Tillage-induced effects on SOC through changes in aggregate stability and soil pore structure

In organic farming, intensive tillage for weed control can degrade soil structure and reduce organic carbon and water retention. Organic no‐tillage with surface mulch offers a potential solution, but its long‐term effectiveness in Andosol soil remains poorly understood. This study evaluated the long‐term effects of organic no‐tillage practices combined with organic mulch on soil organic carbon (SOC) content and storage, water‐stable aggregate distribution (WSAD%), aggregate‐associated carbon, carbon stabilisation within aggregates, bulk density (BD), mean weight diameter (MWD), and soil water retention. The field experiment was conducted using a randomised complete block design with four replications, comparing two treatments: no‐tillage (NT) and conventional tillage (CT), both supplemented with organic mulch. Compared with CT, NT treatment yielded a 65.4% increase in SOC content and a 16.9% decrease in bulk density in the 0–5 cm surface layer, triggering a 16.3% improvement in SOC accumulation in the 0–20 cm soil depth. Furthermore, WSAD and MWD increased at the 0–5 cm, 5–10 cm, and 10–15 cm soil depths. Compared with CT, at all depths, aggregates exceeding 4 mm showed high SOC content and increased SOC stock within macroaggregates in NT, with field capacity and total plant available water (PAW) content also increasing. This study emphasises the critical role of SOC in enhancing PAW directly and the mean weight diameter in indirectly improving it by regulating field capacity. Overall, in organic farming, NT with residue retention markedly facilitates the overall improvement of SOC, soil structure stability, SOC stabilisation within macroaggregates, and soil water retention.

Conservation tillage methods, including straw return (SR) and no tillage (NT), are widely used to improve the soil organic carbon (SOC) content and crop yield. However, applying SR or NT separately has become a common practice for farmers producing different crops or those in different regions. Evaluating the effects of SR or NT on the SOC content, carbon emissions, and crop yield are important for guiding the correct application of conservation tillage and promoting sustainable agricultural development. Therefore, we conducted a meta-analysis based on 1014 sets of data obtained in China to assess the effects of SR and NT on the SOC content, carbon emissions, and crop yield. Compared with no straw return, SR increased the SOC content and crop yield by 10% and 8.6%, respectively, but with no significant impact on carbon emissions. Compared with conventional tillage, NT increased the SOC content by 2.9% and reduced the carbon emissions and crop yield by 18% and 3.9%, respectively. We also found that SR combined with NT had an additive effect, where the combination improved SOC more than applying SR or NT alone. If applying SR or NT alone, the specific climatic conditions, soil characteristics, and field management strategies need to be considered to maximize SOC. In particular, SR should be used in limited hydrothermal conditions (low temperature or low precipitation) and areas where rice–wheat rotation is implemented. NT can be used under any climate conditions, but it can effectively increase the SOC content in continuous wheat cropping areas.

Microbial regulation of aggregate stability and carbon sequestration under long-term conservation tillage and nitrogen application

Changes in soil organic carbon and aggregate stability after conversion to conservation tillage for seven years in the Huang-Huai-Hai Plain of China

Tillage and drainage impact on soil quality: II. Tensile strength of aggregates, moisture retention and water infiltration

To investigate how reclamation of wetlands in three different soil types impacts the vertical distribution of soil organic carbon (SOC) content in soil profiles, contents and density of soil organic carbon (SOC) in soil profiles of three types of wetland soils in wetland, soybean and paddy field in Sanjiang Plain were determined. Both soybean and paddy field were reclaimed from wetland. We observed that reclamation significantly reduced SOC content in 0-10,10-20 and 20-30 cm soil layers in meadow albic soil and meadow marsh soil, and 0-10,10-20,20-30 and 30-40 cm soil layers in peat bog soil, there were no significant difference in SOC contents in soil layers under 0-30 or 0-40 cm before and after reclamation. After reclamation, SOC density in three types of wetland soils decreased, and SOC density in soybean field were higher than that in paddy field. Either in wetlands or farm lands in the three types of wetland soils, most of the SOC storage in 0-100 cm soil layer was stored in 0-50 cm soil layer. Though wetland reclamation reduced the SOC content, it hasn’t changed the regularity of SOC vertical distribution. The relationships between SOC content and soil depth in wetlands and farm lands all could be described by exponential functions in three types of soils. The specific functions are useful to estimate and predict the regional SOC pool by models.

Carbon sequestration potential and its main drivers in soils under alfalfa (Medicago sativa L.)

Physical and chemical properties of soils under some piñon-juniper-oak canopies in a semi-arid ecosystem in New Mexico

Distribution characteristics and controls of soil organic carbon at different spatial scales in China′s Loess Plateau

Residue management induced changes in soil organic carbon and total nitrogen under different tillage practices in the North China Plain

Long-term saline water irrigation decreased soil organic carbon and inorganic carbon contents

A 10-year field experiment was conducted to determine the effect of no-tillage (NT) on soil organic carbon (SOC) and nitrogen (N) in an irrigated rice-based cropping system. The results showed that concentrations of SOC, soil total N (STN), and soil organic N (SON) were higher at 0–5 cm depth but lower at 5–10 cm depth under NT than conventional tillage (CT), while at 10–20 cm depth the differences were not significant. Consequently, stocks of SOC, STN, and SON under NT were higher at 0–5 cm depth but lower at 5–10 cm depth than those under CT. However, no significant differences were observed in stocks of SOC, STN, and SON at 0–20 cm depth between NT and CT, indicating that the lower st ocks of SOC, STN, and SON at 5–10 cm depth could offset the greater stocks of them at 0–5 cm depth under NT. In addition, there were no significant differences in soil inorganic N concentration and soil C:N ratio between NT and CT at all the three depths. Our study suggests that (1) NT farming does not necessarily store SOC and N more than CT soils for the upper soil layer and (2) converting from CT to NT farming may not cause a significant change in soil N mineralization in the irrigated rice-based cropping systems.

Soil aggregate-associated carbon and organic carbon pools as affected by conversion of forest lands to agriculture in an acid soil of India

Changes in soil organic carbon and total nitrogen in apple orchards in different climate regions on the Loess Plateau

Conservation tillage has been adopted worldwide as an attractive alternative to conventional tillage. However, suitable conservation tillage for increasing soil organic carbon (SOC) and crop yield simultaneously is still limited. Two conservation tillage methods, subsoiling to the 40 cm depth (ST) and no-tillage (NT), were combined with three straw return treatments (i.e., no return [−0], return of whole wheat (<i>Triticum aestivum</i> L.) straw and 1 m high maize (<i>Zea mays</i> L.) stubble [−1], and return of whole wheat and maize straw [-a]) to study their impacts on SOC content, labile C fractions, and crop yields, with conventional tillage (CT) used as a control in a 15-year field experiment. Subsoiling with 1 m high maize stubble return (ST–1) increased the mean annual grain yields by 18% and the mean SOC content by 39% at the 0 to 100 cm depth compared with conventional tillage with no maize straw return (CT–0) in 2016 and 2017. The mean SOC at the 0 to 100 cm depth of the NT treatment was lower than those of ST and CT because of the reduced transformation from straw to SOC and labile C fractions. One meter high maize stubble return can maintain high SOC content, C fractions, and crop yield compared with whole maize straw return. Thus, subsoiling combined with 1 m high maize stubble return was an effective conservation tillage to increase the SOC content and crop yield.