Decrease of soil organic matter stabilization with increasing inputs: Mechanisms and controls

Shahbaz, Muhammad; Kuzyakov, Yakov; Heitkamp, Felix

doi:10.1016/j.geoderma.2016.05.019

Cited by 159 publications

(76 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In line with this observation, Shahbaz et al . () found that with increasing amounts of wheat residue added to the soil – regardless of whether it was shoot or root residue – there was both increased microbial priming of SOC and a reduced proportion of fresh inputs that were retained as SOC. Similar observations have been found in forest ecosystems with the experimental doubling of litter inputs (Sulzman et al ., ; Pisani et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Evidence for the primacy of living root inputs, not root or shoot litter, in forming soil organic carbon

et al. 2018

View full text Add to dashboard Cite

Soil organic carbon (SOC) is primarily formed from plant inputs, but the relative carbon (C) contributions from living root inputs (i.e. rhizodeposits) vs litter inputs (i.e. root + shoot litter) are poorly understood. Recent theory suggests that living root inputs exert a disproportionate influence on SOC formation, but few field studies have explicitly tested this by separately tracking living root vs litter inputs as they move through the soil food web and into distinct SOC pools. We used a manipulative field experiment with an annual C grass in a forest understory to differentially track its living root vs litter inputs into the soil and to assess net SOC formation over multiple years. We show that living root inputs are 2-13 times more efficient than litter inputs in forming both slow-cycling, mineral-associated SOC as well as fast-cycling, particulate organic C. Furthermore, we demonstrate that living root inputs are more efficiently anabolized by the soil microbial community en route to the mineral-associated SOC pool (dubbed 'the in vivo microbial turnover pathway'). Overall, our findings provide support for the primacy of living root inputs in forming SOC. However, we also highlight the possibility of nonadditive effects of living root and litter inputs, which may deplete SOC pools despite greater SOC formation rates.

show abstract

Section: Discussionmentioning

confidence: 97%

Evidence for the primacy of living root inputs, not root or shoot litter, in forming soil organic carbon

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The SOM increase because of large C additions (such as crop residue) is mostly explained by C accumulation in HF. However, because of the limited physical or physicochemical protection capacity, large C additions may cause only minor increase of bulk SOM, especially in high‐C soils (Six et al, ; Shahbaz et al, ). This indicates that C‐input driven by, for example, high crop residue return, therefore, would not be directly beneficial for SOM.…”

Section: Introductionmentioning

confidence: 99%

Decadal Nitrogen Fertilization Decreases Mineral‐Associated and Subsoil Carbon: A 32‐Year Study

et al. 2017

Self Cite

View full text Add to dashboard Cite

Crop residues and manure are important sources of carbon (C) for soil organic matter (SOM) formation. Crop residue return increases by nitrogen (N) fertilization because of higher plant productivity, but this often results only in minor increases of SOM. In our study, we show how N fertilization and organic C additions affected SOM and its fractions within a 32‐year‐long field‐experiment at Puch, Germany. Five organic additions, no‐addition (control), manure, slurry, straw and straw + slurry, were combined with three mineral N fertilization rates (no, medium and high fertilization), which resulted in 1·17–4·86 Mg C‐input ha‐1 y‐1. Topsoil (0–25 cm) SOM content increased with N fertilization, mainly because of the C in free light fraction (f‐LF). In contrast, subsoil (25–60 cm) SOM decreased with N fertilization, probably because of roots' relocation in Ap horizon with N fertilization at the surface. Despite high inputs, straw contributed little to f‐LF but prevented C losses from the mineral‐associated SOM fraction (ρ > 1·6 g cm‐3) with N fertilization, which was observed without straw addition. Above (straw) and belowground (roots) residues had opposite effects on SOM fractions. Root C retained longer in the light‐fractions and was responsible for SOM increase with N fertilization. Straw decomposed rapidly (from f‐LF) and fueled the mineral‐associated SOM fraction. We conclude that SOM content and composition depended not only on residue quantity, which can be managed by the additions and N fertilization, but also on the quality of organics. This should be considered for maintaining the SOM level, C sequestration, and soil fertility. Copyright © 2016 John Wiley & Sons, Ltd.

show abstract

“…As any pieces of litter were removed as much as possible during the sieving process (<2 mm) prior to analysis for SOC, these corn residues would have not contributed much to the amount of SOC measured. Beyond this, it is possible that the corn residues induced positive priming, wherein the addition of fresh residues stimulates microbial activity and increases SOM decomposition rates [26,28,29] with high C: N ratio residues, such as corn, have a stronger effect than lower C: N ratio residues [30]. These possible explanations are further supported by the differences among crop phases of the CSW rotation.…”

Section: Resultsmentioning

confidence: 96%

Carbon and Nitrogen Content of Soil Organic Matter and Microbial Biomass under Long-Term Crop Rotation and Tillage in Illinois, USA

et al. 2018

View full text Add to dashboard Cite

Abstract:Crop rotation and tillage alter soil organic matter (SOM) dynamics by influencing the soil environment and microbes carrying out C and N cycling. Our goal was to evaluate the effect of long-term crop rotation and tillage on the quantity of C and N stored in SOM and microbial biomass. Two experimental sites were used to evaluate four rotations-continuous corn (Zea mays L.) (CCC), corn-soybean (Glycine max [L.] Merr.) (CS), corn-soybean-wheat (Triticum aestivum L.) (CSW), and continuous soybean (SSS), each split into chisel tillage (CT) and no-till (NT) subplots. The CSW rotation increased soil organic carbon (SOC) content compared to SSS; SSS also reduced total nitrogen (TN) compared to other rotations. Levels of SOC and TN were 7% and 9% greater under NT than CT, respectively. Rotation did not affect microbial biomass C and N (MBC, MBN) while tillage reduced only MBN at 10-20 cm compared to NT, likely related to dispersion of N fertilizers throughout the soil. Despite the apparent lack of sensitivity of microbial biomass, changes in SOC and TN illustrate the effects of rotation and tillage on SOM dynamics. The inclusion of crops with high C: N residues and no-till use both support higher C and N content in the top 20 cm of the soil.

show abstract

Decrease of soil organic matter stabilization with increasing inputs: Mechanisms and controls

Cited by 159 publications

References 38 publications

Evidence for the primacy of living root inputs, not root or shoot litter, in forming soil organic carbon

Evidence for the primacy of living root inputs, not root or shoot litter, in forming soil organic carbon

Decadal Nitrogen Fertilization Decreases Mineral‐Associated and Subsoil Carbon: A 32‐Year Study

Carbon and Nitrogen Content of Soil Organic Matter and Microbial Biomass under Long-Term Crop Rotation and Tillage in Illinois, USA

Contact Info

Product

Resources

About