Changes in soil organic carbon under perennial crops

Abstract

This study evaluates the dynamics of soil organic carbon (SOC) under perennial crops across the globe. It quantifies the effect of change from annual to perennial crops and the subsequent temporal changes in SOC stocks during the perennial crop cycle. It also presents an empirical model to estimate changes in the SOC content under crops as a function of time, land use, and site characteristics. We used a harmonized global dataset containing paired‐comparison empirical values of SOC and different types of perennial crops (perennial grasses, palms, and woody plants) with different end uses: bioenergy, food, other bio‐products, and short rotation coppice. Salient outcomes include: a 20‐year period encompassing a change from annual to perennial crops led to an average 20% increase in SOC at 0–30 cm (6.0 ± 4.6 Mg/ha gain) and a total 10% increase over the 0–100 cm soil profile (5.7 ± 10.9 Mg/ha). A change from natural pasture to perennial crop decreased SOC stocks by 1% over 0–30 cm (−2.5 ± 4.2 Mg/ha) and 10% over 0–100 cm (−13.6 ± 8.9 Mg/ha). The effect of a land use change from forest to perennial crops did not show significant impacts, probably due to the limited number of plots; but the data indicated that while a 2% increase in SOC was observed at 0–30 cm (16.81 ± 55.1 Mg/ha), a decrease in 24% was observed at 30–100 cm (−40.1 ± 16.8 Mg/ha). Perennial crops generally accumulate SOC through time, especially woody crops; and temperature was the main driver explaining differences in SOC dynamics, followed by crop age, soil bulk density, clay content, and depth. We present empirical evidence showing that the FAO perennialization strategy is reasonable, underscoring the role of perennial crops as a useful component of climate change mitigation strategies.

Perennial Staple Crops: Yields, Distribution, and Nutrition in the Global Food System

“…Soil organic carbon estimates for perennial crops in different climatic regions.Reproduced from Supplementary Material,Ledo et al (2020).…”

Natural Climate Solutions for China: The Last Mile to Carbon Neutrality

“…• Developing project with multiple phases to allow for regular monitoring, potential pitfalls and corrections, e.g., inappropriate species selection in early reforestation projects in China was corrected by shifting species and combining other ecosystem types (Liu et al, 2008;Cao et al, 2011;Ma et al, 2013) • Protecting existing ecosystems with rich and irrecoverable carbon pools (e.g., wetlands, peatlands and tropical forest) (Roe et al, 2019;Goldstein et al, 2020); restricting harvest and lengthening harvest cycles in forests (Law et al, 2018) • Exploring ocean-based pathways that can also contribute to additional large-scale mitigation (e.g., aquaculture, seabed, seafood) (Hoegh-Guldberg et al, 2019;Jiao et al, 2020) • Prioritizing NCS pathways, starting with pathways with instantaneous mitigation responses and those requiring less intensive investment, e.g., using alternatives to avoid wood fuels, managing crop nutrient uses, or growing trees in agricultural lands (Chen et al, 2010;Law et al, 2018;Chapman et al, 2020) • Selecting region-specific best NCS pathway(s), e.g., plantation failed in some of China's arid and semiarid areas, but grazing management can be effective (Cao et al, 2011;Ma et al, 2013) • Speeding up mitigation technology deployment by initializing NCS projects across the country, e.g., China's nationwide ecological projects on reforestation and grassland restoration (Liu et al, 2008;Lu et al, 2018) • Avoiding failure and unintended consequences, e.g., inappropriate species or ecosystem choice may cause water stress in arid regions (Cao et al, 2011;Feng et al, 2016) • Managing emission intensive nutrients, e.g., increasing farm size and using new technologies to reduce excessive use of synthetic nitrogen (Zhang et al, 2013;Ju et al, 2016) • Improving feed quality and manure management to reduce GHG emissions in livestock sector, especially CH 4 and N 2 O (Bai et al, 2018) • Exploring alternative options to wood fuels, e.g., adopting household biogas (Chen et al, 2010) • Minimizing disturbances to native ecosystems during land transition, e.g., reducing soil disturbances during establishment of plantation and reforestation (Anderson-Teixeira et al, 2009;Ledo et al, 2020), and avoiding soil erosion by minimizing disturbance to surface crust in China's arid region (Cao et al, 2011) • Imp...…”

Integrating beef cattle on cropland affects net global warming potential

“…As treatments in this study were managed using no-till practices, soil C losses through these pathways were minimized. Opportunities to increase SOC stocks in semiarid cropping systems include incorporation of perennial grasses and woody plant species (Ledo et al 2020). Abundant evidence supports the potential for large increases in SOC stocks under highly productive forage and/or biofeedstock grass species (Franzluebbers et al 2012;Schmer et al 2011), while there is complementary evidence for SOC stock increases when transitioning from cropland or pasture to silvopastural systems (De Stefano and Jacobson 2017), with potential for soil carbon storage in deeper soil depths ([ 0.75 m) (Howlett et al 2011).…”