Land management effects on wet aggregate stability and carbon content

Abstract

Land management affects soil structure and many other soil properties and processes. Our objectives were to evaluate soil organic C (SOC), aggregate size distribution, aggregate‐associated C, and soil structure as affected by long‐term land management and slope. A chronosequence of 38 on‐farm sites with low to high (5–18%) slopes was selected to evaluate 5–40 yr of management. The sites were classified as business as usual (BAU) cropland (BAU‐Crop), BAU pasture (BAU‐Past), newly established conservation reserve program (CRP) areas (CRP‐New), and established CRP (CRP‐Old). Soil samples were collected from the 0‐to‐5‐ and 5‐to‐15‐cm depth increments and processed for soil property measurements including fractionation by wet sieving into five aggregate size classes (>2,000, 1,000–2,000, 500–1,000, 250–500, and 53–250 μm). Within the surface 5 cm, mean weight diameter (MWD) and geometric mean diameter (GMD) were used to characterize soil structural stability. The BAU‐Past and CRP‐Old sites had 79% more macroaggregates (>2,000, 1,000–2,000, and 500–1,000 μm), 123% higher MWD, 38% higher GMD, and 47% higher SOC than BAU‐Crop or CRP‐New sites. The 5‐to‐15‐cm depth increment showed a similar but lower magnitude response. Aggregate‐associated C was quantified using a constant soil mass that reflected aggregate size distribution to prevent overestimating C content. Lower‐slope locations had more SOC, more macroaggregates, more C associated with macroaggregates, and higher GMD and MWD compared with high‐slope locations across all management classifications and soil depths. The results support our hypothesis that the high‐slop soils may benefits from specific management decisions than the lower‐sloping soils as a function of landscape property. We recommend reestablishing grassland on sloping land that is susceptible to excessive soil erosion, although those practices will likely take a long time to restore soil structural stability and SOC content to precultivation levels.

No-Tillage Does Not Always Stop the Soil Degradation in Relation to Aggregation and Soil Carbon Storage in Mediterranean Olive Orchards

“…This CPC aggregate sizes order differs under CT1 and NT+H where microagreggates fraction stored the most SOC (4.5 and 4.4 g kg −1 ), followed by small macroaggregates (3.5 and 2.0 g kg −1 ), silt+clay fraction (2.2 and 1.5 g kg −1 ) and large macroaggregates (0.31 and 0.62 g kg −1 ), respectively. Therefore, in this management, the C sequestration effect of microaggregates was stronger than that of macroaggregates in line with other studies [76,77]. The predominance of SOC in the microaggregates in CT1 and NT+H showed that, under these management strategies, the aggregates-associated SOC had less physical protection, lost macroaggregate integrity and reduced soil binding agents.…”

Winter wheat grain yield stability under different tillage practices

“…Lack of yield differences among tillage practices should not be used as a sole basis for choosing a particular type of tillage because there may be other benefits accrued from adopting other tillage practices. For example, studies conducted at the same site found soil organic carbon and aggregate stability to be more substantial in NT plots than in MP plots (Blanco‐Canqui, Mikha et al., 2009) which could be beneficial to enhance soil structural stability and maintain land sustainability (Mikha et al., 2021).…”

"3S" Technology in Land Resource Management

“…Land survey requires on-site investigation and sampling, collecting data on land attributes, soil samples, etc. [13][14]. Public data sources can utilize public data provided by government agencies, research institutions, or other organizations, such as geographic data, land use data, climate data, etc.…”