. Sixteen years after the experiment was established, the effects of crop rotation, fertilization, and soil depth on SOC were analyzed. Furthermore, we defined a simple carbon balance model to estimate the dynamics of δ13C in soil. Simulations were compared to topsoil data (0–30 cm) from 2009, 2017, and 2020, and to subsoil data (30–60 cm) from 2020. (3) Results: Crop rotation and soil depth had significant effects, but fertilization had no effect on SOC content and δ13C. SOC significantly differed between the two crop rotations regarding δ13C in both depths but not regarding content. Annual enrichment in C4 (maize) carbon was 290, 34, 353, and 70 kg C ha−1 per maize year in the topsoil and subsoil of the unfertilized and fertilized treatments, respectively. These amounts corresponded to carbon turnover rates of 0.8, 0.3, 0.9, and 0.5% per maize year. Despite there being 50% maize in the rotation, maize carbon only accounted for 20% of the observed carbon sequestration in the topsoil. Even with pre-defined parameter values, the simple carbon model reproduced observed δ13C well. The optimization of model parameters decreased the carbon use efficiency of digestate carbon in the soil, as well as the response of belowground carbon allocation to increased aboveground productivity of maize. (4) Conclusions: Two main findings resulted from this combination of measurement and modelling: (i) the retention of digestate carbon in soil was low and its effect on δ13C was negligible, and (ii) soil carbon inputs from maize only responded slightly to increased above-ground productivity. We conclude that SOC stocks in silage maize rotations can be preserved or enhanced if leys with perennial crops are included that compensate for the comparably low maize carbon inputs.

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Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Perennial Crops Can Compensate for Low Soil Carbon Inputs from Maize in Ley-Arable Systems

Poyda

Levin

Hülsbergen

et al. 2022

Plants

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“…One reason for the much higher N 2 O fluxes in the fertilized variants (compared to the unfertilized plots) is the different fertilization of the experimental plots over 15 years. Results from Levin 2021 show significant increases in soil organic carbon after fertilization with biogas digestate in the same trial [63]. The intense N 2 O fluxes occurred predominantly during the periods when high soil ammonium and nitrate levels were also observed.…”

Section: Discussion Of Resultsmentioning

confidence: 87%

“…Due to the very high yields that can be achieved at this site under ecological conditions [63], the high amount of fermentation residues in this trial also results. The digestate applications (and the N-inputs) in the trial correspond to the theoretical accumulation of the respective system (system-conform fertilization)-derived from the yields of the energy crops taking into account the fermentation in the biogas process [63,64]. The moderate N balances (Table 4) also show that these N quantities can be well utilized by the plants.…”

Section: Discussion Of Resultsmentioning

confidence: 96%

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Effects of Organic Maize Cropping Systems on Nitrogen Balances and Nitrous Oxide Emissions

et al. 2022

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Silage maize cultivation is gaining importance in organic farming, and thus its environmental and climate impacts. The effects of digestate fertilization in combination with different catch crops and tillage intensities in maize cultivation are investigated in a long-term field experiment in southern Germany. The tested variants are (a) maize after winter rye, plowed, unfertilized and (b) fertilized with biogas digestate, (c) maize after legume-rich cover crop mixture, mulch seeding, fertilized with digestate, and (d) maize in a white clover living mulch system, fertilized with digestate. Over three years (2019 to 2021), crop yields and N balance were analyzed, N2O emissions were measured in high temporal resolution using the closed chamber method, and soil moisture, ammonium, and nitrate contents were continuously determined. Maize dry matter yields ranged from 4.2 Mg ha−1 (variant a, 2021) to 24.4 t ha−1 (variant c, 2020) depending on cropping intensity and annual weather conditions. Despite relatively high nitrogen fertilization with digestate, the N balances were negative or nearly balanced; only in 2021 did the N surplus exceed 100 kg ha−1 (variant b and c) due to low yields. In maize cultivation, relatively low N2O-N emissions (1.0 to 3.2 kg ha−1) were measured in the unfertilized variant (a), and very high emissions in variant b (5.6 to 19.0 kg ha−1). The sometimes extremely high N2O emissions are also due to soil and climatic conditions (high denitrification potential). The experimental results show that cover crops, living mulch, and reduced tillage intensity in silage maize cultivation can reduce N2O emissions, improve nitrogen balance and increase maize yields.

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Reducing greenhouse gas emissions and increasing yield through manure substitution and supplemental irrigation in dryland of northwest China

Yang

Yue

Chang

et al. 2022

Agriculture, Ecosystems & Environment

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Effects of Organic Energy Crop Rotations and Fertilisation with the Liquid Digestate Phase on Organic Carbon in the Topsoil

Cited by 11 publications

References 52 publications

Perennial Crops Can Compensate for Low Soil Carbon Inputs from Maize in Ley-Arable Systems

Perennial Crops Can Compensate for Low Soil Carbon Inputs from Maize in Ley-Arable Systems

Effects of Organic Maize Cropping Systems on Nitrogen Balances and Nitrous Oxide Emissions

Reducing greenhouse gas emissions and increasing yield through manure substitution and supplemental irrigation in dryland of northwest China

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