Soil carbon improvement under long‐term (36 years) no‐till sorghum production in a sub‐tropical environment

Abstract

Soil organic matter (SOM) is considered an important indicator of soil quality, which can be impacted by crop production practices such as tillage. In this study, two long‐term tillage regimes (conventional tillage [CT] and no tillage [NT], conducted for 36 years) were compared in continuous sorghum production in a sub‐tropical environment in southeast Texas. The positive effects of long‐term NT practice were more conspicuous at the soil surface compared with the deeper soil profiles. The SOC was greater (1.5 t C ha−1 greater) in the NT system compared with the CT system. Results from an incubation study indicate that the rate of C‐min at 0–5 cm soil depth was significantly greater (164 μg of CO2–C g−1 of soil greater) in NT than that of CT, but this trend was reversed at 10–20 cm depth wherein the C‐min rates were 106 μg of CO2–C g−1 of soil greater in CT compared with NT, which is likely because of soil disturbance during the study. Soil cumulative CO2‐C emissions were greater in the CT system (7.28 g m−2) than in the NT system (5.19 g m−2), which is primarily attributed to high soil temperature conditions in the CT system. Sorghum grain yield however was not influenced by the differences in SOC content in this long‐term experiment. Overall, the present study found that long‐term conservation tillage improved SOC stock and reduced carbon loss, thus had a positive impact on soil health and sustainability.

Biochar for sustainable soil management

“…Soil represents the largest terrestrial carbon pool (Le Quere et al., 2018). Soil carbon storage is affected by farm management strategies (Chowaniak et al., 2020; Govindasamy et al., 2020; Singh & Whelan, 2020) and soil microbial processes can also result in the emission of N 2 O (Davidson, 2009; Hu et al., 2020; Wang et al., 2020), a greenhouse gas with 298 times the atmospheric heat‐trapping ability of CO 2 (IPCC, 2014). Biochar application increases soil organic content in soil, resulting in carbon sequestration (Zhao, Lin, et al, 2020).…”

Land Use Change Affects Soil Organic Carbon: An Indicator of Soil Health

“…In addition to carbon sequestration, conservation tillage can reduce CO 2 emissions [60]. Accumulation of SOC exhibit a positive correlation with the sequestration of atmospheric CO 2 , while oxidation of SOC, as a result of practices such as tillage, can contribute to CO 2 emission from agricultural fields [48]. For example, CO 2 emission in conventional tillage was 29% greater than in no till in a loamy soil as reported by Bista et al [61].…”

“…Soil organic matter is considered an important indicator of soil quality and health, which can be impacted by crop production practices such as tillage [48]. Tillage has the potential to increase the rate of C mineralization through breaking larger macro aggregates, mixing crop residues and exposing protected SOC in the aggregates to soil microorganisms [5,6,49,50].…”

“…Hence, conservation tillage/no-tillage has been considered as a suitable practice to maintain or increase SOC stocks compared to conventional tillage [12,51,52]. Conservation tillage practices such as no till can enhance assimilation of SOC by decreasing soil disturbance and increasing crop residue accumulation in comparison to conventional tillage [12,25,48,53]. For example; Blanco-Canqui and Lal [54] indicated an increase in SOC with increasing crop residue retention, whereby 16.0 t C ha −1 of SOC was reported without straw additions, 25.3 t SOC ha −1 with 8 t ha −1 of straw added and 104.9 t C ha −1 with 16 t ha −1 of straw added.…”

Sustainable soil management and climate change mitigation

“…Conservation agriculture practices, such as zero tillage and residue retention, could potentially improve carbon sequestration in surficial soil (Dey et al., 2020). A 36‐year long‐term study found that no tillage resulted in 1.5 t C ha −1 of soil organic matter in comparison with conventional tillage (Govindasamy et al., 2021). Recent studies showed that microbial residue represents an important source of stable SOC (Kallenbach et al., 2016).…”