Root carbon inputs under moderately diverse sward and conventional ryegrass-clover pasture: implications for soil carbon sequestration

Abstract

Background and aims A strategy to increase soil C under pasture-based systems is to increase the root mass inputs or increase rooting depth of plants. Our objective in this study was to measure the seasonal dynamics of root mass and C inputs under two different pasture types (ryegrass-clover vs moderately diverse) that differ in plant diversity and which are commonly used in New Zealand agriculture. Methods This study was carried out on an existing plant diversity field trial containing six replicate paddocks of both moderately-diverse and ryegrass-clover pastures. Soil cores (0-100-200-300 mm sections) were collected seasonally across 1 year and individual root traits assessed from all species. Results The moderately diverse pasture had greater root mass (5320-9350 kg ha −1 ) than the ryegrass-clover pasture (3810-5700 kg ha −1 ) for all seasons and had greater root mass lower in the soil profile. A secondary objective demostrated no significant difference in root mass between high and low sugar ryegrass cultivar. Increased root mass results in an estimated increase of C input to the soil of about 1203 kg C ha −1 (0-300 mm depth) under the moderately diverse pasture, excluding root exudates. Root trait measurements demonstrated a greater diversity of root traits in the moderately diverse sward compared to the ryegrass-clover pasture. Conclusions Moderately diverse pasture systems offer scope to increase soil C under grazed pastures through increased root mass inputs and rooting depth.

Allocation of photosynthestically-fixed carbon in plant and soil during growth of reed (Phragmites australis) in two saline soils

“…However, the SO 13 C content (Fig. 3) depends mainly on plant biomass (McNally et al 2015). In our study, there was a significant positive correlation between the SO 13 C content and root biomass (Fig.…”

“…2c) and SO 13 C content (Fig. 3) from end 6-h to the final day further indicates that substantial photosynthetically-fixed C enters the SOC pools (Pausch et al 2013;McNally et al 2015), but microbial respiration can decrease the actual amount of SO 13 C deposited (Bahn et al 2009;Kuzyakov and Gavrichkova 2010).…”

“…Moreover, plant senescence on the final day may have released more organic compounds from root cells and tissues into the soil (Pausch et al 2013;McNally et al 2015). Thus, the percentage of net assimilated 13 C showed a decrease in the shoots as well as increases in the roots and soil ( Fig.…”

Revegetation of artificial grassland improve soil organic and inorganic carbon and water of abandoned mine

“…While a slight decreased of SOC content was found in 20-year restoration land, the trend was consist with the changed of biomass. Because plant roots made significant contributions to soil carbon under grassland (McNally et al, 2015). Lv and Liang (2012) also found that during forest restoration, SOC did not consistently increase linearly with restoration years.…”

Soil Carbon Dioxide Respiration in Switch Grass Fields: Assessing Annual, Seasonal and Daily Flux Patterns

“…Consequently, changes in land use and management practices that affect soil respiration rates can have a significant impact on atmospheric CO2 concentrations and soil C pools (McNally et al 2015). In the United States, agriculture alone occupies 51.3% (1.16 billion acres) of the total land area (Nickerson et al 2011) and is among the largest net sources of atmospheric C resulting from land use change (US EPA 2004).…”