Effects of long-term fertilization and residue management on soil organic carbon changes in paddy soils of China: A meta-analysis

https://doi.org/10.1016/j.agee.2015.02.008Get rights and content

Highlights

  • We draw a general conclusions at national scales on SOC changes in China’s paddy by meta-analysis.

  • Increasing long-term fertilization information will increase quality to refine national quantification of SOC changes.

  • We provide confidence intervals for estimates of soil C change rates.

  • We quantify the potential SOC sequestration with considering sequestration duration and SOC saturation level.

Abstract

Quantification of changes in soil organic carbon (SOC) and SOC stock as influenced by fertilization practices is needed for the improvement of carbon (C) sequestration and soil quality. A meta-analysis of 582 paired-treatment data from 95 long-term field experiments published from 1980 to 2012 was used to characterize the changes in SOC under different fertilization treatments and residue management practices in China’s paddy soils. All treatments sequestrated significant amounts of C compared with the control (CK, no fertilizer application). The greatest mean difference in SOC change rates was measured in the NPKM (mineral nitrogen, phosphorus and potassium plus manure) treatment, i.e., 0.401 g kg−1 yr−1, followed by the M (manure only) treatment (0.36 g kg−1 yr−1), while the N (mineral nitrogen only) treatment caused the lowest rate of 0.046 g kg−1 yr−1. The rates of SOC change in the fertilization treatments with C incorporation (e.g., manure application or straw return) were noticeably higher than those treated with inorganic chemical fertilizers only. The mean difference in the SOC change rates decreased with time and duration of the experiments. The effects of the initial SOC content on the rates of SOC change were not significant, and the effects of SOC accumulation originating from the fertilization treatments depended on the cropping systems. Potential SOC sequestration estimates were more accurate when two factors (sequestration duration and SOC saturation level) were taken into consideration. Our results indicate that the application of manure (e.g., M or NPKM) showed the greatest potential for C sequestration in agricultural soil and produced the longest SOC sequestration duration (45–51 yr).

Introduction

Soil organic carbon (SOC) in agricultural ecosystems plays a positive role in soil fertility, soil tilth, soil sustainability and crop production (Bauer and Black, 1994, Lal and Kimble, 1997). It is well known that agricultural management can increase or decrease SOC content due to variations in tillage, fertilization, irrigation and other activities (Paustian et al., 1997, Ogle et al., 2005). Consequently, improved management practices should aim to increase SOC accumulation, as these practices affect both world food security and global climate change (Lal, 2004, Lal, 2007).

Increasing evidence indicates that improved management practices can increase agricultural SOC to levels similar to those found in natural lands (Smith et al., 2000, West and Post, 2002, Lal, 2004, Gattinger et al., 2012). The SOC change rate results from the net balance between the rate of SOC input and the rate of mineralization (Post and Kwon, 2000). Carbon inputs to soil are mainly controlled by the biomass productivity of cropping systems, which is a function of the variations in climate, soil conditions, fertilizer inputs and agronomic management. Fertilizer application can enhance crop yield and biomass productivity, which increases the biomass input into the soil from crop residues and roots. Straw return and/or organic manures add carbon directly to soil. Several field experiments have proven that these measures can increase soil carbon and sequester C from the atmosphere (Halvorson et al., 1999, Kapkiyai et al., 1999, Wu et al., 2004, Ogunwole, 2005, Cong et al., 2012). In general, the application of organic fertilizers, especially manure, applied alone or in combination with inorganic fertilizers, increases SOC concentration (Manna et al., 2007, Purakayastha et al., 2008, Gong et al., 2009, Cong et al., 2012).

Paddy soils are a major form of cultivated soil in China. These soils, which account for approximately 25% of the total cultivated land, cover a total area of 30 M ha and are widely distributed across a broad range of temperate, subtropical and tropical climates (Shi et al., 2010, Zhang et al., 2012). Therefore, accurate estimates of the SOC changes in China’s paddy soils are critical for understanding their contribution to agro-ecosystem sustainability and the sequestration of atmospheric CO2. SOC change is a process that is controlled by many factors, including organic C inputs from crop residue or applied organic manure, climatic and soil conditions, and original C levels, and thus has high spatiotemporal heterogeneity. A realistic estimate of the change in SOC at regional and national scales must account for the effects of heterogeneity in soil and climate conditions and spatiotemporal management practices on SOC changes (Yan et al., 2007, Luo et al., 2013). However, there is a significant lack of spatiotemporally explicit quantification of SOC change and its sustainability with improved soil management in the paddy soils of China.

Process-based biogeochemical models, such as DNDC (Li et al., 1994), Century (Parton et al., 1987), RothC (Coleman et al., 1997), CEVSA (Cao et al., 2003) and EPIC (Izaurralde et al., 2006), are useful tools for simulating SOC changes in agricultural soils (Paustian et al., 1992) and provide a means of predicting, monitoring and verifying SOC changes under diverse conditions at a field scale (Bricklemyer et al., 2007). Some attempts have been made to upscale individual site results to quantify potential C sequestration at regional and national scales in China (Li et al., 2003, Tang et al., 2006, Yan et al., 2007, Wang et al., 2011, Xu et al., 2012). However, these process-based models usually require detailed input information, particularly spatially distributed information on agricultural practices and management history, which is typically not available at regional and/or global scales (Luo et al., 2013, Jandl et al., 2014). Hence, there is great uncertainty in simulating SOC changes and upscaling the results from individual sites to a regional scale (Ogle et al., 2006, Ogle et al., 2010, Smith et al., 2010). A meta-analysis is an effective statistical method to quantitatively summarize the results of numerous individual and independent studies and allows general conclusions to be drawn at regional and global scales (Gurevitch and Hedges, 1999, Guo and Gifford, 2002). The effects of agricultural practices on soil carbon changes have been investigated in numerous field experiments. Therefore, we conducted a meta-analysis to integrate the results of previous studies that examined changes in SOC due to fertilization and residue return in paddy fields in China. SOC measurements and auxiliary data were specifically compiled to

  • (a)

    comprehensively assess the spatiotemporal changes in SOC in paddy soils in China;

  • (b)

    provide confidence intervals for estimates of soil C change rates;

  • (c)

    quantitatively estimate the duration of soil C sequestration rates and soil C sequestration potential.

Section snippets

Data sources

We collected data on the changes in soil organic carbon (SOC) contents under different fertilization treatments from all peer-reviewed research papers published before 2013. The SOC contents in the analysis were obtained from the published tables and text of all of the selected research articles, and some data were extracted from published figures using graph digitizing software. Experimental site information, including the experimental periods, cropping systems, fertilization schemes and soil

The mean difference in SOC change rates in the fertilization treatments

There were positive SOC sequestration effects in all fertilization trials (Fig. 2a). The bias-corrected CIs of the mean differences were greater than zero for all treatments, indicating a significant effect on carbon sequestration in the paddy topsoil (Fig. 2a). Specifically, the greatest mean difference in SOC change rates occurred under NPKM treatment, with a rate of 0.401 g kg−1 yr−1, while the N treatment resulted in the lowest rate of 0.046 g kg−1 yr−1 compared with the control (CK). The

Initial SOC content

According to the soil C saturation hypothesis, changes in SOC may be affected by initial C levels (Campbell et al., 1991, Stewart et al., 2007). A greater SOC sequestration potential was observed in soils with a low C content compared with those with a high C content because they were further from their saturation level (Stewart et al., 2007, Stewart et al., 2008). A linear equation or a logarithmic function has been used to describe the relationship between SOC changes and their initial C

Conclusion

Our meta-analysis indicated that fertilizer application and straw return can significantly increase the SOC content compared with a control (CK) without fertilization. The combination of manure and inorganic fertilizers (NPKM) is the most promising strategy to maximize SOC levels. In contrast, the lowest increase in SOC levels were observed in response to mineral nitrogen (N) applied alone. The rates of the SOC change decreased with time and experiment duration. The duration of SOC

Acknowledgements

We are grateful to the authors who shared additional information on studies chosen for our meta-analysis. We acknowledge the support for this research from the Natural Science Foundation of China (41471177), the Strategic Priority Research Program of Chinese Academy of Sciences–Climate Change: Carbon Budget and Relevant Issues (XDA05050509) and the National Basic Research Program of China (973 Program) (2010CB950702).

References (84)

  • J.K. Ladha et al.

    How extensive are yield declines in long-term rice–wheat experiments in Asia?

    Field Crop Res.

    (2003)
  • I. Kogel-Knabner et al.

    Biogeochemistry of paddy soils

    Geoderma

    (2010)
  • R. Lal

    Forest soils and carbon sequestration

    For. Ecol. Manage.

    (2005)
  • Z.K. Luo et al.

    Soil carbon change and its responses to agricultural practices in Australian agro-ecosystems: a review and synthesis

    Geoderma

    (2010)
  • T. Müller et al.

    Soil organic matter turnover as a function of the soil clay content: consequences for model applications

    Soil Biol. Biochem.

    (2004)
  • M.C. Manna et al.

    Long-term fertilization, manure and liming effects on soil organic matter and crop yields

    Soil Tillage Res.

    (2007)
  • G.X. Pan et al.

    The role of soil organic matter in maintaining the productivity and yield stability of cereals in China

    Agric. Ecosyst. Environ.

    (2009)
  • T.J. Purakayastha et al.

    Long-term impact of fertilizers on soil organic carbon pools and sequestration rates in maize–wheat–cowpea cropping system

    Geoderma

    (2008)
  • W.Y. Rui et al.

    Effect size and duration of recommended management practices on carbon sequestration in paddy field in Yangtze Delta Plain of China: a meta-analysis

    Agric. Ecosyst. Environ.

    (2010)
  • S.W. Shi et al.

    A synthesis of change in deep soil organic carbon stores with afforestation of agricultural soils

    For. Ecol. Manage.

    (2013)
  • P. Smith et al.

    Measurements necessary for assessing the net ecosystem carbon budget of croplands

    Agric. Ecosyst. Environ.

    (2010)
  • C.E. Stewart et al.

    Soil carbon saturation: evaluation and corroboration by long-term incubations

    Soil Biol. Biochem.

    (2008)
  • H.J. Tang et al.

    Estimations of soil organic carbon storage in cropland of China based on DNDC model

    Geoderma

    (2006)
  • S.H. Wang et al.

    Regional simulation of soil organic carbon dynamics for dry farmland in East China by coupling a 1:500,000 soil database with the century model

    Pedosphere

    (2011)
  • N. Wiebe et al.

    A systematic review identifies a lack of standardization in methods for handling missing variance data

    J. Clin. Epidemiol.

    (2006)
  • T.Y. Wu et al.

    Influence of cultivation and fertilization on total organic carbon and carbon fractions in soils from the Loess Plateau of China

    Soil Tillage Res.

    (2004)
  • S.X. Xu et al.

    Spatially explicit simulation of soil organic carbon dynamics in China's paddy soils

    Catena

    (2012)
  • H.M. Yan et al.

    Potential and sustainability for carbon sequestration with improved soil management in agricultural soils of China

    Agric. Ecosyst. Environ.

    (2007)
  • L.M. Zhang et al.

    Simulation soil organic carbon change in China’s Tai-Lake paddy soils

    Soil Tillage Res.

    (2012)
  • D.C. Adams et al.

    Resampling tests for meta-analysis of ecological data

    Ecology

    (1997)
  • A. Bauer et al.

    Quantification of the effect of soil organic matter content on soil productivity

    Soil Sci. Soc. Am. J.

    (1994)
  • R. Bhattacharyya et al.

    Long term effects of fertilization on carbon and nitrogen sequestration and aggregate associated carbon and nitrogen in the Indian sub-himalayas

    Nutr. Cycling Agroecosyst.

    (2010)
  • R.S. Bricklemyer et al.

    Sensitivity of the century model to scale-related soil texture variability

    Soil Sci. Soc. Am. J.

    (2007)
  • Z.C. Cai et al.

    Options for mitigating methane emission from a permanently flooded rice field

    Global Change Biol.

    (2003)
  • M.K. Cao et al.

    Response of terrestrial carbon uptake to climate interannual variability in China

    Global Change Biol.

    (2003)
  • R.H. Cong et al.

    An analysis of soil carbon dynamics in long-term soil fertility trials in China

    Nutr. Cycling Agroecosyst.

    (2012)
  • A. Gattinger et al.

    Enhanced top soil carbon stocks under organic farming

    Proc. Natl. Acad. Sci.

    (2012)
  • W. Gong et al.

    Long-term manuring and fertilization effects on soil organic carbon pools under a wheat–maize cropping system in North China Plain

    Plant Soil

    (2009)
  • E. Gregorich et al.

    Fertilization effects on soil organic matter turnover and corn residue C storage

    Soil Sci. Soc. Am. J.

    (1996)
  • L.B. Guo et al.

    Soil carbon stocks and land use change: a meta analysis

    Global Change Biol.

    (2002)
  • L.P. Guo et al.

    Carbon sink in cropland soils and the emission of greenhouse gases from paddy soils: a review of work in China

    Chemosphere-Global Change Sci.

    (2001)
  • J. Gurevitch et al.

    Meta-analysis: combining the results of independent experiments

  • Cited by (0)

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