Temporal changes in soil organic carbon and aggregate-associated organic carbon after reclamation of abandoned, salinized farmland

Abstract

SUMMARYA field experiment was conducted to quantify changes in soil aggregation and aggregate-associated soil organic carbon (SOC) concentration 1, 3, 5 and 10 years after abandoned, salinized land in the Manasi River Basin was reclaimed for cotton (Gossypium hirsutum L.). Results showed that reclamation significantly increased SOC concentrations and SOC stocks. Specifically, 10 years of cotton production increased SOC concentrations by 45% in the 0–60 cm depth and SOC stocks by 35%. The SOC concentrations and stocks decreased as soil depth increased. Reclamation time, season and soil depth had significant interaction effects on SOC. The SOC concentrations were significantly and positively correlated with available soil nitrogen and available soil phosphorus. Compared with abandoned farmland, macro-aggregate-associated (>250 µm) SOC concentrations in the 0–60 cm depth increased by 47% after 5 years of cotton production and by 53% after 10 years of cotton production. The contribution of macro-aggregate-associated SOC to total SOC in the 0–60 cm depth increased by 87% after 5 years of cotton production and by 69% after 10 years of cotton production. The findings indicate that soil aggregates were more stable after abandoned, salinized farmland was reclaimed for cotton production. Furthermore, cotton production can increase SOC concentrations and sequester C in this arid area.

Effects of reclamation years on composition and diversity of soil bacterial communities in Northwest China

“…Significantly lower soil EC was observed in the 5-, 10-, and 15-year fields than in the abandoned field. This is consistent with our previous study, which showed that soil EC declined as time since reclamation increased (Zhang et al 2017). The SOC concentrations in the 5-, 10-, and 15-year fields were significantly greater than those in the abandoned field (p < 0.05).…”

Impact of Abandoned Salinized Farmland Reclamation on Distribution of Inorganic Phosphorus in Soil Aggregates in Northwest China

“…We observed that the CL treatment result in > 2-mm aggregates than that in other treatments (Table 1), indicating that the vegetation reclamation of salinized farmland effectively increases soil aggregation. This result corroborated the conclusions of related previous study (An et al 2013;Zhang et al 2017). Crops can affect soil aggregates as crop residues are important physical binding agents for the formation of macroaggregates (Six et al 2004).…”

“…These two values have significant statistical differences between soil samples from CK and other reclamation treatments (P < 0.05). Compared with reclaimed treatments, vegetation on the CK is sparse, resulting in a lower amount of organic matter input into the soil (Zhang et al 2017). In addition, soil salinization is serious and soil structure is deteriorated in CK, resulting in the collapse of macroaggregates, thus decreasing stability of soil aggregates.…”

Inorganic Phosphorus Distribution in Soil Aggregates Under Different Cropping Patterns in Northwest China

“…Our results showed that macroaggregates (> Ca2-P Ca8-P Al-P Fe-P O-P Ca10-P Soil inorganic P content of fractions (mg kg 0.25 mm) accounted for more than 89% of the total soil mass in all three cropping patterns ( Table 2), suggesting that all three cropping patterns might increase the stability of aggregates and reduce the risk of surface erosion in the study area. Several studies have focused on changes in soil P associated with agricultural development, land use, soil type, and organic fertilizer use (Zhang et al 2017;Sims et al 2000;Bai et al 2013). Zhang et al (2003) observed that available P concentrations were greatest in the 0.5-0.25 and 0.25-0.125 mm aggregates in sandy soil.…”