scholarly journals Changes in soil organic carbon in croplands subjected to fertilizer management: a global meta-analysis

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Pengfei Han ◽  
Wen Zhang ◽  
Guocheng Wang ◽  
Wenjuan Sun ◽  
Yao Huang

Abstract Cropland soil organic carbon (SOC) is undergoing substantial alterations due to both environmental and anthropogenic changes. Although numerous case studies have been conducted, there remains a lack of quantification of the consequences of such environmental and anthropogenic changes on the SOC sequestration across global agricultural systems. Here, we conducted a global meta-analysis of SOC changes under different fertilizer managements, namely unbalanced application of chemical fertilizers (UCF), balanced application of chemical fertilizers (CF), chemical fertilizers with straw application (CFS), and chemical fertilizers with manure application (CFM). We show that topsoil organic carbon (C) increased by 0.9 (0.7–1.0, 95% confidence interval (CI)) g kg−1 (10.0%, relative change, hereafter the same), 1.7 (1.2–2.3) g kg−1 (15.4%), 2.0 (1.9–2.2) g kg−1 (19.5%) and 3.5 (3.2–3.8) g kg−1 (36.2%) under UCF, CF, CFS and CFM, respectively. The C sequestration durations were estimated as 28–73 years under CFS and 26–117 years under CFM but with high variability across climatic regions. At least 2.0 Mg ha−1 yr−1 C input is needed to maintain the SOC in ~85% cases. We highlight a great C sequestration potential of applying CF, and adopting CFS and CFM is highly important for either improving or maintaining current SOC stocks across all agro–ecosystems.

Agronomy ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2474
Author(s):  
Arthur Gross ◽  
Tobias Bromm ◽  
Bruno Glaser

Biochar application to soil has the potential to sequester carbon in the long term because of its high stability and large-scale production potential. However, biochar technologies are still relatively new, and the global factors affecting the long-term fate of biochar in the environment are still poorly understood. To fill this important research gap, a global meta-analysis was conducted including 64 studies with 736 individual treatments. Field experiments covered experimental durations between 1 and 10 years with biochar application amounts between 1 and 100 Mg ha−1. They showed a mean increase in soil organic carbon (SOC) stocks by 13.0 Mg ha−1 on average, corresponding to 29%. Pot and incubation experiments ranged between 1 and 1278 days and biochar amounts between 5 g kg−1 and 200 g kg−1. They raised SOC by 6.3 g kg−1 on average, corresponding to 75%. More SOC was accumulated in long experimental durations of >500 days in pot and incubation experiments and 6–10 years in field experiments than in shorter experimental durations. Organic fertilizer co-applications significantly further increased SOC. Biochar from plant material showed higher C sequestration potential than biochar from fecal matter, due to higher C/N ratio. SOC increases after biochar application were higher in medium to fine grain textured soils than in soils with coarse grain sizes. Our study clearly demonstrated the high C sequestration potential of biochar application to agricultural soils of varying site and soil characteristics.


2021 ◽  
Author(s):  
Thomas Guillaume ◽  
David Makowski ◽  
Zamir Libohova ◽  
Luca Bragazza ◽  
Sokrat Sinaj

<p>Increasing soil organic carbon (SOC) in agro-ecosystems enables to address simultaneously food security as well as climate change adaptation and mitigation. Croplands represent a great potential to sequester atmospheric C because they are depleted in SOC. Hence, reliable estimations of SOC deficits in agro-ecosystems are crucial to evaluate the C sequestration potential of agricultural soils and support management practices. Using a 30-year old soil monitoring networks with 250 sites established in western Switzerland, we identified factors driving the long-term SOC dynamics in croplands (CR) and permanent grasslands (PG) and quantified SOC deficit. A new relationship between the silt + clay (SC) soil particles and the C stored in the mineral-associated fraction (MAOMC) was established. We also tested the assumption about whether or not PG can be used as carbon-saturated reference sites. The C-deficit in CR constituted about a third of their potential SOC content and was mainly affected by the proportion of temporary grassland in the crop rotation. SOC accrual or loss were the highest in sites that experienced land-use change. The MAOMC level in PG depended on the C accrual history, indicating that C-saturation level was not coincidental. Accordingly, the relationship between MAOMC and SC to determine soil C-saturation should be estimated by boundary line analysis instead of least squares regressions. In conclusion, PG do provide an additional SOC storage capacity under optimal management, though the storage capacity is greater for CR.</p>


2007 ◽  
Vol 87 (3) ◽  
pp. 291-300 ◽  
Author(s):  
Carol Luca ◽  
Bing C Si ◽  
Richard E Farrell

Quantifying soil organic carbon (SOC) is important to aide in assessing carbon (C) sequestration potential, and as an indicator of soil quality. However, intensive s ampling of SOC for quantification can be expensive and time consuming. The objectives of this study were to identify which topographic index correlated best with SOC and determine if incorporating the index improved interpolation of limited SOC data. A transect with 93 sample points spaced 6 m apart was set up, and four topographical indices (curvature, wetness index, upslope length, and elevation) were evaluated for their potential as secondary variables. Three Kriging-based interpolation methods, ordinary kriging, cokriging, and simple kriging with varying local means were compared to determine if incorporating topographical indices improved interpolation of SOC. The upslope length, which takes into consideration the quantity of water that will be redistributed to a point, was found to have the strongest relationship with SOC (R2 = 0.48, P < 0.01) and was used as a secondary variable for kriging. Thirty points from the SOC data were randomly selected and used in the kriging algorithms to estimate the remain ing 63 points. The sum of squared differences (SSD) showed a significant reduction (from 1677 to 1455 for SKlm and from 1677 to 1464 for cokriging) in estimates when upslope length was used as a secondary variable. These results indicate that fewer samples may be taken to estimate SOC accurately and precisely if upslope length is incorporated. On a landscape scale this could facilitate quantification of carbon credits and management decisions in precision farming systems. Key words: Geostatics, kriging, cokriging, organic carbon, landscape processes, wetness index


Author(s):  
Qiuju Wang ◽  
Xin Liu ◽  
Jingyang Li ◽  
Xiaoyu Yang ◽  
Zhenhua Guo

Straw return is considered an effective way to improve the soil organic carbon (SOC) content of farmland. Most studies have suggested that a straw application increases the SOC content; however, some suggest that a straw application reduces the SOC content when used in combination with mineral fertilisation. Therefore, a meta-analysis of the effect of a straw application on the SOC change is needed. This study comprises a meta-analysis of 115 observations from 65 research articles worldwide. Straw applications can significantly increase the proportion of the SOC in the soil. Straw applications caused a significant microbial biomass carbon (MBC) increase in tropical and warm climatic zones. The MBC increase was higher than the SOC increase. For agriculture, the most important soil functions are the maintenance of the crop productivity, the nutrient and water transformation, the biological flora and activity, and the maintenance of the microbial abundance and activity. These functions should be prioritised in order to maintain the SOC function and services. Straw applications should not be excessive, especially when combined with mineral fertilisation, in order to avoid the loss of carbon from the straw in the form of greenhouse gases. A large amount of unused fertiliser also leads to a series of environmental problems.


2021 ◽  
Author(s):  
David Emde ◽  
Kirsten Hannam ◽  
Ilka Most ◽  
Louise Nelson ◽  
Melanie Jones

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 484
Author(s):  
Andrew M. Bierer ◽  
April B. Leytem ◽  
Robert S. Dungan ◽  
Amber D. Moore ◽  
David L. Bjorneberg

Insufficient characterization of soil organic carbon (SOC) dynamics in semi-arid climates contributes uncertainty to SOC sequestration estimates. This study estimated changes in SOC (0–30 cm depth) due to variations in manure management, tillage regime, winter cover crop, and crop rotation in southern Idaho (USA). Empirical data were used to drive the Denitrification Decomposition (DNDC) model in a “default” and calibrated capacity and forecast SOC levels until 2050. Empirical data indicates: (i) no effect (p = 0.51) of winter triticale on SOC after 3 years; (ii) SOC accumulation (0.6 ± 0.5 Mg ha–1 year–1) under a rotation of corn-barley-alfalfax3 and no change (p = 0.905) in a rotation of wheat-potato-barley-sugarbeet; (iii) manure applied annually at rate 1X is not significantly different (p = 0.75) from biennial application at rate 2X; and (iv) no significant effect of manure application timing (p = 0.41, fall vs. spring). The DNDC model simulated empirical SOC and biomass C measurements adequately in a default capacity, yet specific issues were encountered. By 2050, model forecasting suggested: (i) triticale cover resulted in SOC accrual (0.05–0.27 Mg ha–1 year–1); (ii) when manure is applied, conventional tillage regimes are favored; and (iii) manure applied treatments accrue SOC suggesting a quadratic relationship (all R2 > 0.85 and all p < 0.0001), yet saturation behavior was not realized when extending the simulation to 2100. It is possible that under very large C inputs that C sequestration is favored by DNDC which may influence “NetZero” C initiatives.


2021 ◽  
Vol 288 ◽  
pp. 112391
Author(s):  
Yanli Wang ◽  
Pengnian Wu ◽  
Fujian Mei ◽  
Yue Ling ◽  
Yibo Qiao ◽  
...  

2021 ◽  
Author(s):  
Sylvia Vetter ◽  
Michael Martin ◽  
Pete Smith

&lt;p&gt;Reducing greenhouse gas (GHG) emissions in to the atmosphere to limit global warming is the big challenge of the coming decades. The focus lies on negative emission technologies to remove GHGs from the atmosphere from different sectors. Agriculture produces around a quarter of all the anthropogenic GHGs globally (including land use change and afforestation). Reducing these net emissions can be achieved through techniques that increase the soil organic carbon (SOC) stocks. These techniques include improved management practices in agriculture and grassland systems, which increase the organic carbon (C) input or reduce soil disturbances. The C sequestration potential differs among soils depending on climate, soil properties and management, with the highest potential for poor soils (SOC stock farthest from saturation).&lt;/p&gt;&lt;p&gt;Modelling can be used to estimate the technical potential to sequester C of agricultural land under different mitigation practices for the next decades under different climate scenarios. The ECOSSE model was developed to simulate soil C dynamics and GHG emissions in mineral and organic soils. A spatial version of the model (GlobalECOSSE) was adapted to simulate agricultural soils around the world to calculate the SOC change under changing management and climate.&lt;/p&gt;&lt;p&gt;Practices like different tillage management, crop rotations and residue incorporation showed regional differences and the importance of adapting mitigation practices under an increased changing climate. A fast adoption of practices that increase SOC has its own challenges, as the potential to sequester C is high until the soil reached a new C equilibrium. Therefore, the potential to use soil C sequestration to reduce overall GHG emissions is limited. The results showed a high potential to sequester C until 2050 but much lower rates in the second half of the century, highlighting the importance of using soil C sequestration in the coming decades to reach net zero by 2050.&lt;/p&gt;


2012 ◽  
Vol 367 (1606) ◽  
pp. 3076-3086 ◽  
Author(s):  
Andrew D. Thomas

Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO 2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO 2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO 2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO 2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO 2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a , organic carbon and scytonemin . Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands.


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