Marginal land conversion to perennial energy crops with biomass removal enhances soil carbon sequestration

Abstract

Marginal land conversion to perennial energy crops can provide biomass feedstocks and climate change mitigation. However, the effect of perennial energy crop cultivation on soil organic carbon (SOC) sequestration and its underlying mechanism in marginal land still remains incomplete. Here, SOC turnover, stability, and its potential sequestration were evaluated based on 10 years of land use change from C3 grass‐dominated marginal land to C4 energy crops Miscanthus and switchgrass cultivation. The naturally occurring 13C signature down to 60 cm depth was used to determine the energy crops‐derived C. Compared to reference marginal land, Miscanthus plantation increased the SOC stock at 0–60 cm depth by 17.8% and 64.3% in bulk and root zone, respectively. Similarly, the SOC stock under switchgrass was also 16.5% and 93.0% higher in bulk and root zone than in reference marginal land, respectively. The higher SOC stock in the root zone of switchgrass relative to Miscanthus was supported by the higher contribution of C4‐derived C to SOC (44.5% vs. 32.4%). The mean residence time of old C was higher under switchgrass than Miscanthus in the bulk zone across 0–60 cm (p < 0.05) but remained the same at 0–20 cm in the root zone. Specific SOC mineralization and temperature sensitivity were lower in soils under Miscanthus and switchgrass compared to reference marginal land. The partial least squares path model revealed that perennial energy crop cultivation enhances soil C stock via increased C4‐derived C input and reduced mineralization. In conclusion, marginal land conversion to perennial energy crops is a win–win strategy for C sequestration to mitigate climate change and support the growing bioenergy sector with biomass supply.

Short‐term reduction in cropping intensity improves soil quality of topsoil rather than subsoil

“…This was further supported by the positive correlation between four enzymes (i.e., BG, BX, CE, and ACP) and TN and NH 4 + and NO 3 − (Figure 4b). Concurrently, N can change the nutrient distribution ratio and indirectly affect soil enzyme activities (Xu et al, 2022). Also, soil pH influenced enzyme activities and enzymatic stoichiometry (Figure 4a).…”

“…The activities of soil enzymes, β‐1,4‐glucosidase (BG), β‐ D ‐xylopyranoside (BX), β‐ D ‐celliobiosidase (CE), β‐1,4‐ N ‐acetylglucosaminidas (NAG), L ‐leucine aminopeptidase (LAP), and acid phosphatase (ACP), were quantified with fluorogenically labelled substrates (Nayab et al, 2022; Xu et al, 2022; Zhou et al, 2021). In brief, add 50 mL distilled water to 1 g fresh soil, shake for 0.5 hr, and then aspirate 50 μL of the suspension.…”

Can natural undisturbed revegetation restores soil organic carbon to levels under native climax vegetation under tropical semiarid climate?

“…These plants are considered perennial energy, whose root systems efficiently sequester SOC through a rapid rate of renovation of the SOC. In other words, the new C4-derived C replaced the old C3-C at a rate sufficient to offset the losses (Xu et al, 2022). The SOM content derived from C4 cultures has a faster decomposition than C3.…”

Amendment with controlled release urea increases leaf morpho‐physiological traits, grain yield and NUE in a double‐cropping rice system in southern China

“…Controlled release N fertilizer has advantages with respect to maintaining and increasing leaf greenness as a result of providing continuous N supplement, which indirectly increases carbon dioxide assimilation for the remobilization of non‐structural carbohydrates to grain organs 5,15 . Both controlled and field experiments suggest that supplementation with controlled release N fertilizer increases cereal crop morphology traits, gas exchange attributes, and soil inorganic N and organic C content over the reproductive period 16‐18 . Short‐term straw returning fertilization effects on crop yields are likely to reduce because of the uncertainty in the quality and quantality of straw decomposition to nutrients over the changing growing season 19,20 …”

“…5,15 Both controlled and field experiments suggest that supplementation with controlled release N fertilizer increases cereal crop morphology traits, gas exchange attributes, and soil inorganic N and organic C content over the reproductive period. [16][17][18] Short-term straw returning fertilization effects on crop yields are likely to reduce because of the uncertainty in the quality and quantality of straw decomposition to nutrients over the changing growing season. 19,20 Conventional N urea application practices (such as multiple application and subsurface placement) enhance leaf development, N allocation to harvest organs and decrease the N losses to environment.…”