Advances in Agronomy

1. Auflage 2015
ISBN: 978-0-12-803051-6
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, Band Volume 134, 262 Seiten

Reihe: Advances in Agronomy

Advances in Agronomy continues to be recognized as a leading reference and a first-rate source for the latest research in agronomy. Each volume contains an eclectic group of reviews by leading scientists throughout the world. As always, the subjects covered are rich and varied and exemplary of the abundant subject matter addressed by this long-running serial. - Includes numerous, timely, state-of-the-art reviews - Features distinguished, well recognized authors from around the world - Builds upon this venerable and iconic review series - Covers the extensive variety and breadth of subject matter in crop and soil sciences

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Chapter One Management-Induced Changes to Soil Organic Carbon in China
A Meta-analysis
Xin Zhao*, Ran Zhang*, Jian-Fu Xue*, Chao Pu*, Xiang-Qian Zhang*, Sheng-Li Liu*, Fu Chen*, Rattan Lal§ and Hai-Lin Zhang*,1     *College of Agronomy and Biotechnology, China Agricultural University, Key Laboratory of Farming System, Ministry of Agriculture, Beijing, China     §Carbon Management and Sequestration Center, School of Environment and Natural Resources, The Ohio State University, Columbus, OH, USA
1 Corresponding author: E-mail: [e-mail] 
Abstract
Soil carbon (C) sequestration is an environmentally friendly and efficient strategy to offset emissions of greenhouse gases and mitigate climate change. However, inappropriate farming practices can deplete soil organic carbon (SOC) stock and degrade soil quality. Thus, we conducted a meta-analysis to assess and identify the effects of improved farming practices on SOC sequestration in China by compiling a data set of 83 studies. The results indicated that SOC concentration and stocks at 0–30 cm depth significantly increased by 1.00 ± 0.26 g kg-1 and 0.97 ± 0.24 Mg ha-1 when plow tillage with residue removal was converted to no-till with residue retention (NT); 1.11 ± 0.21 g kg-1 and 2.09 ± 0.46 Mg ha-1 when no fertilization was changed to chemical fertilization (CF); and 1.99 ± 0.62 g kg-1 and 3.09 ± 0.99 Mg ha-1 when CF was changed to manure application (MF) (P < 0.05), respectively. However, increases in SOC were primarily observed in the surface layer and decreased with soil depth. Therefore, the adoption of NT and MF in conjunction with CF is an effective strategy to enhance SOC stock in the surface layer. Further, in single-crop farming regions, the effects are more significant at 0–10 cm depth; and the new equilibrium can occur within 11–20 years after the adoption of NT. In double-crop farming regions, conversion to MF enhanced the SOC at 0–20 cm depth over 16 years. Additional research is warranted to credibly assess the rates of residue and manure input, soil “C saturation,” and soil type on the potential SOC sink capacity in China's croplands. Keywords
Climate-smart agriculture; Farm practices; Meta-analysis; Soil organic carbon; Soil organic carbon stock List of Abbreviations BD    Soil bulk density C    Carbon CA    Conservation agriculture CF    Chemical fertilization application CI    Confidence interval F0    No fertilization MAP    Mean annual precipitation MAT    Mean annual temperature MD    Mean difference MF    Manure application NT    No-till with residue retained NT0    No-till with residue removal PT0    Plow tillage with residue removal R0    Residue removal RR    Residue retained SOC    Soil organic carbon SOM    Soil organic matter 1. Introduction
The Fifth Intergovernmental Panel on Climate Change (IPCC) reported that the global mean surface temperature has significantly increased since the late nineteenth century: the global combined land and ocean temperature increased by 0.89 °C (0.69–1.08 °C) between 1901 and 2012 (IPCC, 2013). Climate change is attributed to anthropogenic emissions of greenhouse gases (GHGs), which include CO2, CH4, and N2O (Lal, 2004a). The use of fossil fuels and land use conversion have released 545 (460–630) Pg (Pg = petagram = 1015 g = 1 giga ton) of carbon (C) to the atmosphere, leading to an increase in atmospheric CO2 concentration from 275–281 ppmv in 1750 to 390.5 ppm in 2011 (IPCC, 2013) and 400 ppmv in 2013 (WMO, 2014). Thus, identifying strategies of reducing GHGs emissions and mitigating climate change are global issues (Paustian et al., 2000; Lal, 2004c, 2007; Lal et al., 2007). Soil C pool is the third principal global C stock containing 1220–1550 Pg to 1 m and 2376–2450 Pg to 2 m depth as soil organic carbon (SOC) and 695–748 Pg to 1 m depth as inorganic C (Lal et al., 1995; Batjes, 1996). The potential of SOC sequestration is estimated to be 0.4–1.2 Pg C yr-1 throughout the world's croplands (Lal, 2004c). Thus, enhancing SOC sequestration is important to partially offsetting anthropogenic emissions and mitigating climate change. In addition, SOC is a key soil property and an important determinant of soil quality (Reeves, 1997; Sá and Lal, 2009; Brandão et al., 2011). However, conversion of natural to agricultural ecosystems may deplete the SOC pool by as much as 60% in temperate regions and 75% or more in tropical regions, degrading soil quality and biomass productivity, exacerbating risks of food insecurity, and aggravating climate change (Lal, 2004c, 2010; Lal et al., 2007). Thus, promoting farming practices which can restore SOC stock is important to mitigating climate change, improving soil quality, and advancing food security (Lal, 2007). The SOC pool is affected by a wide range of agricultural management practices including tillage (West and Post, 2002; Ussiri and Lal, 2009; Dalal et al., 2011; Zhang et al., 2014), residue management (Lu et al., 2009; Ding et al., 2014; Liu et al., 2014b), fertilization (Lu et al., 2009; Ding et al., 2014), manure application (MF) (Ding et al., 2014; Maillard and Angers, 2014), water management and soil drainage (Abid and Lal, 2008), etc. Thus, a wide range of C-smart practices have been adopted and popularized to replace traditional management practices. Conservation agriculture (CA) is widely practiced and typically leads to minimal soil disturbance (e.g., no-till, NT) and residue retention on the surface as mulch. In addition to enhancing the SOC pool, CA has numerous benefits of relevance to the environment and crop production (Delgado et al., 2013; Zhang et al., 2014). Thus, conversion of conventional tillage (e.g., plow tillage) to NT can result in redistribution of SOC within the soil profile (Powlson et al., 2014) and in soil-specific situations also enhance the SOC pool (West and Post, 2002; Zhang et al., 2014), particularly in surface soil (West and Post, 2002; Lu et al., 2009; Zhang et al., 2013b). Conversion to CA also enhances soil quality, increases aggregation, and improves aeration by enriching the surface SOC (Doran and Parkin, 1994; Franzluebbers et al., 2007). Agronomic yield in degraded soils can be increased by restoring the SOC pool (Lal, 2004c). Adoption of recommended management practices (RMPs) and integrated nutrient management are some of the strategies that can be used to restore SOC stock in depleted and degraded soils. However, the rate of SOC restoration is affected by numerous factors including climate (rainfall, temperature, evaporation, and seasonal distribution), soil texture and structure, farming system, and specific RMPs of soil and crop management (Lal, 2004c; Johnston et al., 2009). SOC sequestration is to enhance the SOC stock compared to the pretreatment status due to soil humus through land unit plants, plant residues, and other organic solids that originate from the atmospheric CO2 pool (Olson, 2013; Olson et al., 2014). Because of the complexity of SOC sequestration, the amounts of SOC sequestration attained under different farming practices are not clear and have numerous uncertainties. For example, the impact of NT on SOC concentration and pool follows different trends in the long- or short-terms due to experimental...